SUBSURFACE SOIL INVESTIGATION IN RESIDENTIAL AREAS · Subsurface Soil Investigation in Residential...

$: SUBSURFACE SOIL INVESTIGATION IN RESIDENTIAL AREAS · Subsurface Soil Investigation in Residential Areas St. Francois County Mining Areas July 6, 2011 ii \\Hinrichs-xp\projects\DR-StFran$
SUBSURFACE SOIL INVESTIGATION IN RESIDENTIAL AREAS St. Francois County Mined Areas July 6, 2011 Prepared by:

730 17th Street, Suite 925 Denver, Colorado 80202

Subsurface Soil Investigation in Residential Areas St. Francois County Mining Areas July 6, 2011

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Table of Contents Page

1.0 BACKGROUND..................................................................................................... 1 1.1 Site Description and Physical Setting........................................................ 1 1.2 Nature and Extent of Contamination ......................................................... 3

2.0 PURPOSE AND OBJECTIVES............................................................................. 4 3.0 FIELD ACTIVITIES................................................................................................ 6

3.1 Residential Yards Sampled ....................................................................... 6 3.2 Surface Soil Supplemental Sampling ........................................................ 6 3.3 Subsurface Soil Characterization .............................................................. 8 3.4 Common (Both Surface and Subsurface) Sampling Requirements .......... 8

3.4.1 Quality Assurance/Quality Control ................................................. 8 3.4.2 XRF Calibration Models................................................................. 9

4.0 DISCUSSION...................................................................................................... 12 4.1 Surface Soil Supplemental Sampling ...................................................... 12 4.2 Subsurface Soil Characterization ............................................................ 13

4.0 CONCLUSIONS.................................................................................................. 15 5.0 REFERENCES.................................................................................................... 16

List of Tables

Table 1 Number of Newly Sampled Surface Soil Yards with Designated Areas above 400 ppm Lead .................................................................................... 12

Table 2 Yard Statistics or Percentages for Newly Sampled Surface Soil Yards with Designated Areas above 400 ppm Lead .............................................. 13

Table 3 Lead Concentrations with Depth in the Yard Soil Borings............................. 14

List of Figures

Page

Figure 1 Response Area and Halo ..................................................................................2 Figure 2 Average Surface Soil Lead Concentrations in Yard Quadrant Samples ...........5 Figure 3 Subsurface Soil Sampling Locations ................................................................7 Figure 4 XRF Calibration Model for Lead, 2011 samples ...............................................9 Figure 5 Comparison of the Lead XRF Calibration Curves for the Interim Action/Halo

Removal Action Samples and the 2011 Samples ...........................................10 Figure 6 XRF Calibration Curve for Zinc, 2011 samples ...............................................11


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List of Appendices

Appendix A

Detailed Areas of Figures Appendix B

Surface Soil Sampling Results and Yard Sketches Appendix C

Subsurface Soil Sampling Results and Sampling Forms Appendix D

Laboratory Data and Data Quality Assessment Report Appendix E

XRF Data Quality Assessment Report, XRF Calibration Models and Paired Calibration Sample Results


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Subsurface Soil Investigation in Residential Areas St. Francois County Mined Areas

This report for Subsurface Soil Investigation in Residential Areas is submitted as an Addendum to the Focused Remedial Investigation (Focused RI), St. Francois County, Missouri site dated March 6, 2006 (NewFields 2006) and to fill a data gap for completing the Feasibility Study for Residential Areas in the St. Francois County Mined Areas (Site). This investigation provides an assessment of the nature and vertical extent of elevated lead concentrations within residential yard soil. This report has been prepared by NewFields on behalf of The Doe Run Resources Corporation d/b/a The Doe Run Company (Doe Run) and is being conducted as Additional Work pursuant to Administrative Order on Consent (AOC), U.S. Environmental Protection Agency (EPA) Docket No. VII-97-F-0002, dated January 29, 1997.

1.0 BACKGROUND

1.1 Site Description and Physical Setting

The Site (Figure 1) is located in southeastern Missouri entirely within St. Francois County, approximately 70 miles south of St. Louis. St. Francois County is located in a historic mining area called the Old Lead Belt. The Old Lead Belt is on the northeastern edge of the Precambrian igneous core of the St. Francois Mountains. This area is one of the world’s largest lead mining districts, having produced more than nine million tons of pig lead (HUD et al. 1997). The first recorded mining in St. Francois County occurred at Mine-a-Gabore between 1742 and 1762. The important discoveries of disseminated lead in the Bonne Terre, Leadwood, and Flat River areas occurred in 1864. Mining ceased in the Old Lead Belt in 1972 with the closing of the Federal mine (NewFields 2006).

It has been estimated that some 250 million tons of mill waste, tailings and chat, were produced in the Old Lead Belt from ore milling and beneficiation processes. The chat has been used extensively as aggregate for ballast in railroads, aggregate in concrete and asphalt, and fill. Some chat is used today as aggregate and fill. Tailings have been used as agricultural amendments due to the lime content.

The AOC identified eight designated mining areas: • Desloge (aka Big River Mine Tailings) • Federal (aka St. Joe State Park) • Leadwood • Bonne Terre • National Lead Site • Elvins (aka Rivermines) • Hayden Creek • Doe Run Lead Company Site (not associated with The Doe Run Resources Corp.).

Elvins/Rivermines

National

Doe Run

Federal

Leadwood

Desloge

Bonne Terre

Hayden Creek

LegendHalo - 100 ft from ShaftsHalo - 1000 ft from SmeltersHalo - 500 ft from TPondsHalo - 500 ft from Chat Piles

0 6,000 12,000 18,000 24,0003,000Feet

Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds

Historic Railroads (inactive)

Railroad

World Street Map St. Francois Co. Mined Areas

Figure 1Response Area and Halo



Within the Site are the incorporated towns of Desloge, Bonne Terre, Park Hills, Leadwood, and Leadington and the unincorporated towns of Doe Run, Frankclay, Wortham, Gumbo, and East Bonne Terre. The population within the Site is roughly 30,000 according to the 2000 Census. The area within the Site that is residential is called the Response Area. While the exact number of residential yards within the Response Area is unknown, based on the 2000 census data and home canvassing activities during the Interim Action, the number of residential yards within the St. Francois County Mined Areas’ Response Area is estimated to be 7,129 yards.

Appendix A includes magnified views of all the following figures (Figures 2 and 3) to allow the reader to distinguish the detailed information.

1.2 Nature and Extent of Contamination

Past ore extraction, milling, separation, and smelting conducted in the area have resulted in elevated lead levels in soils. The use of leaded gasoline, lead solder, lead-based paint, and other lead-containing products has contributed to increased lead in soils (HUD et al. 1997). Sampling in residential yards indicates surface soil lead concentrations are elevated (greater than 400 ppm lead) well away or distant from the piles. Anthropogenic (human caused) redistribution is probably the most significant source of surface soil lead contamination. Homeowners have used mined-related materials for driveways (chat) and as fill material (chat or tailings). The use of chat in road bed construction, in ballast for historical railroads, and as de-icing materials for roads is probably another source of elevated lead concentrations within residential yards. Natural mineralization of bedrock and associated soils is a likely source of lead, as EPA noted in Washington County, Missouri soils (EPA 2010c, 2010d, 2010e).

In 2000, extensive surface soil sampling was initiated as part of the Interim Action (EPA Docket No. CERCLA-7-2000-0015, dated April 7, 2000) at residential yards surrounding the mill waste piles. Residential yards were sampled for lead in soil using an x-ray fluorescence spectrometer (XRF), beginning closest to the mine waste sources and then radiating outward. Composite samples of the top one inch of soil were collected from each of the four quadrants of the yard (front left, front right, back left, back right) and the drip line from each house. Yards were then selected for remediation based on the concentration of lead within the surface soil.

In anticipation of the expiration of the Interim Action, Doe Run volunteered and EPA agreed to replace the Interim Action with the Halo Removal Action (EPA Docket No. CERCLA-7-2004-0167, effective date March 30, 2004). The Halo Removal Action was conducted within the areas jointly called the “Halo” around the six major mine sites located in St. Francois County (see Figure 1). The Halo Removal Action included sampling and remediation of yards within the Halo. Yard soil remediation practices were consistent between the Interim and Halo Removal Actions. If a portion of the yard



qualified for yard soil removal, the soil was removed to a depth of one foot. The subgrade soils were screened with an XRF; and if subgrade soil lead concentrations were above 400 ppm, then a visual barrier was placed across the subgrade. The excavation was backfilled with clean soil (less than 240 ppm lead). Of the remediated yards, over 50 percent had at least some portion with subgrade lead concentrations greater than 1,200 ppm.

While anthropogenic redistribution might explain the widespread distribution of elevated surface lead (see Figure 2), the elevated lead concentration at the 12-inch subgrade depth is not consistent with results from other Missouri residential remedies where anthropogenic redistribution is believed to be a major factor in the distribution of lead.

2.0 PURPOSE AND OBJECTIVES

During the preparation of the Draft Feasibility Study for Residential Areas (NewFields 2010), the observation regarding lead concentrations at depth was used to estimate that 50 percent of yards to be remediated would have subgrade soils (soil greater than 12 inches below the surface) with lead concentrations greater than 1,200 ppm. EPA commented that the estimate was too high since the percentage was based on yards that are close to the mine-related waste piles. EPA believes the subgrade lead concentration as well as surface soil lead concentration will decrease with distance away from the sources (EPA 2010a). Since the 50 percent estimate was a key distinguishing factor between the two evaluated alternatives, EPA stated that additional subgrade data would be required. Doe Run concurred that additional sampling would provide information that would be useful for finalizing the Feasibility Study and agreed to collect the data. This report discusses the findings of that additional data collection.

The primary objective of the sampling is to estimate the number of yards for which subgrade lead concentrations below 12 inches below ground surface (bgs) will be above 1,200 ppm. If the lead concentrations at 12 inches are above 1,200 ppm, there is a need to characterize the depth to which these elevated lead concentrations extend.

Secondary objectives include:

• Potentially identifying the source or cause of elevated lead concentrations that are found in the subsurface (especially if lead concentrations are found at higher concentrations at depth compared to surface)

• Characterizing surface soil lead concentrations at yards that have not been characterized as part of the Interim or Halo Removal Actions.

LegendYard Quadrant Average Lead

Paved Yard/Non Yard<400 ppm400-1,200 ppm>=1,200 ppm

0 6,000 12,000 18,000 24,0003,000Feet

Figure 2Average Surface Soil Lead Concentrations

in Yard Quadrant SamplesResponse Area

Shafts

Smelters

Chat Piles

Tailing Ponds

NGS USA Topographic Maps

St. Francois Co. Mined Areas

Average concentration of the yard quadrant samples: Front Yard Left (FL), Front Yard Right (FR), Back Yard Left (BL), and Back Yard Right (BR). Subfigures are included in Appendix A



3.0 FIELD ACTIVITIES

The following activities were conducted to meet the sampling objectives:

• Selecting and gaining access to residential yards for characterization of the Response Area

• Characterizing subsurface soils in residential yards

• Characterizing surface yard soil in yards selected for subsurface soil characterization data.

3.1 Residential Yards Sampled

As discussed in the SAP for this work, 50 sampling locations were randomly located within the residentially dense portions of the Response Area using Visual Sample Plan (VSP, PNNL 2010). Additionally, 8 sampling locations were added to provide further coverage in areas of the Response Area that were not as densely populated with residential yards but were judged to have a sufficient number of residential yards to be considered a “neighborhood” versus an isolated rural residence.

One homeowner initially provided access for the sampling program, only to change her mind when she was contacted regarding the timing of the sampling and utility clearance that would be conducted. The yard was replaced with a nearby yard, so the number of sampled yards remained at 58 yards.

Each “new” residence was located using a global positioning system (GPS), and the address and the GPS coordinates were entered into a contact log and the project GIS. Figure 3 presents the location of the yards included in this sampling program. A letter with sampling results was provided to each homeowner.

3.2 Surface Soil Supplemental Sampling

Of the 58 yards included in this sampling program, 13 yards previously had the surface soil sampled as part of the Interim or Halo Removal Actions. The surface soil was sampled in the other 45 yards as part of this sampling program. Two of these yards had been previous sampling refusals during the Interim Action.

The surface soils in the 45 yards were sampled by Doe Run in accordance with procedures established in the Interim and Halo Removal Actions and described in the SAP. Four general yard quadrant samples and one drip line sample was collected in each yard (unless the area was paved). Additionally, other potential “hot spots” such as gardens, chat driveways, play areas, etc., were sampled. Each sample was a composite of aliquots from the top 1 inch of the yard soil.

LegendSubsurface Soil Sampling Locations

Subsurface Soil Sampling Locations

0 6,000 12,000 18,000 24,0003,000Feet

Figure 3Subsurface Soil Sampling LocationsResponse Area

Shafts

Smelters

Chat Piles

Tailing Ponds


St. Francois Co. Mined AreasLocations are labeled on the subfiguresSubfigures are included in Appendix A



Appendix B presents the tabulated XRF lead concentrations in the surface soil samples as well as the yard sampling sketches.

3.3 Subsurface Soil Characterization

One subsurface sample “core” was collected per residential property/yard. All sampling was conducted at readily accessible portions of the yard and was therefore conducted in the front yard in all but two yards. A direct-push soil Geoprobe was used to sample continuously from the surface to the target depth of 4 feet or refusal. Refusal did occur in one yard (PH20499) at 15 inches after penetrating 2 inches of limestone gravel.

Boring locations are provided on the Subsurface Soil Sampling Forms provided in Appendix C. The soil “core” was collected within a plastic liner. Character of the soil was described using typical non-quantitative field observations, including, but not limited to, color, visual grain size, consistency (plasticity, moisture content, etc.), and organic content. Vertical composite samples were collected in 6-inch depth increments to the target depth of 30 inches. A full 30 inches was recovered and sampled at all but four locations. Two locations had recovery of 24 inches, one 18 inches and one 12 inches.

A summary of the lead and zinc concentrations measured by XRF are provided in Appendix C.

3.4 Common (Both Surface and Subsurface) Sampling Requirements

Wet weather extended the processing time to air dry, to hand crush hardened samples for sieving through a #10 screen (2 mm), and to homogenize the sample prior to analysis in bulk mode using the XRF. To allow for calibration samples to be assembled into one laboratory batch, all sample processing was conducted prior to any sample analysis.

Due to the wet weather prior to and during the sampling, the XRF was not used in the in situ mode during the sampling. Therefore, no additional sample collection was conducted due to real-time knowledge of lead concentrations in soil.

3.4.1 Quality Assurance/Quality Control

The general quality control objective is to ensure that data are not biased by contamination or sampling error. To meet this objective, the following QC samples were collected in the field:

• Field XRF duplicate samples were collected and analyzed at a 5 percent frequency.



• XRF confirmation samples of the quadrant samples were collected at a 5 percent frequency. Ten (10) percent of the 6-inch vertical composite samples were selected for fixed laboratory confirmation analysis. These samples were analyzed for lead, cadmium, and zinc.

Appendix D and Appendix E present data quality assessment reports for the laboratory and XRF samples, respectively, collected and analyzed as part of this investigation.

3.4.2 XRF Calibration Models

Figure 4 presents the lead calibration model using the 40 sample pairs collected as part of this sampling program (2011 samples). All confirmation samples from the surface soil and subsurface soil samples are included on the lead calibration model to assess the measurement of lead via the XRF relative to the laboratory SW-846 Method 3050/6010B. Appendix E presents the paired XRF and laboratory data for the calibration samples. The relationship between the XRF lead concentration and the laboratory method was determined using a linear relationship for all samples, surface soil (area composites) and vertical 6-inch composites. The slight variation seen between the two different sample sets (based on method of compositing) is believed to be based on sample set rather than a true variation between SW-846 and XRF.

y = 0.83xR2 = 0.97

y = 1.03xR2 = 0.93

y = 0.81xR2 = 0.99

0

200

400

600

800

1000

1200

1400

1600

1800

0 200 400 600 800 1000 1200 1400 1600 1800

Lead by XRF (ppm)

Lead

by

SW-8

46

Met

hod

30

50

/60

10

B;

Labo

rato

ry (

mg/

kg)

All Samples (n=40) Vertical Composites (n=28) Surface Soil (n=12)

Linear (All Samples (n=40)) Linear (Vertical Composites (n=28)) Linear (Surface Soil (n=12))

Figure 4 XRF Calibration Model for Lead, 2011 samples



As part of the Interim Action and Halo Removal Action, a calibration model was developed using lead concentrations for site-specific samples (SSS) and site sample confirmation duplicates (a total of 371 sample results pairs were made). As a multi-element XRF was used in this sampling program as opposed to a lead-only XRF that was used in the Interim and Halo Removal Actions, the samples collected as part of this sampling program were kept separate from the previous calibration model. The calibrations of these data sets are compared to the existing Interim/Halo model to assess whether the comparability of the two XRF models and their comparison to the laboratory method (see Figure 5). As shown in the comparison both XRFs appear to show enrichment of lead relative to the laboratory method. Additionally while the trend of the multi-element XRF calibration pairs appears to be more enriched than the lead-only XRF, this variation in trend is again probably due to the sample size rather than a true correlation variation.

2011 Samplesn=40

y = 0.83xR2 = 0.97

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

Lead by XRF, ppm

Lead

by

Labo

rato

ry (

SW-8

46

30

50

/60

10

B),

mg/

kg

Interim/Halo 2011 SamplesLinear (Interim/Halo) Linear (2011 Samples)

Notes:Laboratory results are reported with two significant figures in the Interim/Halo results and with three significant figures in the 2011 results.XRF results are reported to the closest ppmInterim/Halo samples are only shown on the scale presented but all sample results (>2000 by either method) are used to determine the correlation.

Interim/Halon=371

y = 0.92xR2 = 0.92

Figure 5 Comparison of the Lead XRF Calibration Curves for the

Interim Action/Halo Removal Action Samples and the 2011 Samples



As a multi-element XRF was used in this sampling program, a calibration model was also prepared for zinc (see Figure 6). As seen in the figure, the multi-element XRF’s results are highly enriched versus the SW-846 Method 3050/6010B results. Comparison of the XRF results of the NIST standards used for accuracy evaluations (see Appendix E for data quality assessment report) indicate the XRF is accurately measuring the zinc in the standards and the relationship might be more a factor with the matrix interference problem with the laboratory method than with the XRF actually reporting an “enriched” sample results.

y = 0.65xR2 = 0.96

y = 0.63xR2 = 0.91

y = 0.65xR2 = 0.95

0

50

100

150

200

250

300

350

400

450

500

550

0 50 100 150 200 250 300 350 400 450 500 550

Zinc by XRF (ppm)

Zin

c by

SW

-84

6 M

eth

od 3

050

/60

10B

; La

bora

tory

(m

g/kg

)

All Samples (n=40) Vertical Composites (n=28) Surface Soil (n=12)Linear (All Samples (n=40)) Linear (Vertical Composites (n=28)) Linear (Surface Soil (n=12))

Figure 6 XRF Calibration Curve for Zinc, 2011 samples

Calibration curves for cadmium were not produced as the multi-element XRF that was used cannot measure cadmium.



4.0 DISCUSSION

4.1 Surface Soil Supplemental Sampling

Table 1 presents a summary of the elevated lead in the newly sampled yards.

Table 1 Number of Newly Sampled Surface Soil Yards with Designated Areas above 400 ppm Lead

Additional Area or Hot Spot (1) Yards

Yards with Quads

>1200 ppm Driveway Garden Play Area Drip Zone

One Yard Quadrant 3 0 0 0 0 3 Two Yard Quadrants 6 1 1 0 0 4 Three Yard Quadrants 10 3 1 3 2 7 Four Yard Quadrants 19 6 4 1 4 18 Additional Area (Hot Spot) only (1) 1 -- 0 0 0 1

No Action Required 6 -- -- -- -- -- Notes: (1) Hot Spots are areas of the yard that could be subject to specialized uses, such as driveways, vegetable gardens, and

child play areas (including swing sets and sandboxes) and that have soil concentrations >=400 ppm.

Of the 45 new yards sampled, 6 yards exhibited surface lead concentrations less than 400 ppm and, therefore, would not require any further action under any of the alternatives proposed in the Feasibility Study. One yard exhibited an elevated lead concentration within the drip zone soils. Of the 38 yards that would require some action per the Feasibility Study, 19 yards, or 50 percent, had all four yard quadrants greater than 400 ppm lead.

Table 2 presents the yard statistics for the presence of elevated lead using both this 2011 study and the previous statistics presented in the Draft Feasibility Study (NewFields 2010). Overall the results are consistent with the results for the Interim and Halo Removal Actions reported in the Draft Feasibility Study. The results predict that some portion of the yard (yard quadrant, driveway, garden, play area, or drip zone) will exhibit lead concentrations above 400 ppm in 87 percent of the new yards sampled, or 84 percent when elevated drip zone only yards are excluded. Since all the 45 yards sampled are out of the Halo (see Figure 1) the results are expected to be representative of conditions in future residential yard removals. An 84 percent rate of yard inclusion is appropriate for use in the Feasibility Study (NewFields 2011).

Concentrations of zinc and cadmium were similar to concentrations observed during the previous surface sampling as reported in the Focused RI. All detected concentrations of both zinc and cadmium are well below the EPA regional screening levels for residential soil of 23,000 and 70 mg/kg, respectively (EPA 2010b).



Table 2 Yard Statistics or Percentages for Newly Sampled Surface Soil Yards with Designated Areas above 400 ppm Lead

Additional Area or Hot Spot (2,3)

Previously Sampled Yards(1)

2011 Sampled

Yards Driveway Garden Play Area

All Yards 83% 84% 13% 9% 13% One Yard Quadrant 15% 8% 0% 0% 0% Two Yard Quadrants 17% 16% 17% 0% 0% Three Yard Quadrants 22% 26% 10% 30% 20% Four Yard Quadrants 45% 50% 21% 5% 21%

No Action Required 17% 16% -- -- -- Notes: (1) Percentages are from Table 1 of the Draft Feasibility Study for Residential Areas (NewFields 2010) and

are based on the 2,003 residential yards that were sampled as part of the Interim and Halo Removal Actions.

(2) Hot Spots are areas of the yard that can be identified for specialized use, such as driveways, vegetable gardens, child play areas (including swing sets and sandboxes).

(3) Percentage of additional areas is the percentage of the yards (sampled in 2011) within the quadrant category that has an elevated additional area or Hot Spot.

4.2 Subsurface Soil Characterization

In the Draft Feasibility Study (NewFields 2010) it was assumed that 50 percent of the excavated yards would require excavation beyond 12 inches. This estimate was based on subgrade samples that contained greater than 1,200 ppm lead. As discussed in Section 2.0, EPA believed this assumption was too high and required this subsurface soil study.

Table 3 presents a summary of the lead concentration data obtained from the subsurface sampling program. The protocol used of compositing the soil in 6-inch vertical intervals is very different from any of the prior surface or subsurface soil sample procedures. Results from the Interim and Halo Removal Actions were either for in situ assays or a near surface samples (vertical interval 0 to 1 inch). The previous samples were horizontal composites typically containing 5 aliquots or in situ assays spread over the yard quadrant. Sample protocol for the 2011 investigation was designed to characterize variation with depth, and therefore a single point within the yard was selected and was appropriate to meet the sampling objective. Additionally, discussions with EPA regarding alternatives for the Feasibility Study indicated 1) that EPA would require the confirmation sample at the 12-inch subgrade in any future residential yard soil removal actions to be a 5-aliquot composite with vertical 6-inch aliquots rather than the shallow (1-inch) subgrade aliquots or subgrade in situ monitoring, and 2) that these samples would be used to determine further action at the 12-inch depth during excavation. So while this sampling protocol is appropriate for the objectives of the 2011 study, the comparability of these samples to the previous subgrade samples has inherent and noted limitations.



Table 3 Lead Concentrations with Depth in the Yard Soil Borings

BT40295 BTK0309 BTK0310 BTK0311 BTK0312 BTK0313 Surface Soil (0-1 inch) Quadrant Composite 892 2000 1515 586 838 326 Vertical Soil Composite 0-6 inches 903 163 3094 351 463 1434 Vertical Soil Composite 6-12 inches 133 83 453 45 57 283 Vertical Soil Composite 12-18 inches 25 113 17 15 25 13 Vertical Soil Composite 18-24 inches 30 1272 15 10 30 16 Vertical Soil Composite 24-30 inches 22 691 14 20 26 74 BTK0314 BTK0315 BTK0316 BTK0317 DL00010 DL10162 Surface Soil (0-1 inch) Quadrant Composite 805 663 639 1067 2259* 702 Vertical Soil Composite 0-6 inches 313 947 459 137 >2000* 4075 Vertical Soil Composite 6-12 inches 93 556 172 13 >2000* 1039 Vertical Soil Composite 12-18 inches 21 215 212 17 2027 177 Vertical Soil Composite 18-24 inches 14 81 219 14 248 133 Vertical Soil Composite 24-30 inches 11 62 354 17 35 123 DL10182 DL20257 DLK0452 DLK0453 DLK0454 DLK0455 Surface Soil (0-1 inch) Quadrant Composite 943 194 809 619 1281 63 Vertical Soil Composite 0-6 inches 82 188 483 206 182 47 Vertical Soil Composite 6-12 inches 24 64 88 29 45 114 Vertical Soil Composite 12-18 inches 24 39 42 28 28 117 Vertical Soil Composite 18-24 inches 25 66 49 36 27 93 Vertical Soil Composite 24-30 inches 31 67 44 30 23 214 DLK0456 DLK0457 DLK0458 DLK0459 DLK0460 DLK0461 Surface Soil (0-1 inch) Quadrant Composite 262 600 303 280 1063 220 Vertical Soil Composite 0-6 inches 77 669 108 326 701 128 Vertical Soil Composite 6-12 inches 21 151 108 34 324 65 Vertical Soil Composite 12-18 inches 30 116 33 39 559 27 Vertical Soil Composite 18-24 inches 30 149 33 28 456 13 Vertical Soil Composite 24-30 inches 38 268 33 37 581 23 DR10020 DRK0058 DRK0059 DRK0060 FC10028 GUK0001 Surface Soil (0-1 inch) Quadrant Composite 2400 681 644 800 214 211 Vertical Soil Composite 0-6 inches 2175 289 406 341 478 166 Vertical Soil Composite 6-12 inches 2223 49 601 293 42 121 Vertical Soil Composite 12-18 inches 2630 17 88 43 45 44 Vertical Soil Composite 18-24 inches 665 16 22 15 49 33 Vertical Soil Composite 24-30 inches 116 18 28 23 74 47 LW30166 LWK0210 LWK0211 LWK0212 WHK0058 WHK0059 Surface Soil (0-1 inch) Quadrant Composite 731 452 274 588 1639 335 Vertical Soil Composite 0-6 inches 393 201 175 494 1934 417 Vertical Soil Composite 6-12 inches 38 52 14 317 435 139 Vertical Soil Composite 12-18 inches 14 45 14 26 281 71 Vertical Soil Composite 18-24 inches 13 21 14 15 218 NR Vertical Soil Composite 24-30 inches NR NR 12 15 210 NR LTK0002 PH20350 PH20499 PH20525 PH30701 PH40846 Surface Soil (0-1 inch) Quadrant Composite 248 516 267 564 406 222 Vertical Soil Composite 0-6 inches 227 600 706 520 201 590 Vertical Soil Composite 6-12 inches 94 136 1073 85 44 761 Vertical Soil Composite 12-18 inches 41 88 Refusal 30 32 277 Vertical Soil Composite 18-24 inches 24 66 Refusal 10 22 75 Vertical Soil Composite 24-30 inches 35 61 Refusal 13 21 64



Table 3 Lead Concentrations with Depth in the Yard Soil Borings

PHK0888 PHK0889 PHK0890 PHK0891 PHK0892 PHK0893 Surface Soil (0-1 inch) Quadrant Composite 1197 654 633 452 1944 1414 Vertical Soil Composite 0-6 inches 263 311 347 351 1242 2374 Vertical Soil Composite 6-12 inches 554 51 126 19 557 2579 Vertical Soil Composite 12-18 inches 443 15 265 14 95 5459 Vertical Soil Composite 18-24 inches 383 22 256 16 29 5344 Vertical Soil Composite 24-30 inches 397 11 297 18 45 3889 PHK0894 PHK0895 PHK0896 PHK0897 PHK0898 PHK0899 Surface Soil (0-1 inch) Quadrant Composite 541 522 804 511 668 1048 Vertical Soil Composite 0-6 inches 1566 526 1995 29 198 317 Vertical Soil Composite 6-12 inches 255 252 1530 15 14 33 Vertical Soil Composite 12-18 inches 136 284 866 16 13 15 Vertical Soil Composite 18-24 inches 74 216 34 15 14 16 Vertical Soil Composite 24-30 inches 57 15 42 15 12 12 PHK0900 PHK0901 PHK0902 PHK0903 Surface Soil (0-1 inch) Quadrant Composite 536 1585 802 288 Vertical Soil Composite 0-6 inches 357 1051 591 14 Vertical Soil Composite 6-12 inches 96 177 112 303 Vertical Soil Composite 12-18 inches 38 22 63 72 Vertical Soil Composite 18-24 inches 25 12 14 130 Vertical Soil Composite 24-30 inches 27 43 10 358 Notes: * Yard quadrant was remediated in 2001, original soil concentrations are assumed to be greater than

2,000 ppm. NR – no recovery

4.0 CONCLUSIONS

This subsurface soil investigation was conducted primarily to aide in refinement of the assumptions made in the Draft Feasibility Study for Residential Areas (OU-1) of the St. Francois County Mined Areas. The following statistics were drawn from the sample results and used to develop the alternatives in the Feasibility Study (NewFields 2011).

• Twelve (12) percent of the yard quadrants after a 1 foot excavation would have confirmation subgrade soil lead concentrations (measured in the next 6 inches) greater than 400 ppm.

• Seven (7) percent of the yard quadrants after a 1 foot excavation would have confirmation subgrade soil lead concentrations greater than 1,200 ppm.

• Five (5) percent of the excavations to 12 inches will require excavation to 18 inches before subgrade soil lead concentrations are below 1,200 ppm.

• Two (2) percent of the excavated areas would require excavation to 24 inches. At that depth, the subgrade lead concentration will be greater than 1,200 ppm.



The study results indicate that lead concentrations generally decrease with depth. Lead concentrations were greater than 1,200 ppm at the surface in 8 of 58 core samples (14%), in 10 of 58 core samples (17%) at 0-6 inches, in 3 of 57 core samples (5%) at 12-18 inches, in 2 of 56 core samples (4%) at 18-24 inches, and 1 of 54 core samples (2%) at 24-30 inches.

The secondary objectives of the study were:

• Potentially identifying the source or cause of elevated lead found in the subsurface (especially if lead concentrations are found at higher concentrations at depth compared to surface)

• Characterizing surface soil lead concentrations at yards that have not been characterized as part of the Interim or Halo Removal Actions.

The potential sources or cause of elevated lead in the subsurface could not cleanly be identified.

The characterization of surface soil lead concentrations in yards that were not part of the Interim or Halo Removal Actions was accomplished. In 43 of the 58 quadrants (84%) soil removal would be required based on a soil lead action level of 400 ppm.

5.0 REFERENCES

EPA, 2010a. Comments on the Draft Feasibility Study for Residential Areas, OU-1, Big River Mine Tailings, St. Francois County, Missouri. July 9, 2010.

EPA, 2010b. Regional Screening Levels for Chemical Contaminants at Superfund Sites. Developed by Oak Ridge National Laboratory under an Interagency Agreement with EPA. Available at http://epa-prgs.ornl.gov/chemicals/index.shtml. Dated November 2010 (website last updated December 29, 2010).

EPA, 2010c. Proposed Plan, Residential Property Soils – Operable Unit 1 at the Washington County Lead District – Potosi Superfund Site in Washington County, Missouri. June 15, 2010.

EPA, 2010d. Proposed Plan, Residential Property Soils – Operable Unit 1 at the Washington County Lead District – Richwoods Superfund Site in Washington County, Missouri. July 2, 2010.

EPA, 2010e. Proposed Plan, Residential Property Soils – Operable Unit 1 at the Washington County Lead District – Old Mines Superfund Site in Washington County, Missouri. July 2, 2010.



HUD, EPA, MDOH, Jasper and St. Francois County Health Departments, Doe Run, and Saint Louis University, 1997. The Jasper – St. Francois Lead Intervention Project. Working together to protect children’s health.

NewFields, 2006. Focused Remedial Investigation for Mined Areas in St. Francois County, Missouri. March 3, 2006.

NewFields, 2010. Feasibility Study for Residential Areas, St. Francois County Mined Areas (Big River Mine Tailings Site), Missouri. Draft dated June 15, 2010.

NewFields, 2011. Feasibility Study for Residential Areas (OU-1), St. Francois County Mined Areas (Big River Mine Tailings Site), Missouri. Dated July 6, 2011 submitted concurrently with this report.

Pacific Northwest National Laboratory (PNNL), 2010. Visual Sampling Plan (VSP) Version 6.0. http://vsp.pnl.gov/

Appendix A Detailed Areas of Figures

LegendSub-Figure Key

a - Bonne Terreb - Desloge, Park Hills, Leadington, and Gumboc - Leadwood, Frankclay, and Worthamd - Doe Run

0 6,000 12,000 18,000 24,0003,000Feet

Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds

Historic Railroads (inactive)

Railroad

NGS USA Topographic Maps St. Francois Co. Mined Areas

Index to Sub-Figures



0 1,000 2,000 3,000 4,000500Feet

Figure 2a:Bonne Terre

Average Surface Soil Lead Concentrationsin Yard Quadrant Samples

Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds



Average concentration of the yard quadrant samples: Front Yard Left (FL), Front Yard Right (FR), Back Yard Left (BL), and Back Yard Right (BR).



0 2,000 4,000 6,000 8,0001,000Feet

Figure 2b:Desloge, Park Hills, Leadington, and Gumbo


Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds

NGS USA Topographic MapsSt. Francois Co. Mined Areas




0 1,000 2,000 3,000 4,000500Feet

Figure 2c:Leadwood, Frankclay, and Wortham



Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds





0 1,000 2,000 3,000 4,000500Feet

Figure 2d:Doe Run



Response Area

Shafts

Smelters

Chat Piles

Tailing Ponds



BT40295

BTK0317BTK0316

BTK0315

BTK0314

BTK0313

BTK0312

BTK0311

BTK0310

BTK0309



0 1,000 2,000 3,000 4,000500Feet

Figure 3a:Bonne Terre

Subsurface Soil Sampling LocationsResponse Area

Shafts

Smelters

Chat Piles

Tailing Ponds



PH30701

PH20525PH20499

PHK0899

PH40846

PH20350

DL20257

DL10182

PHK0902PHK0901

PHK0900

PHK0898PHK0897

PHK0896

PHK0895

PHK0894

PHK0893

PHK0892

PHK0891

PHK0890

PHK0889

PHK0888

PHK0903

LTK0002

GUK0001

DLK0461

DLK0460

DLK0459

DLK0458

DLK0457

DLK0456

DLK0455

DLK0454

DLK0453

DLK0452

DL10162

DL00010



0 2,000 4,000 6,000 8,0001,000Feet

Figure 3b:Desloge, Park Hills, Leadington, and Gumbo


Shafts

Smelters

Chat Piles

Tailing Ponds


LW30166

WHK0059WHK0058

LWK0212

LWK0211

LWK0210

FC10028



0 1,000 2,000 3,000 4,000500Feet

Figure 3c:Leadwood, Frankclay, and Wortham


Shafts

Smelters

Chat Piles

Tailing Ponds


DR10020

DRK0060

DRK0059

DRK0058



0 1,000 2,000 3,000 4,000500Feet

Figure 3d:Doe Run


Shafts

Smelters

Chat Piles

Tailing Ponds


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