DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

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Superfund Rcconto Center SITE 5\fo ITE: DRAFT ' o SDMS DocID 000201276 Gamma Walkover and Civil Survey Report Shpack Landfill Superfund Site Norton/Attleboro, Massachusetts Contract No. DACW3399C0023 Preparedfor. U.S. Army Corps of Engineers New England District Prepared by: Cabrera Services, Inc. 809 Main Street East Hartford, CT 06108 July 13,2000 t CABRERA SERVICES, live. 809 Main Street East Hartford, CT 06108 Phone: (860) 289-1885 • Fax (860) 289-2261 www.cabreraservices.com

Transcript of DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

Page 1: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

Superfund Rcconto Center SITE 5foITE

DRAFT o

SDMS DocID 000201276

Gamma Walkover and Civil Survey Report

Shpack Landfill Superfund Site NortonAttleboro Massachusetts

Contract No DACW3399C0023

Preparedfor

US Army Corps of Engineers New England District

Prepared by

Cabrera Services Inc 809 Main Street

East Hartford CT 06108

July 132000

t CABRERA SERVICES live

809 Main Street bull East Hartford CT 06108 bull Phone (860) 289-1885 bull Fax (860) 289-2261 bull wwwcabreraservicescom

DRAFT

Gamma Walkover and Civil Survey Report

Shpack Landfill Superfund Site NortonAttleboro Massachusetts

Contract No DACW3399C0023

Prepared for

US Army Corps of Engineers New England District

Prepared by

Cabrera Services Inc 809 Main Street

East Hartford CT 06108

July 132000

This page intentionally left blank

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

TABLE OF CONTENTS

TABLE OF CONTENTS i

10 INTRODUCTION 1

11 SITE DESCRIPTION AND HISTORY 1

20 FIELD ACTIVITIES AND METHODOLOGY 3

21 OBJECTIVES 3 22 SCOPE OF WORK 3 23 HEALTH AND SAFETY 4

231 Radiological Safety 4 232 Industrial Safety 5

24 MOBILIZATION AND SITE PREPARATION 6 241 Site Mobilization 6 242 Site Clearing 7 243 Civil Survey 8 244 Repair of Perimeter Fence 8 245 Site Radiological Posting 9

25 GAMMA WALKOVER SURVEY 9 257 Instrumentation 9 252 Background Measurements and Quality Assurance 10

(A) Background Measurements 10 (B) Daily Instrument Quality Control 10

253 Survey Performance 10 (A) Data File Naming 10 (B) Survey Lines I I

26 ISOCS MODELING 12

30 SURVEY RESULTS 15

31 DATA HANDLING AND QUALITY ASSURANCE 15 32 GWS SURVEY RESULTS 16 33 ISOCS SURVEY RESULTS 16

331 Uranium Results 16 332 Radium-226 Results 20 333 Thorium-232 Results 21

34 CORRELATION OF PORT ABLE INSTRUMENT RESPONSE TO ISOCS DATA 22

40 CURRENT SITE STATUS 33

50 CONCLUSIONS 35

60 REFERENCES 36

Appendix A Civil Survey Map

Appendix B Instrument Control Charts

Appendix C Gamma Survey Result Contour Plots

Appendix D ISOCS Locations and FIDLER Gamma Contour Plot

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List of Tables

TABLE 1 SHPACK LANDFILL SUPERFUND SITE ISOCS RESULTS 25

TABLE 2 LOCATIONS SELECTED FOR INSTRUMENT RESPONSE EVALUATION 32

List of Figures

FIGURE 3 INSTRUMENT RESPONSE VS RADIUM CONCENTRATION 29

FIGURE 4 INSTRUMENT RESPONSE VS DU CONCENTRATION 30

FIGURE 5 INSTRUMENT RESPONSE VS EU CONCENTRATION 31

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10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

99023-1 CABRERA SERVICES INC Page 37 of 38

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 2: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

DRAFT

Gamma Walkover and Civil Survey Report

Shpack Landfill Superfund Site NortonAttleboro Massachusetts

Contract No DACW3399C0023

Prepared for

US Army Corps of Engineers New England District

Prepared by

Cabrera Services Inc 809 Main Street

East Hartford CT 06108

July 132000

This page intentionally left blank

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

TABLE OF CONTENTS

TABLE OF CONTENTS i

10 INTRODUCTION 1

11 SITE DESCRIPTION AND HISTORY 1

20 FIELD ACTIVITIES AND METHODOLOGY 3

21 OBJECTIVES 3 22 SCOPE OF WORK 3 23 HEALTH AND SAFETY 4

231 Radiological Safety 4 232 Industrial Safety 5

24 MOBILIZATION AND SITE PREPARATION 6 241 Site Mobilization 6 242 Site Clearing 7 243 Civil Survey 8 244 Repair of Perimeter Fence 8 245 Site Radiological Posting 9

25 GAMMA WALKOVER SURVEY 9 257 Instrumentation 9 252 Background Measurements and Quality Assurance 10

(A) Background Measurements 10 (B) Daily Instrument Quality Control 10

253 Survey Performance 10 (A) Data File Naming 10 (B) Survey Lines I I

26 ISOCS MODELING 12

30 SURVEY RESULTS 15

31 DATA HANDLING AND QUALITY ASSURANCE 15 32 GWS SURVEY RESULTS 16 33 ISOCS SURVEY RESULTS 16

331 Uranium Results 16 332 Radium-226 Results 20 333 Thorium-232 Results 21

34 CORRELATION OF PORT ABLE INSTRUMENT RESPONSE TO ISOCS DATA 22

40 CURRENT SITE STATUS 33

50 CONCLUSIONS 35

60 REFERENCES 36

Appendix A Civil Survey Map

Appendix B Instrument Control Charts

Appendix C Gamma Survey Result Contour Plots

Appendix D ISOCS Locations and FIDLER Gamma Contour Plot

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

List of Tables

TABLE 1 SHPACK LANDFILL SUPERFUND SITE ISOCS RESULTS 25

TABLE 2 LOCATIONS SELECTED FOR INSTRUMENT RESPONSE EVALUATION 32

List of Figures

FIGURE 3 INSTRUMENT RESPONSE VS RADIUM CONCENTRATION 29

FIGURE 4 INSTRUMENT RESPONSE VS DU CONCENTRATION 30

FIGURE 5 INSTRUMENT RESPONSE VS EU CONCENTRATION 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

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DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

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Contour Plots

TARGET SHEET

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(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

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TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

TABLE OF CONTENTS

TABLE OF CONTENTS i

10 INTRODUCTION 1

11 SITE DESCRIPTION AND HISTORY 1

20 FIELD ACTIVITIES AND METHODOLOGY 3

21 OBJECTIVES 3 22 SCOPE OF WORK 3 23 HEALTH AND SAFETY 4

231 Radiological Safety 4 232 Industrial Safety 5

24 MOBILIZATION AND SITE PREPARATION 6 241 Site Mobilization 6 242 Site Clearing 7 243 Civil Survey 8 244 Repair of Perimeter Fence 8 245 Site Radiological Posting 9

25 GAMMA WALKOVER SURVEY 9 257 Instrumentation 9 252 Background Measurements and Quality Assurance 10

(A) Background Measurements 10 (B) Daily Instrument Quality Control 10

253 Survey Performance 10 (A) Data File Naming 10 (B) Survey Lines I I

26 ISOCS MODELING 12

30 SURVEY RESULTS 15

31 DATA HANDLING AND QUALITY ASSURANCE 15 32 GWS SURVEY RESULTS 16 33 ISOCS SURVEY RESULTS 16

331 Uranium Results 16 332 Radium-226 Results 20 333 Thorium-232 Results 21

34 CORRELATION OF PORT ABLE INSTRUMENT RESPONSE TO ISOCS DATA 22

40 CURRENT SITE STATUS 33

50 CONCLUSIONS 35

60 REFERENCES 36

Appendix A Civil Survey Map

Appendix B Instrument Control Charts

Appendix C Gamma Survey Result Contour Plots

Appendix D ISOCS Locations and FIDLER Gamma Contour Plot

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List of Tables

TABLE 1 SHPACK LANDFILL SUPERFUND SITE ISOCS RESULTS 25

TABLE 2 LOCATIONS SELECTED FOR INSTRUMENT RESPONSE EVALUATION 32

List of Figures

FIGURE 3 INSTRUMENT RESPONSE VS RADIUM CONCENTRATION 29

FIGURE 4 INSTRUMENT RESPONSE VS DU CONCENTRATION 30

FIGURE 5 INSTRUMENT RESPONSE VS EU CONCENTRATION 31

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10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

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TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

TABLE OF CONTENTS

TABLE OF CONTENTS i

10 INTRODUCTION 1

11 SITE DESCRIPTION AND HISTORY 1

20 FIELD ACTIVITIES AND METHODOLOGY 3

21 OBJECTIVES 3 22 SCOPE OF WORK 3 23 HEALTH AND SAFETY 4

231 Radiological Safety 4 232 Industrial Safety 5

24 MOBILIZATION AND SITE PREPARATION 6 241 Site Mobilization 6 242 Site Clearing 7 243 Civil Survey 8 244 Repair of Perimeter Fence 8 245 Site Radiological Posting 9

25 GAMMA WALKOVER SURVEY 9 257 Instrumentation 9 252 Background Measurements and Quality Assurance 10

(A) Background Measurements 10 (B) Daily Instrument Quality Control 10

253 Survey Performance 10 (A) Data File Naming 10 (B) Survey Lines I I

26 ISOCS MODELING 12

30 SURVEY RESULTS 15

31 DATA HANDLING AND QUALITY ASSURANCE 15 32 GWS SURVEY RESULTS 16 33 ISOCS SURVEY RESULTS 16

331 Uranium Results 16 332 Radium-226 Results 20 333 Thorium-232 Results 21

34 CORRELATION OF PORT ABLE INSTRUMENT RESPONSE TO ISOCS DATA 22

40 CURRENT SITE STATUS 33

50 CONCLUSIONS 35

60 REFERENCES 36

Appendix A Civil Survey Map

Appendix B Instrument Control Charts

Appendix C Gamma Survey Result Contour Plots

Appendix D ISOCS Locations and FIDLER Gamma Contour Plot

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List of Tables

TABLE 1 SHPACK LANDFILL SUPERFUND SITE ISOCS RESULTS 25

TABLE 2 LOCATIONS SELECTED FOR INSTRUMENT RESPONSE EVALUATION 32

List of Figures

FIGURE 3 INSTRUMENT RESPONSE VS RADIUM CONCENTRATION 29

FIGURE 4 INSTRUMENT RESPONSE VS DU CONCENTRATION 30

FIGURE 5 INSTRUMENT RESPONSE VS EU CONCENTRATION 31

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10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 5: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

List of Tables

TABLE 1 SHPACK LANDFILL SUPERFUND SITE ISOCS RESULTS 25

TABLE 2 LOCATIONS SELECTED FOR INSTRUMENT RESPONSE EVALUATION 32

List of Figures

FIGURE 3 INSTRUMENT RESPONSE VS RADIUM CONCENTRATION 29

FIGURE 4 INSTRUMENT RESPONSE VS DU CONCENTRATION 30

FIGURE 5 INSTRUMENT RESPONSE VS EU CONCENTRATION 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 6: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

10 INTRODUCTION

Cabrera Services Inc (CABRERA) completed field activities on May 31 2000 on a project to characterize radiological surface contamination at the Shpack Landfill Superfund Site (the Site) The work was carried out on behalf of US Army Corps of Engineers (USAGE) New England District (NED) under Contract Number DACW33-99-C-0023 The Site located in Norton and Attleboro MA is being characterized and remediated under the Formerly Utilized Sites Remedial Action Program (FUSRAP)

During an earlier project phase CABRERA prepared the work plans under which the field effort was carried out These plans include the Gamma Walkover and Civil Survey Work Plan (Work Plan) (CABRERA 1999a) the Site Specific Health and Safety Plan (SSHP) (CABRERA 1999b) and the Quality Assurance Project Plan (QAPP) (CABRERA 1999c) In addition CABRERA prepared a Records SearchSite Walkover Report (CABRERA 1999d) summarizing results of historical site research and documenting physical conditions observed during a site inspection as well as a technical memorandum (CABRERA 1999e) describing radiation detection technology applicable to the Site and providing cost estimates for applying that technology to the project The recently completed field work provides information to aid in determining the accuracy of assumptions regarding the existing site conceptual model and will be used to support planning for a full three-dimensional site characterization field effort currently being designed

This report summarizes the activities measurements and results of fieldwork under the CABRERA contract Site preparations civil survey activities gamma walkover surveys (GWS) and radionuclide-specific gamma spectroscopic measurements are discussed in detail It should be noted that while the Site contains both radiological and chemical contamination activities discussed in this report are limited to tasks designed to address only radiological contaminants being remediated under FUSRAP Chemical safety issues are discussed only as they apply to tasks targeted at radiological contamination

11 Site Description and History

The Shpack Landfill Superfund site is an 8-acre abandoned domestic and industrial landfill that operated from 1946 to 1965 when a court order forced its closing It is located along the NortonAttleboro MA town boundary line The landfill consists of land formerly owned by Lea and Isadore Shpack now owned by the town of Norton and land formerly owned by Albert Dumont now owned by Attleboro Landfill Inc (ALI) Approximately 5-12 acres is on the Norton side of the town line and 2-12 acres is on the Attleboro side

Approximately 40000 people live within a 3-mile radius of the site Municipal water supplies for both townships do not extend to the area around the site Therefore residents in this area use private drinking water wells most of which withdraw water from the bedrock aquifer The distance from Shpack Landfill to the nearest residential well is about 150 feet There are 27 private wells within 1 mile of the site that serve 103 people The two municipal water supply well fields for Norton are situated in the shallow aquifer and are located 3 miles east and 514 miles northeast of the area Municipal well fields for Attleboro also are

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 7: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

installed in the shallow aquifer and are located approximately 12000 feet and 24000 feet west of the Site The Shpack Landfill directly borders the currently operating 50-acre Attleboro Landfill

The US Atomic Energy Commission (AEC) established the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 1974 under authority granted by the Atomic Energy Act of 1954 as amended FUSRAP currently encompasses 21 remaining sites in 8 states The Shpack Landfill was designated for remedial action under FUSRAP in 1981

On June 10 1986 the Site was listed on the National Priorities List (NPL) and the EPA signed an Administrative Order by Consent in September 1990 with a group of settling parties for the performance of a remedial investigation and feasibility study (RIFS) The initial phase of the RI has been completed

At the time of this project the Site contained two bodies of standing water that persisted throughout the fieldwork Other site areas contained standing water that varied in depth proportional to the amount of precipitation received New England Electric Service (NEES) maintains a series of high-voltage electricity transmission lines that traverse the site in a northeast to southwest direction Four discreet sets of lines exist three of which are 115kV lines and a fourth that carries 345 kV At project commencement the site was heavily vegetated making some areas impassable

99023-1 CABRERA SERVICES INC Page 2 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

99023-1 CABRERA SERVICES INC Page 4 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

99023-1 CABRERA SERVICES INC Page 5 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 8: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

20 FIELD ACTIVITIES AND METHODOLOGY

21 Objectives

The gamma walkover and civil surveys at the Shpack site was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities Previous site investigation results lead to a radiological site conceptual model that includes uranium of various enrichments and radium deposited in relatively small discrete locations around the site This model does not include widespread soil contamination The overall goal of the GWS project was to validate or invalidate that model for near surface radionuclides

22 Scope of Work

This field effort was carried out within a well-defined scope of work (SOW) SOW included the following

bull Mobilization This task included delineating zones to control site ingress and egress setting up site offices locating radiological control points and gaining positive control over site access

bull Site Preparation This task comprised cutting site vegetation to a height that allowed the radiation survey to proceed collecting and chipping brush cuttings and generally ensuring that all site areas were made as accessible as practically achievable

bull Site Posting and Fence Repair This task included designing procuring and placing appropriate site-specific radiological warning signs and effecting repairs on damaged sections of the site perimeter fence

bull Civil Survey This task included retaining a subcontracted licensed civil survey firm to verify and update the existing site horizontal survey map As part of this task the civil survey firm laid out a ten-meter square grid pattern to facilitate GWS activities

bull Gamma Walkover Survey This task included performing a 100 coverage gross gamma walkover survey of accessible site areas The survey was performed using two different gross gamma detectors (see Section 25) and using Global Positioning System (GPS) receivers and data loggers to establish radiation measurement locations to within one-meter accuracy

bull High Purity Germanium (HPGe) Detector Survey This task included performing radionuclide-specific in situ gamma spectroscopic measurements These measurements performed with an In Situ Object Counting System (ISOCS) were to be designed to provide both quantitative and qualitative information regarding site near surface source

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

term detection sensitivity of gross gamma survey instruments and isotope-specific distribution of radiological contaminants

bull Other Additional tasks were included in the SOW related to data quality assurance (QA) providing technical support to the USAGE on radiological issues attending public meetings and providing training appropriate radiological and industrial safety training to project personnel

23 Health and Safety

Activities performed by CABRERA employees and its subcontractors were performed in accordance with the SSHP and Work Plan Radiological and industrial safety practices at the Site are further described in the following sections

231 Radiological Safety

Radiological health and safety practices at the Site conformed to the SSHP and Work Plan Specific requirements and practices included the following

bull Anyone entering the site signed in and out of the site log noting time of site arrival and departure Unescorted access to the Site required training per the provisions of the SSHP and Work Plan All personnel entering the site were required to have completed OSHA 40-hour training Personnel sign-in sheets and records of OSHA training are filed in the project file at CABRERAS East Hartford CT offices

bull Personnel entering the Exclusion Zone wore seventeen-inch tall thick rubber slush boots Boots were inspected daily and replaced when excess wear was noticed For work in which hand contact with site soils or other materials was anticipated work gloves were required Upon exiting the Exclusion Zone workers performed radiological scans on potential contact areas of the body prior to proceeding Equipment andor materials exiting the site were surveyed for contamination prior to removal from the Exclusion Zone

bull To avoid personnel contamination land clearing workers wore anti-contamination clothing consisting of Tyvek oversuits and protective glasses or full-face shields while working

bull Beginning at the project commencement a radiological engineer surveyed site areas using a microrem dose meter prior to entry into each area by any other workers Survey results indicated no areas which according to applicable requirements (USAGE 1997a) (USAGE 1997b) would require occupational radiological exposure monitoring

bull Support Zone areas inside the fence line were surveyed daily for radiological contamination Surveys included both routine and random locations Areas surveyed routinely include the portable toilet the office trailer the site entrance area and radiological counting equipment

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

232 Industrial Safety

Industrial health and safety practices at the Site were carried out in conformance to the SSHP and Work Plan Specific industrial health and safety requirements and practices included the following

bull Entry to the exclusion zone required safety shoes at all times

bull At a minimum two individuals with current first aidCPR training were required to be on-site while work was in progress Additionally at least one individual with OSHA Supervisor training was required to be present during work at the site

bull Due to the presence of mechanized machinery the possibility of falling tree limbs and related physical hazards the land clearing workers wore hardhats and safety glasses These individuals also wore hearing protection when using machinery

bull Daily safety meetings were held each morning chaired by the senior CABRERA representative present All personnel present signed in and topics discussed were documented Personnel had the opportunity to ask questions raise safety concerns and discuss work plans for the coming day Meeting documentation was retained and is stored in the project file at CABRERAS East Hartford CT offices

bull The high voltage lines traversing the Site presented a series of potential safety problems starting from project inception The issues included

o Induced Voltage in the site office trailer Personnel received minor electrical shocks inside the trailer and at the trailer entrance A licensed electrician traced this problem to an approximately 30 V potential difference between the trailer and the soil on which it was placed This voltage was present even with the trailers electric service disconnected The electrician grounded the trailer to the metal stairs in front of the trailer using a heavy wire which resolved this issue

o Field safety under the 345 kV lines As seasonal temperatures increased increasing sag was observed in these lines which are located closest to ALL Personnel performing ISOCS measurements and support in this area experienced electric shocks from metal tape measures laptop computer screens and ISOCS equipment Upon observance of these problems and following consultation with the CABRERA Health and Safety Officer entry to this area was prohibited

gt Note that the following provisions of Occupational Safety and Health Administration (OSHA) regulations (29 CFR 1910333(C)(3)(i)(A)(2)) apply to all site work For voltages to ground over 50kV - 10 feet (305cm) plus 4 inches (10 cm) for every 10 kV over 50 kV (OSHA 1994) For a 115kV line the required separation distance is 122 feet For a 345kV line the required separation distance is 198 feet The 345kV lines were observed to be approximately 20-25 feet above the ground at certain areas in May 2000 These separation distances were enforced during all site operations

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Chemical Hazard Evaluation The CABRERA Health and Safety Officer who conducted a survey of site ground surfaces using a Photo lonization Detector (PID) addressed potential chemical exposure concerns No chemical presence was observed at levels greater than background The CABRERA Health and Safety Officer remained on call for the project duration to address additional chemical safety issues

bull Physical hazards from submerged andor buried metal objects As work progressed it became apparent that in areas of the site in which standing water combined with phragmite growth hidden physical hazards existed Two areas in particular exhibited the highest degree of hazard the phragmite stand in the approximate center of the Site and the pond located along the eastern site boundary In these areas buried and partially buried metallic debris exists hidden from sight Additionally numerous drums are buried slightly below the land surface As workers attempted to traverse these areas encounters with the submerged debris caused cuts in protective boots while buried drums routinely collapsed under workers weight causing risks from falls and jagged metal drum edges As a result of these conditions and following consultation with the CABRERA Health and Safety Officer restrictions were placed on work in site areas with water deeper than six inches Site personnel were urged to use extreme caution and to exercise conservative judgement in deciding which site areas to enter This topic was discussed numerous times at daily safety briefings No personnel injuries occurred as a result of these conditions

24 Mobilization and Site Preparation

24 1 Site Mobilization

Upon initial site arrival CABRERAS staff evaluated site conditions with emphasis on potential health and safety hazards locations for placement of Site trailer and toilet facilities and radiological control issues such as delineations for Support Contamination Reduction and Exclusion Zones as well as necessary postings Following this evaluation and planning stage CABRERA proceeded with mobilization activities as discussed in the Work Plan

During the initial evaluation it was determined that the office trailer should be located immediately inside and just northeast of the Peckham Street gate (Figure 1) To prevent potential contamination of this support facility CABRERA personnel placed plastic tarpaulines over the ground surface prior to placing the trailer The temporary toilet facility was also placed over a plastic tarp immediately southwest of the trailer This area is declared a clean Support Zone (SZ) and was separated from the Contamination Reduction Zone (CRZ) and Exclusion Zone (EZ) using yellow and magenta ropes and postings to delineate the boundary accordingly The contamination reduction zone (CRZ) was designated as the area immediately adjacent to and east of the trailer placed between the EZ and SZ Open SZ areas inside the fence are covered with geotechnical filter fabric which allows water to pass through but resists passage by solids thereby reducing the potential of personnel and equipment contamination Figure 1 shows the site entrance area prior to placement of the geotechnical fabric

A copy of the NRC Form 3 along with various OSHA and other general postings were placed on the trailer walls as appropriate

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

99023-1 CABRERA SERVICES INC Page 37 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

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TARGET SHEET

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Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

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Phone and electric lines were installed in the trailer for purposes of communication and the operation of various project support equipment Radiological support equipment (eg smear counters computers personnel monitors etc) were set up and checked for proper operation

242 Site Clearing

The objective of clearing the Site was to remove vegetation to a height of 4 inches or less leaving non-vegetation obstacles and large trees (greater than approximately four inches in diameter) in place to allow the GWS to proceed The Site clearing was performed in accordance with the Work Plan Prior to project commencement CABRERAS Project Manager met with the Conservation Director for Norton and discussed the clearing operations During these discussions the

Figure 1 Site Entrance Area Configuration Conservation Director requested that when phragmite plants were cut they not be moved beyond the extent of areas

where they currently grow Phragmites are an invasive and persistent plant species As such the intent of the request was to limit the spread of phragmites that might be encouraged by transporting the cut plants to other site areas

CABRERA subcontractor Enviroscapes Inc (El) conducted the site clearing operation This task commenced on March 15 2000 and completed on March 31 2000 El used gasoline powered machinery to complete clearing operations and complied with both the SSHP and CABRERA field restrictions on refueling operations and fuel handling These restrictions required that all fuel handling be performed over a tarpauline on which absorbent material is placed to minimize the potential for soil contamination from spilled fuel

El conducted vegetation clearing using chain saws weed whackers and a Skidsteer with a bushwacker attachment In the days prior to clearing commencement a great deal of rain had fallen As a result the site land surface was saturated and standing water predominated over approximately the eastern one half of the site El encountered difficulties with the Skidsteer sinking into the land in numerous areas To remedy this El brought a tracked backhoe onto the site with the dual goals of gaining access to areas with soft ground surfaces and enabling clearance of areas with work access restrictions due to submerged debris (see description in Section 232) The backhoe was applied with limited success A combination of the soft ground surface and the proximity of the high voltage lines restricted its movements to the northeastern portion of the site The backhoe was removed from site on March 21 Land clearing continued with weed whackers and chainsaws until completed On March 31 2000 CABRERA and El performed an acceptance tour during which it was determined that as much of the site as practical had been cleared and subsequent project work could begin El demobilized and removed their equipment from site on March 31

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243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 13: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

243 Civil Survey

During previous site work undertaken by ERM New England Holden Engineering and Surveying Inc (Holden) of New Hampshire had prepared a site base map (Holden 1991) During CABRERAS fieldwork the civil survey task objective was to update that base map and ensure that Site features (eg fencelines wells etc) are correctly located on the map As part of this effort site benchmarks used to tie the 1991 survey to the Massachusetts Plane Coordinate System NAD 87 (MCP) were verified

Given their prior site knowledge and experience Holden was subcontracted to perform the civil survey work Holdens fieldwork commenced on April 3 2000 and completed on April 11 2000 During their site work the surveyors established a ten-meter by ten-meter reference coordinate grid system and marked each grid with a tall flagged wooden stake in order to establish horizontal control points in the study area The surveyors used existing granite benchmarks from previous survey tasks as a reference from which to establish the grids As much of the site was surveyed as practicable However due to health and safety considerations discussed in Section 23 at the discretion of the surveyors and the CABRERA Project Manager some site areas were not surveyed The survey map is included as Appendix A to this report The AutoCad file from which the map was generated is included on the data CDROM appended to this report with the file name survey mapdwg

244 Repair of Perimeter Fence

During a site inspection tour in the Fall of 1999 it was observed that the site perimeter fence is damaged in certain areas The damage includes approximately 100 feet of missing fence along the ALI border approximately 50 feet of missing fence near the southernmost fence corner and two small cuts in the fence fronting Union Street in Norton (See Survey Map in Appendix A) CABRERA originally intended to replace the ALI border fence in its entirety install new fence cloth in the 20-foot south end gap and repair the small holes in the frontage fence

During initial planning for this task it was assumed that fencing subcontractors would not require 40-hour HAZWOPER training because the fence being located on the site perimeter However upon review of past chemical characterization results including those from the Initial Site Characterization Report (ISCR) prepared by ERM-New England Inc (ERM 1993) it was determined that some of the highest chemical contamination concentrations were found along the ALIShpack boundary As such CABRERA in consultation with the USAGE Project Manager decided to require that fencing subcontractors be OSHA 40-hour qualified CABRERA located several subcontractor candidates for this task By mutual agreement between the USAGE Project Manager and CABRERA in order to avoid interference with radiological survey schedules it was decided to postpone fence repairs until late in the fieldwork By that time however due to increased sag the high voltage lines had become a safety issue and given the proximity of the two fence gaps to the 345 kV lines an alternate solution was sought As an interim measure a fencing subcontractor was hired to repair the Union Street frontage fence and CABRERA personnel installed temporary plastic safety fencing in the gaps As of this writing resolution of the electrical safety issues is still pending and permanent fence repairs are deferred until such resolution is reached

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

99023-1 CABRERA SERVICES INC Page 10 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

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(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

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(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

245 Site Radiological Posting

As discussed in the Work Plan CABRERA placed radiological warning signs at 50 foot intervals along the site perimeter fenceline Wording on the signs is specific to the Shpack site and was approved by the USAGE Project Manager prior to sign placement The signs are bear standard yellow and magenta radiological warning colors measure 17 x 20 and read Caution Radioactive Material No Entry by Unauthorized Personnel Contact the US Army Corps of Engineers at (978) 318-8657 for More Information

25 Gamma Walkover Survey

The GWS was carried out to provide an indication of the areal extent of elevated radiological Contaminants of Concern (COCs) guide the selection of direct surface and possible future downhole measurement and sampling locations and provide data to determine radiological health and safety requirements for future field characterization activities The GWS was performed in accordance with the Work Plan and applicable radiological and industrial safety procedures as supplemented by additional field guidance developed and applied as the project progressed

251 Instrumentation

The GWS was performed using a Ludlum Model 44-10 two inch x two inch sodium iodide (Nal) detector (44-10) and a Bicron field instrument for detecting low-energy radiation (FIDLER) Each instrument was coupled to a Ludlum Model 2221 ratemeter The ratemeters were connected to the TSC-1 data logger of a Trimble Pro XR GPS receiver The ratemeters and GPS data logger were configured such that radiation count rate data was downloaded every two seconds to the datalogger The GPS unit also collected positioning data every second and stored this data in tandem with the count rate data The GPS unit associated gamma readings with spatial locations by interpolating between the locations immediately preceding and following its receipt of a gamma reading The GPS unit was operated such that positional accuracy was maintained to less than one meter

The FIDLER is fitted with a sensitive mylar window which was protected from the environment by placing the detector into a fitted piece of polystyrene Detector calibration performed prior to field operations was performed with this protective cover in place Through experimental observation it was determined that the cover had a negligible effect on detector response to the gamma energies of interest

Other survey support instrumentation included one Ludlum Model 3 ratemeter coupled to a Ludlum 43-5 alpha radiation detector two Ludlum Model 3 ratemeters coupled to 44-9 beta gamma radiation detectors a Ludlum 2224 ratemeter coupled to a 43-89 alphabeta radiation detector a Bicron microrem exposure meter and a Ludlum 2224-1 ratemeter coupled to a Ludlum 120 gas proportional alphabeta radiation detector

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252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 15: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

252 Background Measurements and Quality Assurance

(A) Background Measurements

Prior to performing gross gamma walkover surveys each day GWS survey instruments were used to obtain background readings in a designated reference area across Peckham Street from the Site It should be noted that daily background values were not subtracted from GWS data but were obtained for qualitative comparison of day to day background fluctuations During post-field data review the magnitude of daily background fluctuations could prove an important input to GWS data analysis Excessive daily background fluctuations might require adjustments to GWS data to remove backgrounds effect on the data Daily background measurements were also made and recorded for static and portable radiological support instruments

(B) Daily Instrument Quality Control

Radiological instruments were calibrated prior to mobilization and checked daily to ensure that each calibration was current (ie done within the past six months) Instrument QC was performed in accordance with the Work Plan and QAPP Prior to daily use instruments used to obtain radiological data were inspected for physical damage and checked to ensure that each had a current calibration Additionally project radiological instrumentation was subjected to daily source checks Per the Work Plan and QAPP in the cases of instruments used for the GWS sources used for these checks were National Institute of Standards and Technology (NIST) traceable Results of the source checks were recorded and compared to pre-established acceptance criteria In cases where instruments failed to meet the acceptance criteria the instruments in question were removed from service Instrument calibration records were kept on site for review and inspection

GPS point features were collected on a daily basis at the west corner post of the Site entrance gate This data was inspected to ensure that the positions obtained did not change substantially from day to day

Control charts were generated for both radiological survey instruments and GPS units These charts are included as Appendix B to this document

253 Survey Performance

The GWS was planned and executed such that 100 of practically accessible land surface was surveyed Since the GPS data loggers served a crucial role in collecting project data particular attention was paid to ensuring meaningful file naming conventions and data handling procedures were used Using a custom GPS data dictionary prepared for this task gamma surveys adhered to the following naming conventions

(A) Data File Naming

Gamma survey data files were named with a 7 or 8 digit conventions of the form xxxxyyzssf or xxxxyyzzssf where

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

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DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

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Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

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TARGET SHEET

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Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull xxxx represents the four digit date (eg a survey conducted on March 28 was named 0328yyzssf or 0328yyzzssf)

bull yy is a two digit code representing the detector used for the survey The codes used were 44 for a 44-10 2 x 2 Nal detector and fd for a FIDLER

bull z is a lowercase letter representing the sequential file designation for a given date (eg the second FIDLER survey file of March 28 was named 0328fdbssf)

bull zz is the code bk representing a background survey file (eg the daily background survey file for the 44-10 on March 28 was named 032844bkssf)

bull ssf is the default file extension for the Trimble Pro XR GPS unit with TSC1 data logger

(B) Survey Lines

To ensure that survey data collected in the data loggers was readily identifiable in the event of GPS signal loss or other positional malfunction each survey line walked was assigned a unique name As discussed in the Work Plan surveys were performed by walking successive one-meter wide paths To accomplish this and achieve 100 coverage surveyors adhered to the following protocol (Note that in the following discussion grid columns refers to the ten-meter wide north-south corridors between successive grid intersections The north-south path between adjacent grid stakes visually describes these corridors)

bull It was determined that surveys would proceed along one-meter wide north-south paths beginning at the western corner of the site and proceeding to the east

bull Each ten-meter wide grid column was subdivided into ten one-meter intervals by use of small stake flags

bull Each one-meter wide survey path was assigned a unique name in the form xxxxy where xxxx represents the northernmost grid number on the survey path and y represents sequential number of the path in that grid line beginning in western side of the grid path and proceed to the east For example the westernmost survey path beginning along grid column 1019 was designated 10190 while the easternmost path in the same grid column was designated 10199

bull At the beginning of each survey path the unique path name was entered into the data logger permanently associating that name with the survey path

bull Surveys were performed by walking successive linear passes along each survey path while moving the detector in a serpentine manner perpendicular to the travel path The detector was maintained as close to the land surface as practically achievable In most cases this kept the detector within approximately four inches of the ground except where obstacles made maintenance of the four-inch separation impossible

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bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 17: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull While walking the survey paths the surveyor listened to audible ratemeter clicks via headphones and visually observed ratemeter response and GPS signal reception status In the event of GPS signal loss the surveyor paused until signal was regained In cases of where ratemeter click rate increased the surveyor paused investigated the elevated area then continued on his survey path

bull In a small fraction of site areas (eg areas with dense trees) GPS reception was inadequate to ensure positional accuracy Surveyors recorded gamma levels manually in these cases In almost all site areas enough GPS readings were obtained to automatically located GWS data

bull Travel velocity was maintained at approximately 14 to 13 meter per second (ms) giving the detector a velocity over the land surface of approximately 05 ms

bull Survey data was downloaded several times daily to the site desktop computer and was backed up daily prior to site departure Data backups were removed from site daily

The only areas in which the survey was not performed were those in which water andor debris impeded access to the surface or where safety hazards described in Section 23 prevented access The Senior Radiological Engineer determined which areas were unacceptable for survey

26 ISOCS Modeling

ISOCS was used to measure the concentration of gamma emitting radionuclides in site soils An essential component of this process is to develop and apply an assumed model of the contaminated area being analyzed The source model comprises a description of assumed source being analyzed This description includes

bull Area and depth of the contaminated soil (source term)

bull Uniformity of contaminant concentration in the source term (eg homogeneous exponential etc)

bull Elemental composition of the source term and its density

bull Area and depth of non-contaminated cover material (eg soil) between the source term and the detector

This description is entered into the ISOCS software which uses this information to develop a mathematical model The ISOCS software uses the mathematical model in conjunction with an ISOCS detector-specific database to calculate a detection efficiency as a function of gamma energy for the model The gamma spectroscopy software applies the efficiency file to the spectroscopic data to determine the concentration of teach detected radionuclide in the source term

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

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TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 18: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

The assumed area and depth of the source term and thickness of the clean cover have a large impact on the estimated concentration as follows

1 For example if a source term only covers a small area and the model assumes that it covers a larger area the model will underpredict concentration The converse is also true To minimize the potential for this type of model discrepancy the size of contaminated areas at the site was estimated using field gross gamma instruments Maximum count rates were noted as well as the distance to half maximum and quarter maximum count rate locations

2 For example if the depth of clean cover assumed in the model is larger than the actual depth the model will overpredict concentration The converse is also true To minimize the potential for this type of modeling discrepancy CABRERA evaluates model concentration estimates using different gamma energies for the same radionuclide Low energy gamma photons will be attenuated to a much greater degree than high energy photons for the same cover thickness Consequently if the wrong cover thickness is assumed the concentration calculated using a low energy photon will differ from that calculated using a high energy photon from the same radionuclide It should be noted that naturally occurring radioactive material will exist in both the cover and the source term Consequently ISOCS models that utilize clean covers will tend to over predict the concentration of naturally occurring radioactive material (NORM)

99023 -1 CABRERA SERVICES INC Page 13 of 3 8

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99023-1 CABRERA SERVICES INC Page 14 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

99023-1 CABRERA SERVICES INC Page 15 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

99023-1 CABRERA SERVICES INC Page 37 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

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(X) OVERSIZED

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() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

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DESCRIPTION DOC 201276 44-10 Gamma Contour Map

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AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

30 SURVEY RESULTS

31 Data Handling and Quality Assurance

Project data was collected and handled as described in the Work Plan supplemented by additional field protocols specified by the Senior Radiological Engineer Data collected during the GWS activities discussed in Section 25 was processed daily to reduce the data to its necessary components The processing included differential correction of GPS spatial information (post-processing) data export from proprietary GPS format and data review and collation in spreadsheet format Following completion of field activities the data was collated sorted and reviewed for QA purposes Each data transaction defined as any movement transfer or manipulation of a project data file was recorded in the Project Data Logbook

Upon fieldwork completion collated data was imported into a three dimensional contouring software package and overlaid onto a CADD map of the survey grid In this package project data was contoured by plotting spatial coordinates on the X and Y axes and gamma readings on the Z-axis The software generated filled color-gradient contour maps describing the relative gamma count rates as gradient color changes This visual model facilitated data review and QA tasks as anomalous data points were readily visible Indications of data anomalies included non-gradient color changes color variations exhibiting unusual shapes blank spaces etc Data contour plots for both the 44-10 and FIDLER surveys are included as Appendix C to this report

Prior to posting gamma data to the contour maps the data was reviewed for positional accuracy Data failing this review was disqualified from further use Through data sorting disqualified data points were inspected to determine if any of the points indicated count rates significantly greater than background In cases where disqualified data was of a significant magnitude (ie gt10000 cpm for the 44-10 and gt15000 cpm for the FIDLER) the positional coordinates for the data point(s) were qualified by interpolation from surrounding points or by extrapolation from neighboring points In cases where the data was not of significant magnitude no qualification efforts were made

Posted data indicating sharp variation from surrounding data points (ie sharp non-gradient color change) was examined to determine the cause of the variability Several points showing count rates orders of magnitude greater than immediately adjacent points were disqualified

Posted data exhibiting unusual color variation or blank portions was examined to determine the cause of variability In cases of blank areas on the contour map data gaps existed and additional data collection was performed In cases of unusual color variation suspect data was disqualified and additional data collection was performed if deemed appropriate by the CABRERA Senior Radiological Engineer

All data review and QA methodologies and actions were recorded in the Project Data Logbook

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32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

32 GWS Survey Results

As can be seen in the gamma data contour plots in Appendix C the site conceptual model assumptions discussed in Section 21 appear to be valid as concerns near surface radionuclide distribution Elevated areas were observed in relatively small discreet areas On the majority of the site for both the 44-10 and the FIDLER background levels predominated This is demonstrated by the fact that the average 44-10 gamma count rate observed on the Site is 7568 counts per minute (cpm) compared to an average 44-10 background count rate of 7759 cpm For the FIDLER average gamma count rate was 11866 cpm while the average FIDLER background count rate was 11530 cpm

Examination of background data revealed that daily background variation was minimal For the FIDLER the relative standard deviation of daily mean background values was approximately 0011 or 1 For the 44-10 the relative standard deviation of daily mean background values was approximately 073 or 73 As such no adjustment to GWS data was required

An examination of the survey data reveals that as predicted by the site conceptual model count rates exhibited a high degree of non-homogeneity across the Site Gamma count rates observed with the 44-10 ranged from 1585 cpm to 999960 cpm while FIDLER count rates ranged from 2939 cpm to 999960 cpm It should be noted that the Ludlum 2221 ratemeter has a maximum reading of 999960 cpm Based on surveyors observations maximum count rates are substantially in excess of this value in two site areas one in grid 1224 and one on the border between grids 1099 and 1100 Of these two the grid 1224 location exhibits the highest count rate To measure relative radiation levels in these two locations CABRERA used a microrem meter and measured approximately 1500 rhr in grid 2224 and approximately 900 tfhr in grids 10991100 This compared to background levels of approximately 6-12 rhr in other site areas

Comparing FIDLER results depicted in Appendix C with those of the 44-10 in the same appendix it can be observed that the FIDLER showed better sensitivity overall than the 44shy10 While the FIDLER observed areas of elevated activity the 44-10 did not there were no apparent elevated areas detected by the 44-10 that the FIDLER failed to detect

Due to the high volume of data to be presented with this report survey data generated during this project is included on CDROM appended to this report

33 ISOCS Survey Results

ISOCS in situ gamma spectroscopy results are summarized on Table 1

331 Uranium Results

Uranium ranging in U-235 enrichment from depleted to fully enriched was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Three different uranium isotopes typically predominate in uranium contamination U-234 Ushy235 and U-238 Only U-238 and U-235 can be measured using gamma spectroscopy

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techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 22: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

techniques such as those employed by ISOCS U-234 is typically analyzed in a laboratory using wet chemistry techniques

Some of the properties of depleted natural and enriched uranium are summarized below

bull Naturally occurring uranium occurs in all soils with U-235 being 07 by weight and U-238 comprising the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull Depleted uranium contains less than 05 by weight of U-235 and U-238 comprises the remainder of the mass U-234 is also present but represents a negligible mass contribution

bull The mass of U-235 in enriched uranium is specified as the enrichment (eg 10 enriched uranium is 10 U-235 by mass U-238 comprises the remainder of the

bull On an activity bases naturally occurring uranium is comprised of equal concentrations of U-238 and U-234 however the U-235 concentration is approximately one-twentieth of the U-238 or U-234 concentration

bull On an activity basis depleted uranium is comprised almost exclusively of U-238

bull As enrichment of U-235 is increased the activity of U-234 and U-235 is increased relative to that of U-238 U-234 rapidly becomes the majority of the activity with increasing enrichment In fully enriched uranium (eg greater than 90) over 95 of the activity is U-234 with the remainder being U-235 A small amount of U-238 will also be present

Total naturally occurring uranium concentration in soil in this area of the country ranges from less than 1 to a few pCig The minimum detectable concentrations (MDC) achieved by ISOCS measurements of U-238 during this effort were typically greater than 4 pCig which is less than the expected background concentrations Consequently any positive detections of U-238 are considered elevated concentrations U-235 is easier to measure and has MDCs as low as 01 pCig however this would represent approximately 40 pCig of total naturally occurring uranium which is likely in excess of background Consequently any positive detections of U-235 are considered elevated concentrations

Uranium enrichments were calculated for all positive detections of U-235 U-235 was positively detected whenever U-238 was positively detected however the converse was not true When U-238 was not detected its MDC was used to estimate the enrichment which results in a minimum enrichment for the sample (eg actual enrichment may be higher)

Of the 97 measurements only 82 exhibited concentrations of U-235 less than the MDC Concentrations ranged from 009 pCig to 472 pCig The vast majority of these results indicate the presence of enriched uranium and it must be realized that the concentration of Ushy234 can be 25 to 35 times higher than the U-235 concentration even though ISOCS cannot measure the U-234 A summary of U-235 concentrations greater than 5 pCig follows

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

99023-1 CABRERA SERVICES INC Page 18 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

99023-1 CABRERA SERVICES INC Page 19 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

99023-1 CABRERA SERVICES INC Page 37 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 23: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull One measurement out of two in Grid 1056 exhibited a U-235 concentration of 558 pCig U-238 was below the MDC and the estimated enrichment is greater than 17

bull Two measurements out of four in Grid 1096 exhibited U-235 concentrations of 632 pCig (U-238 of 215 pCig and 44 enrichment) and 109 pCig (U-238 of 234 pCig and 67 enrichment)

bull Two measurements out of four in Grid 1097 exhibited U-235 concentrations of 62 pCig (U-238 of MDC pCig and greater than 665 enrichment) and 290 pCig (U-238 of 164 pCig and 215 enrichment)

bull The only measurement in Grid 1098 and one out of two measurements in adjacent Grid 1099 exhibited U-235 concentrations of 116 pCig (U-238 of MDC pCig and greater than 2704 enrichment) and 876 pCig (U-238 of MDC pCig and greater than 388 enrichment) pCig respectively

bull Elevated U-235 concentrations were observed in one out of two measurements in Grid 1131 as 111 pCig (U-238 of 238 pCig and 67 enrichment) and two out of two measurements in adjacent Grid 1132 as 125 pCig (U-238 of 160 pCig and 108 enrichment) and 791 pCig (U-238 of 291 pCig and 4 enrichment)

bull One out of two measurements in Grid 1174 exhibited a U-235 concentration of 935 pCig (U-238 of 701 pCig and 171 enrichment)

bull One out of two measurements in Grid 1205 exhibited a U-235 concentration of 705 pCig (U-238 of 197 pCig and 53 enrichment)

bull Two out of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 362 pCig (U-238 of 3581 pCig and 15 enrichment) and 1547 pCig (U-238 of 1078 pCig and 02 enrichment)

bull Three out of three measurements in Grid 1225 exhibited elevated U-235 concentrations of 212 pCig (U-238 of 2818 pCig and 12 enrichment) 18 pCig (U-238 of 943 pCig and 03 enrichment) and 197 pCig (U-238 of 172 pCig and 17 enrichment)

bull The only measurement in Grid 1234 exhibited elevated U-235 concentrations of 584 pCig (U-238 of 910 pCig and 01 enrichment)

bull The only measurement in Grid 1249 exhibited elevated U-235 concentrations of 545 pCig (U-238 of 260 pCig and 03 enrichment)

bull One out of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 102 pCig (U-238 of MDC pCig and greater than 2239 enrichment)

bull The only measurement in Grid 1258 exhibited elevated U-235 concentrations of 672 pCig (U-238 of 466 pCig and 183 enrichment)

99023-1 CABRERA SERVICES INC Page 18 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

99023-1 CABRERA SERVICES INC Page 19 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

99023-1 CABRERA SERVICES INC Page 20 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull The only measurement in Grid 1264 exhibited elevated U-235 concentrations of 70 pCig (U-238 of 342 pCig and 31 enrichment)

bull The only measurement in Grid 1266 exhibited elevated U-235 concentrations of 653 pCig (U-238 of 413 pCig and 24 enrichment)

bull The only measurement in Grid 1267 exhibited elevated U-235 concentrations of 126 pCig (U-238 of 300 pCig and 06 enrichment)

bull The only measurement in Grid 1270 exhibited elevated U-235 concentrations of 186 pCig (U-238 of 434 pCig and 62 enrichment)

bull Five out of five in Grid 1273 one out of one in Grid 1274 four out of four in Grid 1278 and one out of one in Grid 1279 exhibited elevated U-235 concentrations This area has the highest concentration of elevated U-235 measurements For individual results refer to Table 1

Of the 97 measurements 49 exhibited U-238 concentrations greater than the MDC Concentrations ranged from 466 to 3581 pCig The vast majority of these results indicate the presence of depleted uranium and it must be realized that concentrations of U-234 can be close to those of U-238 even though ISOCS cannot measure the U-234 The amount of U-235 in these samples is probably negligible The following summarizes locations that exhibited U-238 concentrations greater than 20 pCig but had U-235 concentrations less than 5 pCig

bull The only measurement in Grid 1087 exhibited elevated U-235 concentrations of 259 pCig (U-238 of 208 pCig and 02 enrichment)

bull One of two measurements in Grid 1195 exhibited elevated U-235 concentrations of 324 pCig (U-238 of 242 pCig and 02 enrichment)

bull One of two measurements in Grid 1205 exhibited elevated U-235 concentrations of 048 pCig (U-238 of 684 pCig and 01 enrichment)

bull One of two measurements in Grid 1214 exhibited elevated U-235 concentrations of 287 pCig (U-238 of 115 pCig and 04 enrichment)

bull One of three measurements in Grid 1224 exhibited elevated U-235 concentrations of 2 pCig (U-238 of 328 pCig and 1 enrichment)

bull The only measurement in Grid 1236 exhibited elevated U-235 concentrations of 141 pCig (U-238 of 737 pCig and 03 enrichment)

bull The only measurement in Grid 1237 exhibited elevated U-235 concentrations of 304 pCig (U-238 of 305 pCig and 15 enrichment)

bull One of two measurements in Grid 1254 exhibited elevated U-235 concentrations of 257 pCig (U-238 of 933 pCig and 04 enrichment)

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 25: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

332 Radium-226 Results

Radium-226 was identified as a contaminant of potential concern (COPC) during previous investigative activities at the site Because of the relatively short half-life of its decay products down through Bisumuth-210 (all less than 4-days) Ra-226 will be in secular equilibrium with its decay products (ie the concentration of decay products equals the concentration of Ra-226) Consequently the concentration of Ra-226 may be inferred by measuring gamma emissions from Ra-226 or from one of its decay products down through Ra-226

Ra-226 is a decay product of Uranium-238 However previous investigative activities at the site indicate that only processed uranium was disposed there Uranium-238 is stripped of its decay products during processing so no Ra-226 would initially be present Because of the long half-life of some U-238 decay products down through Ra-226 less virtually no Ra-226 activity would build in since the U-238 was processed and disposed The presence of any detected Ra-226 would be due to radium contamination not uranium contamination

Thirty-four locations were identified with elevated Ra-226 concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull The only measurement in Grid 1035 and the only Measurement in adjacent Grid 1036 exhibited Ra-226 concentrations of 611 and 67 pCig respectively

bull The only measurement in Grid 1038 exhibited a Ra-226 concentration of 244 pCig

bull The only measurement in Grid 1043 and two out of two measurements in adjacent Grid 1044 exhibited Ra-226 concentration from 319 to 492 pCig

bull One out two measurements in Grid 1056 exhibited a Ra-226 concentration of 292 pCig

bull The only measurement in Grid 1063 exhibited a Ra-226 concentration of 143 pCig

bull One out of three measurements in Grid 1087 exhibited a Ra-226 concentration of 251 pCig two out of two measurements in adjacent Grid 1088 exhibited Ra-226 concentrations of 116 and 224 pCig and one out of two measurements in adjacent grid 1099 exhibited a Ra-226 concentration of 171 pCig

bull Two out of four measurements in Grid 1097 exhibited Ra-226 concentrations of 358 and 116pCig

bull One out of two measurements in Grid 1131 exhibited a Ra-226 concentration of 301 pCig One out of two measurements in adjacent Grid 1132 exhibited a Ra-226 concentration of 219 pCig

bull Three out of three measurements in Grid 1157 the only measurement in adjacent Grid 1158 three out of three measurements in adjacent Grid 1164 and the only measurement in adjacent Grid 1165 exhibited Ra-226 concentrations from 326 to 481 pCig

99023-1 CABRERA SERVICES INC Page 20 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

99023-1 CABRERA SERVICES INC Page 22 of 3 8

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Page 26: DRAFT GAMMA WALKOVER AND CIVIL SURVEY REPORT

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

bull Two measurements out of two in Grid 1223 and two measurements out of three in Grid 1224 exhibited Ra-226 concentrations from 286 to 154 pCig

bull The only measurement in Grid 1237 exhibited a Ra-226 concentration of 589 pCig

bull One measurement out of five in Grid 1273 exhibited a Ra-226 concentration of 34 pCig One measurement out of four in Grid 1278 which is adjacent to Grid 1273 exhibited a Ra-226 concentration of 273 pCig The only measurement in Grid 1279 which is adjacent to Grid 1278 exhibited a Ra-226 concentration of 340 pCig

bull The only measurement in Grid 1281 exhibited a Ra-226 concentration of 161 pCig

333 Thorium-232 Results

Uranium and Radium-226 were identified as the contaminants of potential concern (COPC) during previous investigative activities at the site However at some locations elevated concentrations of Th-232 decay products were also identified The presence of elevated concentrations of Th-232 decay products could be caused by one or more of the following 1) it is an artifact of modeling a clean cover due to the presence of naturally occurring Th-232 2) it is due to the presence of Ra-228 which is a daughter product of Th-232 but is often present as a co-contaminant with Ra-226 and 3) it is due to the actual presence of Th-232

Th-232 is the initiating radionuclide in the thorium series All of its decay products have half-lives less than 67 years so even if starting with pure Th-232 all of its daughters will essentially reach secular equilibrium (ie concentration of decay products equals the concentration of Th-232) in 25 years Consequently any of Th-232 decay products may be used to infer the concentration of Th-232

However Ra-228 is a decay product of Th-232 and it is typically associated with artifacts containing Ra-226 so Th-232 decay products may also infer the presence of Ra-228 Because Ra-228 has a short half-life of 67 years it decays away much faster than Ra-226 with a half-life of 1602 years Considering that the deposited Ra-226 is likely over 25 years old Ra-228 would be present in much lower quantities than Ra-226 So Th-232 decay products would only infer the presence of Ra-228 when Ra-226 was also detected

Twelve locations were identified with elevated Th-232 decay product concentrations in excess of 2 pCig (background concentrations appear to be less than 1 pCig)

bull One measurement out of four in Grid 1097 exhibited a Th-232 decay product concentration of 82 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration may be an artifact of the model The presence of Ra-226 at 11 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1132 exhibited a Th-232 decay product concentration of 184 pCig Use of a four-inch clean overburden and the large relative uncertainty in the measurement indicates that some or all of the elevated concentration

99023-1 CABRERA SERVICES INC Page 21 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

may be an artifact of the model The presence of Ra-226 at 219 pCig indicates the some or all of this concentration may be due to the presence of Ra-228

bull One measurement out of two in Grid 1225 and the only measurement in Grid 1234 exhibited thorium decay product concentrations of 242 and 20 pCig respectively Use of a two-inch clean overburden the large relative uncertainty in the measurements and the absence of Ra-226 indicate that these slightly elevated concentrations are probably an artifact of the model

bull One measurement in two in Grid 1249 close to the Border of Grid 1273 five out of five measurements in Grid 1273 and two out of four measurements in Grid 1278 close to the border of Grid 1273 exhibited Th-232 decay product concentrations ranging from 271 to 153 pCig One measurement in Grid 1273 and one measurement in Grid 1278 exhibited Ra-226 concentrations of 34 and 273 pCig respectively A metal container filled with brick is located in Grid 1273 possibly some type of a furnace (Figure 2) The majority of the brick is in the container but a number of bricks are strewn about the general area of the furnace Refractory brick such as those used for insulation of a furnace can contain fairly high concentrations of Th-232 The presence of the brick indicates that some or all of the concentration may by due to naturally occurring Th-232 in the brick However the presence of Ra-226 in two locations indicates that some of it Figure 2 Brick-filled Metal Object may also be due the presence of Ra-228

34 Correlation of Portable Instrument Response to ISOCS Data

One of the objectives of the GWS was to evaluate the sensitivity of both the 44-10 detector and the FIDLER in measuring Ra-226 and uranium contamination of various enrichments in soil Selected ISOCS data was used along with field readings obtained during the GWS to perform the evaluation

Based on the characteristics of the instruments and their known response to different gamma ray energies they will have a different response to Ra-226 depleted uranium and enriched uranium The primary difficulty in performing this analysis was separating and quantifying the response of each instrument to the different COPCs because they exist in different proportions to each other throughout the site

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US Army Corps of Engineers Gamma Walkover and Civil Survey Report

In order to accomplish the analysis three groups of measurements were selected from the ISOCS data (Table 1) measurements where 1) the vast majority of the activity is Ra-226 2) the vast majority of the activity is depleted uranium and 3) the vast majority of the activity is enriched uranium Depth of clean cover has a large impact on the response of the instruments especially to uranium so selection of measurements was also limited to ISOCS measurements that indicated surface contamination where possible The measurements selected for each group are shown in Table 2

Instrument response for the 44-10 and FIDLER for each group of measurements are plotted on Figures 3 4 and 5 for Ra-226 depleted uranium and enriched uranium respectively The equation for each curve and its linear regression correlation coefficient are also shown on each figure The equations were fitted so that each line passes through zero

FIDLER response is 17 times as sensitive as the 44-10 for Ra-226 23 times as sensitive for depleted uranium and 16 times as sensitive for enriched uranium FIDLER response is much more sensitive than the 44-10 in all cases as was demonstrated during the GWS (discussed in Section 32) The largest sensitivity difference observed for depleted uranium is expected because depleted uranium consists almost entirely of U-238 which emits relatively low energy gammas and the FIDLER was designed to have an improved efficiency for low energy gamma radiation compared to a 44-10

FIDLER response to enriched uranium is 11 times more sensitive than its response to depleted uranium 44-10 response to enriched uranium is 17 times more sensitive than its response to depleted uranium 44-10 response to Ra-226 is approximately 21 times greater than its response to depleted uranium and 13 times greater than its response to enriched uranium FIDLER response to Ra-226 is approximately 16 times greater than its response to depleted uranium and 14 times greater than its response to enriched uranium

The FIDLER appears to be the better GWS instrument for the Site because it is more sensitive than the Nal for all COPCs it has an essentially uniform response to depleted and enriched uranium and it has a smaller sensitivity difference between Ra-226 and uranium However use of either will present some problems in the field because their relative over-response to radium will tend to overwhelm their response to uranium when both contaminants are present This can easily be addressed by use of ISOCS during field measurements or a portable gamma spectroscopy laboratory to estimate the relative proportion of each contaminant in various Site locations

The importance of this over-response depends on the ratio of the Ra-226 cleanup criteria to the uranium cleanup criteria If the uranium criterion is ten times higher than the Ra-226 criteria the instruments have essentially an equal response from the perspective of sensitivity for measuring compliance with cleanup criteria The uranium cleanup criterion is typically greater than the Ra-226 cleanup criterion For example the NRC default surface soil cleanup criterion for U-238 and U-235 uranium are approximately 14 and 8 pCig respectively and the cleanup criterion for Ra-226 is 06 pCig

It should be noted that the presence of a clean cover over the COPCs (ie burial depth) has a substantial effect on reducing the response of either detector However the effect will be far

99023 -1 CABRERA SERVICES INC Page 23 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

less for Ra-226 because its higher energy gamma energies can more easily penetrate the soil cover and reach the detector The effect of burial depth was not evaluated in detail as part of this survey since it was designed to measure surface contamination

99023-1 CABRERA SERVICES INC Page 24 of 38

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US Army Corps cf Engineers Gamma Walkover and Civil Survey Report

Table 2

Locations Selected for Instrument Response Evaluation

Map Location Selected Locations Number ID Radium EU DU 49 1043sw X 90 1063sw X 52 1087nw X 65 1088ne X 57 1 088se X 94 1096se X 95 1096sw X

85 1131sw X 62 1157se X 56 1164sw X 50 1165ne X 3 1174se X 7 1205ne X 4 1205se X 6 1214ne X 77 1225se(3) X 27 1236se X 13 1249se X 37 1254sw X 33 1270nw X

19 1273nw X 16 1273se(2) X 11 1273sw X

17 1278se X 14 1278sw X 34 1298sw X

CABRERA SERVICES INC Page 32 of 3 899023-1

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

40 CURRENT SITE STATUS

Upon completion of field activities CABRERA performed a partial demobilization which involved removing all electronic equipment such as radiation detectors GPS and computer equipment By mutual consent between the CABRERA and USAGE Project Managers the trailer and portable toilet facility remained in place and telephone and electric was kept active A minimal complement of protective clothing and other miscellaneous items was left to support short-term site visits Prior to departing the site used Tyvek oversuits gloves boots etc used in the Exclusion Zone were collected bagged andor drummed and placed in the shed located in the EZ Power to the trailer was turned off at the main circuit breaker The trailer and main site gate were locked prior to site departure With the addition of appropriate radiation monitoring equipment the site can be remobilized within one day as necessary

99023-1 CABRERA SERVICES INC Page 33 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 34 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

50 CONCLUSIONS

The GWS indicated that most of the elevated surface activity at the site is highly localized to several discrete areas Based on the relatively sharp edges demarcating these areas it does not appear that the contamination is spreading laterally Several areas of the site were covered with water and could not be safely surveyed and in some areas partially buried debris was unsafe to walk on and also could not be surveyed Techniques other than walkover surveys will have to be used to evaluate these areas during future characterization activities at the site

The vast majority of the contamination appears to be uranium of various enrichments In some cases uranium of different enrichments is present in the same location Ra-226 is also present in a number of locations around the site It is typically co-located with the uranium contamination but in some locations it is not Some indications of Th-232 decay product contamination were identified during the ISOCS evaluations These indications may be due to small amounts of Ra-228 as a co-contaminant with Ra-226 and in one highly localized area may be due to the presence of firebrick with a high naturally occurring Th-232 content (see Figure 2) The next phase of characterization should include an investigation to evaluate and quantify the potential presence of Th-232 on the Site

Several lessons were learned that will affect future phases of the characterization and remediation and must be addressed in plans for those efforts The Site is heavily vegetated which re-grows rapidly so it will likely have to be cleared prior to initiating each field effort The presence of low hanging power lines creates a serious safety concern especially when using vehicles drilling and earth moving equipment In their current condition the low clearance under these lines will be a serious impediment to future work activities

Although the results of the GWS indicate that the FIDLER is the better GWS instrument for the Site problems were identified with use of either 44-10 or FIDLER field instruments to quantify the presence of COPCs Neither field instrument nor the gamma spectroscopy techniques are sensitive to U-234 which can be a substantial component of depleted uranium contamination and the majority component of enriched uranium contamination Both instruments are much more sensitive to Ra-226 than uranium thus quantifying contamination consisting of mixtures of these COPCs using field instruments will be difficult This sensitivity difference can be compensated in the field using the results of ISOCS or portable gamma spectroscopy equipment and can be minimized based on the difference in clean up criteria between the COPCs Limitations of field instruments must be considered in the design of subsequent characterization and remediation plans

In general the results of this survey were consistent with the surface contamination aspects of the existing Site Conceptual Model with the exception that Th-232 decay products should be added as a COPC In addition this effort provided no information regarding the depth distribution of the contamination which will be the emphasis of the next characterization phase

99023-1 CABRERA SERVICES INC Page 35 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 36 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

60 REFERENCES

CABRERA 1999a Gamma Walkover and Civil Survey Work Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999b Site Specific Health and Safety Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999c Quality Assurance Project Plan Shpack Landfill Superfund Site Cabrera Services Inc December 30 1999

CABRERA 1999d Records SearchSite Walkover Report Shpack Landfill Superfund Site Cabrera Services Inc August 1999

CABRERA 1999e Technical Memorandum Cost Estimate to Perform Civil and Gamma Walkover Surveys and Description of the Applicability of Field Gamma Spectroscopy Shpack Landfill Superfund Site Cabrera Services Inc November 161999

ERM 1993 Initial Site Characterization Report Shpack Landfill Superfund Site ERM New England March 17 1993

Holden 1991 Civil Survey of Shpack Landfill Superfund Site Performed for ERM New England January 8 1991

OSHA 1994 Code of Federal Regulations Title 29 Section 1910333 Selection and Use of Work Practices United States Occupational Safety and Health Administration as amended through January 31 1994

USAGE 1997a Engineering Manual EM-385-1-80 Radiation Protection Manual United States Army Corps of Engineers May 30 1997

USAGE 1997b Engineering Regulation ER-385-1-80 Radiation Safety United States Army Corps of Engineers May 30 1997

99023-1 CABRERA SERVICES INC Page 37 of 38

US Army Corps of Engineers Gamma Walkover and Civil Survey Report

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99023-1 CABRERA SERVICES INC Page 38 of 38

Appendix A

Civil Survey Map

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Civil Survey Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix B

Instrument Control Charts

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Appendix C Gamma Survey Result

Contour Plots

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 44-10 Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

Appendix D

ISOCS Locations and FIDLER Gamma

Contour Plot

TARGET SHEET

THE MATERIAL DESCRIBED BELOW WAS NOT SCANNED BECAUSE

(X) OVERSIZED

() NON-PAPER MEDIA

() OTHER

DESCRIPTION DOC 201276 Fidler Gamma Contour Map with ISOCS Locations

THE OMITTED MATERIAL IS AVAILABLE FOR REVIEW BY APPOINTMENT

AT THE EPA NEW ENGLAND SUPERFUND RECORDS CENTER BOSTON MA

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