paul rosasco collins; stephanie pickens; cecilia greene ...please let us know if you have any...

From: Paul RosascoTo: Jump, Christine; Mahler, Tom; Barker, Justin; Juett, Lynn; "Seabaugh, Ryan"Cc: McGahren, John; Feingold, Stephanie R.; "Guariglia, Dale"; "Lintecum, Sarah E. (LG)"; Beck, Bill (LG); Merrigan,

Jessie; Victoria Warren; Fanning, Erin; Sklenar, Scott E:(GenCo-Nuc); Sincox, Dana; "Mike Bollenbacher"; "BeckyCollins"; "Stephanie Pickens"; "Cecilia Greene"

Subject: RE: Responses to EPA Comments on the Updated Baseline Risk AssessmentDate: Monday, September 11, 2017 9:35:02 AMAttachments: TOC 20170815.pdf

The revised pages for the updated BRA did not include a revised Table of Contents. Attached is arevised Table of Contents.

From: Paul Rosasco [mailto:[email protected]] Sent: Wednesday, August 16, 2017 8:54 AMTo: 'Jump, Christine' ; 'Mahler, Tom' ; Barker, Justin ; '[email protected]' ; 'Seabaugh, Ryan' Cc: McGahren, John ; Feingold, Stephanie R. ; 'Guariglia, Dale' ; 'Lintecum, Sarah E. (LG)' ; Beck, Bill(LG) ; Merrigan, Jessie ; Victoria Warren ([email protected]) ; Fanning, Erin ; Sklenar,Scott E:(GenCo-Nuc) ; Sincox, Dana ; 'Mike Bollenbacher ([email protected])' ; 'Becky Collins' ;'Stephanie Pickens' ; 'Cecilia Greene' Subject: Responses to EPA Comments on the Updated Baseline Risk AssessmentChrisAttached to this e-mail are the responses to EPA comments on the updated Baseline RiskAssessment along with errata pages to the document.In preparing the RAGs Part D tables that we previously submitted, some minor changes to thepreviously calculated results were identified that necessitated revisions to the values presented inthe text for consistency. The pages that were revised and the reasons for the revisions are describedbelow.Table ES.1 Summary of Human Health Risks, page 2, this table was revised to include revisednumbers for Total ILCR, Total ILCR without Radon, and percentages for the Future Off-propertyCommercial Building User- Off-property west and Adjacent property, Lot 2A2.Page 17 was revised to remove the statement that uranium-235 concentrations are commonlyoverestimated.Page 27-29, the first page of Table 5 was revised to include footnote a in the Maximum ScreeningConcentration column and footnote b was removed at the end of the table.Page 57, Figure 6 was referenced at the end of section 3.1.5.1Page 59, In the second paragraph of section 3.1.5.3, last sentence, commercial building user waschanged to grounds keeper.Page 63, In section 3.2.3, the following sentence was removed: "Soil exposure point concentrationsto evaluate exposures under current conditions were calculated using samples taken from the topone foot of soil."Page 110, The following sentence was added at the end of 5.1.1.1 - "Once PRGs were calculatedusing the EPA PRG calculator, risk for a COPC was calculated by dividing the target risk by the COPC-specific PRG and then multiplying that quotient by the COPC's exposure point concentration."Section 5, pages 108 - 155, This section was revised to include updated risk tables and revised textthat reflected the table information.Table 57, Summary of ILCR(Risk) with and without Radon, page 168.- This table was revised toinclude the changes to Future Off-property Commercial Building User Off-property west andAdjacent property, Lot 2A2.
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]

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TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................ 1

1. INTRODUCTION .................................................................................................................. 3

1.1 Overview ............................................................................................................................. 3

1.1.1 Objectives of the Baseline Risk Assessment ............................................................... 4

1.2 Background ......................................................................................................................... 4

1.2.1 West Lake Landfill Description ................................................................................... 5

1.2.2 Summary of Landfill Operations at the Landfill .......................................................... 5

1.2.3 Summary of Landfill Contamination ........................................................................... 5

1.2.3.1 Area 1 ...................................................................................................................... 6

1.2.3.2 Area 2 ...................................................................................................................... 6

1.2.3.3 Buffer Zone and Crossroad Lot 2A2 ...................................................................... 7

1.2.4 Land Use ...................................................................................................................... 8

1.2.4.1 Current Land Use .................................................................................................... 8

1.2.4.2 Future Land Use ...................................................................................................... 8

1.2.4.3 Surrounding Land Use ............................................................................................ 9

1.2.5 Groundwater Use ......................................................................................................... 9

1.3 Radionuclides inthe Environment ....................................................................................... 9

1.4 Organization of this Report ............................................................................................... 10

2. IDENTIFICATION OF CONSTITUENTS OF POTENTIAL CONCERN ........................ 13

2.1 Data Sources for ConstituentConcentrations .................................................................... 13

2.2 Summary Statistics for Representative Data ..................................................................... 14

2.3 Selection of Constituents of Potential Concern ................................................................ 14

2.3.1 Essential Nutrient Screening for Chemicals .............................................................. 15

2.3.2 Toxicity Screening for Chemicals .............................................................................. 15

2.3.3 Aggregate Screening Results ..................................................................................... 16

2.4 Additional Data/screening Considerations ....................................................................... 16

2.4.1 Uranium-235 .............................................................................................................. 16

2.4.2 Naturally Occurring Uranium .................................................................................... 18

2.4.3 Chromium .................................................................................................................. 18

2.4.4 Potassium-40 .............................................................................................................. 18

2.5 OU1 COPC Summary Statistics ....................................................................................... 19

2.5.1 Use of EPA’s ProUCL Statistical Application ........................................................... 19

3. HUMAN EXPOSURE ASSESSMENT ............................................................................... 49

3.1 Conceptual Site Model for OU1 ....................................................................................... 49

3.1.1 Sources ....................................................................................................................... 51

3.1.2 Potential Release Mechanisms ................................................................................... 51

3.1.2.1 Resuspension of Dust ............................................................................................ 51

3.1.2.2 Volatilization of Organics ..................................................................................... 51

3.1.2.3 Radon Emission .................................................................................................... 52

3.1.2.4 Leaching from Soil to Groundwater ..................................................................... 52

3.1.2.5 Soil Erosion by Surface Water .............................................................................. 53

3.1.3 Potential Exposure Media and Routes ....................................................................... 53

3.1.4 Potential Receptors ..................................................................................................... 54

3.1.4.1 Selection of Farmer or Resident for Quantification .............................................. 55

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3.1.4.2 Selection of Transient Receptor for Quantification .............................................. 55

3.1.4.3 Selection of Worker Receptors for Quantification ............................................... 56

3.1.5 Potential Scenarios ..................................................................................................... 56

3.1.5.1 Current On-Property Scenarios ............................................................................. 56

3.1.5.2 Current Off-Property Scenarios ............................................................................ 58

3.1.5.3 Future Landfill Scenarios – 1,000 Years .............................................................. 59

3.1.5.4 1,000-Year Future Off-Property Scenarios ........................................................... 61

3.2 Exposure Point Concentrations ......................................................................................... 61

3.2.1 Evaluation of Series Radionuclides ........................................................................... 62

3.2.2 Segregation of Concentration Data by Depth ............................................................ 62

3.2.3 Current Exposure Point Concentrations in Soil ......................................................... 63

3.2.4 1,000-Year Future Exposure Point Concentrations in Soil ........................................ 63

3.2.5 Exposure Point Air Concentrations ............................................................................ 64

3.3 Quantification of Exposure ............................................................................................... 65

3.3.1 Quantification of Intakes and Exposures from Multiple Pathways ........................... 66

3.3.2 Scenario-Specific Assumptions and Exposure Parameters ........................................ 66

3.4 Results of Exposure Assessment ...................................................................................... 67

4. TOXICITY ASSESSMENT ................................................................................................. 86

4.1 Toxicity Information for Chemicals of Potential Concern ............................................... 86

4.1.1 Radiocarcinogens ....................................................................................................... 86

4.1.2 Chemical Carcinogens ............................................................................................... 88

4.1.3 Noncarcinogenic Chemicals ....................................................................................... 89

4.1.4 Hierarchy of Chemical Toxicity Sources ................................................................... 91

5. HEALTH RISK CHARACTERIZATION ......................................................................... 108

5.1 Methods Used for Risk Characterization ........................................................................ 108

5.1.1 Carcinogenic Risks ................................................................................................... 108

5.1.1.1 Radiocarcinogenic Risks ..................................................................................... 109

5.1.1.2 Chemocarcinogenic Risks ................................................................................... 110

5.1.2 Noncarcinogenic Effects .......................................................................................... 111

5.1.3 Lead .......................................................................................................................... 111

5.1.4 Multiple Pathways .................................................................................................... 112

5.1.5 Exposures to Multiple Constituents ......................................................................... 112

5.2 Risk Estimates for Current Exposure Scenarios ............................................................. 113

5.2.1 Hypothetical On-Property Grounds Keeper Adjacent to Area 1 and Area 2 ............ 113

5.2.2 Hypothetical On-Property Commercial Building User Adjacent to Area 1 ............. 114


5.2.4 Hypothetical Off-Property Resident ......................................................................... 114

5.2.5 Hypothetical Off-Property Commercial Building User ........................................... 114

5.3 Risk Estimates for Future (1,000-year) Exposure Scenarios .......................................... 115

5.3.1 1,000-Year Future Exposure Scenarios for the Landfill ........................................... 115

5.3.1.1 Hypothetical Landfill Outdoor Storage Yard Worker – Area 1 ........................... 116


5.3.1.3 Hypothetical Landfill Grounds Keeper – Area 1 ................................................ 117


5.3.1.5 Hypothetical Landfill Grounds Keeper – Buffer Zone ....................................... 118

5.3.1.6 Hypothetical Off-Property Farmer – Off-Property North ................................... 118

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5.3.1.7 Hypothetical Off-Property Farmer – Off-Property Southeast ............................. 118

5.3.1.8 Hypothetical Off-Property Farmer – Off-Property South ................................... 119

5.3.1.9 Hypothetical Off-Property Farmer – Off-Property West .................................... 119

5.3.1.10 Hypothetical Off-Property Commercial Building User Off-Property North ...... 119

5.3.1.11 Hypothetical Off-Property Commercial Building User Off-Property West ........ 120

5.3.1.12 Hypothetical Off-Property Commercial Building User Adjacent Property, Lot 2A2

............................................................................................................................. 120

5.4 Summary of Human Health Risk Characterization ........................................................ 120

5.4.1 Summary of Human Health Risks under Current Conditions .................................. 121

5.4.2 Summary of Human Health Risks under Future (1,000-year) Conditions ............... 121

6. UNCERTAINTY ASSESSMENT ..................................................................................... 156

6.1 Analytical Data uncertainties .......................................................................................... 156

6.1.1 Sampling Bias .......................................................................................................... 156

6.1.2 Inclusion of Background .......................................................................................... 157

6.2 COPC-Specific Uncertainties ......................................................................................... 157

6.2.1 Radon ....................................................................................................................... 157

6.2.1.1 Radon Flux from OU1 Ground Surface .............................................................. 157

6.2.1.2 Modeling Considerations (AERMOD) ............................................................... 158

6.2.1.3 Use of Air Transport Modeling to Determine Exposure Point Concentration ... 158

6.2.1.4 Risks at Ambient Background and Acceptable Regulatory Limits .................... 158

6.3 Receptor Specific Uncertainties ...................................................................................... 159

6.3.1 Land Use Assumptions ............................................................................................ 159

6.3.2 Representative Receptors ......................................................................................... 159

6.3.3 Numerical Descriptions of Receptors and their Behaviors ...................................... 160

6.4 Exposure Point Concentration Uncertainties .................................................................. 161

6.4.1 Landfill Heterogeneity ............................................................................................. 161

6.4.2 Groundwater ............................................................................................................. 161

6.4.3 Analytical Variation ................................................................................................. 161

6.4.4 Representative Exposure Point Concentrations ....................................................... 162

6.4.5 Projected Future Concentrations .............................................................................. 162

6.4.6 Toxicity Factors ....................................................................................................... 163

6.4.6.1 General ................................................................................................................ 163

6.4.6.2 Zirconium ............................................................................................................ 164

6.4.7 Metals Relative Bioavailability Assumptions .......................................................... 165

7. SUMMARY ....................................................................................................................... 170

7.1 Ecological Assessment Summary ................................................................................... 172

7.2 Conclusions ..................................................................................................................... 172

8. REFERENCES ................................................................................................................... 174

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LIST OF TABLES

Table 1 Summary Statistics for Concentrations of Radionuclides in Samples Collected from

OU1 ............................................................................................................................................... 22

Table 2 Summary Statistics for Concentrations of Inorganic Chemicals, Polychlorinated

Biphenyls, and Pesticides in Samples Collected from OU1 ......................................................... 23

Table 3 Summary Statistics for Concentrations of Remaining Organic Chemicals in Samples

Collected from OU1 ...................................................................................................................... 25

Table 4 Screening Test Results for Radiological Constituents .................................................... 26

Table 5 Summary of Screening of Non-Radiological Constituents ............................................. 27

Table 6 Essential Nutrient Soil Screening Values for West Lake OU1 ...................................... 30

Table 7 Summary Statistics for COPCs in Area 1 – Surface Soil ............................................... 31

Table 8 Summary Statistics for COPCs in Area 1 – All Soil Depths .......................................... 34


Table 10 Summary Statistics for Concentration Data from Area 2 – All Soil Depths ................ 40

Table 11 Summary Statistics for Concentration Data from the Buffer Zone – Surface Soil ....... 43

Table 12 Summary Statistics for Concentration Data from the Buffer Zone – All Soil Depths . 46

Table 13 Summary of Potential Exposure Pathways ................................................................... 68

Table 14 Parameters Used to Estimate Potential Current Exposure ............................................ 69

Table 15 Parameters Used to Estimate Potential Future (1,000 years) Exposure ....................... 71

Table 16 Surrogate Radionuclides, Current Conditions .............................................................. 73

Table 17 Surrogate Radionuclides, Future(1,000 years) Conditions ........................................... 74

Table 18 Current Exposure Point Concentrations in Area 1 Soil ................................................ 75


Table 20 Current Exposure Point Concentrations for Buffer Zone Soil ...................................... 77

Table 21 Future (1,000 years) Exposure Point Concentrations for Area 1 Soil .......................... 78


Table 23 Future (1,000 years) Exposure Point Concentrations for Buffer Zone Soil ................. 80

Table 24 Summary of Future (1,000 years) Particulate Air Concentrations at Exposure Locations

....................................................................................................................................................... 81

Table 25 Projected Radon Concentrations at Selected Locations from all Source Groups ......... 83

Table 26 Radiological Carcinogenic Slope Factors ..................................................................... 93

Table 27 Chemical Oral Slope Factor Toxicity Values ............................................................... 97

Table 28 Chemical Inhalation Unit Risk Toxicity Values ......................................................... 100

Table 29 Chemical Oral Reference Dose Toxicity Values ........................................................ 102

Table 30 Chemical Inhalation Reference Concentration Toxicity Values ................................ 105

Table 31 Projected Blood Levels in Outdoor Workers Exposed to Future (1,000 years)

Concentrations of Lead in Soil from All Depths ........................................................................ 122

Table 32 Calculated Current ILCRs, On-Property Grounds Keeper Scenario -Area 1 and Area 2

..................................................................................................................................................... 123

Table 33 Calculated Current ILCRs, On-Property Commercial Building User Scenario - Area 1

..................................................................................................................................................... 124


..................................................................................................................................................... 125

Table 35 Calculated Current ILCRs, Off-Property Resident Scenario - Off-Property Southeast

and South .................................................................................................................................... 126

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Table 36 Calculated Current ILCRs, Commercial Building User Scenario, Off-Property North,

Off-Property West, and Adjacent Property, Lot 2A2 ................................................................. 127

Table 37 Calculated Future (1,000 years) ILCRs, Landfill Outdoor Storage Yard Worker

Scenario - Area 1 ........................................................................................................................ 128


Scenario - Area 2 ........................................................................................................................ 130

Table 39 Calculated Future (1,000 years) Hazard Quotients and Hazard Indices, Landfill

Outdoor Storage Yard Worker – Area 1 and Area 2 .................................................................. 132

Table 40 Calculated Future (1,000 years) ILCRs, Landfill Grounds Keeper Scenario - Area 1 133


Table 42 Calculated Future (1,000 years) ILCRs, Landfill Grounds Keeper Scenario - Buffer

Zone ............................................................................................................................................ 137

Table 43 Calculated Hazard Quotients and Hazard Indices, Future (1,000 years) Landfill

Grounds Keeper – Area 1, Area 2 and Buffer Zone ................................................................... 139

Table 44 Calculated Future (1,000 years) ILCRs, Off-Property Farmer Scenario – Off-Property

North ........................................................................................................................................... 141


Southeast ..................................................................................................................................... 142


South ........................................................................................................................................... 143


West ............................................................................................................................................ 144

Table 48 Calculated Future (1,000 years) Hazard Quotients and Hazard Indices, Off-Property

Farmer ......................................................................................................................................... 145

Table 49 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario – Off-

Property North ............................................................................................................................ 147

Table 50 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario –Off-

Property West .............................................................................................................................. 148

Table 51 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario –

Adjacent Property, Lot 2A2 ........................................................................................................ 149


Commercial Building User ......................................................................................................... 150

Table 53 Summary of Risks and HIs for All Receptor Scenarios Evaluated by the West Lake

OU1 Baseline Risk Assessment .................................................................................................. 152

Table 54 Hazard Quotient Sums by Target Organ Future (1,000 years) Storage Yard Worker,

Soil Ingestion .............................................................................................................................. 153

Table 55 Hazard Quotient Sums by Target Organ Future (1,000 years) Grounds Keeper, Soil

Ingestion ...................................................................................................................................... 154

Table 56 Uncertainties Associated with Estimated Risks for OU1 ........................................... 167

Table 57 Summary of ILCR (Risk) with and without Radon .................................................... 168

Table 58 Radon Concentration from Health Protective Standards ............................................ 169

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LIST OF FIGURES

Figure 1 Conceptual Grouping of Areas within the Modeling Domain ........................................ 3

Figure 2 General Location ........................................................................................................... 11

Figure 3 Site Layout ..................................................................................................................... 12

Figure 4 All Soil Isotope Distributions ........................................................................................ 21

Figure 5 Conceptual Model ......................................................................................................... 84

Figure 6 Sources and Locations of Hypothetical Receptors ........................................................ 85

Figure 7 Landfill Location Map ................................................................................................. 155

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LIST OF ACRONYMS

ABS absorption factor

AF adherence factor

ALM Adult Lead Methodology

AT averaging time

ATSDR Agency for Toxic Substances and Disease Registry

BCa bias-corrected and accelerated

BRA Baseline Risk Assessment

BW body weight

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CNS central nervous system

COPC constituents of potential concern

CSF cancer slope factor

DEHP diphthalate

DHHS Department of Health and Human Services

ED exposure duration

EF exposure frequency

EFH Exposure Factor Handbook

EMSI Engineering Management Support, Inc.

EPA U.S. Environmental Protection Agency

EPC Exposure Point Concentration

ERA Ecological Risk Assessment

ET exposure time

FI fraction of ingestion

FFS Final Feasibility Study

GAF gastrointestinal absorption factor

HEAST Health Effects Assessment Summary Tables

HI hazard index

HQ hazard quotient

IARC International Agency for Research on Cancer

ILCR incremental lifetime cancer risks

IR inhalation rates

IR soil ingestion rates

IRIS Integrated Risk Information System

IUR Inhalation Unit Risk Factor

LOAEL lowest observed adverse effect level

MDA minimum detectable activity

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MDNR Missouri Department of Natural Resources

MDOC Missouri Department of Conservation

MRL Minimal Risk Levels

NAAQS National Ambient Air Quality Standard

NOAEL no observed adverse effect level

OEHHA Office of Environmental Health Hazard Assessment

ORNL Oak Ridge National Laboratory

OSWER Office of Solid Waste and Emergency Response

OU Operable Unit

PCB polychlorinated biphenyls

PP Proposed Plan

PPRTV Provisional Peer Reviewed Toxicity Values

RBA Relative Bioavailability

REL Reference Exposure Level

RfC reference concentration

RfD reference dose

RIM Radiologically Impacted Materials

RI/FS Remedial Investigation/Feasibility Study

RME reasonable maximum exposure

ROD Record of Decision

RSL Regional Screening Level

SA surface area

SCS U.S. Soil Conservation Service

SCSR Site Characterization Summary Report

SFS Supplemental Feasibility Study

SLERA Screening Level Ecological Risk Assessment

SOW Statement of Work

UCL upper confidence limit

UF uncertainty factor

URF unit risk factors

USDA United States Department of Agriculture

USFWS U.S. Fish & Wildlife Service

UTLDI upper tolerance limit daily intakes

WOE weight-of-evidence

Please let us know if you have any questions.Thank-you, PaulPaul V. Rosasco P.E.Engineering Management Support, Inc.25923 Gateway DriveGolden, CO 80401(303) [email protected]

mailto:[email protected]

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TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................ 1

1. INTRODUCTION .................................................................................................................. 3

1.1 Overview ............................................................................................................................. 3

1.1.1 Objectives of the Baseline Risk Assessment ............................................................... 4

1.2 Background ......................................................................................................................... 4

1.2.1 West Lake Landfill Description ................................................................................... 5

1.2.2 Summary of Landfill Operations at the Landfill .......................................................... 5

1.2.3 Summary of Landfill Contamination ........................................................................... 5

1.2.3.1 Area 1 ...................................................................................................................... 6

1.2.3.2 Area 2 ...................................................................................................................... 6

1.2.3.3 Buffer Zone and Crossroad Lot 2A2 ...................................................................... 7

1.2.4 Land Use ...................................................................................................................... 8

1.2.4.1 Current Land Use .................................................................................................... 8

1.2.4.2 Future Land Use ...................................................................................................... 8

1.2.4.3 Surrounding Land Use ............................................................................................ 9

1.2.5 Groundwater Use ......................................................................................................... 9

1.3 Radionuclides inthe Environment ....................................................................................... 9

1.4 Organization of this Report ............................................................................................... 10

2. IDENTIFICATION OF CONSTITUENTS OF POTENTIAL CONCERN ........................ 13

2.1 Data Sources for ConstituentConcentrations .................................................................... 13

2.2 Summary Statistics for Representative Data ..................................................................... 14

2.3 Selection of Constituents of Potential Concern ................................................................ 14

2.3.1 Essential Nutrient Screening for Chemicals .............................................................. 15

2.3.2 Toxicity Screening for Chemicals .............................................................................. 15

2.3.3 Aggregate Screening Results ..................................................................................... 16

2.4 Additional Data/screening Considerations ....................................................................... 16

2.4.1 Uranium-235 .............................................................................................................. 16

2.4.2 Naturally Occurring Uranium .................................................................................... 18

2.4.3 Chromium .................................................................................................................. 18

2.4.4 Potassium-40 .............................................................................................................. 18

2.5 OU1 COPC Summary Statistics ....................................................................................... 19

2.5.1 Use of EPA’s ProUCL Statistical Application ........................................................... 19

3. HUMAN EXPOSURE ASSESSMENT ............................................................................... 49

3.1 Conceptual Site Model for OU1 ....................................................................................... 49

3.1.1 Sources ....................................................................................................................... 51

3.1.2 Potential Release Mechanisms ................................................................................... 51

3.1.2.1 Resuspension of Dust ............................................................................................ 51

3.1.2.2 Volatilization of Organics ..................................................................................... 51

3.1.2.3 Radon Emission .................................................................................................... 52

3.1.2.4 Leaching from Soil to Groundwater ..................................................................... 52

3.1.2.5 Soil Erosion by Surface Water .............................................................................. 53

3.1.3 Potential Exposure Media and Routes ....................................................................... 53

3.1.4 Potential Receptors ..................................................................................................... 54

3.1.4.1 Selection of Farmer or Resident for Quantification .............................................. 55

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3.1.4.2 Selection of Transient Receptor for Quantification .............................................. 55

3.1.4.3 Selection of Worker Receptors for Quantification ............................................... 56

3.1.5 Potential Scenarios ..................................................................................................... 56

3.1.5.1 Current On-Property Scenarios ............................................................................. 56

3.1.5.2 Current Off-Property Scenarios ............................................................................ 58

3.1.5.3 Future Landfill Scenarios – 1,000 Years .............................................................. 59

3.1.5.4 1,000-Year Future Off-Property Scenarios ........................................................... 61

3.2 Exposure Point Concentrations ......................................................................................... 61

3.2.1 Evaluation of Series Radionuclides ........................................................................... 62

3.2.2 Segregation of Concentration Data by Depth ............................................................ 62

3.2.3 Current Exposure Point Concentrations in Soil ......................................................... 63

3.2.4 1,000-Year Future Exposure Point Concentrations in Soil ........................................ 63

3.2.5 Exposure Point Air Concentrations ............................................................................ 64

3.3 Quantification of Exposure ............................................................................................... 65

3.3.1 Quantification of Intakes and Exposures from Multiple Pathways ........................... 66

3.3.2 Scenario-Specific Assumptions and Exposure Parameters ........................................ 66

3.4 Results of Exposure Assessment ...................................................................................... 67

4. TOXICITY ASSESSMENT ................................................................................................. 86

4.1 Toxicity Information for Chemicals of Potential Concern ............................................... 86

4.1.1 Radiocarcinogens ....................................................................................................... 86

4.1.2 Chemical Carcinogens ............................................................................................... 88

4.1.3 Noncarcinogenic Chemicals ....................................................................................... 89

4.1.4 Hierarchy of Chemical Toxicity Sources ................................................................... 91

5. HEALTH RISK CHARACTERIZATION ......................................................................... 108

5.1 Methods Used for Risk Characterization ........................................................................ 108

5.1.1 Carcinogenic Risks ................................................................................................... 108

5.1.1.1 Radiocarcinogenic Risks ..................................................................................... 109

5.1.1.2 Chemocarcinogenic Risks ................................................................................... 110

5.1.2 Noncarcinogenic Effects .......................................................................................... 111

5.1.3 Lead .......................................................................................................................... 111

5.1.4 Multiple Pathways .................................................................................................... 112

5.1.5 Exposures to Multiple Constituents ......................................................................... 112

5.2 Risk Estimates for Current Exposure Scenarios ............................................................. 113

5.2.1 Hypothetical On-Property Grounds Keeper Adjacent to Area 1 and Area 2 ............ 113



5.2.4 Hypothetical Off-Property Resident ......................................................................... 114

5.2.5 Hypothetical Off-Property Commercial Building User ........................................... 114

5.3 Risk Estimates for Future (1,000-year) Exposure Scenarios .......................................... 115

5.3.1 1,000-Year Future Exposure Scenarios for the Landfill ........................................... 115





5.3.1.5 Hypothetical Landfill Grounds Keeper – Buffer Zone ....................................... 118

5.3.1.6 Hypothetical Off-Property Farmer – Off-Property North ................................... 118

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5.3.1.7 Hypothetical Off-Property Farmer – Off-Property Southeast ............................. 118

5.3.1.8 Hypothetical Off-Property Farmer – Off-Property South ................................... 119

5.3.1.9 Hypothetical Off-Property Farmer – Off-Property West .................................... 119

5.3.1.10 Hypothetical Off-Property Commercial Building User Off-Property North ...... 119

5.3.1.11 Hypothetical Off-Property Commercial Building User Off-Property West ........ 120

5.3.1.12 Hypothetical Off-Property Commercial Building User Adjacent Property, Lot 2A2

............................................................................................................................. 120

5.4 Summary of Human Health Risk Characterization ........................................................ 120

5.4.1 Summary of Human Health Risks under Current Conditions .................................. 121

5.4.2 Summary of Human Health Risks under Future (1,000-year) Conditions ............... 121

6. UNCERTAINTY ASSESSMENT ..................................................................................... 156

6.1 Analytical Data uncertainties .......................................................................................... 156

6.1.1 Sampling Bias .......................................................................................................... 156

6.1.2 Inclusion of Background .......................................................................................... 157

6.2 COPC-Specific Uncertainties ......................................................................................... 157

6.2.1 Radon ....................................................................................................................... 157

6.2.1.1 Radon Flux from OU1 Ground Surface .............................................................. 157

6.2.1.2 Modeling Considerations (AERMOD) ............................................................... 158

6.2.1.3 Use of Air Transport Modeling to Determine Exposure Point Concentration ... 158

6.2.1.4 Risks at Ambient Background and Acceptable Regulatory Limits .................... 158

6.3 Receptor Specific Uncertainties ...................................................................................... 159

6.3.1 Land Use Assumptions ............................................................................................ 159

6.3.2 Representative Receptors ......................................................................................... 159

6.3.3 Numerical Descriptions of Receptors and their Behaviors ...................................... 160

6.4 Exposure Point Concentration Uncertainties .................................................................. 161

6.4.1 Landfill Heterogeneity ............................................................................................. 161

6.4.2 Groundwater ............................................................................................................. 161

6.4.3 Analytical Variation ................................................................................................. 161

6.4.4 Representative Exposure Point Concentrations ....................................................... 162

6.4.5 Projected Future Concentrations .............................................................................. 162

6.4.6 Toxicity Factors ....................................................................................................... 163

6.4.6.1 General ................................................................................................................ 163

6.4.6.2 Zirconium ............................................................................................................ 164

6.4.7 Metals Relative Bioavailability Assumptions .......................................................... 165

7. SUMMARY ....................................................................................................................... 170

7.1 Ecological Assessment Summary ................................................................................... 172

7.2 Conclusions ..................................................................................................................... 172

8. REFERENCES ................................................................................................................... 174

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LIST OF TABLES

Table 1 Summary Statistics for Concentrations of Radionuclides in Samples Collected from

OU1 ............................................................................................................................................... 22

Table 2 Summary Statistics for Concentrations of Inorganic Chemicals, Polychlorinated

Biphenyls, and Pesticides in Samples Collected from OU1 ......................................................... 23

Table 3 Summary Statistics for Concentrations of Remaining Organic Chemicals in Samples

Collected from OU1 ...................................................................................................................... 25

Table 4 Screening Test Results for Radiological Constituents .................................................... 26

Table 5 Summary of Screening of Non-Radiological Constituents ............................................. 27

Table 6 Essential Nutrient Soil Screening Values for West Lake OU1 ...................................... 30


Table 8 Summary Statistics for COPCs in Area 1 – All Soil Depths .......................................... 34


Table 10 Summary Statistics for Concentration Data from Area 2 – All Soil Depths ................ 40

Table 11 Summary Statistics for Concentration Data from the Buffer Zone – Surface Soil ....... 43

Table 12 Summary Statistics for Concentration Data from the Buffer Zone – All Soil Depths . 46

Table 13 Summary of Potential Exposure Pathways ................................................................... 68

Table 14 Parameters Used to Estimate Potential Current Exposure ............................................ 69

Table 15 Parameters Used to Estimate Potential Future (1,000 years) Exposure ....................... 71

Table 16 Surrogate Radionuclides, Current Conditions .............................................................. 73

Table 17 Surrogate Radionuclides, Future(1,000 years) Conditions ........................................... 74



Table 20 Current Exposure Point Concentrations for Buffer Zone Soil ...................................... 77



Table 23 Future (1,000 years) Exposure Point Concentrations for Buffer Zone Soil ................. 80

Table 24 Summary of Future (1,000 years) Particulate Air Concentrations at Exposure Locations

....................................................................................................................................................... 81

Table 25 Projected Radon Concentrations at Selected Locations from all Source Groups ......... 83

Table 26 Radiological Carcinogenic Slope Factors ..................................................................... 93

Table 27 Chemical Oral Slope Factor Toxicity Values ............................................................... 97

Table 28 Chemical Inhalation Unit Risk Toxicity Values ......................................................... 100

Table 29 Chemical Oral Reference Dose Toxicity Values ........................................................ 102

Table 30 Chemical Inhalation Reference Concentration Toxicity Values ................................ 105

Table 31 Projected Blood Levels in Outdoor Workers Exposed to Future (1,000 years)

Concentrations of Lead in Soil from All Depths ........................................................................ 122

Table 32 Calculated Current ILCRs, On-Property Grounds Keeper Scenario -Area 1 and Area 2

..................................................................................................................................................... 123


..................................................................................................................................................... 124


..................................................................................................................................................... 125

Table 35 Calculated Current ILCRs, Off-Property Resident Scenario - Off-Property Southeast

and South .................................................................................................................................... 126

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Table 36 Calculated Current ILCRs, Commercial Building User Scenario, Off-Property North,

Off-Property West, and Adjacent Property, Lot 2A2 ................................................................. 127


Scenario - Area 1 ........................................................................................................................ 128


Scenario - Area 2 ........................................................................................................................ 130

Table 39 Calculated Future (1,000 years) Hazard Quotients and Hazard Indices, Landfill

Outdoor Storage Yard Worker – Area 1 and Area 2 .................................................................. 132



Table 42 Calculated Future (1,000 years) ILCRs, Landfill Grounds Keeper Scenario - Buffer

Zone ............................................................................................................................................ 137

Table 43 Calculated Hazard Quotients and Hazard Indices, Future (1,000 years) Landfill

Grounds Keeper – Area 1, Area 2 and Buffer Zone ................................................................... 139


North ........................................................................................................................................... 141


Southeast ..................................................................................................................................... 142


South ........................................................................................................................................... 143


West ............................................................................................................................................ 144


Farmer ......................................................................................................................................... 145

Table 49 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario – Off-

Property North ............................................................................................................................ 147

Table 50 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario –Off-

Property West .............................................................................................................................. 148

Table 51 Calculated Future (1,000 years) ILCRs, Commercial Building User Scenario –

Adjacent Property, Lot 2A2 ........................................................................................................ 149


Commercial Building User ......................................................................................................... 150

Table 53 Summary of Risks and HIs for All Receptor Scenarios Evaluated by the West Lake

OU1 Baseline Risk Assessment .................................................................................................. 152

Table 54 Hazard Quotient Sums by Target Organ Future (1,000 years) Storage Yard Worker,

Soil Ingestion .............................................................................................................................. 153

Table 55 Hazard Quotient Sums by Target Organ Future (1,000 years) Grounds Keeper, Soil

Ingestion ...................................................................................................................................... 154

Table 56 Uncertainties Associated with Estimated Risks for OU1 ........................................... 167

Table 57 Summary of ILCR (Risk) with and without Radon .................................................... 168

Table 58 Radon Concentration from Health Protective Standards ............................................ 169

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LIST OF FIGURES

Figure 1 Conceptual Grouping of Areas within the Modeling Domain ........................................ 3

Figure 2 General Location ........................................................................................................... 11

Figure 3 Site Layout ..................................................................................................................... 12

Figure 4 All Soil Isotope Distributions ........................................................................................ 21

Figure 5 Conceptual Model ......................................................................................................... 84

Figure 6 Sources and Locations of Hypothetical Receptors ........................................................ 85

Figure 7 Landfill Location Map ................................................................................................. 155

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LIST OF ACRONYMS

ABS absorption factor

AF adherence factor

ALM Adult Lead Methodology

AT averaging time

ATSDR Agency for Toxic Substances and Disease Registry

BCa bias-corrected and accelerated

BRA Baseline Risk Assessment

BW body weight

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CNS central nervous system

COPC constituents of potential concern

CSF cancer slope factor

DEHP diphthalate

DHHS Department of Health and Human Services

ED exposure duration

EF exposure frequency

EFH Exposure Factor Handbook

EMSI Engineering Management Support, Inc.

EPA U.S. Environmental Protection Agency

EPC Exposure Point Concentration

ERA Ecological Risk Assessment

ET exposure time

FI fraction of ingestion

FFS Final Feasibility Study

GAF gastrointestinal absorption factor

HEAST Health Effects Assessment Summary Tables

HI hazard index

HQ hazard quotient

IARC International Agency for Research on Cancer

ILCR incremental lifetime cancer risks

IR inhalation rates

IR soil ingestion rates

IRIS Integrated Risk Information System

IUR Inhalation Unit Risk Factor

LOAEL lowest observed adverse effect level

MDA minimum detectable activity

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MDNR Missouri Department of Natural Resources

MDOC Missouri Department of Conservation

MRL Minimal Risk Levels

NAAQS National Ambient Air Quality Standard

NOAEL no observed adverse effect level

OEHHA Office of Environmental Health Hazard Assessment

ORNL Oak Ridge National Laboratory

OSWER Office of Solid Waste and Emergency Response

OU Operable Unit

PCB polychlorinated biphenyls

PP Proposed Plan

PPRTV Provisional Peer Reviewed Toxicity Values

RBA Relative Bioavailability

REL Reference Exposure Level

RfC reference concentration

RfD reference dose

RIM Radiologically Impacted Materials

RI/FS Remedial Investigation/Feasibility Study

RME reasonable maximum exposure

ROD Record of Decision

RSL Regional Screening Level

SA surface area

SCS U.S. Soil Conservation Service

SCSR Site Characterization Summary Report

SFS Supplemental Feasibility Study

SLERA Screening Level Ecological Risk Assessment

SOW Statement of Work

UCL upper confidence limit

UF uncertainty factor

URF unit risk factors

USDA United States Department of Agriculture

USFWS U.S. Fish & Wildlife Service

UTLDI upper tolerance limit daily intakes

WOE weight-of-evidence

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