Mr. Norm E. Riley 1001 “1” Street In reply refer to SHEA ...€¦ · USPAS1NETAPP1\DEI\#SSFL...

$: Mr. Norm E. Riley 1001 “1” Street In reply refer to SHEA ...€¦ · USPAS1NETAPP1\DEI\#SSFL Files\6.0 Deliverables\Agency\RFI\#sitewide\SRAM\SRAM Rev 3\Rural Res RBSL TM (July$
The Boeing CompanySanta Susana Field Laborat5600 Woolsey Canyon RoadCanoga Park, CA 91304-1148

Via FedEx

July 13, 2009In reply refer to SHEA-108866

Mr. Norm E. Riley~ SSFL Program Director

California Dept. of Toxic Substances Control1001 “1” Streetaarzva P.O. Box 806Sacramento, CA 958 12-0806

Subject: Submittal of Rural Residential Risk-Based Screening Levels for Chemicalsin Soil, Draft Technical Memorandum, Santa Susana Field Laboratory

Dear Mr. Riley:

On behalf of The Boeing Company (Boeing), the National Aeronautics and SpaceAdministration (NASA), and the Department of Energy (DOE), Boeing hereby submits theabove-referenced draft technical memorandum describing procedures and results forcalculation of rural residential (agricultural) risk-based screening levels (RBSLs) forchemicals in soil. This technical memorandum was prepared pursuant to DTSC’s requestmade during recent meetings conducted regarding risk assessment requirements to complywith Senate Bill 990 (5B990).

This technical memorandum presents the rural residential RBSLs and the underlyingcalculations and assumptions for a representative list of chemicals. DTSC review, comment,and approval are needed prior to preparation of all chemical RBSLs required for the ruralresidential (agricultural) land use scenario to be included in future SSFL risk assessments asrequired by SB990. The Rural Residential RBSLs presented in this technical memorandumare compliant with DTSC specifications regarding SB990 requirements discussed duringrecent meetings.

Boeing, NASA, and DOE look forward to discussing this technical memorandum with yourteam. If you have any questions, please call me at (818) 466-8795.

Sincerely,

1’ Art LenoxEnvironmental RemediationEnvironment, Health and Safety

AJL:bjcAttachment

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RURAL RESIDENTIAL RISK-BASED SCREENING LEVELSFOR CHEMICALS IN SOILDRAFT TECHNICAL MEMORANDUMSANTA SUSANA FIELD LABORATORYVENTURA COUNTY, CALIFORNIA

Prepared For:

TILE BOEING COMPANY

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

DEPARTMENT OF ENERGY

Prepared By:

MWH618 Michillinda Aye, Suite 200Arcadia, CA 91007

July 2009

Ia aDixie A. Hambrick,Program Director

Prepared by:

Traci L. ThomasSenior Risk Assessor

Reviewed by:

Bruce A. Narloch, Ph.D., DARTRisk Assessment Project Director

Kris~i M. Rodriguez(J (_)Risk Assessor

eP.G. 5487

DRAFT

Rural Residential RBSLs for Chemicals in Soil Draft Technical Memorandum Santa Susana Field Laboratory, Ventura County, California July 2009

i

TABLE OF CONTENTS

Section No. Page No.

1.0 INTRODUCTION................................................................................................................ 1 1.1 Background ..................................................................................................................... 1 1.2 Purpose and Scope .......................................................................................................... 2

2.0 APPROACH ......................................................................................................................... 6 3.0 EXPOSURE ASSESSMENT .............................................................................................. 7

3.1 Potential Exposure Pathways for Soil ............................................................................. 7 3.2 Direct Soil Contact Pathways ......................................................................................... 8 3.3 Ingestion of Fruits and Vegetables ............................................................................... 13 3.4 Ingestion of Beef ........................................................................................................... 15 3.5 Ingestion of Milk........................................................................................................... 17 3.6 Ingestion of Poultry....................................................................................................... 20 3.7 Ingestion of Eggs .......................................................................................................... 22 3.8 Ingestion of Swine ........................................................................................................ 25 3.9 Ingestion of Fish ........................................................................................................... 27 3.10 Cumulative Rural Residential RBSL Equation ........................................................... 30 3.11 Suburban Residential RBSL Calculations .................................................................. 31 3.12 Exposure and Chemical-Specific Parameters ............................................................. 32

4.0 TOXICITY ASSESSMENT .............................................................................................. 33 5.0 SUBURBAN AND RURAL RESIDENTIAL RBSLs FOR CHEMICALS IN SOIL .. 34 6.0 UNCERTAINTY DISCUSSION ...................................................................................... 35 7.0 REFERENCES ................................................................................................................... 38 DRAFT


ii

LIST OF TABLES

Table 1 RME Exposure Parameters Used in Suburban and Rural Residential Risk-Based

Screening Level Calculations

Table 2 Chemical-Specific Parameters Used in Suburban and Rural Residential Risk-Based Screening Level Calculations

Table 3 Toxicity Values Used in Suburban and Rural Residential Risk-Based Screening Level Calculations

Table 4 Direct Soil Contact Pathway- Specific Suburban and Rural Residential Risk-Based Screening Levels Calculations

Table 5 Indirect Soil Pathway-Specific Rural Residential Risk-Based Screening Levels Calculations

Table 6 Cumulative Suburban and Rural Residential Risk-Based Screening Levels for Chemicals in Soil

LIST OF FIGURES

Figure 1 SSFL Regional Location Map

Figure 2 SSFL RFI Site Location Map

Figure 3 Conceptual Site Model for Hypothetical Future Rural Residents Exposed to Soil and Weathered Bedrock

LIST OF ATTACHMENTS

File 1 Suburban and Rural Residential Soil Risk-Based Screening Level Calculations (electronic copy)

USPAS1NETAPP1\DEI\#SSFL Files\6.0 Deliverables\Agency\RFI\#sitewide\SRAM\SRAM Rev 3\Rural Res RBSL TM (July 09)\Rural Res RBSL TM_071309

DRAFT


iii

LIST OF ACRONYMS AND ABBREVIATIONS

ATSDR Agency for Toxic Substances and Disease Registry Boeing The Boeing Company Cal-EPA California Environmental Protection Agency CHHSL California Human Health Screening Level CMI Corrective Measures Implementation CMS Corrective Measures Study CSM conceptual site model D&D decommissioning and decontamination DOE Department of Energy DTSC Department of Toxic Substances Control HEAST Health Effects Assessment Summary Table IRIS Integrated Risk Information System kg kilogram(s) L liter(s) m2 square meters mg/kg milligram(s) per kilogram MRL minimum risk level NASA National Aeronautics and Space Administration NCEA National Center for Environmental Assessment ORISE Oak Ridge Institute of Science and Education PPRTV Provisional Peer Reviewed Toxicity Values PRG Preliminary Remediation Goals RAGS Risk Assessment Guidance for Superfund RAIS Risk Assessment Information System RBSL risk-based screening level RCRA Resource Conservation and Recovery Act RFI RCRA Facility Investigation RME reasonable maximum exposure SB990 California Senate Bill 990 SRAM Standardized Risk Assessment Methodology

DRAFT


iv

LIST OF ACRONYMS AND ABBREVIATIONS (continued)

SSFL Santa Susana Field Laboratory UCL upper confidence limit USC unit soil concentration USEPA United States Environmental Protection Agency yr year(s)

DRAFT


1

1.0 INTRODUCTION

This technical memorandum presents the approach, methods and assumptions used in the

calculation of rural residential (agricultural) risk-based screening levels (RBSLs) for chemicals

in soil, hereafter referred to as rural residential RBSLs. These rural residential RBSLs for soil

have been developed to meet the requirements of California Senate Bill 990 (SB990), for the

Santa Susana Field Laboratory (SSFL), as specified by the California Environmental Protection

Agency (Cal-EPA) Department of Toxic Substances Control (DTSC). This document has been

prepared on behalf of The Boeing Company (Boeing), the National Aeronautics and Space

Administration (NASA), and the United States Department of Energy (DOE) in response to

DTSC’s request to review and approve rural residential RBSLs for soil.

1.1 BACKGROUND

The SSFL is located approximately 29 miles northwest of downtown Los Angeles, California, in

the southeast corner of Ventura County (Figure 1). The site is divided into four administrative

areas (Areas I, II, III, and IV) with undeveloped land areas to both the north and south (Figure 2).

Areas I, III, and IV are operated by Boeing. Area II is owned by NASA. Ninety acres of Area IV

were leased to DOE. The northern and southern undeveloped lands of the SSFL were not used

for industrial activities and are owned by Boeing.

Chemical investigation and cleanup at the SSFL is currently being performed as part of the

Resource Conservation and Recovery Act (RCRA) Corrective Action Program with oversight by

the DTSC. The SSFL RCRA Corrective Action Program is currently in the RCRA Facility

Investigation (RFI) phase. Subsequent phases include remedial alternatives evaluation in the

Corrective Measures Study (CMS), and the implementation of remedial actions in the Corrective

Measures Implementation (CMI) phases.

Currently the RCRA Corrective Action Program at the SSFL is being conducted under the

authority of Chapter 6.5 of Division 20 of the California Health and Safety Code (HSC) in

accordance with the Consent Order for Corrective Action, Docket No. P3-07/08-003, issued by

DTSC in 2007 (DTSC, 2007b). However, the 2007 Consent Order is in the process of being

DRAFT


2

revised and the regulatory framework for SSFL cleanup is planned to be transitioned from

RCRA Corrective Action to the California Superfund Remedial Investigation / Feasibility Study

(RI/FS) Process under authority of the Chapter 6.8 of the HSC. Thus, this technical

memorandum has been prepared to meet both RFI and RI requirements, and references to the

RCRA process/documentation herein will also be applied to future respective CERCLA

process/documentation.

The RFI/RI Sites identified for investigation at the SSFL are shown on Figure 2. The site

boundaries shown on this figure generally include the known or suspected chemical use

operational areas at the SSFL, and are not meant to represent the extent of sampling or

contamination. In many cases, environmental sampling is conducted outside of these site

boundaries to delineate the nature and extent of contamination.

Radiological investigation and cleanup at the SSFL is being performed by DOE. To date, 25 of

the 27 radiological facilities have been remediated and released for unrestricted use. Additional

radiological cleanup is on hold. Both buildings and land for DOE facilities within Area IV

undergo a formal closure process of decommissioning and decontamination (D&D) involving

cleanup, surveys by Boeing, surveys by a third party DOE contractor (usually the Oak Ridge

Institute of Science and Education [ORISE]), and the State Department of Public Health. Eleven

of the radiological facilities have also undergone validation surveys and/or document reviews by

the United States Environmental Protection Agency (USEPA). Documentation of this process

for all radiological facilities may be found at http://www.etec.energy.gov/Reading-

Room/DDTable.html.

1.2 PURPOSE AND SCOPE

Site-specific RBSLs for chemicals in soil at the SSFL have been developed for hypothetical

suburban residential and recreational exposure scenarios based on the risk assessment procedures

and equations provided in the DTSC-approved Standardized Risk Assessment Methodology

Work Plan, Revision 2 (MWH, 2005). The SRAM Revision 2 suburban residential RBSLs

developed previously were calculated separately for adults and children for both carcinogenic

DRAFT

http://www.etec.energy.gov/Reading-Room/DDTable.html

http://www.etec.energy.gov/Reading-Room/DDTable.html


3

and non-carcinogenic effects. These suburban residential RBSLs have been used in the SSFL

RFI process to 1) determine characterization completeness and 2) identify soil impact locations

for CMS recommendations. Although the SRAM Revision 2 suburban residential RBSLs have

been used in the RFI process, they have not been used in any previous human health or

ecological risk assessments completed for the various SSFL RFI/RI sites.

SB990 was passed by the California legislature and signed into law in October 2007, and is codified at California Health and Safety Code Section 25359.20. The portion of SB990 that refers to risk assessment and site cleanup states:

"In calculating risk, the cumulative risk from radiological and chemical contaminants at the site shall be summed, and the land use assumption shall be either suburban residential or rural residential (agricultural), whichever produces the lower permissible residual concentration for each contaminant. In the case of radioactive contamination, the department shall use as its risk range point of departure the concentrations in the Preliminary Remediation Goals (PRGs) issued by the Superfund Office of the USEPA in effect as of January 1, 2007." (acronyms and definitions inserted)

As indicated above, compliance with SB990 will require evaluation of human health risks

associated with potential exposures of a hypothetical, future rural resident to chemicals and

radionuclides in soil. Potential exposures of a rural resident to chemicals in soil at the SSFL are

planned to be evaluated using site-specific rural residential soil RBSLs developed using the

methodology presented herein. Potential exposures of a rural resident to radionuclides in soil at

the SSFL will be evaluated using PRGs issued by the Superfund Office of the USEPA in effect

as of January 1, 2007. Soil PRGs for radionuclides include direct and indirect soil exposure

pathways, as well as exposure pathways related to consumption of plants and animals that are

representative of a rural residential scenario. Because soil PRGs for radionuclides already exist,

they are not presented in this technical memorandum

This technical memorandum presents the approach, methods and assumptions to be used in the

calculation of rural residential RBSLs for chemicals in soil at the SSFL, and presents rural

residential soil RBSLs for a short list of chemical constituents. The short list of chemical

DRAFT


4

constituents for which rural residential soil RBSLs were calculated is generally representative of

the major risk drivers and/or risk contributors identified in risk assessments completed for

various SSFL RFI sites according to the SRAM, Revision 2 (MWH, 2005). The short list of

chemical risk drivers and/or risk contributors was determined based on the following pathways:

incidental ingestion of soil, dermal contact with soil, inhalation of dust, and inhalation of

chemical constituents in indoor and ambient air. These constituents are also generally considered

to be the primary chemical contaminants and potential risk drivers/contributors across the entire

SSFL. These selected constituents also represent the various chemical groups, i.e., metals,

volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), polychlorinated

biphenyls (PCBs), dioxin and furan compounds (dioxins), and pesticides/herbicides that will

provide insight into the rural residential soil RBSLs for that chemical group. The selected short

list of chemical constituents evaluated in this technical memorandum is provided in tables

presented in Sections 2 through 4.

In addition to rural residential soil RBSLs, this technical memorandum also provides updated

suburban residential soil RBSLs calculated for an age-adjusted composite adult and child

resident for carcinogenic effects and a child resident for non-carcinogenic effects. The updated

suburban residential soil RBSLs are presented for comparison to the rural residential RBSLs for

the short list of representative chemicals.

The suburban and rural residential RBSLs for chemicals in soil presented herein are planned to

be used in future SSFL risk assessments to estimate suburban and rural residential risks from

potential exposure to chemicals in soil. A detailed description of the methods that will be used to

estimate risks using these RBSLs will be provided in the SRAM, Revision 3. These RBSLs are

health-conservative and should not be considered de facto cleanup standards and should not be

applied as such. These RBSLs will be used to estimate human health risks and hazards.

Chemical concentrations detected above RBSLs will not automatically trigger a response action.

The final decisions regarding remediation will be based on a weight-of-evidence evaluation

performed using the nine National Contingency Plan (NCP) balancing criteria.

DRAFT


5

This technical memorandum was prepared for DTSC review and approval prior to the

preparation and submittal of SRAM Revision 3, so that the SSFL addresses DTSC’s

requirements in a timely manner and to avoid delay in completion of the RFI/RI for the SSFL.

Once DTSC approves the rural residential soil RBSLs for the short list of chemicals presented

herein, and the methods and assumptions used in their derivation, rural residential RBSLs will be

calculated for the remaining chemical constituents detected in soil at the SSFL.

The scope of this technical memorandum is limited to the calculation of updated suburban

residential RBSLs for chemicals in soil based on direct contact pathways (i.e., incidental

ingestion of soil, dermal contact with soil, and inhalation of particulates), and rural residential

RBSLs for chemicals in soil based on direct contact pathways (i.e., incidental ingestion of soil,

dermal contact with soil, and inhalation of particulates) and consumption of biota (i.e., plants and

animals). Vapor pathways (i.e., indoor air) have not been included in the updated suburban

residential soil RBSL calculations or in the rural residential soil RBSL calculations. For future

risk assessments, risks from vapor pathways will be evaluated separately using soil vapor RBSLs

and soil vapor data (either measured concentrations or concentrations extrapolated from soil or

groundwater concentrations), and site-specific indoor air models. Potential risks estimated for

the indoor air pathway will thus be available for consideration in cleanup decisions.

Suburban and rural residential RBSLs for domestic use of groundwater have not been calculated

because groundwater at the SSFL is not currently used as a drinking water source, and it is

anticipated that deed restrictions will prevent the use of SSFL groundwater for drinking water in

the future.

Rural residential RBSLs for incidental ingestion and dermal contact with surface water will be

presented in the SRAM, Revision 3. For sites where surface water is present, potential rural

residential risks from exposure to surface water will be estimated using surface water RBSLs.

Potential rural residential risks estimated for surface water pathways will then be available for

consideration in cleanup decisions.

DRAFT


6

As described above, this technical memorandum does not address radiological constituents. For

evaluating potential rural residential exposures to radiological constituents in soil, the PRGs

issued by the Superfund Office of the USEPA in effect as of January 1, 2007 will be used.

Procedures for estimating risk from radiological constituents and cumulative risk from

radiological and chemical constituents will be described in the SRAM, Revision 3.

2.0 APPROACH

The approach used in the derivation of rural residential RBSLs for chemical constituents in soil

at the SSFL is consistent with general methods for the calculation of RBSLs for soil described in

USEPA’s Risk Assessment Guidance for Superfund: Volume 1, Human Health Evaluation

Manual, Part B - Development of Risk-based Preliminary Remediation Goals (RAGS, Part B;

USEPA, 1991). Direct soil exposure pathways include ingestion of soil, dermal contact with

soil, and inhalation of dust. Updated suburban residential RBSLs for the direct soil exposure

pathways and rural residential RBSLs for the direct soil exposure pathways and homegrown

fruits and vegetables, beef, milk, poultry, eggs, and swine were calculated using risk assessment

procedures and equations provided in the online Risk Assessment Information System (RAIS,

2009). These equations are based on guidance in Risk Assessment Guidance for Superfund:

Volume 1, Human Health Evaluation Manual, Part A - Baseline Risk Assessment (RAGS,

Part A; USEPA, 1989). The RBSLs for homegrown fish were calculated using risk assessment

procedures and equations provided by RAIS and the equations presented in the online USEPA

PRGs for radionuclides (USEPA, 2009a).

The soil PRGs for radionuclides were calculated by the USEPA for an age-adjusted composite

adult and child resident using the equations and parameters provided on the online USEPA PRG

calculator for radionuclides (USEPA, 2009a). Therefore, suburban and rural residential RBSLs

for chemicals will also use age-adjusted composites. Soil PRGs for radionuclides are only

calculated based on carcinogenic effects. Soil PRGs for chemicals are calculated based on both

carcinogenic and noncarcinogenic effects, as applicable. Therefore, suburban and rural

residential soil RBSLs were estimated separately for an age-adjusted composite adult and child

resident for carcinogenic effects and for a child resident for non-carcinogenic effects using the

DRAFT


7

equations presented in Section 3.0, below. The rural resident soil RBSLs were calculated in this

manner in order to be consistent with PRGs for radionuclides and to allow the summation of

chemical and radionuclide risks into a total cumulative chemical-radionuclide risk estimate. This

approach is also consistent with the procedures and equations presented in the online RAIS

(RAIS, 2009).

3.0 EXPOSURE ASSESSMENT

Exposure assessment begins with the development of a site-specific conceptual site model

(CSM) that describes the relationship between contaminants source(s), known or potentially

impacted environmental media, potentially exposed receptors, and complete and incomplete

exposure pathways between site contaminants and receptors. A generalized CSM for the rural

residential scenario at the SSFL is graphically depicted in Figure 3. Potentially complete

exposure pathways for these receptors include direct contact with soil and weathered bedrock, as

well as indirect exposure to constituents in soil via uptake into plants, beef cattle, milk, chickens,

eggs, swine, and fish. These direct and indirect soil exposure pathways were used in the

derivation of rural residential RBSLs for chemicals in soil, as described further in the following

subsections.

3.1 POTENTIAL EXPOSURE PATHWAYS FOR SOIL

At the direction of DTSC, the following default exposure pathways were included in the calculation of soil RBSLs for hypothetical future rural residents:

• Incidental ingestion of soil and weathered bedrock • Dermal contact with soil • Inhalation of dust • Ingestion of homegrown produce (i.e., fruits and vegetables) • Ingestion of home-raised beef • Ingestion of milk from home-raised cows • Ingestion of home-raised poultry

• Ingestion of eggs from home-raised poultry

DRAFT


8

• Ingestion of home-raised swine

• Ingestion of home-raised fish

The above exposure pathways were included in the calculation of rural residential RBSLs for

chemicals in soil because they are included in USEPA's PRGs for radionuclides (USEPA,

2009a). However, it should be noted that not all of these exposure pathways are considered

practical under a future rural residential scenario at the SSFL (refer to Section 6.0), and including

all of these exposure pathways in the rural residential RBSL calculations is extremely

conservative.

3.2 DIRECT SOIL CONTACT PATHWAYS

Direct soil contact pathways for the rural residential scenario include incidental ingestion of soil

and weathered bedrock, dermal contact with soil, and inhalation of dust. Rural residential soil

RBSLs for carcinogenic effects were estimated for the incidental ingestion of soil and weathered

bedrock pathway using the following equations:

mgkgIFEFCSFoATTR

RBSLresso

cing /10 6

_−×××

×=

where:

c

csoc

a

asoaresso BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLing = rural residential soil RBSL for incidental ingestion of soil and weathered bedrock (mg/kg)

TR = target cancer risk of 1 x 10-6 (unitless)

ATc = averaging time for carcinogens (year x day/year)

CSFo = oral cancer slope factor (mg/kg-day)-1

EF = exposure frequency (day/year)

IFso_res = age-adjusted composite resident soil ingestion factor (mg-year/kg-day)

DRAFT


9

EDa = adult exposure duration (years)

IRso_a = adult resident soil ingestion rate (mg/day)

EDc = child exposure duration (years)

IRso_c = child resident soil ingestion rate (mg/day)

BWa = adult body weight (kg)

BWc = child body weight (kg)

Rural residential soil RBSLs for non-carcinogenic effects were estimated for the incidental

ingestion of soil and weathered bedrock pathway using the following equation:

mgkgIRRfDo

EDEF

BWATTHQRBSL

csoc

cning

/101 6_

−××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

where:


THQ = target hazard quotient of 1 (unitless)

ATn = averaging time for non-carcinogens (year x day/year)




RfDo = chronic oral reference dose (mg/kg-day)

IRso_c = child resident soil ingestion rate (mg/day)

DRAFT


10

RBSLs for carcinogenic effects were estimated for the dermal contact soil pathway using the

following equations:

mgkgABSDFEFCSFATTR

RBSLdressod

cder /10 6

_−××××

×=

where:

c

ccc

a

aaaresso BW

AFSAEDBW

AFSAEDDF

××+

××=_

and where:

RBSLder = rural residential soil RBSL for incidental ingestion of soil and weathered bedrock (mg/kg)



CSFd = dermal cancer slope factor (mg/kg-day)-1


DFso_res = age-adjusted composite resident dermal factor (mg-year/kg-day)

ABSd = dermal absorption factor (unitless)

EDa = adult exposure duration (years)

SAa = adult resident skin surface area for dermal exposure (cm2/day)

AFa = adult resident soil adherence factor (mg/cm2)


SAc = child resident skin surface area for dermal exposure (cm2/day)

AFc = child resident soil adherence factor (mg/cm2)



DRAFT


11

Rural residential soil RBSLs for non-carcinogenic effects were estimated for the dermal contact

soil pathway using the following equation:

mgkgABSAFSARfDd

EDEF

BWATTHQRBSL

dccc

cnder

/101 6−××××××

××=

where:

RBSLder = rural residential soil RBSL for incidental ingestion of soil and weathered bedrock (mg/kg)






RfDd = chronic dermal reference dose (mg/kg-day)

SAc = child resident skin surface area for dermal exposure (cm2/day)

AFc = child resident soil adherence factor (mg/cm2)

ABSd = dermal absorption factor (unitless)

Rural residential soil RBSLs for carcinogenic effects were estimated for the inhalation of dust

pathway using the following equation:

hoursdayETEDPEFVF

EFmggIUR

ATTRRBSL

res

cinh

/24111/1000 ×××⎟

⎠⎞

⎜⎝⎛ +×××

×=

μ

where:

RBSLinh = rural residential soil RBSL for inhalation of dust (mg/kg)



DRAFT


12

IUR = inhalation unit risk (μg/m3)-1


VF = volatilization factor (m3/kg)

PEF = particulate emission factor (m3/kg)

EDres = age-adjusted composite resident exposure duration (years)

ET = resident exposure time (hours/day)

Rural residential soil RBSLs for non-carcinogenic effects were estimated for the inhalation of

dust pathway using the following equation:

⎟⎠⎞

⎜⎝⎛ +×⎟⎟

⎠

⎞⎜⎜⎝

⎛×⎟⎠⎞

⎜⎝⎛×××

×=

PEFVFRfChoursdayETEDEF

ATTHQRBSL

c

ninh 111/

241

where:

RBSLinh = rural residential soil RBSL for inhalation of dust (mg/kg)




EDc = child resident exposure duration (years)

ET = resident exposure time (hours/day)

RfC = chronic inhalation reference concentration (mg/m3)

VF = volatilization factor (m3/kg)

PEF = particulate emission factor (m3/kg)\

DRAFT


13

3.3 INGESTION OF FRUITS AND VEGETABLES

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of fruits

and vegetables pathway using the following equations:

MLFBvC

RBSLwet

fvfv +=

where:

( ) presvresf

cfv CFIFIFCSFoEF

ATTRC

×+×××

=__

and where:

c

cfc

a

afaresf BW

IREDBW

IREDIF __

_

×+

×=

and where:

c

cvc

a

avaresv BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLfv = rural residential soil RBSL for fruits and vegetables pathway (mg/kg)

Cfv = target constituent concentration in fruits and vegetables (mg/kg)

Bvwet = soil to plant uptake wet weight (kg/kg)

MLF = plant mass loading factor (unitless)





IFf_res = age-adjusted composite resident fruit ingestion factor (kg-year/kg-day)

DRAFT


14

IFv_res = age-adjusted composite resident vegetable ingestion factor (kg-year/kg-day)

CFp = fraction of produce consumed that is contaminated (unitless)

EDa = exposure duration (years)

IRf_a = adult resident fruit ingestion rate (kg/day)

EDc = exposure duration (years)

IRf_c = child resident fruit ingestion rate (kg/day)



IRv_a = adult resident vegetable ingestion rate (kg/day)

IRv_c = child resident vegetable ingestion rate (kg/day)

Rural residential soil RBSLs for non-carcinogenic effects were estimated for the ingestion of

fruits and vegetables pathway using the following equations:

MLFBvC

RBSLwet

fvfv +=

where:

( ) pcvcfc

cnfv

CFIRIRRfDo

EDEF

BWATTHQC

×+×⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

__1

and where:

RBSLfv = rural residential soil RBSL for fruits and vegetables pathway (mg/kg)

Cfv = target constituent concentration in fruits and vegetables (mg/kg)

Bvwet = soil to plant uptake wet weight (kg/kg)

MLF = plant mass loading factor (unitless)



DRAFT


15

BWc = body weight (kilogram[s] [kg])


EDc = exposure duration (years)

RfDo = oral chronic reference dose (mg/kg-day)

IRf_c = fruit ingestion rate (kg/day)

IRv_c = vegetable ingestion rate (kg/day)

CFp = fraction of produce consumed that is contaminated (unitless)

3.4 INGESTION OF BEEF

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of beef

pathway using the following equations:

( )( ) ( )[ ]bbbdrybbbb

bb fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

bresb

cb CFIFCSFoEF

ATTRC

××××

=_

and where:

c

cbc

a

abaresb BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLb = rural residential soil RBSL for beef pathway (mg/kg)

Cb = target constituent concentration in beef (mg/kg)

Fb = beef transfer coefficient (day/kg)

Qpb = quantity of pasture ingested – beef cattle (kg/day)

fpb = fraction of year animal is on site – beef cattle (unitless)

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16

fsb = fraction of animal’s food is from site – beef cattle (unitless)

Bvdry = soil to plant uptake dry weight (kg/kg)

MLFb = plant mass loading factor –beef pasture (unitless)

Qsb = quantity of soil ingested – beef cattle (kg/day)





IFb_res = age-adjusted composite resident beef ingestion factor (kg-year/kg-day)

CFb = fraction of beef consumed that is contaminated (unitless)

EDa = adult resident exposure duration (years)

IRb_a = adult resident beef ingestion rate (kg/day)


IRb_c = child resident beef ingestion rate (kg/day)

BWa = adult resident body weight (kg)

BWc = child resident body weight (kg)


beef pathway using the following equations:

( )( ) ( )[ ]bbbdrybbbb

bb fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

bcbc

cnb

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

DRAFT


17

and where:


Cb = target constituent concentration in beef (mg/kg)

Fb = beef transfer coefficient (day/kg)

Qpb = quantity of pasture ingested – beef cattle (kg/day)

fpb = fraction of year animal is on site – beef cattle (unitless)

fsb = fraction of animal’s food is from site – beef cattle (unitless)


MLFb = plant mass loading factor –beef pasture (unitless)

Qsb = quantity of soil ingested – beef cattle (kg/day)







IRb_c = child resident beef ingestion rate (kg/day)

CFb = fraction of beef consumed that is contaminated (unitless)

3.5 INGESTION OF MILK

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of milk


( )( ) ( )[ ]mmmdrymmmm

mm fpQsMLFBvfsfpQpF

CRBSL

×++××××=

DRAFT


18

where:

mresm

cm CFIFCSFoEF

ATTRC

××××

=_

and where:

c

cmc

a

amaresm BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLm= rural residential soil RBSL for milk pathway (mg/kg)

Cm = target constituent concentration in milk (mg/kg)

Fm = milk transfer coefficient (day/kg)

Qpm = quantity of pasture ingested – dairy cattle (kg/day)

fpm = fraction of year animal is on site – dairy cattle (unitless)

fsm = fraction of animal’s food is from site – dairy cattle (unitless)


MLFm = plant mass loading factor –dairy pasture (unitless)

Qsm = quantity of soil ingested – dairy cattle (kg/day)





IFm_res = age-adjusted composite resident milk ingestion factor (kg-year/kg-day)

CFm = fraction of milk consumed that is contaminated (unitless)


IRm_a = adult resident milk ingestion rate (kg/day)


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19

IRm_c = child resident milk ingestion rate (kg/day)



Rural residential soil RBSLs for non-carcinogenic effects were estimated for the ingestion of milk pathway using the following equations:

( )( ) ( )[ ]mmmdrymmmm

mm fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

mcmc

cnm

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

and where:

Cm = target constituent concentration in milk (mg/kg)

Fm = milk transfer coefficient (day/kg)

Qpm = quantity of pasture ingested – dairy cattle (kg/day)

fpm = fraction of year animal is on site – dairy cattle (unitless)

fsm = fraction of animal’s food is from site – dairy cattle (unitless)


MLFm = plant mass loading factor –dairy pasture (unitless)

Qsm = quantity of soil ingested – dairy cattle (kg/day)







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20

IRm_c = child resident milk ingestion rate (kg/day)

CFm = fraction of milk consumed that is contaminated (unitless)

3.6 INGESTION OF POULTRY

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of poultry


( )( )[ ]( )pppdrypppp

pp fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

presp

cp CFIFCSFoEF

ATTRC

××××

=_

and where:

c

cpc

a

aparesp BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLp = rural residential soil RBSL for poultry pathway (mg/kg)

Cp = target constituent concentration in poultry (mg/kg)

Fp = poultry transfer coefficient (day/kg)

Qpp = quantity of pasture ingested – poultry (kg/day)

Fpp = fraction of year animal is on site – poultry (unitless)

Fsp = fraction of animal’s food is from site – poultry (unitless)


MLFp = plant mass loading factor –poultry pasture (unitless)

Qsp = quantity of soil ingested – poultry (kg/day)


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21




IFp_res = age-adjusted composite resident poultry ingestion factor (kg-year/kg-day)

CFp = fraction of poultry consumed that is contaminated (unitless)


IRp_a = adult resident poultry ingestion rate (kg/day)


IRp_c = child resident poultry ingestion rate (kg/day)




poultry pathway using the following equations:

( )( )[ ]( )pppdrypppp

pp fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

pcpc

cnp

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

and where:


Cp = target constituent concentration in poultry (mg/kg)

Fp = poultry transfer coefficient (day/kg)


fpp = fraction of year animal is on site – poultry (unitless)

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22

fsp = fraction of animal’s food is from site – poultry (unitless)










IRp_c = child resident poultry ingestion rate (kg/day)

CFp = fraction of poultry consumed that is contaminated (unitless)

3.7 INGESTION OF EGGS

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of eggs


( )( )[ ]( )pppdrypppe

ee fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

erese

ce CFIFCSFoEF

ATTRC

××××

=_

and where:

c

cec

a

aearese BW

IREDBW

IREDIF __

_

×+

×=

DRAFT


23

and where:

RBSLe = rural residential soil RBSL for egg pathway (mg/kg)

Ce = target constituent concentration in egg (mg/kg)

Fe = egg transfer coefficient (day/kg)











IFe_res = age-adjusted composite resident egg ingestion factor (kg-year/kg-day)

CFe = fraction of eggs consumed that are contaminated (unitless)


IRe_a = adult resident poultry ingestion rate (kg/day)


IRe_c = child resident poultry ingestion rate (kg/day)



DRAFT


24


eggs pathway using the following equations:

( )( )[ ]( )pppdrypppe

ee fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

ecec

cne

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

and where:


Ce = target constituent concentration in egg (mg/kg)

Fe = egg transfer coefficient (day/kg)













DRAFT


25

IRe_c = child resident egg ingestion rate (kg/day)

CFe = fraction of eggs consumed that are contaminated (unitless)

3.8 INGESTION OF SWINE

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of swine


( )( ) ( )[ ]sssdryssss

ss fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

sress

cs CFIFCSFoEF

ATTRC

××××

=_

and where:

c

csc

a

asaress BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLs = rural residential soil RBSL for swine pathway (mg/kg)

Cs = target constituent concentration in swine (mg/kg)

Fs = swine transfer coefficient (day/kg)

Qps = quantity of pasture ingested – swine (kg/day)

fps = fraction of year animal is on site – swine (unitless)

fss = fraction of animal’s food is from site – swine (unitless)


MLFs = plant mass loading factor –swine pasture (unitless)

Qss = quantity of soil ingested – swine (kg/day)


DRAFT


26




IFs_res = age-adjusted composite resident swine ingestion factor (kg-year/kg-day)

CFs = fraction of swine consumed that is contaminated (unitless)


IRs_a = adult resident swine ingestion rate (kg/day)


IRs_c = child resident swine ingestion rate (kg/day)




swine pathway using the following equations:

( )( ) ( )[ ]sssdryssss

ss fpQsMLFBvfsfpQpF

CRBSL

×++××××=

where:

scsc

cns

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

and where:


Cs = target constituent concentration in swine (mg/kg)

Fs = swine transfer coefficient (day/kg)

Qps = quantity of pasture ingested – swine (kg/day)

fps = fraction of year animal is on site – swine (unitless)

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27

fss = fraction of animal’s food is from site – swine (unitless)


MLFs = plant mass loading factor –swine pasture (unitless)

Qss = quantity of soil ingested – swine (kg/day)







IRs_c = child resident swine ingestion rate (kg/day)

CFs = fraction of swine consumed that is contaminated (unitless)

3.9 INGESTION OF FISH

Rural residential soil RBSLs for carcinogenic effects were estimated for the ingestion of fish


;

where:

firesfi

cfi CFIFCSFoEF

ATTRC

××××

=_

DRAFT


28

and where:

c

cfic

a

afiaresfi BW

IREDBW

IREDIF __

_

×+

×=

and where:

RBSLfi = rural residential soil RBSL for fish pathway (mg/kg)

Cfi = target constituent concentration in fish (mg/kg)

Kd = soil to water partition coefficient (L/kg)

σ = total soil porosity (L water/L pore space)

S = fraction water content (L water/L pore space)

ρ = soil bulk density (kg/L soil)

BCF = bioconcentration factor (kg/ L)

As = surface area of contaminated site (square meters [m2])

Aw = surface area of watershed (m2)





IFfi_res = age-adjusted composite resident fish ingestion factor (kg-year/kg-day)

CFfi = fraction of fish consumed that is contaminated (unitless)

EDa = adult resident exposure duration (year)

IRfi_a = adult resident fish ingestion rate (kg/ day)

EDc = child resident exposure duration (year)

IRfi_c = child resident fish ingestion rate (kg/ day)



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29

Rural residential soil RBSLs for non-carcinogenic effects were estimated for the ingestion of fish


;

where:

ficfic

cnfi

CFIRRfDo

EDEF

BWATTHQC

××⎟⎟⎠

⎞⎜⎜⎝

⎛××

××=

_1

and where:


Cfi = target constituent concentration in fish (mg/kg)

Kd = soil to water partition coefficient (L/kg)

σ = total soil porosity (L water/L pore space)

S = fraction water content (L water/L pore space)

ρ = soil bulk density (kg/L soil)

BCF = bioconcentration factor (kg/ L)

As = surface area of contaminated site (square meters [m2])

Aw = surface area of watershed (m2)





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30

EDc = child resident exposure duration (year)


IRfi_c = child resident fish ingestion rate (kg/ day)

CFfi = fraction of fish consumed that is contaminated (unitless)

3.10 CUMULATIVE RURAL RESIDENTIAL RBSL EQUATION

Cumulative rural residential RBSLs for chemicals in soil were calculated based on a combination

of the pathway-specific RBSLs presented in Sections 3.2 through 3.9. Because each pathway-

specific rural residential RBSL was calculated using a target cancer risk of 1 x 10-6 or a hazard

quotient of 1, merely summing all of the pathway-specific RBSLs for a given chemical in soil

would result in a cumulative RBSL that equates to a cancer risk higher than 1 x 10-6 or a hazard

quotient above 1. In order to calculate a cumulative rural residential RBSL that represents a

chemical concentration in soil that is protective of all exposure pathways at a cumulative target

cancer risk of 1 x 10-6 or a hazard index of 1, the target risk or hazard quotient for each pathway-

specific RBSL was apportioned across all pathways. Therefore, cumulative rural residential

RBSLs for soil were estimated using the following equations:

SUMRBSLRR

1=

where:

+⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟

⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟

⎟⎠

⎞⎜⎜⎝

⎛=

bfvinhdering RBSLRBSLRBSLRBSLRBSLSUM 11111

⎟⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛+⎟

⎟⎠

⎞⎜⎜⎝

⎛+⎟⎟

⎠

⎞⎜⎜⎝

⎛

fisepm RBSLRBSLRBSLRBSLRBSL11111

DRAFT


31

and where:

RBSLRR = cumulative rural residential soil RBSL (mg/kg)

SUM = sum of 1/pathway-specific RBSLs


RBSLder = rural residential soil RBSL for dermal contact with soil (mg/kg)

RBSLinh = suburban residential soil RBSL for inhalation of dust (mg/kg)

RBSLfv = rural residential soil RBSL for fruit and vegetable pathway (mg/kg)


RBSLm = rural residential soil RBSL for milk pathway (mg/kg)





Pathway-specific and cumulative soil RBSL calculations for a hypothetical future rural resident are included in the attached File 1.

3.11 SUBURBAN RESIDENTIAL RBSL CALCULATIONS

Updated cumulative suburban residential RBSLs for chemicals in soil were calculated based on a

combination of the pathway-specific RBSLs presented in Section 3.2 and the cumulative RBSL

equation presented in Section 3.10. As indicated in Table 1 and Section 3.2, the updated

cumulative suburban residential RBSLs were calculated using updated toxicity criteria and

default parameters and equations from RAIS (RAIS, 2009), and they reflect an age-adjusted

composite resident. Consequently, the updated suburban residential RBSLs are not directly

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32

comparable to the suburban residential RBSLs estimated previously based on the equations and

procedures provided in the SRAM, Revision 2.

Pathway-specific and cumulative soil RBSL calculations for a hypothetical future suburban

resident are included in the Attachment File 1. Consistent with standard published suburban

residential screening levels, including Cal-EPA CHHSLs and USEPA Regional Screening

Levels, suburban residential RBSLs presented herein do not include the fruits and vegetables

consumption pathway. This approach is consistent with current risk assessment practice where

the majority of the residential population does not grow a significant proportion of the fruits and

vegetables they consume. Also as described in Section 5.0, most rural residential RBSLs are

significantly lower than the suburban residential RBSLs. Thus, rural residential risk estimates

will significantly exceed risk estimates for the suburban resident. Therefore, exclusion of the

fruit and vegetable consumption pathway from the suburban residential RBSL has no material

bearing on the ultimate SSFL cleanup.

3.12 EXPOSURE AND CHEMICAL-SPECIFIC PARAMETERS

The exposure parameters and rationale for the rural residential pathway are presented in Table 1.

As requested by DTSC, the exposure parameters used in the rural residential RBSL calculations

are default parameters from either the online RAIS (RAIS, 2009) or USEPA PRGs for

radionuclides (USEPA, 2009a). A value of 30 years was used as the exposure duration for the

composite adult and child resident as recommended by RAGS (USEPA, 1989) and RAIS

(RAIS 2009).

Chemical-specific parameters including physical-chemical properties, uptake factors, transfer

coefficients, and fish bioconcentration factors are presented in Table 2. Chemical-specific

parameters used in the rural residential RBSL calculations were either obtained from the

following sources, or calculated using equations from these sources:

• RAIS (http://rais.ornl.gov/cgi-bin/prg/PRG_search?select=chem); 2009

• Human Health Risk Assessment Protocol (HHRAP) Companion Database; USEPA, 2005a.

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http://rais.ornl.gov/cgi-bin/prg/PRG_search?select=chem


33

• Human Health Assessment Protocol for Hazardous Waste Combustion Facilities; USEPA, 2005b.

• McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463.

• International Atomic Energy Agency. 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environment. Tech. Rep. Ser. No. 364, Vienna, Austria.

Chemical-specific parameters are not provided in the sources listed above for every constituent

and every exposure pathway included in the rural residential RBSL calculations. For example, no

chemical-specific parameters could be found for perchlorate; and poultry, egg, and swine transfer

coefficients could not be found for several metals. It should be noted that this is also the case for

USEPA's PRGs for radionuclides (USEPA, 2009a) (i.e., some pathways are omitted from the

cumulative soil PRG calculation when insufficient parameters are available to quantify those

pathways). The source of each chemical-specific parameter is provided in the footnotes to

Table 2.

4.0 TOXICITY ASSESSMENT

Toxicity values for the RBSL calculations were obtained from the following hierarchy of toxicity

information sources:

1. California Environmental Protection Agency Office of Environmental Health Hazard Assessment (OEHHA, 2009)

2. Integrated Risk Information System (IRIS; USEPA 2009b)

3. Provisional Peer Reviewed Toxicity Values (PPRTV), as cited in the Regional Screening Levels Tables (USEPA, 2009c)

4. Agency for Toxic Substances and Disease Registry (ATSDR) Minimum Risk Levels (MRLs), as cited in the Regional Screening Levels Tables (USEPA, 2009c)

5. Health Effects Assessment Summary Table (HEAST; USEPA 1997)

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34

6. National Center for Environmental Assessment (NCEA), as cited in USEPA Region 9 PRG tables (USEPA, 2004a)

7. Other sources

The toxicity values used in the RBSL calculations are presented in Table 3.

5.0 SUBURBAN AND RURAL RESIDENTIAL RBSLS FOR CHEMICALS IN SOIL

Pathway-specific suburban and rural residential soil RBSLs for the direct soil pathways for the

short list of SSFL risk drivers and risk contributors are presented in Table 4. Pathway-specific

rural residential soil RBSLs for the indirect soil pathways for the short list of SSFL risk drivers

and risk contributors are presented in Table 5. Cumulative rural residential soil RBSLs for the

short list of SSFL risk drivers and risk contributors are presented in Table 6. Suburban residential

soil RBSLs are also presented in Table 6 for purposes of comparison. As described in Section

3.12, chemical-specific parameters were not available for all chemicals and all pathways. When

a parameter was not found in the published literature for a given chemical and pathway, that

pathway was excluded from the RBSL calculation. This process is consistent with the manner in

which radionuclide PRGs were calculated by the USEPA (USEPA, 2009a).

A comparison of rural residential RBSLs and suburban residential RBSLs for the short list of

SSFL chemical risk drivers or contributors shows that the rural residential RBSLs are always

lower than suburban residential RBSLs. The range of differences between suburban residential

and rural residential RBSLs is from approximately 1 order of magnitude (10-times) to

approximately 4 orders of magnitude (10,000 times), with the majority of differences between 2

to 3 orders or magnitude (100 to 1,000-times) lower. There may be other chemical constituents

not included in the short list that have an even greater difference between suburban and rural

residential RBSLs. In addition, all eight metals evaluated in this technical memorandum and the

dioxin congeners (i.e., the constituents with SSFL-specific background concentrations), have

rural residential RBSLs that are below maximum detected background concentration in soil (see

Table 6). Methods and assumptions that contribute to the highly conservative nature of the rural

residential RBSLs presented herein are described in Section 6.0, below.

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35

Considering collectively the assumptions used for their derivation, the RBSLs presented in this

memorandum are health-conservative and should not be considered de facto cleanup standards

and should not be applied as such. These RBSLs will be used to estimate human health risks and

hazards. Chemical concentrations detected above RBSLs will not automatically trigger a

response action. The final decisions regarding remediation will be based on a weight-of-

evidence evaluation performed using the nine NCP balancing criteria.

6.0 UNCERTAINTY DISCUSSION

There is some degree of uncertainty associated with nearly all of the exposure assumptions,

exposure parameter values, chemical-specific parameter values, and toxicity values used in the

calculation of rural residential RBSLs for chemicals in soil. Uncertainties in exposure

assumptions, exposure parameters, and toxicity values typically err on the conservative side and

result in health protective estimates of risks, or in this case, RBSLs. Following are some of the

major uncertainties associated with the rural residential soil RBSL calculations:

• There is a high degree of uncertainty associated with the exposure pathways assumed for the rural residential soil RBSL calculations. It is unlikely that the SSFL could support all of the animals assumed to be present for the rural residential soil RBSL calculations (i.e., beef cattle, dairy cattle, poultry, swine, and fish) given site-specific topographic, climactic, bedrock, and forage constraints. Additionally, it is not possible that the RFI/RI sites could support all the exposure pathways as hundreds of acres would be needed for all agricultural activities. Examples are provided below. o Beef consumption pathway. It was assumed in the calculation of pathway-specific,

rural residential RBSLs for consumption of beef that a beef cow obtains 100 percent of their dietary requirements from an RFI/RI site. Based on information obtained from the Bureau of Land Management (BLM), a grazing permit would require 3 – 6 acres of grazing land per cow per month (or 36 – 72 acres of grazing land per cow per year). Because the SSFL is dominated by scrub brush, the amount of land required to support the foraging requirements for a single cow could be 120 acres or more. If an RFI/RI site is equivalent to the minimum lot size of 5 acres allowed under current zoning (R-A-5ac), then the fraction of a beef cow’s forage obtained from the site would be 5 acres / 120 acres = 0.042 (or about 4%). The remaining 96% of a cow’s dietary requirements would have to be met by supplemental, non-contaminated feed. Thus, the pathway-specific rural residential RBSLs for the beef consumption pathway are overly conservative by a factor of at least 100% / 4% = 25-fold.

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36

o Milk consumption pathway. It was assumed in the calculation of pathway-specific, rural residential RBSLs for milk consumption that a dairy cow obtains 100 percent of their dietary requirements from an RFI/RI site. As described above, if an RFI/RI site is equivalent to the minimum lot size of 5 acres allowed under current zoning (R-A-5ac), then the fraction of a dairy cow’s forage obtained from the site would be 5 acres / 120 acres = 0.042 (or about 4%). If the RFI/RI site is supporting both a beef cow and a dairy cow (as assumed in the calculation of the cumulative rural residential RBSLs presented herein), then the fraction of a dairy cow’s forage obtained from the site is 4% / 2 = 2%. The remaining 98% of a dairy cow’s dietary requirements would have to be met by supplemental, non-contaminated feed. Thus, pathway-specific rural residential RBSLs for the milk consumption pathway are overly conservative by a factor of at least 100% / 2% = 50-fold.

o Poultry consumption pathway. It was assumed in the calculation of pathway-specific,

rural residential RBSLs for poultry consumption that chickens obtain 100% of their dietary requirements from an RFI/RI site. Based on information obtained from the American Pastured Poultry Producers Association (Jean Nick, 2008), free-range chickens can obtain up to 5 – 20% of their calories from ideal pasture, which has abundant clover, weed seeds, and insects. Native vegetation communities at the SSFL are primarily comprised of scrub and other arid vegetation which provides limited caloric value. In addition, large areas of many SSFL sites contain extensive bedrock outcrops. Therefore, in order for chickens to obtain even the lower percentage of their calories from pasture (i.e., 5%) , the land would have to be cleared, irrigated, and converted from native vegetation to non-native, annual grassland. It would be unlikely for supplemental feed to be grown on site because the specialized equipment and amount of land required would make it cost-prohibitive. Most, if not all, poultry producers buy specialized supplemental feed (Jean Nick, 2008). Based on the above, home-raised poultry are unlikely to obtain their total dietary requirements from a particular RFI/RI site.

o Swine consumption pathway. It was assumed in the calculation of pathway-specific, rural residential RBSLs for swine consumption that locally harvested swine (i.e., domesticated pigs and hogs) obtain 100% of their dietary requirements from an RFI/RI site. It should be noted that domesticated swine are not grazers (such as beef and dairy cattle) and lack the tusks present in wild pigs and (boars) to allow them to grub in the subsurface for plant roots and animals. As a result, domesticated swine are unlikely to obtain their total dietary requirements from a particular RFI/RI site.

o Fish consumption pathway. It was assumed in the calculation of pathway-specific, rural residential RBSLs for fish consumption that default bioconcentration factors (BCFs) based on log Kow are applicable. It should be noted, however, that BCFs based on log Kow for chemicals that are readily metabolized are highly conservative because such chemicals are not anticipated to bioaccumulate or biomagnify in the food chain. In addition, it was assumed in the calculation of pathway-specific, rural residential RBSLs for fish consumption that sediment pore water concentrations are in equilibrium with pond water concentrations. This is a highly conservative

DRAFT


37

assumption and results in 10-to-100-fold overestimation of risks associated with the fish consumption pathway.

• There is some uncertainty in the exposure parameters used in the rural residential soil

RBSL calculations. In most cases, exposure parameters are upper-bound estimates that result in conservative estimates of exposure that are protective of human health.

• Some chemical-specific parameter values for several metals and perchlorate could not be found in the sources listed in Section 3.11. When an uptake factor, transfer coefficient, or fish bioconcentration factor was not available for a given chemical, that pathway was excluded from the RBSL calculation. Therefore, the lack of chemical-specific parameters for some constituent’s results in some uncertainty in the rural residential soil RBSLs estimated for these constituents. Since no uptake factors, transfer coefficients, or fish bioconcentration factors could be found for perchlorate, the rural residential soil RBSL is equivalent to the suburban residential soil RBSL for this constituent. The lack of poultry, egg, and swine transfer coefficients for some metals is not considered to be as significant as the lack of chemical-specific parameters for perchlorate because the rural residential RBSLs estimated for metals are below SSFL background concentrations. Therefore, cumulative RBSLs that are even further below background concentrations because they include all potential pathways are not important because they are not pertinent to remedial decisions.

• Uncertainties are introduced into the toxicity assessment when constituents lack toxicity values. For some constituents lacking toxicity values, surrogate values were used (see Table 3). In such instances, there is greater uncertainty than when toxicity values were developed specifically for a compound.

• Reference doses typically have safety factors of 100 to 1,000 incorporated into their development. These safety factors account for the potential for humans to be more sensitive to the chemical than the laboratory animal, for some humans to be more sensitive to the chemical than the general population, and accounts for chronic exposure durations when the toxicity experiments were conducted over shorter durations, etc. This creates many conditions that can lead to an overestimate of risk. For example, humans can also be less sensitive to the chemical than the laboratory animal.

• The cancer slope factors are upper-bound values that fit carcinogenicity data to a specific mathematical function. The function selected is in itself generally conservative with respect to other mathematical functions that fit the data equally well.

• For potential carcinogens, current regulatory guidelines (USEPA, 1989) use an extremely conservative approach in which it is assumed that any level of exposure to a carcinogen could hypothetically cause cancer (i.e., a non-threshold effect). This is contrary to the traditional toxicological approach to toxic chemicals, in which finite thresholds are identified below which toxic effects are not expected to occur.

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38

7.0 REFERENCES

Department of Toxic Substances Control (DTSC). 2009. Revised California Human Health Screening Level for Lead. Review Draft. May 14.

International Atomic Energy Agency. 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environment. Tech. Rep. Ser. No. 364, Vienna, Austria.

Jean Nick (personal communication, 2008). American Pastured Poultry Producers Association.

MWH Americas, Inc. (MWH). 2005. Standardized Risk Assessment Methodology (SRAM) Work Plan, Santa Susana Field Laboratory, Ventura County, CA. Revision 2 – Final. September. HDMSE00198.

McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463.

Office of Environmental Health Hazard Assessment (OEHHA). 2009. Toxicity Criteria Database, online. http://www.oehha.ca.gov/risk/ChemicalDB/index.asp, accessed in July 2009.

Risk Assessment Information System (RAIS). 2009. http://rais.ornl.gov/homepage/ tm/for_ag.shtml, accessed in July 2009.

United States Environmental Protection Agency (USEPA). 2009a. Preliminary Remediation Goals for Radionuclides. http://epa-prgs.ornl.gov/radionuclides/equations.shtml, accessed in July 2009.

USEPA, 2009b. Integrated Risk Information System (IRIS) Database, accessed in July 2009.

USEPA, 2009c. Regional Screening Levels for Chemical Contaminants at Superfund Sites (http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/index.htm)

USEPA, 2005a. Human Health Risk Assessment Protocol (HHRAP) Companion Database. EPA530-R-05-006.

USEPA, 2005b. Human Health Assessment Protocol for Hazardous Waste Combustion Facilities. Office of Solid Waste and Emergency Response. September. EPA530-R-05-006.

USEPA, 2004a. Region 9 Preliminary Remediation Goals.

USEPA, 2004b. Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual, Part E, Supplemental Guidance for Dermal Risk Assessment. Office of Emergency and Remedial Response, Washington, D.C. July. EPA 530-R-05-006.

USEPA, 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites.

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http://www.oehha.ca.gov/risk/ChemicalDB/index.asp

http://rais.ornl.gov/homepage/%20tm/for_ag.shtml

http://rais.ornl.gov/homepage/%20tm/for_ag.shtml

http://epa-prgs.ornl.gov/radionuclides/equations.shtml


39

USEPA, 1997. Health Effects Summary Tables. FY 1997 Update. Office of Solid Waste and Emergency Response. July. EPA-540-R-97-036.

USEPA, 1991. Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual, Part B, Development of Risk-based Preliminary Remediation Goals. Office of Emergency and Remedial Response, Washington, D.C.

USEPA, 1989. Risk Assessment Guidance for Superfund, Volume I, Human Health Evaluation Manual, Part A. Office of Emergency and Remedial Response, Washington, D.C.

Van den Berg et al. 2006. The 2005 World Health Organization Re-evaluation of Human and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-like Compounds. ToxSci Advance Access. 7 July 2006.

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DRAFT

TABLES

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Table 1

RME Exposure Parameters and Rationale for Rural Residential Risk-Based Screening Level Calculations

Age-AdjustedAdult Child Composite

Parameter Units Resident Resident Resident Rationale

GeneralBW = body weight kg 70 15 NA (a)ED = exposure duration years 24 6 30 (a)EF = exposure frequency days/year 350 350 350 (a)ATc = averaging time for carcinogens year x days/year 25550 25550 25550 = 70 * 365ATn = averaging time for non-carcinogens year x days/year 8760 2190 NA = ED * 365

Ingestion of SoilIRso = soil ingestion rate mg/day 100 200 NA (a)IFso_res = age-adjusted soil ingestion factor mg-year/kg-day NA NA 114 (a)

Dermal Contact with SoilSAso = skin surface area for dermal exposure cm2/day 5700 2800 NA (a)AFso = soil adherence factor mg/cm2 0.07 0.2 NA (a)DFso_res = age-adjusted dermal factor mg-year/kg-day NA NA 361 (a)

Inhalation of Dust

PEF = particulate emission factor m3/kg 3.3E+09 3.3E+09 3.3E+09 (b)

Ingestion of Fruits and VegetablesCFp = fraction of produce consumed that is contaminated unitless 1 1 1 (a)IRf = fruit ingestion rate kg/day 0.0562 0.0148 NA (a)IRv = vegetable ingestion rate kg/day 0.0285 0.0104 NA (a)IFf_res =age-adjusted fruit ingestion factor kg-year/kg-day NA NA 0.025 (a)IFv_res = age-adjusted vegetable ingestion factor kg-year/kg-day NA NA 0.014 (a)_

MLF = plant mass-loading factor unitless 0.26 0.26 0.26 (a)

Ingestion of BeefCFb = fraction of beef consumed that is contaminated unitless 1 1 1 (a)fpb = fraction of year animal is on site - beef cattle unitless 1 1 1 (a)fsb = fraction of animal's food is on site - beef cattle unitless 1 1 1 (a)IRb = beef ingestion rate kg/day 0.138 0.0129 NA (a)IFb_res = age-adjusted beef ingestion factor kg-year/kg-day NA NA 0.052 (a)

MLFb = plant mass-loading factor - beef pasture unitless 0.25 0.25 0.25 (a)Qpb = quantity of pasture ingested - beef cattle kg/day 11.77 11.77 11.77 (a)Qsb = quantity of soil ingested - beef cattle kg/day 0.39 0.39 0.39 (a)

Ingestion of MilkCFm = fraction of milk consumed that is contaminated unitless 1 1 1 (a)fpm = fraction of year animal is on site unitless 1 1 1 (a)fsm = fraction of animal's food is on site unitless 1 1 1 (a)IRm = milk ingestion rate kg/day 0.615 0.265 NA (a)IFm_res = age-adjusted milk ingestion factor kg-year/kg-day NA NA 0.32 (a)MLFm = plant mass-loading factor - pasture unitless 0.25 0.25 0.25 (a)Qpm = quantity of pasture ingested - dairy cattle kg/day 16.9 16.9 16.9 (a)Qsm = quantity of soil ingested - dairy cattle kg/day 0.41 0.41 0.41 (a)

Rural Res RBSL TM Page 1 of 2 Table 1_rural res exposure param.xls

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Table 1

RME Exposure Parameters and Rationale for Rural Residential Risk-Based Screening Level Calculations

Age-AdjustedAdult Child Composite

Parameter Units Resident Resident Resident Rationale

Ingestion of PoultryCFp = fraction of poultry consumed that is contaminated unitless 1 1 1 (a)Fpp = fraction of year animal is on site - poultry unitless 1 1 1 (a)Fsp = fraction of animal's food is on site - poultry unitless 1 1 1 (a)IRp = poultry ingestion rate kg/day 0.098 0.014 NA (c)IFp_res = age-adjusted poultry ingestion factor kg-year/kg-day NA NA 0.039 (a)MLFp = plant mass-loading factor - poultry pasture unitless 0.25 0.25 0.25 (a)Qpp = quantity of pasture ingested - poultry kg/day 0.2 0.2 0.2 (c)Qsp = quantity of soil ingested - poultry kg/day 0.022 0.022 0.022 (c)

Ingestion of EggsCFe = fraction of eggs consumed that are contaminated unitless 1 1 1 (a)IFe_res = age-adjusted egg ingestion factor kg-year/kg-day NA NA 0.017 (a)IRe = egg ingestion rate kg/day 0.041 0.0063 NA (c)

Ingestion of SwineCFs = fraction of swine consumed that is contaminated unitless 1 1 1 (a)fps = fraction of year animal is on site unitless 1 1 1 (a)fss = fraction of animal's food is on site unitless 1 1 1 (a)IRs = pork ingestion rate kg/day 0.0759 0.0123 NA (c)IFs_res = age-adjusted swine ingestion factor kg-year/kg-day NA NA 0.031 (a)MLFs = plant mass-loading factor - pasture unitless 0.25 0.25 0.25 (a)Qps = quantity of pasture ingested - swine kg/day 4.7 4.7 4.7 (c)

( )Qss = quantity of soil ingested - swine kg/day 0.37 0.37 0.37 (c)

Ingestion of FishAs = surface area of contaminated site m2 10000 10000 10000 (c)Aw = surface area of watershed m2 100000 100000 100000 (c)CFfi = fraction of fish consumed that is contaminated unitless 1 1 1 (c)IRfi = fish ingestion rate kg/day 0.13 0.018 NA (c)IFfi_res = age-adjusted fish ingestion factor kg-year/kg-day NA NA 0.050 (c)

S = fraction water content L water/L pore space 0.30 0.30 0.30 (c)

ρ = soil bulk density kg/L soil 1.5 1.5 1.5 (c)

σ = total soil porosity L water/L pore space 0.50 0.50 0.50 (c)

Notes:kg = kilogram(s)L = liter(s)mg = milligram(s)m = meter(s)NA = not applicableRME = reasonable maximum exposure

(a)(b) Calculated with equations as provided in USEPA's (2002) Soil Screening Guidance using site-specific wind speed and emission source area.(c) EPA PRG calculator for radionuclides (http://epa-prgs.ornl.gov/cgi-bin/radionuclides/rprg_search) default parameter.

RAIS (http://rais.ornl.gov/cgi-bin/prg/PRG_search) default parameter.

Rural Res RBSL TM Page 2 of 2 Table 1_rural res exposure param.xls

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Table 2

Chemical-Specific Parameters Used in Suburban and Rural Residential Risk-Based Screening Level Calculations

Analyte

Log of a

Octanol-Water

Partition Coefficient

Organic a

Carbon Partition

Coefficient

Soil to Plant a

Uptake Wet Weight

Soil to Plant a

Uptake Dry Weight

Beef a

Transfer Coefficient

Milk a


Poultry b


Egg b


Swine b


Fish b

Bioconcentration Factor

Soil to Water b


Dermal Absorption

Fraction

Volitilization c Factor

Henry's Law a

Constant Diffusivity a

in AirDiffusivity a

in WaterApparent d

Diffusivity

log Kow Koc Bvwet Bvdry Fb Fm Fp Fe Fs BCF Kd ABSd VF H ' Dia Diw DA

(unitless) (L/kg) (kg/kg) (kg/kg) (day/kg) (day/kg) (day/kg) (day/kg) (day/kg) (L/kg) (L/kg) (unitless) (m3/kg) (unitless) (cm2/s) (cm2/s) (cm2/s)Inorganic CompoundsAluminum NA NA 1.0E-03 4.0E-03 1.5E-03 2.0E-04 na na na 5.0E+02 1.5E+03 0.01 NA NA NA NA NAAntimony NA NA 1.0E-02 5.0E-02 4.0E-05 2.5E-05 na na na 4.0E+01 4.5E+01 0.01 NA NA NA NA NAArsenic NA NA 1.0E-02 4.0E-02 2.0E-03 6.0E-05 na na na 1.1E+02 2.9E+01 0.03 NA NA NA NA NACadmium NA NA 1.4E-01 5.5E-01 4.0E-04 1.0E-03 1.1E-01 2.5E-03 1.9E-04 9.1E+02 7.5E+01 0.001 NA NA NA NA NALead NA NA 7.6E-04 9.0E-02 4.0E-04 3.0E-04 na na na 9.0E-02 9.0E+02 0.01 NA NA NA NA NAMercury NA NA 3.0E-01 1.0E+00 1.0E-02 4.7E-04 3.0E-02 e na na 1.0E+03 a 1.0E+03 0.01 NA NA NA NA NASelenium NA NA 1.0E-01 5.0E-01 1.0E-01 1.0E-02 1.1E+00 1.1E+00 1.9E-01 1.3E+02 5.0E+00 0.01 NA NA NA NA NAThallium NA NA 1.0E-03 4.0E-03 4.0E-02 2.0E-03 na na na 1.0E+04 7.1E+01 0.01 NA NA NA NA NAZinc NA NA 2.6E-01 9.9E-01 1.0E-01 1.0E-02 8.8E-03 8.8E-03 1.3E-04 2.1E+03 6.2E+01 0.01 NA NA NA NA NA

Volatile Organic Compounds1,1-Dichloroethene NA NA 7.0E-01 3.4E+00 1.6E-06 5.0E-07 2.5E-03 1.4E-03 4.1E-03 8.3E+00 1.2E-01 0.1 7.8E+02 1.1E+00 8.6E-02 1.1E-05 1.2E-02Benzene NA NA 4.7E-01 2.3E+00 3.1E-06 9.9E-07 2.5E-03 1.4E-03 4.1E-03 8.3E+00 1.2E-01 0.1 1.3E+03 2.3E-01 9.0E-02 1.0E-05 4.1E-03cis-1,2-Dichloroethene NA NA 6.1E-01 3.0E+00 2.0E-06 6.3E-07 1.8E-03 1.0E-03 3.0E-03 5.8E+00 7.1E-02 0.1 1.3E+03 1.7E-01 8.8E-02 1.1E-05 3.9E-03Methylene chloride NA NA 1.4E+00 6.7E+00 5.0E-07 1.6E-07 6.5E-04 3.7E-04 1.1E-03 2.0E+00 2.4E-02 0.1 1.2E+03 1.3E-01 1.0E-01 1.3E-05 4.7E-03Tetrachloroethene NA NA 2.4E-01 1.2E+00 1.0E-05 3.1E-06 1.2E-02 6.9E-03 2.0E-02 8.3E+01 3.1E-01 0.1 1.4E+03 7.2E-01 5.1E-02 9.5E-06 3.6E-03Trichloroethene NA NA 3.1E-01 1.5E+00 6.3E-06 2.0E-06 3.8E-03 2.2E-03 6.3E-03 1.4E+01 4.1E-01 0.1 1.7E+03 4.0E-01 6.9E-02 1.0E-05 2.5E-03Vinyl Chloride NA NA 1.2E+00 5.9E+00 6.3E-07 2.0E-07 7.8E-04 4.4E-04 1.3E-03 2.4E+00 3.7E-02 0.1 6.2E+02 1.1E+00 1.1E-01 1.2E-05 1.8E-02

Semi-Volatile Organic CompoundsBenzo(a)anthracene NA NA 3.8E-03 1.9E-02 1.3E-02 4.0E-03 2.9E-02 1.7E-02 4.8E-02 4.9E+03 6.0E+04 0.15 NA NA NA NA NABenzo(a)pyrene NA NA 2.2E-03 1.1E-02 3.1E-02 9.9E-03 2.8E-02 1.6E-02 4.5E-02 8.3E+03 1.6E+05 0.15 NA NA NA NA NABenzo(b)fluoranthene NA NA 2.2E-03 1.1E-02 3.1E-02 9.9E-03 2.7E-02 1.5E-02 4.4E-02 1.0E+04 1.0E+04 0.15 NA NA NA NA NABenzo(k)fluoranthene NA NA 8.8E-04 4.3E-03 1.6E-01 5.0E-02 2.7E-02 1.5E-02 4.4E-02 9.9E+03 1.9E+05 0.15 NA NA NA NA NADibenz(a,h)anthracene NA NA 8.8E-04 4.3E-03 1.6E-01 5.0E-02 2.3E-02 1.3E-02 3.7E-02 2.0E+04 5.8E+05 0.15 NA NA NA NA NAPhenanthrene NA NA 1.7E-02 8.2E-02 1.0E-03 3.1E-04 2.5E-02 1.4E-02 4.1E-02 5.8E+02 3.7E+03 0.15 2.8E+06 1.7E-03 3.5E-02 6.7E-06 8.7E-10

Energetic ConstituentsPerchlorate NA NA na na na na na na na na na 0.01 NA NA NA NA NA

Pesticides4,4'-DDT NA NA 1.6E-03 7.8E-03 5.7E-02 1.8E-02 2.4E-02 1.4E-02 3.9E-02 1.7E+04 4.0E+05 0.05 NA NA NA NA NAAldrin NA NA 1.4E-01 6.9E-01 2.5E-05 7.9E-06 3.0E-02 1.7E-02 4.9E-02 3.4E+03 3.7E+05 0.05 NA NA NA NA NA

HerbicidesMCPP 3.1E+00 4.9E+01 2.4E-01 1.2E+00 1.0E-05 3.1E-06 9.2E-03 f 5.3E-03 f 1.5E-02 f 3.2E+00 a 4.9E-01 g 0.05 NA NA NA NA NA

PCDD/PCDFs2,3,7,8-TCDD NA NA 8.8E-04 4.3E-03 1.6E-01 5.0E-02 1.9E-02 1.1E-02 3.2E-02 3.4E+04 3.9E+04 0.03 NA NA NA NA NA1,2,3,7,8-PeCDD NA NA 1.3E-03 6.5E-03 7.9E-02 2.5E-02 2.1E-02 1.2E-02 3.5E-02 2.6E+04 2.7E+04 0.03 NA NA NA NA NA1,2,3,4,7,8-HxCDD 7.8E+00 b NA 2.3E-04 h 1.1E-03 i 1.6E+00 j 5.0E-01 k 8.1E-03 4.6E-03 1.3E-02 5.2E+03 3.9E+05 0.03 NA NA NA NA NA

Rural Res RBSL TM Page 1 of 3 Table 2_chemical-specific parameters.xlsDRAFT

Table 2


Analyte

Log of a

Octanol-Water


Organic a

Carbon Partition

Coefficient

Soil to Plant a

Uptake Wet Weight

Soil to Plant a

Uptake Dry Weight

Beef a


Milk a


Poultry b


Egg b


Swine b


Fish b


Soil to Water b


Dermal Absorption

Fraction


Henry's Law a


in AirDiffusivity a

in WaterApparent d

Diffusivity


(unitless) (L/kg) (kg/kg) (kg/kg) (day/kg) (day/kg) (day/kg) (day/kg) (day/kg) (L/kg) (L/kg) (unitless) (m3/kg) (unitless) (cm2/s) (cm2/s) (cm2/s)1,2,3,6,7,8-HxCDD 7.3E+00 b NA 4.5E-04 h 2.2E-03 i 5.0E-01 j 1.6E-01 k 1.3E-02 7.6E-03 2.2E-02 2.5E+04 1.2E+05 0.03 NA NA NA NA NA1,2,3,7,8,9-HxCDD 7.3E+00 b NA 4.5E-04 h 2.2E-03 i 5.0E-01 j 1.6E-01 k 1.3E-02 7.6E-03 2.2E-02 2.5E+04 1.2E+05 0.03 NA NA NA NA NA1,2,3,4,6,7,8-HpCDD 8.0E+00 b NA 1.8E-04 h 8.7E-04 i 2.5E+00 j 7.9E-01 k 6.5E-03 3.7E-03 1.1E-02 2.8E+03 6.2E+05 0.03 NA NA NA NA NAOCDD NA NA 6.2E-05 3.1E-04 1.5E+01 4.8E+00 5.1E-03 2.9E-03 8.3E-03 1.5E+03 9.8E+05 0.03 NA NA NA NA NAOCDD NA NA 6.2E 05 3.1E 04 1.5E+01 4.8E+00 5.1E 03 2.9E 03 8.3E 03 1.5E+03 9.8E+05 0.03 NA NA NA NA NA2,3,7,8-TCDF NA NA 3.2E-03 1.6E-02 1.7E-02 5.2E-03 2.7E-02 1.5E-02 4.4E-02 9.9E+03 7.8E+03 0.03 NA NA NA NA NA1,2,3,7,8-PeCDF NA NA 8.9E-04 4.4E-03 1.5E-01 4.9E-02 1.9E-02 1.1E-02 3.2E-02 3.4E+04 3.8E+04 0.03 NA NA NA NA NA2,3,4,7,8-PeCDF NA NA 7.5E-04 3.7E-03 2.1E-01 6.6E-02 2.3E-02 1.3E-02 3.7E-02 2.0E+04 1.9E+04 0.03 NA NA NA NA NA1,2,3,4,7,8-HxCDF 7.0E+00 b NA 6.7E-04 h 3.3E-03 i 2.5E-01 j 7.9E-02 k 1.7E-02 9.6E-03 2.8E-02 4.9E+04 6.2E+04 0.03 NA NA NA NA NA1,2,3,6,7,8-HxCDF 7.0E+00 b NA 6.7E-04 h 3.3E-03 i 2.5E-01 j 7.9E-02 k 1.7E-02 9.6E-03 2.8E-02 4.9E+04 6.2E+04 0.03 NA NA NA NA NA2,3,4,6,7,8-HxCDF 7.0E+00 b NA 6.7E-04 h 3.3E-03 i 2.5E-01 j 7.9E-02 k 1.7E-02 9.6E-03 2.8E-02 4.9E+04 6.2E+04 0.03 NA NA NA NA NA1,2,3,7,8,9-HxCDF 7.0E+00 b NA 6.7E-04 h 3.3E-03 i 2.5E-01 j 7.9E-02 k 1.7E-02 9.6E-03 2.8E-02 4.9E+04 6.2E+04 0.03 NA NA NA NA NA1,2,3,4,6,7,8-HpCDF 7.4E+00 b NA 3.9E-04 h 1.9E-03 i 6.3E-01 j 2.0E-01 k 1.2E-02 6.9E-03 2.0E-02 1.8E+04 1.5E+05 0.03 NA NA NA NA NA1,2,3,4,7,8,9-HpCDF 7.4E+00 b NA 3.9E-04 h 1.9E-03 i 6.3E-01 j 2.0E-01 k 1.2E-02 6.9E-03 2.0E-02 1.8E+04 1.5E+05 0.03 NA NA NA NA NAOCDF NA NA 7.9E-05 3.9E-04 1.0E+01 3.1E+00 6.5E-03 3.7E-03 1.1E-02 2.8E+03 6.2E+05 0.03 NA NA NA NA NA

Polychlorinated Biphenyls (PCBs)Aroclor 1248 6.3E+00 4.4E+04 3.3E-03 1.6E-02 1.6E-02 5.0E-03 2.5E-02 f 1.4E-02 f 4.0E-02 f 6.3E+04 a 4.4E+02 g 0.15 NA NA NA NA NAAroclor 1254 NA NA 2.6E-03 1.3E-02 2.5E-02 7.9E-03 2.3E-02 1.3E-02 3.7E-02 8.4E+04 2.5E+04 0.15 NA NA NA NA NAAroclor 1254 NA NA 2.6E-03 1.3E-02 2.5E-02 7.9E-03 2.3E-02 1.3E-02 3.7E-02 8.4E+04 2.5E+04 0.15 NA NA NA NA NAAroclor 1260 8.3E+00 2.1E+05 5.9E-04 2.9E-03 3.1E-01 9.9E-02 5.1E-03 f 2.9E-03 f 8.3E-03 f 4.9E+03 a 2.1E+03 g 0.15 NA NA NA NA NA

Notes:cm2 = centimeters squaredkg = kilogramL = literm3 = cubic metersmg = milligramsNA = not applicable in the calculations of rural residential risk-based screening levels (RBSLs).na = not availables = second

a Unless otherwise noted, values are obtained from online RAIS (http://rais.ornl.gov/cgi-bin/prg/PRG_search?select=chem) chemical-specific factors, accessed in b Unless otherwise noted, values are obtained from Human Health Risk Assessment Protocol Companion Database , USEPA, 2005a.c Calculated using Equation 4-8 (VF = (Q/C x ((3.14 * Da x T)1/2) * 10-4)/(2 * ρb * DA) from Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites, USEPA, 2002; where:

Poultry Transfer Coefficient = 10log Bafat x 0.14;Egg Transfer Coefficient - 10log Bafat x 0.08; or

e International Atomic Energy Agency. 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environment . Tech. Rep. Ser. No. 364, Vienna, Austria.f Calculated using the following equations from Appendix A of Human Health Assessment Protocol for Hazardous Waste Combustion Facilities, USEPA, 2005b:

Calculated using Equation 4-8 (VF = (Q/C x ((3.14 Da x T) ) 10 )/(2 ρb DA) from Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites, USEPA, 2002; where:DA = (θa

10/3 * Di_a * (H' + θw10/3) * Di_w)/n2)/(ρb * Kd + θw + θa * H')

d Calculated using Equation 4-8 (VF = (Q/C x ((3.14 x Da x T)1/2) x 10-4)/(2 x rb x DA) from Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites, USEPA, 2002.


Table 2


Analyte

Log of a

Octanol-Water


Organic a

Carbon Partition

Coefficient

Soil to Plant a

Uptake Wet Weight

Soil to Plant a

Uptake Dry Weight

Beef a


Milk a


Poultry b


Egg b


Swine b


Fish b


Soil to Water b


Dermal Absorption

Fraction


Henry's Law a


in AirDiffusivity a

in WaterApparent d

Diffusivity


(unitless) (L/kg) (kg/kg) (kg/kg) (day/kg) (day/kg) (day/kg) (day/kg) (day/kg) (L/kg) (L/kg) (unitless) (m3/kg) (unitless) (cm2/s) (cm2/s) (cm2/s)Swine Transfer Coefficient = 10log Bafat x 0.23; where:

log Bafat = -0.099 x (log Kow)2 + 1.07 x log Kow - 3.56 for analytes with log Kow values between -0.67 and 8.2. Transfer Coefficients for analytes with log Kow values less than -0.67 were calculated using a log Kow value of -0.67. Transfer Coefficients for analytes with log Kow values greater than 8.2 were calculated using a log Kow value of 8.2 (USEPA, 2005b).

g C l l d i h f ll i i f H H l h A P l f H d W C b i F ili i USEPA 2005b Kd K f A d f l l f 0 01 d f h f

j Calculated using equation (2.5 x 10-8 x Kow) from McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463. k Calculated using equation (7.9*10-9*Kow) from McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463.

g Calculated using the following equation from Human Health Assessment Protocol for Hazardous Waste Combustion Facilities, USEPA, 2005b: Kd = Koc x foc. A default value of 0.01 was used for the foc.h Calculated using equation (7.7 x Kow-0.58) from McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463.i Calculated using equation (38 x Kow-0.58) from McKone, T. E. 1994. Uncertainty and variability in human exposures to soil contaminants through home-grown food: a Monte Carlo assessment. Risk Anal. 14(4):449-463.


Table 3

Toxicity Values Used in Suburband and Rural Residential Risk-Based Screening Level Calculations

Oral CSF (mg/kg-day)-1 Dermal CSF (mg/kg-day)-1 Inhalation URF (μg/m3)-1 Oral Reference Dose (mg/kg-day) Dermal Reference Dose (mg/kg-day) Inhalation RfC (mg/m3)Analyte GI ABS a Value Source Value Source Value Source Value Source Value Source Value Source

Inorganic CompoundsAluminum 100% NTV NTV NTV 1.0E+00 PPRTV 1.0E+00 route-to-route 5.0E-03 PPRTVAntimony 15% NTV NTV NTV 4.0E-04 IRIS 2009 6.0E-05 route-to-route NTVArsenic 95% 1.5E+00 OEHHA 2009 1.5E+00 route-to-route 3.3E-03 OEHHA 2009 3.0E-04 IRIS 2009 3.0E-04 route-to-route 1.5E-05 OEHHA 2009Cadmium 2.5% NTV NTV 4.2E-03 OEHHA 2009 1.0E-03 IRIS 2009 2.5E-05 route-to-route 1.0E-05 ATSDR 2009Lead 100% 8.5E-03 OEHHA 2009 8.5E-03 route-to-route NTV NTV NTV NTVMercury 7% NTV NTV NTV 3.0E-04 IRIS 2009 2.1E-05 route-to-route 3.0E-05 OEHHA 2009Selenium 55% NTV NTV NTV 5.0E-03 IRIS 2009 5.0E-03 route-to-route 2.0E-02 Cal-EPA 2009Thallium 100% NTV NTV NTV 6.5E-05 IRIS 2009 6.5E-05 route-to-route NTVZinc 100% NTV NTV NTV 3.0E-01 IRIS 2009 3.0E-01 route-to-route NTV

Energetic ConstituentsPerchlorate 100% NTV NTV NTV 7.0E-04 IRIS 2009 7.0E-04 route-to-route NTV

Volatile Organic Compounds1,1-Dichloroethene 100% NTV NTV NTV 5.0E-02 IRIS 2009 5.0E-02 route-to-route 2.0E-01 IRIS 2009Benzene 100% 1.0E-01 OEHHA 2009 1.0E-01 route-to-route 2.9E-05 OEHHA 2009 4.0E-03 IRIS 2009 4.0E-03 route-to-route 6.0E-02 OEHHA 2009cis-1,2-Dichloroethene 100% NTV NTV NTV 1.0E-02 PPRTV 1.0E-02 route-to-route NTVMethylene chloride 100% 1.4E-02 OEHHA 2009 1.4E-02 route-to-route 1.0E-06 OEHHA 2009 6.0E-02 IRIS 2009 6.0E-02 route-to-route 4.0E-01 OEHHA 2009Tetrachloroethene 100% 5.1E-02 OEHHA 2009 5.1E-02 route-to-route 5.9E-06 OEHHA 2009 1.0E-02 IRIS 2009 1.0E-02 route-to-route 2.0E+01 OEHHA 2009Trichloroethene 100% 1.3E-02 OEHHA 2009 1.3E-02 route-to-route 2.0E-06 OEHHA 2009 NTV NTV 6.0E-01 OEHHA 2009Vinyl chloride 100% 2.7E-01 OEHHA 2009 2.7E-01 route-to-route 7.8E-05 OEHHA 2009 3.0E-03 IRIS 2009 3.0E-03 route-to-route 1.0E-01 IRIS 2009

Semi-Volatile Organic CompoundsBenzo(a)anthracene 89% 1.2E+00 OEHHA 2009 1.2E+00 route-to-route 1.1E-04 OEHHA 2009 NTV NTV NTVBenzo(a)pyrene 89% 1.2E+01 OEHHA 2009 1.2E+01 route-to-route 1.1E-03 OEHHA 2009 NTV NTV NTVBenzo(b)fluoranthene 89% 1.2E+00 OEHHA 2009 1.2E+00 route-to-route 1.1E-04 OEHHA 2009 NTV NTV NTVBenzo(k)fluoranthene 89% 1.2E+00 OEHHA 2009 1.2E+00 route-to-route 1.1E-04 OEHHA 2009 NTV NTV NTVDibenz(a,h)anthracene 89% 4.1E+00 OEHHA 2009 4.1E+00 route-to-route 1.2E-03 OEHHA 2009 NTV NTV NTVPhenanthrene 89% NTV NTV NTV 3.0E-01 Surrogate - Anthracene 3.0E-01 route-to-route NTV

Pesticides4,4'-DDT 80% 3.4E-01 IRIS 2009 3.4E-01 route-to-route 9.7E-05 IRIS 2009 5.0E-04 IRIS 2009 5.0E-04 route-to-route NTVAldrin 100% 1.7E+01 OEHHA 2009 1.7E+01 route-to-route 4.9E-03 OEHHA 2009 3.0E-05 IRIS 2009 3.0E-05 route-to-route NTV

HerbicidesMCPP 100% NTV NTV NTV 1.0E-03 IRIS 2009 1.0E-03 route-to-route NTV

PCDD/PCDFs2,3,7,8-TCDD 70% 1.3E+05 OEHHA 2009 1.3E+05 route-to-route 3.8E+01 OEHHA 2009 1.0E-09 ATSDR 1.0E-09 route-to-route NTV1,2,3,7,8-PeCDD 70% 1.3E+05 TCDD x WHO 2005 TEF

(1.0)1.3E+05 route-to-route 3.8E+01 TCDD x WHO 2005 TEF

(1.0)NTV NTV NTV

1,2,3,4,7,8-HxCDD 70% 1.3E+04 TCDD x WHO 2005 TEF (0.1)

1.3E+04 route-to-route 3.8E+00 TCDD x WHO 2005 TEF (0.1)

NTV NTV NTV

1,2,3,6,7,8-HxCDD 70% 1.3E+04 TCDD x WHO 2005 TEF (0.1)


NTV NTV NTV

1,2,3,7,8,9-HxCDD 70% 1.3E+04 TCDD x WHO 2005 TEF 1.3E+04 route-to-route 3.8E+00 TCDD x WHO 2005 TEF NTV NTV NTV(0.1) (0.1)

1,2,3,4,6,7,8-HpCDD 70% 1.3E+03 TCDD x WHO 2005 TEF (0.01)

1.3E+03 route-to-route 3.8E-01 TCDD x WHO 2005 TEF (0.01)

NTV NTV NTV

OCDD 70% 3.9E+01 TCDD x WHO 2005 TEF (0.0003)


NTV NTV NTV

2,3,7,8-TCDF 70% 1.3E+04 TCDD x WHO 2005 TEF (0.1)


NTV NTV NTV

1,2,3,7,8-PeCDF 70% 3.9E+03 TCDD x WHO 2005 TEF (0.03)


NTV NTV NTV

2,3,4,7,8-PeCDF 70% 3.9E+04 TCDD x WHO 2005 TEF (0.3)


NTV NTV NTV

Rural Res RBSL TM Page 1 of 2 Table 3_toxicity criteria.xls

DRAFT

Table 3

Toxicity Values Used in Suburband and Rural Residential Risk-Based Screening Level Calculations

Oral CSF (mg/kg-day)-1 Dermal CSF (mg/kg-day)-1 Inhalation URF (μg/m3)-1 Oral Reference Dose (mg/kg-day) Dermal Reference Dose (mg/kg-day) Inhalation RfC (mg/m3)Analyte GI ABS a Value Source Value Source Value Source Value Source Value Source Value Source

1,2,3,4,7,8-HxCDF 70% 1.3E+04 TCDD x WHO 2005 TEF (0.1)


NTV NTV NTV



NTV NTV NTV



NTV NTV NTV



NTV NTV NTV

1,2,3,4,6,7,8-HpCDF 70% 1.3E+03 TCDD x WHO 2005 TEF (0.01)


NTV NTV NTV

1,2,3,4,7,8,9-HpCDF 70% 1.3E+03 TCDD x WHO 2005 TEF 1.3E+03 route-to-route 3.8E-01 TCDD x WHO 2005 TEF NTV NTV NTV1,2,3,4,7,8,9 HpCDF 70% 1.3E 03 TCDD x WHO 2005 TEF (0.01)

1.3E 03 route to route 3.8E 01 TCDD x WHO 2005 TEF (0.01)

NTV NTV NTV

OCDF 70% 3.9E+01 TCDD x WHO 2005 TEF (0.0003)


NTV NTV NTV

Polychlorinated Biphenyls (PCBs)Aroclor 1248 81% 2.0E+00 OEHHA 2009 2.0E+00 route-to-route 5.7E-04 OEHHA 2009 NTV NTV NTVAroclor 1254 81% 2.0E+00 OEHHA 2009 2.0E+00 route-to-route 5.7E-04 OEHHA 2009 2.0E-05 IRIS 2009 2.0E-05 route-to-route NTVAroclor 1260 81% 2.0E+00 OEHHA 2009 2.0E+00 route-to-route 5.7E-04 OEHHA 2009 NTV NTV NTV

a - Values from Risk Assessment Guidance for Superfund (RAGS): Volume I - Human Health Evaluation Manual, Part E, Supplemental Guidance for Dermal Risk Assessment. (USEPA 2004b). Where a default value is not available, a value of 100% has been entered in accordance with RAGS Part E guidance that no adjustment needs to be made to derive the dermal toxicity values. The actual oral absorption may be less than 100%.

ATSDR - Agency for Toxic Substances and Disease Registry Minimum Risk Levels (MRLs), as cited in the Regional Screening Levels Tables (USEPA, 2009c).IRIS 2009 - Integrated Risk Information System (IRIS) Online database searched in June 2009. http://www.epa.gov/ iriswebp/iris/subst/index.html accessed in July 2009 (USEPA, 2009b).NCEA - National Center for Environmental Assessment, as cited in USEPA Region 9 PRG tables (USEPA, 2004a)OEHHA 2009 - Office of Environmental Health Hazard Assessment (OEHHA) Toxicity Criteria Database, online. http://www.oehha.ca.gov/risk/ChemicalDB/index.asp accessed in July 2009 (OEHHA, 2009).PPRTV - Provisional Peer Reviewed Toxicity Values, as cited in the Regional Screening Levels Tables (USEPA, 2009c).RAIS - Risk Assessment Information System (RAIS, 2009).RAIS Risk Assessment Information System (RAIS, 2009).USEPA 1997 - Health Effects Assessment Summary Tables (HEAST), FY-1997 Update. EPA/540/R-97/036. July 1997 (USEPA, 1997).

CSF = cancer slope factormg/kg-day = milligrams per kilogram per dayNTV - No toxicity valuePCDD/PCDF - Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans.PCB - polychlorinated biphenylsRfD = reference doseSVOC - semi-volatile organic compoundTEF - Toxic equivalency factorVOC - volatile organic compound

Rural Res RBSL TM Page 2 of 2 Table 3_toxicity criteria.xls

DRAFT

Table 4

Direct Soil Contact Pathway-Specific Suburban and Rural Residential Risk-Based Screening Level Calculations

Soil Ingestion RBSL (RBSLing) Soil Dermal Contact RBSL (RBSLder) Inhalation of Dust RBSL (RBSLinh)Analyte Composite Resident Child Composite Resident Child Composite Resident Child

Cancer Noncancer Cancer Noncancer Cancer Noncancer(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)

Inorganic CompoundsAluminum NC 7.8E+04 NC 2.8E+06 NC 6.4E+07Antimony NC 3.1E+01 NC 1.7E+02 NC NCArsenic 4.3E-01 2.3E+01 4.5E-06 2.8E+02 9.0E+03 1.9E+05Cadmium NC 7.8E+01 NC 7.0E+02 7.1E+03 1.3E+05Lead 7.5E+01 NC 2.4E-03 NC NC NCMercury NC 2.3E+01 NC 5.9E+01 NC 3.8E+05Selenium NC 3.9E+02 NC 1.4E+04 NC 2.5E+08Thallium NC 5.1E+00 NC 1.8E+02 NC NCZinc NC 2.3E+04 NC 8.4E+05 NC NC

Volatile Organic Compound1,1-Dichloroethene NC 3.9E+03 NC 1.4E+04 NC 1.6E+02Benzene 6.4E+00 3.1E+02 2.0E-05 1.1E+03 1.1E-01 8.2E+01cis-1,2-Dichloroethene NC 7.8E+02 NC 2.8E+03 NC NCMethylene chloride 4.6E+01 4.7E+03 1.4E-04 1.7E+04 3.0E+00 5.1E+02Tetrachloroethene 1.3E+01 7.8E+02 4.0E-05 2.8E+03 5.8E-01 2.9E+04Trichloroethene 4.9E+01 NC 1.6E-04 NC 2.0E+00 1.0E+03Vinyl chloride 2.4E+00 2.3E+02 7.5E-06 8.4E+02 1.9E-02 6.4E+01

Semi-Volatile Organic ComBenzo(a)anthracene 5.3E-01 NC 1.1E-06 NC 2.7E+05 NCBenzo(a)pyrene 5.3E-02 NC 1.1E-07 NC 2.7E+04 NCBenzo(b)fluoranthene 5.3E-01 NC 1.1E-06 NC 2.7E+05 NCBenzo(k)fluoranthene 5.3E-01 NC 1.1E-06 NC 2.7E+05 NC

Rural Res RBSL TM Page 1 of 3 Table 4_direct soil contact pathway-specific RBSLs.xls

DRAFT

Table 4




Dibenz(a,h)anthracene 1.6E-01 NC 3.3E-07 NC 2.5E+04 NCPhenanthrene NC 2.3E+04 NC 5.6E+04 NC NC

Energetic ConstituentsPerchlorate NC 5.5E+01 NC 2.0E+03 NC NC

Pesticides4,4'-DDT 1.9E+00 3.9E+01 1.2E-05 2.8E+02 3.1E+05 NCAldrin 3.8E-02 2.3E+00 2.4E-07 1.7E+01 6.1E+03 NC

HerbicidesHerbicidesMCPP NC 7.8E+01 NC 5.6E+02 NC NC

PCDD/PCDFs2,3,7,8-TCDD 4.9E-06 7.8E-05 5.2E-11 9.3E-04 7.8E-01 NC1,2,3,7,8-PeCDD 4.9E-06 NC 5.2E-11 NC 7.8E-01 NC1,2,3,4,7,8-HxCDD 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,6,7,8-HxCDD 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,7,8,9-HxCDD 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,4,6,7,8-HpCDD 4.9E-04 NC 5.2E-09 NC 7.8E+01 NCOCDD 1.6E-02 NC 1.7E-07 NC 2.6E+03 NC2,3,7,8-TCDF 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,7,8-PeCDF 1.6E-04 NC 1.7E-09 NC 2.6E+01 NC2,3,4,7,8-PeCDF 1.6E-05 NC 1.7E-10 NC 2.6E+00 NC1,2,3,4,7,8-HxCDF 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC


DRAFT

Table 4




1,2,3,6,7,8-HxCDF 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC2,3,4,6,7,8-HxCDF 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,7,8,9-HxCDF 4.9E-05 NC 5.2E-10 NC 7.8E+00 NC1,2,3,4,6,7,8-HpCDF 4.9E-04 NC 5.2E-09 NC 7.8E+01 NC1,2,3,4,7,8,9-HpCDF 4.9E-04 NC 5.2E-09 NC 7.8E+01 NCOCDF 1.6E-02 NC 1.7E-07 NC 2.6E+03 NC

Polychlorinated Biphenyls (Aroclor 1248 3.2E-01 NC 6.7E-07 NC 5.2E+04 NCAroclor 1254 3.2E-01 1.6E+00 6.7E-07 3.7E+00 5.2E+04 NCAroclor 1260 3 2E-01 NC 6 7E-07 NC 5 2E+04 NCAroclor 1260 3.2E-01 NC 6.7E-07 NC 5.2E+04 NC

mg/kg = milligrams per kilogramna = not applicable/availableNC = not calculatedNTV = no toxicity valueRBSL = Risk-Based Screening LevelUSC = Unit soil concentration (1 mg/kg)


DRAFT

Table 5

Indirect Soil Pathway-Specific Rural Residential Risk-Based Screening Level Calculations

Soil RBSL for Fruits and Soil RBSL for Beef Soil RBSL for Milk Soil RBSL for Poultry Soil RBSL for Eggs Soil RBSL for Swine Soil RBSL for FishVegetables Pathway (RBSLfv) Pathway (RBSLb) Pathway (RBSLm) Pathway (RBSLp) Pathway (RBSLe) Pathway (RBSLs) Pathway (RBSLfi)

Analyte Composite Resident Child Composite Resident Child Composite Resident Child Composite Resident Child Composite Resident Child Composite Resident Child Composite Resident ChildCancer Noncancer Cancer Noncancer Cancer Noncancer Cancer Noncancer Cancer Noncancer Cancer Noncancer Cancer Noncancer(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)

Inorganic CompoundsAluminum NC 2.4E+03 NC 2.4E+05 NC 6.3E+04 NC NC NC NC NC NC NC 2.7E+04Antimony NC 9.2E-01 NC 3.1E+03 NC 1.7E+02 NC NC NC NC NC NC NC 4.0E+00Arsenic 4.6E-03 6.9E-01 1.2E-01 4.8E+01 4.8E-01 5.6E+01 NC NC NC NC NC NC 2.5E-03 6.8E-01Cadmium NC 1.6E+00 NC 3.1E+02 NC 4.2E+00 NC 5.9E+01 NC 5.5E+03 NC 1.6E+03 NC 7.4E-01Lead 8.4E-01 NC 9.3E+01 NC 1.5E+01 NC NC NC NC NC NC NC 1.7E+04 NCMercury NC 3.3E-01 NC 2.4E+00 NC 1.7E+00 NC 4.2E+01 NC NC NC NC NC 2.7E+00Selenium NC 8.6E+00 NC 6.6E+00 NC 2.3E+00 NC 2.9E+01 NC 6.4E+01 NC 8.7E+00 NC 1.8E+00Thallium NC 1.5E-01 NC 5.8E-01 NC 4.1E-01 NC NC NC NC NC NC NC 4.1E-03Zinc NC 3.6E+02 NC 2.4E+02 NC 8.3E+01 NC 1.5E+05 NC 3.2E+05 NC 4.8E+05 NC 8.1E+01

Volatile Organic Compound1,1-Dichloroethene NC 3.2E+01 NC 8.7E+05 NC 9.4E+04 NC 3.0E+04 NC 1.1E+05 NC 8.8E+02 NC 1.2E+01Benzene 2.6E-02 3.4E+00 1.5E+02 5.1E+04 5.4E+01 5.5E+03 1.4E+01 3.4E+03 5.8E+01 1.3E+04 4.7E-01 1.0E+02 3.9E-03 9.5E-01cis-1,2-Dichloroethene NC 7.1E+00 NC 1.6E+05 NC 1.7E+04 NC 9.3E+03 NC 3.5E+04 NC 2.7E+02 NC 2.6E+00Methylene chloride 8.0E-02 2.2E+01 2.4E+03 1.8E+06 8.7E+02 1.9E+05 1.5E+02 7.5E+04 6.1E+02 2.9E+05 4.8E+00 2.2E+03 6.5E-02 3.3E+01Tetrachloroethene 7.3E-02 1.2E+01 1.6E+02 7.0E+04 5.9E+01 7.7E+03 9.9E+00 3.1E+03 4.1E+01 1.2E+04 3.3E-01 9.1E+01 1.4E-03 4.4E-01Trichloroethene 2.5E-01 NC 7.9E+02 NC 2.9E+02 NC 9.9E+01 NC 4.1E+02 NC 3.3E+00 NC 4.0E-02 NCVinyl chloride 4.7E-03 1.3E+00 1.1E+02 7.9E+04 4.1E+01 8.5E+03 7.1E+00 3.5E+03 2.9E+01 1.3E+04 2.3E-01 1.0E+02 3.1E-03 1.5E+00

Semi-Volatile Organic CompBenzo(a)anthracene 5.9E-03 NC 2.5E-02 NC 9.7E-03 NC 7.0E-01 NC 2.9E+00 NC 2.5E-02 NC 1.5E-01 NCBenzo(a)pyrene 5.9E-04 NC 1.1E-03 NC 4.0E-04 NC 7.6E-02 NC 3.1E-01 NC 2.7E-03 NC 2.3E-02 NCBenzo(b)fluoranthene 5.9E-03 NC 1.1E-02 NC 4.0E-03 NC 7.9E-01 NC 3.3E+00 NC 2.8E-02 NC 1.2E-02 NCBenzo(k)fluoranthene 6.0E-03 NC 2.1E-03 NC 8.2E-04 NC 7.9E-01 NC 3.3E+00 NC 2.8E-02 NC 2.3E-01 NCDibenz(a,h)anthracene 1.7E-03 NC 6.3E-04 NC 2.4E-04 NC 2.7E-01 NC 1.1E+00 NC 9.8E-03 NC 1.0E-01 NCPhenanthrene NC 6.7E+02 NC 8.5E+04 NC 9.5E+03 NC 1.6E+05 NC 5.9E+05 NC 4.8E+03 NC 1.7E+04

Energetic ConstituentsPerchlorate NC NC NC NC NC NC NC NC NC NC NC NC NC NC

Pesticides4,4'-DDT 2.1E-02 1.2E+00 2.1E-02 3.1E+00 7.9E-03 3.4E-01 3.1E+00 3.2E+02 1.3E+01 1.2E+03 1.1E-01 1.0E+01 1.0E+00 1.1E+02Ald i 2 7E 04 4 7E 02 2 9E 01 1 3E+02 1 1E 01 1 4E+01 1 7E 02 5 4E+00 7 2E 02 2 1E+01 5 9E 04 1 6E 01 9 3E 02 2 9E+01Aldrin 2.7E-04 4.7E-02 2.9E-01 1.3E+02 1.1E-01 1.4E+01 1.7E-02 5.4E+00 7.2E-02 2.1E+01 5.9E-04 1.6E-01 9.3E-02 2.9E+01

HerbicidesMCPP NC 1.2E+00 NC 7.0E+03 NC 7.7E+02 NC 4.0E+02 NC 1.5E+03 NC 1.2E+01 NC 1.7E+00

PCDD/PCDFs2,3,7,8-TCDD 5.5E-08 2.4E-06 2.0E-08 2.2E-06 7.5E-09 2.5E-07 1.0E-05 8.1E-04 4.2E-05 3.1E-03 3.7E-07 2.6E-05 1.3E-07 1.0E-051,2,3,7,8-PeCDD 5.5E-08 NC 4.0E-08 NC 1.5E-08 NC 9.2E-06 NC 3.8E-05 NC 3.3E-07 NC 1.2E-07 NC1,2,3,4,7,8-HxCDD 5.5E-07 NC 2.0E-08 NC 7.6E-09 NC 2.5E-04 NC 1.0E-03 NC 8.8E-06 NC 8.4E-05 NC1,2,3,6,7,8-HxCDD 5.5E-07 NC 6.4E-08 NC 2.4E-08 NC 1.5E-04 NC 6.2E-04 NC 5.4E-06 NC 5.5E-06 NC1,2,3,7,8,9-HxCDD 5.5E-07 NC 6.4E-08 NC 2.4E-08 NC 1.5E-04 NC 6.2E-04 NC 5.4E-06 NC 5.5E-06 NC1,2,3,4,6,7,8-HpCDD 5.5E-06 NC 1.3E-07 NC 4.8E-08 NC 3.1E-03 NC 1.3E-02 NC 1.1E-04 NC 2.5E-03 NCOCDD 1.8E-04 NC 7.1E-07 NC 2.7E-07 NC 1.3E-01 NC 5.4E-01 NC 4.7E-03 NC 2.5E-01 NC2,3,7,8-TCDF 5.5E-07 NC 1.8E-06 NC 7.0E-07 NC 7.1E-05 NC 2.9E-04 NC 2.5E-06 NC 8.8E-07 NC1,2,3,7,8-PeCDF 1.8E-06 NC 7.0E-07 NC 2.6E-07 NC 3.4E-04 NC 1.4E-03 NC 1.2E-05 NC 4.2E-06 NC2,3,4,7,8-PeCDF 1.8E-07 NC 5.0E-08 NC 1.9E-08 NC 2.9E-05 NC 1.2E-04 NC 1.0E-06 NC 3.6E-07 NC1,2,3,4,7,8-HxCDF 5.5E-07 NC 1.3E-07 NC 4.8E-08 NC 1.2E-04 NC 4.9E-04 NC 4.2E-06 NC 1.4E-06 NC1,2,3,6,7,8-HxCDF 5.5E-07 NC 1.3E-07 NC 4.8E-08 NC 1.2E-04 NC 4.9E-04 NC 4.2E-06 NC 1.4E-06 NC2,3,4,6,7,8-HxCDF 5.5E-07 NC 1.3E-07 NC 4.8E-08 NC 1.2E-04 NC 4.9E-04 NC 4.2E-06 NC 1.4E-06 NC1,2,3,7,8,9-HxCDF 5.5E-07 NC 1.3E-07 NC 4.8E-08 NC 1.2E-04 NC 4.9E-04 NC 4.2E-06 NC 1.4E-06 NC1,2,3,4,6,7,8-HpCDF 5.5E-06 NC 5.1E-07 NC 1.9E-07 NC 1.6E-03 NC 6.8E-03 NC 5.9E-05 NC 9.5E-05 NC1,2,3,4,7,8,9-HpCDF 5.5E-06 NC 5.1E-07 NC 1.9E-07 NC 1.6E-03 NC 6.8E-03 NC 5.9E-05 NC 9.5E-05 NCOCDF 1.8E-04 NC 1.1E-06 NC 4.1E-07 NC 1.0E-01 NC 4.3E-01 NC 3.7E-03 NC 8.4E-02 NC

Polychlorinated Biphenyls (PAroclor 1248 3.5E-03 NC 1.2E-02 NC 4.7E-03 NC 5.0E-01 NC 2.1E+00 NC 1.8E-02 NC 5.1E-05 NCAroclor 1254 3.6E-03 4.7E-02 8.0E-03 2.8E-01 3.0E-03 3.1E-02 5.5E-01 1.3E+01 2.3E+00 5.1E+01 2.0E-02 4.2E-01 2.1E-03 5.2E-02Aroclor 1260 3.6E-03 NC 6.7E-04 NC 2.5E-04 NC 2.5E+00 NC 1.1E+01 NC 9.1E-02 NC 3.1E-03 NC

mg/kg = milligrams per kilogramna = not applicable/availableNC = not calculatedNTV - No toxicity valueRBSL = Risk-Based Screening LevelUSC = Unit soil concentration (1 mg/kg)

Rural Res RBSL TM Page 1 of 1 Table 5_indirect soil contact pathway-specific RBSLs.xlsDRAFT

Table 6

Cumulative Suburban and Rural Residential Risk-Based Screening Levels for Chemicals in Soil

2005 Background Suburban Residential Soil RBSL (RBSLres) b Rural Residential Soil RBSL (RBSLRR) c

Comparison Composite Resident Child Composite Resident ChildAnalyte Concentration a Cancer (10-6) Noncancer (HQ=1) Lowest Cancer (10-6) Noncancer (HQ=1) Lowest

(mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg)

Inorganic CompoundsAluminum 20,000 - 76,000 76,000 - 2,000 2,000Antimony 8.7 - 26 26 - 0.72 0.72Arsenic 15 0.39 22 0.39 0.0016 0.33 0.0016Cadmium 1.0 7,100 70 70 7,100 0.44 0.44Lead 34 73 - 73 0.78 - 0.78Mercury 0.090 - 17 17 - 0.22 0.22Selenium 0.66 - 380 380 - 0.69 0.69Thallium 0.46 - 4.9 4.9 - 0.0039 0.0039Zinc 110 - 23,000 23,000 - 32 32

Volatile Organic Compounds1,1-Dichloroethene - - 150 150 - 8.1 8.1Benzene - 0.11 61 0.11 0.0032 0.73 0.0032cis-1,2-Dichloroethene - - 610 610 - 1.9 1.9Methylene chloride - 2.7 450 2.7 0.035 13 0.035Tetrachloroethene - 0.55 600 0.55 0.0014 0.42 0.0014T i hl th 1 9 1 000 1 9 0 034 1 000 0 034Trichloroethene - 1.9 1,000 1.9 0.034 1,000 0.034Vinyl chloride - 0.019 48 0.019 0.0017 0.68 0.0017

Semi-Volatile Organic CompoundsBenzo(a)anthracene - 0.36 - 0.36 0.0027 - 0.0027Benzo(a)pyrene - 0.036 - 0.036 0.00018 - 0.00018Benzo(b)fluoranthene - 0.36 - 0.36 0.0016 - 0.0016Benzo(k)fluoranthene - 0.36 - 0.36 0.00053 - 0.00053Dibenz(a,h)anthracene - 0.11 - 0.11 0.00015 - 0.00015Phenanthrene - - 17,000 17,000 - 520 520

Energetic ConstituentsPerchlorate - - 53 53 - 53 53

Rural Res RBSL TM Page 1 of 3 Table 6_cumulative suburban and rural residential RBSLs.xls

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Table 6





Pesticides4,4'-DDT - 1.6 34 1.6 0.0043 0.24 0.0043Aldrin - 0.032 2.1 0.032 0.00018 0.035 0.00018

HerbicidesMCPP - - 69 69 - 0.66 0.66

PCDD/PCDFsd2,3,7,8-TCDD 0.0000005 (ND) 0.0000045 0.000072 0.0000045 0.0000000047 0.00000020 0.00000000471,2,3,7,8-PeCDD 0.00000018 0.0000045 - 0.0000045 0.0000000082 - 0.00000000821,2,3,4,7,8-HxCDD 0.00000034 0.000045 - 0.000045 0.0000000055 - 0.00000000551,2,3,6,7,8-HxCDD 0.00000095 0.000045 - 0.000045 0.000000017 - 0.0000000171,2,3,7,8,9-HxCDD 0.0000011 0.000045 - 0.000045 0.000000017 - 0.0000000171,2,3,4,6,7,8-HpCDD 0.000013 0.00045 - 0.00045 0.000000035 - 0.000000035OCDD 0.00014 0.015 - 0.015 0.00000019 - 0.000000192,3,7,8-TCDF 0.0000018 0.000045 - 0.000045 0.00000019 - 0.000000191,2,3,7,8-PeCDF 0.00000059 0.00015 - 0.00015 0.00000016 - 0.000000162,3,4,7,8-PeCDF 0.00000064 0.000015 - 0.000015 0.000000012 - 0.000000012, , , ,1,2,3,4,7,8-HxCDF 0.00000073 0.000045 - 0.000045 0.000000032 - 0.0000000321,2,3,6,7,8-HxCDF 0.00000030 0.000045 - 0.000045 0.000000032 - 0.0000000322,3,4,6,7,8-HxCDF 0.00000045 0.000045 - 0.000045 0.000000032 - 0.0000000321,2,3,7,8,9-HxCDF 0.00000043 0.000045 - 0.000045 0.000000032 - 0.0000000321,2,3,4,6,7,8-HpCDF 0.0000025 0.00045 - 0.00045 0.00000014 - 0.000000141,2,3,4,7,8,9-HpCDF 0.00000019 0.00045 - 0.00045 0.00000014 - 0.00000014OCDF 0.0000081 0.015 - 0.015 0.00000030 - 0.00000030

Polychlorinated Biphenyls (PCBs)Aroclor 1248 - 0.22 - 0.22 0.000049 - 0.000049Aroclor 1254 - 0.22 1.1 0.22 0.00079 0.013 0.00079Aroclor 1260 - 0.22 - 0.22 0.00016 - 0.00016

Notes:- = None established/not applicable.


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Table 6





mg/kg = Milligram per kilogramND = Not detectedRBSL = Risk-based Screening LevelRBSLres = Suburban Residential Soil RBSLRBSLRR = Rural Residential Soil RBSLWHO TEF = World Health Organization Toxicity Equivalency Factor

a - Values shown are the 2005 background comparison values presented in SRAM Rev.2 and approved by DTSC. Currently, a new chemical background study is being conducted by DTSC, so these comparison values may change in the future.

b - Suburban Residential Soil RBSLs include the following pathways: ingestion of soil, dermal contact with soil, and inhalation of dust.c - Rural Residential Soil RBSLs include the following pathways: ingestion of soil, dermal contact with soil, inhalation of dust, ingestion of fruits/vegetables,

ingestion of beef, ingestion of milk, ingestion of poultry, ingestion of eggs, ingestion of swine, and ingestion of fish.d - Calculated based on 2,3,7,8-TCDD and 2005 WHO TEFs.


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FIGURES

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SANTA SUSANA FIELD LABORATORYDocument: Misc-CMS_RegionalMap.mxd Date: Sep 10, 2008

1 inch = 1.5 miles

0 1.5 3Miles Regional Map FIGURE

1

Ve nt u ra C o un t yVe nt u ra C o un t y

UNDEVELOPEDUNDEVELOPED

AREA IV

AREA IIIAREA II(NASA) AREA I

UNDEVELOPED LAND

NASA

SSFLSITE BOUNDARY

RunkleCanyon

Brandeis-Bardin Black Canyon

Simi Valley

Ve nt u ra C o un t y

Lo s A n g e l e s C o un t y

Ahmanson RanchRocketdyne Canoga Av Facility

Rocketdyne De Soto Av Facility

LOS ANGELES AVE

FITZGERALD RDSANTA SUSANA PASS RD

LAKE MANOR DR

VALL

EY C

IRIC

LE B

LVD

VENTURA BLVD

NONCHALANT RD

ROSCOE BLVD

CHATSWORTH RESERVOIR(Normally Dry)

ThousandOaks

SageRanch

BO

X C

AN

YON

RO

AD

TAP

O C

AN

YON

RO

AD

KANAN ROAD

Bell Canyon

Gas

ton

Rd.

Woolsey Canyon

DaytonCanyon

RockyPeakPark

Rocketdyne Recreational Center

WestHills

Chatsworth

San FernandoValley

118

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0 1,300

FEET

MAP COORDINATES INSTATEPLANE, NAD 27, ZONE V

RFI Site Location Map

NASA PROPERTYAREA I

AREA IV AREA III AREA II (NASA) AREA I

UNDEVELOPEDLAND

UNDEVELOPED

LAND

R-2 Ponds

FSDF

RIHL

PDU

OCY

B204

ELV

Ash Pile

B515 STP

ABFF

Area II Landfill

LOXB-1

IEL

APTF

Canyon

BowlR-1 Pond

Perimeter Pond

CTL-V

Delta

PLF

CDFF

Silvernale

Compound A

SE Drum Storage

ECL

CTL-III

Bravo

Coca

SNAP HMSA

STL-IV

SPA

WCT

B4093Leach Field

B4011Leach Field

B4363LeachField

B4353Leach Field

Pond Dredge

B4064Leach Field

B4030 Leach Field

B4100

B4383Leach Field

Happy Valley South

B359

Area I Landfill

Building 4056Landfill

STP Pond

RMHF

ESADA

Metals Clarifier

B4008Warehouse

EEL

SRE

B4009Leach Field

Alfa

B4010Leach Field

B4373 Leach Field

LETF/CTL-I

NCY

Area IBurn Pit

B4029 Storage Yard

B4133 SodiumBurn Facility

Happy Valley North

Area IV Borrow Pit

UNDEVELOPED LAND

Outfall 003

Outfall 001

Outfall 002

Outfall 005

Outfall 004

Outfall 007

Outfall 006

Outfall 008

Outfall 009

Outfall 011

Outfall 012

Outfall 018

Outfall 010

Outfall 014

Outfall 013

Outfall 015Outfall 017

Outfall 016

Outfall 019

1783400

1783400

1788400

1788400

1793400

1793400

1798400

1798400

262

400

262

400

267

400

267

400

FIGURE2

SANTA SUSANA FIELD LABORATORY

Please Note: The original version of this figure includes colorized features and shading. A black and white copy of the figure shouldnot be used because it may not accurately represent the information presented.

LegendSSFL Property Boundary

Administrative Boundary

Report Group Boundary

RFI Site Boundary

Building

Pond

Drainage

Dirt Road

Road

NPDES Outfall

Date: Jun 26, 2009Document: Misc-RFI_Site_Location.mxd

AREA I AREA II AREA II (cont) AREA IV (cont)SWMU 4.1 - B1 Area SWMU 5.1 - Area II Landfill AOC - Building 2224 Leach Field SWMU 7.7 - Rockwell International Hot Laboratory (RIHL)SWMU 4.2 - Area I Landfill SWMU 5.2 - ELV Final Assembly Building 2206 AREA III SWMU 7.8 - New Conservation Yard (NCY)SWMUs 4.3, 4.4 and AOC - Instrument and Equipment Laboratories (IEL) SWMU 5.5 and AOC - Building 2204 Area SWMUs 6.1, 6.3, AOC - Engineering Chemistry Laboratory (ECL) Area SWMU 7.9 - ESADA Chemical Storage AreaSWMU 4.5, 4.6 - LOX Plant Former Sump/Clarifier and Drum Disposal Area SWMU 5.6 - Former Incinerator Ash Pile SWMU 6.4 - Compound A Facility SWMU 7.10 - Former Coal Gasification PDUSWMU 4.7 - Component Test Laboratory III (CTL-III) Area SWMU 5.7 - Hazardous Waste Storage Area Waste Coolant Tank (WCT) SWMU 6.5 - Systems Test Laboratory IV (STL-IV) Area SWMU 7.11 - Building 4029, Reactive Metal Storage YardSWMU 4.8 - Area I Burn Pit SWMU 5.9, 5.10, 5.11 - Alfa Area SWMU 6.8 - Silvernale Reservoir AOC - Former Hazardous Materials Storage Area (HMSA)SWMU 4.9, 4.10, 4.11, AOC - Advanced Propulstion Test Facility (APTF) Area SWMU 5.12, 5.13, 5.14, 5.15 - Alfa/Bravo Skim Pond and Bravo Area SWMU 6.9 - Environmental Effects Laboratory (EEL) AOC - Chemistry Laboratory Metals ClarifierSWMU 4.12 - Laser Engineering Test Facility (LETF) Component Test Lab (CTL-1) Area SWMU 5.18, 5.19 - Coca Area AOC - SewageTreatment Plant (STL) Pond Area AOC - Pond Dredge AreaSWMU 4.14 Canyon Area SWMU 5.20, 5.21, 5.22 - Propellant Load Facility (PLF) AREA IV AOC - Sodium Reactor Experiment (SRE) AreaSWMU 4.15 and AOC - Bowl Area and Building 901 Leachfield SWMU 5.23, 5.24 - Delta Area SWMU 7.1 - Building 4056 Landfill AOC - SE Drum Storage YardSWMU 4.16 - Area I Reservoir (R-1 Pond) SWMU 5.26 - R-2A and R2B Ponds SWMU 7.2 - Building 4133, Sodium Burn Facility AOC - SNAP FacillitySWMU 4.17 - Perimeter Pond AOC - Building 2515 Sewage Treatment Plant SWMU 7.3 -Former Sodium Disposal Facility (FSDF) AOC - Boeing Area IV Leach FieldsAOC - Building 1359 Sump AOC - Storable Propellant Area (SPA) SWMU 7.4 - Old Conservation Yard (OCY) AOC - DOE Area IV Leach FieldsAOC - Happy Valley Area AOC - Alfa/Bravo Fuel Farm SWMU 7.5 - Building 4100 Trench AOC - Building 4008 WarehouseAOC - CTL-V AOC - Coca/Delta Fuel Farm SWMU 7.6 - Radioactive Materials Handling Facility (RMHF)

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Figure 3

PRIMARY SOURCEPRIMARY RELEASE

MECHANISMSECONDARY

SOURCE

SECONDARY RELEASE

MECHANISM TERTIARY SOURCE EXPOSURE ROUTE

POTENTIALFUTURERURAL

STORAGE RESIDENT

ACCIDENTALSPILLS & SPILLS

RELEASES VOLATILIZATION DUST and/or INHALATION (vapor) (*)and/or VOLATILE INHALATION (dust)

EROSION EMISSIONS

ABOVEGROUNDTANKS

SOIL ANDUNDERGROUND LEAKAGE WEATHERED direct contact with soil or weathered bedrock DERMAL ABSORPTION

TANKS BEDROCK INGESTION

ROCKET TEST/DRAINAGE FRUITS AND INGESTION

CHANNELS & VEGETABLESIMPOUNDMENTS ROOT UPTAKE BEEF INGESTION

FROMSOIL MILK INGESTION

PISTOL LEACHING FORAGEPRACTICE INFILTRATION SWINE INGESTIONRANGES PERCOLATION

POULTRY INGESTION

WASTE PRIORDISPOSAL WASTE EGGS INGESTION

AREAS DISPOSALPRACTICES

SEDIMENT FISH INGESTION

NOTES:(*) Exposure limited to volatile organic compounds (VOCs), as defined in the text; rural resident exposure pathways include inhalation exposures to VOCs in both indoor air and outdoor air.

- potentially complete exposure pathways - incomplete exposure pathways not evaluated in this risk assessment evaluated in this risk assessment

Conceptual Site Model for Hypothetical Future Rural Residents Exposed to Soil and Weathered BedrockSanta Susana Field Laboratory (SSFL)

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FILE 1

SUBURBAN AND RURAL RESIDENTIAL

SOIL RISK-BASED SCREENING LEVEL CALCULATIONS

(Electronic Copy)

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