CASMALIA SITE REMEDIATION PROJECT Resources Superfund Site Final Feasibility Study ii 4.5...

Casmalia Office San Luis Obispo Office 3401 NTU Road 3575 Camino Purisima Casmalia, CA 93429 Arroyo Grande, CA 93420 (805) 801-1529

CASMALIA SITE REMEDIATION PROJECT

Corey Bertelsen Project Manager

February 15, 2016 To: Russell Mechem EPA Mark Samolis EPA Subject: Final Feasibility Study Report The Casmalia Resources Site Steering Committee (CSC) has prepared this Final Feasibility Study (FS) Report for EPAs review. The Final FS Report incorporates all previous EPA comments and edits. As was the case with previous drafts of the FS Report that we have submitted, this Final FS Report was prepared as required by Section 11.6 of the Remedial Investigation/ Feasibility Study (RI/FS) Work Plan (CSC, 2004). The Final FS utilizes the information developed during the investigation and remedial activities undertaken for the Casmalia Resources Superfund Site (Site) and reported in the January, 2011 Final Remedial Investigation (RI) Report to evaluate and propose remediation alternatives for the Casmalia Superfund Site. The CSC is distributing copies of the Final FS Report to the distribution list that EPA provided us for the earlier submittal. The CSC is sending complete hard copies of the document to all of those you requested and the remainder of the distribution list is receiving a complete electronic copy (text, tables and figures). We look forward to your approval of the Final FS Report submittal. Regards,

Corey Bertelsen Casmalia Project Coordinator cc: Jim Dragna Bingham McCutcheon Scott Mansholt Chevron Dave Roberson Exxon Mobil Jill Tracy Sempra Chris Sherman DSTC

Russell Mechem EPA Mark Samolis EPA Page 2 of 2

Casmalia Office San Luis Obispo Office 3401 NTU Road 3575 Camino Purisima Casmalia, CA 93429 Arroyo Grande, CA 93420 (805) 801-1529

Mark Wuttig CH2MHill Matthew Plate EPA Gary Santolo CH2MHill Patty Velez DFG Christine Bucklin DTSC Dan Niles RWQCB Steve Henry USFWS Artemis Antipas CH2MHill Jaime Williams CH2MHill

Casmalia Resources Superfund Site

Final Feasibility Study

February 2016

Prepared for:

USEPA, Region 9 75 Hawthorne Street

San Francisco, CA 94105

Prepared by:

Casmalia Resources Site Steering Committee

Casmalia Resources Superfund Site Final Feasibility Study

CERTIFICATION STATEMENT This Final Feasibility Study (FS) for the Casmalia Resources Superfund Site, Santa Barbara County, California has been prepared in a manner consistent with the normal level of care and skill ordinarily exercised by professional engineers, geologists and environmental scientists. This report was prepared under the technical direction of the undersigned.

__________________________ Corey Bertelsen Project Coordinator Principal, CB Consulting, Inc.

__________________________ Jude Francis, PhD, PE Principal Engineer, URS Corporation (an AECOM company)

__________________________ Gib Fates, PG Principal Geologist, URS Corporation (an AECOM company)

__________________________ Brian Bjorklund, PG, CHG Principal Geologist, Environmental Resources Management (ERM) West, Inc

__________________________ Ted Cota, PG Technical Director, Environmental Resources Management (ERM) West, Inc.

__________________________ Warren Chamberlain, PE, PG, CHG Principal, AMEC Environmental & Infrastructure, Inc.


__________________________ Mala Pattanayak Senior Scientist, Risk Assessor, Arcadis-US, Inc.

__________________________ Ruth Custance, Principal Scientist, Geosyntec Consultants


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TABLE OF CONTENTS EXECUTIVE SUMMARY ES-1 1.0 INTRODUCTION 1-1

1.1 Purpose and Scope 1-1 1.2 Feasibility Study Approach 1-1 1.3 FS Report Organization 1-5 1.4 References 1-5

2.0 SITE BACKGROUND 2-1

2.1 Site Description 2-1 2.2 Site History and Use 2-1

2.2.1 Site Operational Information 2-2 2.2.2 Site History Review 2-3 2.2.3 Facilities 2-4 2.2.4 NPDES Permits 2-17 2.2.5 Existing Surface Impoundments 2-18 2.2.6 Closure Activities and Response Actions, and Ongoing Monitoring 2-18 2.2.7 Groundwater and Surface Water Monitoring 2-22

2.3 References 2-24 3.0 SUMMARY OF PREVIOUS INVESTIGATIONS 3-1

3.1 Previous Site Investigations 3-1 3.1.1 Pre-EPA Assessment Activities 3-1 3.1.2 USEPA Response Activities 3-3 3.1.3 CSC Site Work Activities 3-3 3.1.4 RI/FS Activities 3-7

3.2 Previous Response Actions 3-10 3.3 References 3-10

4.0 PHYSICAL CHARACTERISTICS OF SITE AND STUDY AREAS 4-1

4.1 Surface Features 4-1 4.1.1 Site Boundaries 4-1 4.1.2 Physiography 4-1

4.2 Meteorology 4-2 4.3 Surface Water Hydrology 4-2

4.3.1 Surface Water Drainage Within Site Boundary 4-2 4.3.2 Site Storm Water Runoff Collection Ponds and Liquid Treatment Impoundments 4-3 4.3.3 Surface Water Drainages Outside Site Boundaries 4-4

4.4 Geologic Setting 4-4 4.4.1 Regional Geology 4-5 4.4.2 Local Geology 4-5 4.4.3 Regional Structure 4-7 4.4.4 Site Structural Features 4-7


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4.5 Hydrogeology 4-13 4.5.1 Regional and Site Hydrogeologic Setting 4-13 4.5.2 Site Hydrogeologic Physical Characteristics 4-14 4.5.3 Site Groundwater Flow Conditions 4-19

4.6 Demography and Land Use 4-30 4.6.1 Regional Land Use 4-30 4.6.2 Nearby Populations 4-30

4.7 Ecology 4-30 4.7.1 Site Habitats 4-30

4.8 B-Drainage Wetlands 4-31 4.8.1 Goals and Objectives 4-32 4.8.2 Hydrology, Function, and Operation 4-32

4.9 Site Conceptual Model 4-33 4.9.1 Site Features 4-34 4.9.2 Meteorology 4-34 4.9.3 Geology 4-34 4.9.4 Hydrogeology 4-35 4.9.5 Contamination 4-37 4.9.6 Exposure Pathways 4-42

4.10 References 4-43 5.0 NATURE AND EXTENT OF CONTAMINATION 5-1

5.1 Contaminant Sources 5-1 5.2 Affected Media 5-1 5.3 Summary of RI Results 5-2

5.3.1 Soils 5-2 5.3.2 Sediments 5-4 5.3.3 Soil Vapor 5-5 5.3.4 Surface Water 5-6 5.3.5 Groundwater and Nonaqueous Phase Liquids 5-8

5.4 References 5-12 6.0 CONTAMINANT FATE AND TRANSPORT 6-1

6.1 Surface Transport Pathways COPC Fate and Transport 6-1 6.1.1 Surface Soil COPCs 6-1 6.1.2 Sediment COPCs 6-4 6.1.3 Surface Water COPCs 6-6

6.2 Subsurface Transport Pathways COPC Fate and Transport 6-9 6.2.1 Subsurface Soil COPCs 6-9 6.2.2 Soil Vapor COPCs 6-12 6.2.3 Groundwater COPCs 6-15 6.2.4 NAPL COPCs 6-25

6.3 Summary and Conclusions 6-30 6.4 References 6-32


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7.0 SUMMARY OF RISK ASSESSMENT 7-1 7.1 Human Health Risks 7-1 7.2 Ecological Risks 7-13

7.2.1 Tier 1 ERA 7-22 7.2.2 Tier 2 ERA 7-24 7.2.3 Barium Toxicity 7-26

7.3 Land Ownership and Use 7-27 7.4 References 7-27

8.0 AREAS FOR FS EVALUATION, REMEDIAL ACTION OBJECTIVES,

GENERAL RESPONSE ACTIONS, ARARS, TI EVALUATION AND PRELIMINARY REMEDIATION GOALS 8-1

8.1 Summary of Study Areas for FS Evaluation 8-1 8.2 Remedial Action Objectives 8-2

8.2.1 Soil, Soil Vapor, and Sediments 8-3 8.2.2 Groundwater, NAPL, and Surface Water Media 8-3

8.3 General Response Actions 8-5 8.3.1 Soil and Sediment Media 8-5 8.3.2 Groundwater, NAPL, and Stormwater Media 8-6

8.4 Potential ARARs 8-7 8.4.1 Identification of Potential ARARs 8-8

8.5 Technical Impracticability Waiver 8-9 8.5.1 Spatial Extent of the TI Determination 8-10 8.5.2 Conceptual Site Model 8-10 8.5.3 Technical Impracticability Evaluation Process 8-12 8.5.4 Technical Impracticability Evaluation Conclusions 8-13

8.6 Preliminary Remediation Goals 8-15 8.6.1 Groundwater 8-15 8.6.2 Soil 8-16 8.6.3 Pond Surface Water and Sediment 8-18 8.6.4 Seep Surface Water 8-18 8.6.5 Treated Stormwater, Treated Pond Water, or Treated Groundwater for Surface Water Discharge 8-19 8.6.6 Summary of PRGs 8-19

8.7 Principal Threat Wastes 8-19 8.8 Basis for Action 8-20 8.9 References 8-23

9.0 IDENTIFICATION AND SCREENING OF TECHNOLOGIES 9-1

9.1 Initial Screening of Technologies 9-1 9.1.1 Soil/Sediment 9-1 9.1.2 Groundwater 9-2 9.1.3 Water Treatment 9-3 9.1.4 Vapor Treatment 9-4 9.1.5 Surface Water/Stormwater 9-4

9.2 Technology Screening for Soil and Sediment 9-4


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9.2.1 Soil 9-4 9.2.2 Sediments 9-6

9.3 Technology Screening for Groundwater, NAPL and Stormwater 9-7 9.3.1 Groundwater and NAPL 9-7 9.3.2 Stormwater 9-10

9.4 Extracted Water and Vapor Treatment 9-11 9.4.1 Extracted Water Treatment 9-11 9.4.2 Extracted Vapor Treatment 9-12

9.5 Summary of Retained Technologies 9-12 9.5.1 Soil/Sediment Technologies 9-12 9.5.2 Groundwater, NAPL and Stormwater Technologies 9-18

9.6 References 9-23 10.0 DEVELOPMENT AND SCREENING OF AREA-SPECIFIC REMEDIAL

ALTERNATIVES 10-1 10.1 Background Information for Technologies Considered 10-2

10.1.1 Capping and Pond Lining Technologies Considered in the Evaluation 10-2 10.1.2 Soil Management Considerations 10-12 10.1.3 Stormwater and Pond Water Management 10-14 10.1.4 Proposed Evaporation Pond in Remedial Alternatives 10-17 10.1.5 HELP and Groundwater Flow Modeling 10-21 10.1.6 Long Term Groundwater and Soil Vapor Monitoring 10-24 10.1.7 Monitored Natural Attenuation 10-24 10.1.8 Groundwater FS Area 5 North (TI Zone) Source Removal and Containment 10-25 10.1.9 Groundwater FS Area 5 South and West Remediation

and Containment 10-36 10.2 FS Area 1 PCB Landfill, Burial Trench Area, Central

Drainage Area and Existing Capped Landfills Area 10-37 10.2.1 Nature and Extent of Contamination 10-37 10.2.2 Development of Remedial Alternatives 10-38 10.2.3 Screening of Remedial Alternatives 10-42

10.3 FS Area 2 RCRA Canyon and West Canyon Spray Area 10-43 10.3.1 Nature and Extent of Contamination 10-43 10.3.2 Development of Remedial Alternatives 10-45 10.3.3 Screening of Remedial Alternatives 10-51

10.4 FS Area 3 Former Ponds and Pads, Remaining Onsite Areas 10-52 10.4.1 Nature and Extent of Contamination 10-52 10.4.2 Development of Remedial Alternatives 10-55 10.4.3 Screening of Remedial Alternatives 10-59

10.5 FS Area 4 Stormwater Ponds and Treated Liquid Impoundments 10-60 10.5.1 Nature and Extent of Contamination 10-60 10.5.2 Development of Remedial Alternatives 10-61 10.5.3 Screening of Remedial Alternatives 10-67

10.6 FS Area 5 Groundwater 10-68 10.6.1 Nature and Extent of Contamination 10-68


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10.6.2 Existing Remedial Extraction Features 10-74 10.6.3 Development of Remedial Alternatives Area 5 North 10-78 10.6.4 Development of Remedial Alternatives Area 5 South 10-104 10.6.5 Development of Remedial Alternatives Area 5 West 10-111 10.6.6 Screening of Remedial Alternatives Area 5 North 10-115 10.6.7 Screening of Remedial Alternatives Area 5 South 10-118 10.6.8 Screening of Remedial Alternatives Area 5 West 10-119

10.7 References 10-121 11.0 DETAILED EVALUATION OF REMEDIAL ALTERNATIVES 11-1

11.1 Description of CERCLA RI/FS 9-Criteria 11-1 11.1.1 Cost Estimating Approach 11-4

11.2 Detailed Evaluation for FS Area 1 11-5 11.2.1 Description of Remedial Alternatives 11-5 11.2.2 Detailed and Comparative Analysis of Remedial Alternatives 11-15 11.2.3 Area 1 Evaluation Summary 11-17

11.3 Detailed Evaluation for FS Area 2 11-17 11.3.1 Description of Remedial Alternatives 11-18 11.3.2 Detailed and Comparative Analysis of Remedial Alternatives 11-34 11.3.3 Area 2 Evaluation Summary 11-37

11.4 Detailed Evaluation of FS Area 3 11-38 11.4.1 Description of Remedial Alternatives 11-38 11.4.2 Detailed and Comparative Analysis of Remedial Alternatives 11-49 11.4.3 Area 3 Evaluation Summary 11-51

11.5 Detailed Evaluation of FS Area 4 11-52 11.5.1 Description of Remedial Alternatives 11-52 11.5.2 Detailed and Comparative Analysis of Remedial Alternatives 11-70 11.5.3 Area 4 Evaluation Summary 11-72

11.6 Detailed Evaluation of FS Area 5 Groundwater 11-73 11.6.1 Description of Remedial Alternatives for Area 5 North 11-73 11.6.2 Detailed and Comparative Evaluation of Remedial Alternatives for

Area 5 North 11-95 11.6.3 Evaluation Summary for Area 5 North 11-99 11.6.4 Description of Remedial Alternatives for FS Area 5 South 11-100 11.6.5 Detailed and Comparative Evaluation of Remedial Alternatives for FS Area 5 South 11-105 11.6.6 Evaluation Summary for Area 5 South 11-109 11.6.7 Description of Remedial Alternatives for FS Area 5 West 11-109 11.6.8 Detailed and Comparative Evaluation of Remedial Alternatives for FS Area 5 West 11-114 11.6.9 Evaluation Summary for Area 5 West 11-117

11.7 Cost Estimate Uncertainty 11-118 11.8 Assumed Schedule for Cost Estimating Purposes 11-119 11.9 References 11-120


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12.0 DETAILED EVALUATION OF SITE-WIDE REMEDIAL ALTERNATIVES AND SUMMARY OF TOP RANKED REMEDY 12-1

12.1 Description of Site Wide Remedial Alternatives 12-1 12.1.1 SWR #1 No Further Action 12-1 12.1.2 SWR #2 Large Evaporation Pond 12-2 12.1.3 SWR #3 Small Evaporation Pond 12-8 12.1.4 SWR #4 No Evaporation Pond 12-9 12.1.5 SWR #5 P/S Landfill Dewatering 12-11 12.1.6 SWR #6 Aggressive Site Wide Groundwater Restoration 12-14

12.2 Detailed and Comparative Analysis of Site Wide Remedial Alternatives 12-16

12.2.1 Overall Protection of Human Health and Environment 12-16 12.2.2 Compliance with ARARs 12-18 12.2.3 Long Term Effectiveness 12-18 12.2.4 Reduction of Toxicity, Mobility, and Volume through Treatment 12-20 12.2.5 Short Term Effectiveness 12-21 12.2.6 Implementability 12-23 12.2.7 Cost 12-24 12.2.8 Green Impacts Assessment 12-26

12.3 Evaluation Summary and Top Ranked Remedy 12-27 12.3.1 CERCLA Detailed Evaluation Criteria Summary 12-27 12.3.2 Green Impacts Assessment Summary 12-29

12.4 Summary of Top Ranked Site-Wide Remedy SWR #3 12-30 12.4.1 FS Area 1 PCB Landfill, Burial Trench Area, Central Drainage Area 12-30 12.4.2 FS Area 2 RCRA Canyon, WCSA 12-31 12.4.3 FS Area 3 Former Ponds and Pads, Remaining Site Areas, Roadways, Maintenance Shed Area, Liquids Treatment Area,

Administration Building Area 12-32 12.4.4 FS Area 4 Stormwater Ponds and Treated Liquid Impoundments 12-33 12.4.5 Groundwater, FS Area 5 12-35 12.4.6 Area 5 North 12-35 12.4.7 Area 5 South 12-36 12.4.8 Area 5 West 12-37

12.5 Storm Management Plan 12-37 12.5.1 Stormwater Management with Top-Ranked Remedy 12-37 12.5.2 New Evaporation Pond Sizing and Operation 12-38

12.6 Borrow Soil Source and Volumes for Top-Ranked Remedy 12-39 12.6.1 Soil (or Backfill) Requirements for the Top-Ranked Remedy 12-39 12.6.2 Borrow Soil Location 12-40

12.7 Green Remediation 12-41 12.7.1 Energy Use 12-41 12.7.2 Air Emissions 12-41 12.7.3 Impacts on Water 12-42 12.7.4 Impacts on Land and Ecosystems 12-42 12.7.5 Integrating Renewable Energy 12-42


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12.8 Top-Ranked Remedy Work Sequencing 12-43 12.9 References 12-44


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LIST OF TABLES Table 2-1 Waste Management Unit Chronology Table 2-2 General Pond Information Table 2-3 Pond Closure Information Table 2-4 Contaminated Liquids Extraction, Treatment, and Disposal Table 4-1 Meteorological Data Summary for Site Temperature and

Wind Speed (20062007) Table 4-2 Meteorological Data Summary for Site Evaporation and

Rainfall (19962007) Table 5-1 General RI/FS Data Needs Table 5-2 Summary of Chemicals Detected in Media Remedial

Investigation Sampling Program Table 5-3 Summary of Risk-based Concentration Exceedances by

Media, Location, and Constituent Table 5-4 Range of Inorganic Constituents in Surface Water Drainage

Samples Table 5-5 Range of Detected Organic Constituents in Surface Water

Drainage Samples Table 5-6 Summary of Inorganic Analytical Results for Surface Water

Pond Samples Table 5-7 Summary of Detected Organic Analytical Results for Surface

Water Pond Samples Table 6-1 Estimated Physical and Chemical Properties of Detected

Constituents Table 6-2 Summary of Detected Chemicals by Chemical Analyte

Classes and Environmental Media Where Detected Table 6-3 Relative Mobility of Chemical Analytical Classes and

Representative Chemicals Table 6-4 Relative Degradation Potential of Detected Chemicals in

Various Chemical Analyte Classes Table 7-1 Chemicals of Concern in Surface Soil Terrestrial Birds, Soil

Invertebrates, and Plants Table 7-2 Chemicals of Concern in Shallow Soil Terrestrial Mammals,

Soil Invertebrates, and Plants Table 7-3 Chemicals of Concern in Sediment Based on Aquatic Wildlife

and Sediment Invertebrates Table 8-1 Summary of Areas for FS Evaluation Table 8-2 Technologies and Process Options for Soil, Soil Vapor,

and Sediment Table 8-3 Technologies and Process Treatment Options for Surface

Water, Groundwater, and NAPL Table 8-4 Remedial Action Objectives and General Response

Actions Summary by FS Area


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Table 8-5 The Proposed NPDES Standards for Offsite Discharge of Treated Stormwater, Pond Water or Treated Groundwater

Table 8-6A Ecological Chemicals of Concern and Risk-Based Concentrations in Soil

Table 8-6B Human Health Chemicals of Concern and Risk-Based Concentrations in Soil Commercial/Industrial Worker

Table 8-6C Preliminary Remediation Goals for Chemicals of Concern in Soil

Table 9-1 Initial Screening of Remedial Technologies and Process Options

Table 9-2 Screening of Technologies Soil, Soil Vapor and Sediment Table 9-3 Screening of Technologies Groundwater, NAPL and

Stormwater Table 9-4 Screening of Technologies Extracted Groundwater and

Vapor Treatment Table 10-1 List of Remedial Alternatives for Screening Analysis by FS

Area Table 10-2 Screening of Remedial Alternatives for FS Area 1 PCB

Landfill, Burial Trench Area, Central Drainage Area Table 10-3 Screening of Remedial Alternatives for FS Area 2 RCRA

Canyon and WCSA Table 10-4 Screening of Remedial Alternatives for FS Area 3 Former

Ponds and Pads, Remaining On-site Areas, LTA, MSA Table 10-5 Screening of Remedial Alternatives for FS Area 4

Stormwater Ponds and Impoundments Table 10-6A Screening of Remedial Alternatives for Groundwater FS Area

5 North Table 10-6A-1 Risk Analysis for P/S Landfill Dewatering with Horizontal Wells Table 10-6B Screening of Remedial Alternatives for Groundwater FS Area

5 South Table 10-6C Screening of Remedial Alternatives for Groundwater FS Area

5 West Table 11-1 Selected Remedial Alternatives for Detailed 9-Criteria Analysis

by FS Area Table 11-2 Detailed Analysis of Alternatives for FS Area 1, PCB

Landfill, Central Drainage Area and Burial Trench Area Table 11-3 Detailed Analysis of Alternatives for Area 2, RCRA

Canyon and West Canyon Spray Area Table 11-4 Detailed Analysis of Alternatives for Area 3, Former

Pads and Ponds Subarea, Roadways and Remaining On-site Areas

Table 11-5 Detailed Analysis of Alternatives for Area 4, Stormwater Ponds and Treated Liquid Impoundments (RCF, A-Series, A-5, 13, 18 Ponds)

Table 11-6A Detailed Analysis of Alternatives for Area 5 North Groundwater


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Table 11-6B Detailed Analysis of Alternatives for Area 5 South Groundwater

Table 11-6C Detailed Analysis of Alternatives for Area 5 West Groundwater

Table 12-1 Site-Wide Remedial Alternative Components Table 12-2 Detailed Analysis of Site-wide Alternatives Table 12-3 Summary of Area-specific Remedial Alternatives Evaluation Table 12-4 Cost Estimate for Site-wide Remedial Alternatives #2 to #6 Table 12-5 Summary of Site-wide Remedial Alternatives Evaluation Table 12-6 Cost Estimate Summary for Top-Ranked Sitewide Remedial

Alternative #3


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LIST OF FIGURES Figure 1-1 Site Location Map Figure 2-1 Current Site Layout Figure 2-2 Historical Site Layout Figure 2-3 Historical Time Line and Milestones Figure 2-4 Primary Pond/Pad Uses Figure 2-5 Closure Status of Former Surface Impoundments Figure 2-6 Selected Site Photographs (19702002) Figure 3-1 Conceptual Study Areas Figure 4-1 Pre-Development Site Drainage 1959 Figure 4-2 Pond Levels, Volumes, and TDS Figure 4-3 Geologic Map of the Casmalia Quadrangle, Santa Barbara

County, California Figure 4-4 Regional Folds and Faults Figure 4-5 Regional Geologic Cross-Section Figure 4-6 Local Groundwater Basins Figure 4-7 Well Location Map All Site Wells Figure 4-8 Areal Distribution of Historical Seeps Figure 4-9 Statistical Representation of Hydraulic Conductivity Results for

Upper/Lower HSUs Figure 4-10 Water Table Contour Map, December 2008 Figure 4-11 Site-wide Cross-section D-D Figure 4-12 Model Domain and Boundaries Figure 4-13 MODFLOW Model Domain and Layering Figure 4-14 Potentiometric Surface Contours/Particle Flow Map, Upper

HSU, 2004 (Dry) Figure 4-15 Potentiometric Surface Contours/Particle Flow Map, Upper

HSU, 2001 (Wet) Figure 4-16 Potentiometric Surface Contours/Particle Flow Map, Lower

HSU, 2004 (Dry) Figure 4-17 B-Drainage Habitat Pool Design General Arrangement Plan Figure 4-18 B-Drainage Habitat Pool Design Pool Centerline Profile Figure 4-19 Conceptual Site Model 1 Transect through P/S Landfill,

Central Drainage Area, Former Ponds and Pads Area, and RCF Pond

Figure 4-20 Conceptual Site Model 2 Transect through PCB Landfill, Burial Trench Area, Former Ponds and Pads Area, and RCF Pond

Figure 4-21 Conceptual Site Model 3 Transect through RCRA Canyon, Pond A-5, A-Series Pond, and C-Drainage

Figure 4-22 Conceptual Site Model 4 Transect through PSCT-1, Former Ponds and Pads Area, and B-Drainage

Figure 4-23 Conceptual Site Model Block Diagram Figure 4-24 Conceptual Site Model Block Diagram Detail


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Figure 5-1 Summary of Chemical Detections and Exceedances - All Media Figure 5-2 Metals in Soil and Sediment in Excess of RBCs (Cr, Cu, Zn) Figure 5-3 Organics in Soil and Sediment in Excess of RBCs (MCPP, Total

PCB Congeners, PCE, Total DDT, TCE, Dioxin TEQ - Mammalian)

Figure 5-4 Estimated Extent of Total Detected VOCs in Soil Vapor Figure 5-5 LNAPL, DNAPL, Total VOCs in Upper HSU Figure 5-6 LNAPL, DNAPL, Metals in Upper HSU Figure 5-7 LNAPL, DNAPL, Inorganics, Metals in Lower HSU Figure 5-8 DNAPL, Total VOCs in Lower HSU Figure 5-9 Concentration Ranges for Chromium in Soil All On-Site Areas Figure 5-10 Concentration Ranges for Copper in Soil All On-Site Areas Figure 5-11 Concentration Ranges for Zinc in Soil All On-Site Areas Figure 5-12 Concentration Ranges for Total DDT in Soil All On-Site Areas Figure 5-13 Concentration Ranges for Dioxin TEQ (Mammalian) in Soil All

On-Site Areas Figure 5-14 Concentration Ranges for MCPP in Soil All On-Site Areas Figure 5-15 Concentration Ranges for Total PCBs as Congeners in Soil All

On-Site Areas Figure 5-16 Concentration Ranges for Tetrachloroethylene (PCE) in Soil All

On-Site Areas Figure 5-17 Concentration Ranges for Trichloroethylene (TCE) in Soil All

On-Site Areas Figure 5-18 Concentration Ranges for MCPP in Sediment All On-Site Areas Figure 5-19 Concentration Ranges of Acetone in Soil Vapor Figure 5-20 Concentration Ranges of Freon 113 in Soil Vapor Figure 5-21 Concentration Ranges of Methyl Ethyl Ketone in Soil Vapor Figure 5-22 Concentration Ranges of 1,3-Butadiene in Soil Vapor Figure 5-23 Concentration Ranges of Benzene in Soil Vapor Figure 5-24 Concentration Ranges of Tetrachloroethylene in Soil Vapor Figure 5-25 Concentration Ranges of Total Detected VOCs in Soil Vapor Figure 5-26 VOC-GW/Particle Flow Map, Upper HSU, 2004 (Dry) Figure 5-27 VOC-GW/Particle Flow Map, Upper HSU, 2001 (Wet) Figure 5-28 VOC-GW/Particle Flow Map, Lower HSU, 2004 (Dry)

Between PCB Landfill and PSCT-4 Figure 5-29 VOC-GW/Particle Flow Map, Lower HSU, 2004 (Dry) Near

RGPZ-6 and RGPZ-7 Figure 5-30 LNAPL in Upper HSU Observed or Inferred from Groundwater

Concentrations Fall 2004 and Spring 2005 RI Sampling Figure 5-31 DNAPL in Upper HSU Observed or Inferred from Groundwater

Concentrations Fall 2004 and Spring 2005 RI Sampling Figure 5-32 DNAPL in Lower HSU Observed or Inferred from Groundwater

Concentrations Fall 2004 and Spring 2005 RI Sampling Figure 5-33a Arsenic Groundwater Concentrations Upper HSU Zone 1 Area,

North of PSCT Remedial Investigation Sampling


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Figure 5-33b Arsenic Groundwater Concentrations Upper HSU Zone 1 Area, South of PSCT Remedial Investigation Sampling

Figure 5-34 Arsenic Groundwater Concentrations Lower HSU Zone 1 Area Remedial Investigation Sampling

Figure 5-35a Nickel Groundwater Concentrations Upper HSU Zone 1 Area Remedial Investigation Sampling

Figure 5-35b Nickel Groundwater Concentrations Upper HSU Zone 1 Area, South of PSCT Trench Remedial Investigation Sampling

Figure 5-36 Nickel Groundwater Concentrations Lower HSU Zone 1 Area Remedial Investigation Sampling

Figure 5-37a Cadmium Groundwater Concentrations Upper HSU Zone 1 Area, North of PSCT Remedial Investigation Sampling

Figure 5-37b Cadmium Groundwater Concentrations Upper HSU Zone 1 Area, South of PSCT Trench Remedial Investigation Sampling

Figure 5-38 Cadmium Groundwater Concentrations Lower HSU Zone 1 Area Remedial Investigation Sampling

Figure 5-39a Selenium Groundwater Concentrations Upper HSU Zone 1 Area Remedial Investigation Sampling

Figure 5-39b Selenium Groundwater Concentrations Upper HSU Zone 1 Area, South of PSCT Trench Remedial Investigation Sampling

Figure 5-40 Selenium Groundwater Concentrations Lower HSU Zone 1 Area Remedial Investigation Sampling

Figure 6-1 VOC-GW/Particle Flow Map, Upper HSU, 2004 (Dry) Figure 6-2 VOC-GW/Particle Flow Map, Upper HSU, 2001 (Wet) Figure 6-3 VOC-GW/Particle Flow Map, Lower HSU, 2004 (Dry) Figure 7-1 Co-located Risks to Ecological Communities Figure 7-1A Co-located Risks to Ecological Communities Assuming Barium

is Not Toxic Figure 7-2 Co-located Risks to Wildlife Receptors Figure 7-2A Co-located Risks to Wildlife Receptors Assuming Barium is Not

Toxic Figure 7-3 Parcel Ownership in Site Vicinity Figure 8-1A FS Study Areas 1-4 Figure 8-1B FS Study Area 5 Figure 10-1A Caps Considered in FS Evaluation Figure 10-1B Area 5 North P/S Landfill, Gallery Well + NAPL-Only Vertical

Extraction Wells Figure 10-1C Area 5 North P/S Landfill, Gallery Well + Aggressive NAPL

Extraction Wells Figure 10-1D Area 5 North P/S Landfill, Gallery Well + Horizontal Extraction

Wells Figure 10-1E Area 5 North P/S Landfill, Bottom Elevation and Saturation

Thickness Contours


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Figure 10-2 Soil Borrow Areas Figure 10-3 Summary Analytical Results Exceedances for Soil Area 1 Figure 10-4 Summary Analytical Results Exceedances for Soil Area 2 Figure 10-5 Summary Analytical Results Exceedances for Soil Area 3 Figure 10-5A Soil Sampling Locations RISBON-59 Area Figure 10-5B Cross Section A-A Figure 10-5C Cross Section B-B Figure 10-6 Summary Analytical Results Exceedances for Soil Area 4 Figure 11-1A FS Area 1 Alternative 2 RCRA Equivalent Mono Soil Cap

5 (BTA, CDA) + RCRA Prescriptive Cap (PCB Landfill) Figure 11-1B FS Area 1 Alternative 2 RCRA Cap (PCB Landfill), Soil

Cap (BTA) + Grading Plan Figure 11-1C FS Area 1 Alternative 2 Soil Cap (CDA) + Grading Plan Figure 11-2A FS Area 1 Alternative 3 Evapotranspirative Soil Cap 5

(BTA, CDA) + RCRA Prescriptive Cap (PCB Landfill) Figure 11-2B FS Area 1 Alternative 3 Evapotranspirative Cap 5 (BTA)

+ RCRA Cap (PCB Landfill) Grading Plan Figure 11-2C FS Area 1 Alternative 3 Evapotranspirative Cap (CDA) +

Grading Plan Figure 11-3A FS Area 1 Alternative 4 RCRA Cap (BTA, CDA, PCB

Landfill) Figure 11-3B FS Area 1 Alternative 4 RCRA Cap (PCB Landfill, BTA) +

Grading Plan Figure 11-3C FS Area 1 Alternative 4 RCRA Cap (CDA) + Grading Plan Figure 11-4A FS Area 1 Alternative 5 Excavate (Metals, Organics)

(BTA, 20) (CDA, 5) + RCRA Equivalent Mono Soil Cap 5 (BTA, CDA) +RCRA Cap (PCB Landfill)

Figure 11-4B FS Area 1 Alternative 5 RCRA Cap (PCB Landfill), Soil Cap (BTA) + Grading Plan

Figure 11-4C FS Area 1 Alternative 5 Soil Cap (CDA) + Grading Plan Figure 11-5A FS Area 2 Alternative 2 Eco-Cap (West Slope RCRA

Canyon, WCSA) + Grading/BMPs (Uncapped Areas) Figure 11-5B FS Area 2 Alternative 2 Stormwater Plan Figure 11-5C FS Area 2 Alternative 2 Eco Cap, and Grading Plan Figure 11-6A FS Area 2 Alternative 3 RCRA-Equivalent Mono Soil Cap

(West Slope RCRA Canyon) (5) + Excavate (Portion of WCSA) (5) + Grading/BMPs (Uncapped Areas)

Figure 11-6B FS Area 2 Alternative 3 Stormwater Plan Figure 11-6C FS Area 2 Alternative 3 RCRA Equivalent Mono Soil Cap,

Excavation, and Grading Plan Figure 11-7A FS Area 2 Alternative 4 RCRA-Equivalent Mono Soil Cap

(West Slope RCRA Canyon), Portion of WCSA) (5) + Grading/BMPs (Uncapped Areas)

Figure 11-7B FS Area 2 Alternative 4 Stormwater Plan


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Figure 11-7C FS Area 2 Alternative 4 RCRA-Equivalent Mono Soil Cap and Grading Plan

Figure 11-8A FS Area 2 Alternative 5 RCRA-Equivalent Mono Soil Cap (West Slope RCRA Canyon) (5) + Excavation (Portion of WCSA) (5) + Clean Soil Cover (East Slope, WSCA) (2)

Figure 11-8B FS Area 2 Alternative 5 Stormwater Plan Figure 11-8C FS Area 2 Alternative 5 RCRA-Equivalent Mono Soil Cap,

5 Excavation, 2 Soil Cover, and Grading Plan Figure 11-9A FS Area 2 Alternative 6 RCRA-Equivalent Hybrid Cap

(West Slope RCRA Canyon) (5) + Excavation (Portion of WCSA) (5) + Clean Soil Cover (East Slope, WSCA) (2)

Figure 11-9B FS Area 2 Alternative 6 Stormwater Plan Figure 11-9C FS Area 2 Alternative 6 RCRA-Equivalent Hybrid Cap, 5

Excavation, 2 Soil Cover, and Grading Plan Figure 11-10A FS Area 2 Alternative 7 Evapotranspirative Cap (West

Slope RCRA Canyon) (5) + Excavation (Portion of WCSA) (5) + Clean Soil Cover (East Slope, WSCA) (2)

Figure 11-10B FS Area 2 Alternative 7 Stormwater Plan

Figure 11-10C FS Area 2 Alternative 7 Evapotranspirative Cap, 5 Excavation, 2 Soil Cover, and Grading Plan

Figure 11-11A FS Area 2 Alternative 8 RCRA-Equivalent Hybrid Cap (RCRA Canyon, WCSA) Figure 11-11B FS Area 2 Alternative 8 Stormwater Plan

Figure 11-11C FS Area 2 Alternative 8 RCRA-Equivalent Hybrid Cap, Entire Canyon

Figure 11-12A FS Area 2 Alternative 9 Evapotranspirative Cap (RCRA Canyon, WCSA) Figure 11-12B FS Area 2 Alternative 9 Stormwater Plan

Figure 11-12C FS Area 2 Alternative 9 Evapotranspirative Cap, Entire Canyon

Figure 11-13A FS Area 3 Alternative 2 RCRA Cap (Locations 2, 3, 4) + Excavate/Asphalt Cap (Location 1) (5) + GW Monitoring (Location 10) + Grading/BMPs (Rest of Area 3)

Figure 11-13B FS Area 3 Alternative 2 RCRA Cap (Locations 2, 3, 4) + Grading Plan

Figure 11-13C FS Area 3 Alternative 2 Excavation (5') + Asphalt Cover (Location 1) + GW Monitoring (Location 10)

Figure 11-14A

FS Area 3 Alternative 3 RCRA Cap (Locations 2) + Excavate/Place in PCB Landfill (Location 3) (20'); (Location 4) (5') + Excavate/Asphalt Cap (Location 1) (5') + GW Monitoring (Location 10) + Grading/BMPs (Uncapped Areas)

Figure 11-14B FS Area 3 Alternative 3 RCRA Cap (Locations 2) + Excavate/Place in PCB Landfill (Location 3) (20'); (Location 4) (5') + Grading Plan

Figure 11-14C FS Area 3 Alternative 3 Excavation (5') + Asphalt Cover (Location 1) + GW Monitoring (Location 10)


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Figure 11-15A

FS Area 3 Alternative 4 RCRA Cap (Locations 2) + Excavate/Place in PCB Landfill (Location 3) (20'); (Location 4) (5'); (Location 10) (50') + Excavate/Asphalt Cap (Location 1) (5') + GW Monitoring (Location 10) + Grading/BMPs (Uncapped Areas)

Figure 11-15B FS Area 3 Alternative 4 RCRA Cap (Locations 2) + Excavate/Place in PCB Landfill (Location 3) (20'); (Location 4) (5') + Grading Plan

Figure 11-15C FS Area 3 Alternative 4 Excavation (5') + Asphalt Cover (Location 1) + Excavate/Place in PCB Landfill (Location 10) (50')

Figure 11-16A FS Area 3 Alternative 5 Excavate Locations 1, 2, and 4 (5'); Location 3 (20'); Location 10 (50') + Grading/BMPs (Uncapped Areas)

Figure 11-16B FS Area 3 Alternative 5 Excavation (Locations 2, 3, 4) + Grading Plan

Figure 11-16C FS Area 3 Alternative 5 Excavate Locations 1 (5') and Location 10 (50')

Figure 11-17A FS Area 4 Alternative 2 Eco-cap (RCF, A-Series Pond) + RCRA Cap (18) + Lined Retention Basin (A-5, 13) + New 11 Acre Evaporation Pond

Figure 11-17B FS Area 4 Alternative 2 Eco Cap (A-Series Pond, RCF Pond) Cross Sections

Figure 11-18A FS Area 4 Alternative 3 Eco Cap (RCF Pond) + RCRA Cap (18) + Lined Evaporation Pond (A-Series Pond) + Lined Retention Basin (A-5, 13)

Figure 11-18B FS Area 4 Alternative 3 Eco Cap (RCF Pond) + Grading Plan

Figure 11-18C FS Area 4 Alternative 3 Excavation + Lined Evaporation Pond (A-Series Pond) + Grading Plan

Figure 11-18D FS Area 4 Alternative 3 Lined Retention Basin (Pond A-5, Pond 13) + RCRA Cap (Pond 18) + Grading Plan

Figure 11-19A FS Area 4 Alternative 4 Eco Cap (RCF Pond) + RCRA Cap (18) + 11-Acre Evaporation Pond (A-Series Pond) + Lined Retention Basin (A-5, 13)


Figure 11-19C FS Area 4 Alternative 4 Excavation + Lined Evaporation Pond (A-Series Pond) + Grading Plan


Figure 11-20A

FS Area 4 Alternative 5 Eco Cap (RCF Pond, Portion of A-Series Pond) + RCRA Cap (18) + Six 1-Acre Evaporation Ponds (Portion of A-Series Pond) + Lined Retention Basin (A-5, 13)


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Figure 11-20C FS Area 4 Alternative 5 Six 1-Acre Lined Evaporation Ponds (A-Series Pond) + Grading Plan


Figure 11-21A FS Area 4 Alternative 6 Eco Cap (RCF Pond, A-Series Pond) + RCRA Cap (18) + Lined Retention Basin (A-5, 13)

Figure 11-21B FS Area 4 Alternative 6 Eco Cap (A-Series Pond, RCF Pond) Cross Sections

Figure 11-22A

FS Area 4 Alternative 7 ET Cap (RCF Pond, Portion of A-Series Pond) + RCRA Cap (18) + Six Lined 1-Acre Evaporation Ponds (Portion of A-Series Pond) + Lined Retention Basin (A-5, 13)

Figure 11-22B FS Area 4 Alternative 7 ET Cap (RCF Pond) + Six 1-Acre Evaporation Ponds (Portion of A-Series Pond) + Eco-Cap (Portion of A-Series Pond) Cross Sections

Figure 11-23A FS Area 4 Alternative 8 Excavate and Clean Backfill 5' (RCF, A-Series Pond) + RCRA Cap (18) + Lined Retention Basin (A-5, 13) + New 11 Acre Evaporation Pond

Figure 11-23B FS Area 4 Alternative 8 Excavate and Clean Backfill (A-Series Pond, RCF Pond) (5') + Grading Plan

Figure 11-24A FS Area 5 North Groundwater Alternative 2 Extraction (PSCT, Gallery Well) + Discharge Onsite

Figure 11-24B FS Area 5 North Alternative 2 Process Flow Diagram and Treatment System Layout

Figure 11-25A FS Area 5 North Groundwater Alternative 3 Extraction (PSCT, Gallery Well) + Extraction (NAPL Only, P/S Landfill) + Monitoring (12 New LHSU Wells) + Discharge Onsite

Figure 11-25B Area 5 North Alternative 3 Extraction (PSCT, Gallery Well) + Extraction (NAPL-Only, P/S Landfill)

Figure 11-25C Area 5 North Alternative 3 Process Flow Diagram and Treatment System Layout

Figure 11-26A Area 5 North Groundwater Alternative 4 Extraction (PSCT, Gallery Well) + Extraction (NAPL Only, P/S Landfill) + Monitoring (12 New LHSU Wells) + Discharge Offsite

Figure 11-26B Area 5 North Alternative 4 Extraction (PSCT, Gallery Well) + Extraction (NAPL-Only, P/S Landfill) Figure 11-26C Area 5 North Alternative 4 Process Flow Diagram

Figure 11-27A

Area 5 North Groundwater Alternative 5 Extraction (PSCT, Gallery Well) + Aggressive NAPL Extraction + NAPL-Only Extraction (CDA) + Monitoring (12 New LHSU Wells) + Discharge Onsite

Figure 11-27B Area 5 North Alternative 5 Extraction (PSCT, Gallery Well) + Aggressive NAPL Extraction + Extraction (NAPL-Only, CDA)


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Figure 11-27C Area 5 North Alternative 5 Process Flow Diagram

Figure 11-28A

Area 5 North Groundwater Alternative 6 Extraction (PSCT, Gallery Well) + Dewatering P/S Landfill + NAPL-Only Extraction (4 Existing Wells, CDA) + Monitoring (12 LHSU Wells) + Discharge Onsite

Figure 11-28B

Area 5 North Alternative 6 Extraction (PSCT, Gallery Well) + Dewatering P/S Landfill + Extraction (NAPL-Only in CDA, 4 Existing Wells) + Monitoring (12 New wells) + Treat and Discharge Onsite

Figure 11-28C Area 5 North Alternative 6 Process Flow Diagram and Treatment System Layout

Figure 11-29A

Area 5 North Groundwater Alternative 7 Extraction (PSCT, Gallery Well) + Dewatering P/S Landfill + NAPL-Only Extraction (12 New Wells, CDA) + Extraction (4 LHSU Wells) + Monitoring (8 LHSU Wells) + Discharge Offsite

Figure 11-29B

Area 5 North Alternative 7 Extraction (PSCT, Gallery Well) + Dewater P/S Landfill + Extraction (NAPL-Only in CDA, 12 New Wells) + Extraction (4 New LHSU Wells) + Monitoring (8 New LHSU Wells) + Treat and Discharge PSCT Groundwater Offsite

Figure 11-29C Area 5 North Alternative 7 Process Flow Diagram

Figure 11-30A Area 5 South Groundwater Alternative 2 Extraction (PCT-A, PCT-B) + MNA

Figure 11-31A Area 5 South Groundwater Alternative 3 Extraction (PCT-A, PCT-B) + MNA Figure 11-31B Area 5 South Alternative 3 Process Flow Diagram

Figure 11-32A Area 5 South Groundwater Alternative 4 Extraction (PCT-A) + In-Situ Reactive Wall (PCT-B) + MNA

Figure 11-33A Area 5 South Groundwater Alternative 5 Extraction (PCT-A, PCT-B) + Aggressive Extraction + MNA Figure 11-33B Area 5 South Alternative 5 Process Flow Diagram

Figure 11-34A Area 5 West Groundwater Alternative 2 Extraction (PCT-C) + MNA

Figure 11-35A Area 5 West Groundwater Alternative 3 Extraction (PCT-C) + Treat and Discharge Offsite Figure 11-35B Area 5 West Alternative 3 Process Flow Diagram

Figure 11-36A Area 5 West Groundwater Alternative 4 In-Situ Reactive Wall (PCT-C) + MNA

Figure 11-37A Area 5 West Groundwater Alternative 5 Aggressive Extraction (40 Wells) + Extraction (PCT-C) + MNA Figure 11-37B Area 5 West Alternative 5 Process Flow Diagram Figure 12-1A Sitewide Remedial Alternative #2 Larger Evaporation Pond Figure 12-1B Sitewide Remedial Alternative #2 Process Flow Diagram Figure 12-2A Sitewide Remedial Alternative #3 Smaller Evaporation Pond Figure 12-2B Sitewide Remedial Alternative #3 Process Flow Diagram Figure 12-3A Sitewide Remedial Alternative #4 No Evaporation Pond


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Figure 12-3B Sitewide Remedial Alternative #4 Process Flow Diagram

Figure 12-4A Sitewide Remedial Alternative #5 Evaporation Pond + P/S Landfill De-watering Figure 12-4B Sitewide Remedial Alternative #5 Process Flow Diagram

Figure 12-5A Sitewide Remedial Alternative #6 Aggressive Site-wide Extraction Groundwater Restoration Figure 12-5B Sitewide Remedial Alternative #6 Process Flow Diagram

Figure 12-6A Cost Estimate Summary for Sitewide Remedial Alternatives, Millions (30-Year, 3%)

Figure 12-6B Cost Estimate Summary for Sitewide Remedial Alternatives, Millions (30-Year, 3%)

Figure 12-6C Cost Estimate Summary for Sitewide Remedial Alternatives by Area, Millions (30-Year, 3%) Figure 12-7A Top Ranked Sitewide Remedy Map, SWR #3

Figure 12-7B Top Ranked Sitewide Remedy Map Cap Section Details SWR #3 Figure 12-7C Stormwater Plan SWR #3 Figure 12-7D RCF Pond, A-Series Pond, RCRA CYN Cross Sections-SWR

#3 Figure 12-8 Sitewide Earthwork Offsite and Onsite Borrow Areas Figure 12-9 Proposed Remedy Schedule


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LIST OF APPENDICES Appendix A Technical Impracticability Evaluation Appendix B Potential ARARs Appendix C Adjustment of Remedial Footprint FS Areas 2 and 3 Appendix D Groundwater Flow Model Technical Memorandum Appendix E Cost Spreadsheets Appendix F Green Remedial Evaluation Appendix G Monitored Natural Attenuation Appendix H Stormwater Balance Model Appendix I Inorganic Compound Hydrographs Appendix J RBC Calculation Methodologies


xxi

LIST OF ACRONYMS

C temperature degree centigrade F temperature degree Fahrenheit Ci micro-Curies g/dl micrograms per deciliter g/L micrograms per liter g/m2-min micrograms per square meter per minute m micron mhos/cm microhms per centimeter mol/g micromoles per gram R/hr microrems per hour V microvolts SEM total SEM SEM AVS total SEM minus AVS 0/00 per mil or parts per thousand 110-6 one in one million 2-D two-dimensional 3H tritium 3He helium-3 95 UCL 95 percent upper confidence limit ACAP Alternative Cover Assessment Project ADD Average Daily Dose AE assessment endpoint Ag silver Ag2S silver monosulfide Ah aryl hydrocarbon amsl above mean sea level APN Assessors Parcel Number ARAR Applicable or relevant and appropriate requirement ARCH air-rotary casing hammer Area area defined by the three-mile radius from the boundaries of

the Casmalia Site ASTM American Society for Testing and Materials ASTs Aboveground Storage Tanks ATL Air Toxics LTD atm atmosphere ATS Ameripure Treatment System ATV all-terrain vehicle AUF Area Use Factor AVS acid volatile sulfide AVS-SEM Acid Volatile Sulfide-Simultaneously-Extracted Metals BAF bioaccumulation factor Base Vandenberg Air Force Base BBL Blasland, Bouck, and Lee, Inc.


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BC Laboratory BC Analytical Laboratories BERA Baseline Ecological Risk Assessment bgs below ground surface BHHRA Baseline Human Health Risk Assessment Bio/PACT Biologically-activated/Powdered Activated Carbon

Treatment BKG background BMPs Best management practices BO Biological opinion BP before present BSHS Biological Species and Habitat Survey BTA Burial Trench Area BTAG Biological Technical Advisory Group BTEX benzene, toluene, ethylbenzene, and xylenes btoc below top of casing C/C Caustics/Cyanides C14 Carbon 14 age dating CA Caustic/Cyanide and Acid Landfill CaCO3 calcium carbonate Cal Prop 65 Safe Drinking Water and Toxic Enforcement Act of 1986 CalEPA California Environmental Protection Agency CAM California Assessment Method CAO Cleanup and Abatement Order CAS Chemical Abstract Service CASRN Chemical Abstract Services Registry Number CB Calibration Blank CBCI CB Consulting, Inc. CCB Continuing Calibration Blank CCR California Code of Regulations CCV Continuing Calibration Verifications Cd cadmium CD compact disk CDA Central Drainage Area CDD Chlorinated Dioxins CDF Chlorinated dibenzofurans CDFW California Department of Fish and Wildlife CdS Cadmium sulfide CERCLA Comprehensive Environmental Response, Compensation,

and Liability Act CESA California Endangered Species Act CFGC California Fish and Game Commission CFR Code of Federal Regulations CH Highly plastic clays (per Unified Soil Classification System) CHHSL California Human Health Screening Level Cis-1,2-DCE Cis-1,2-Dichloroethene


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CL Clay (per Unified Soil Classification System) cm centimeter cm/g centimeters per gram cm/sec centimeters per second cm2/sec square centimeters per second cm3/minute cubic centimeters per minute CNDDB California Natural Diversity Database CNPS California Native Plant Society CNS Casmalia Neutralization System COC chemical of concern COI chemical of interest COPC chemical of potential concern CPEC/COPEC chemical of potential ecological concern CPEO Center for Public Environmental Oversight cpm counts per minute CPT cone penetrometer test Cr Chromium CRLF California red-legged frog Cs-137 cesium-137 CSC Casmalia Resources Site Steering Committee CSF Cancer Slope Factor CSM Conceptual Site Model CSPE-R Chlorosulfonated polyethylene CTS California tiger salamander Cu copper CVOCs chlorinated volatile organic compounds CVRWQCB Central Valley Regional Water Quality Control Board CY Cubic Yard(s) DBCP 1,2 dibromo 3 chloropropane DBM Design Basis Memorandum DCA dichloroethane DCB dichlorobenzene DCE dichloroethylene/dichloroethene DDD dichlorodiphenyldichloroethane DDE dichlorodiphenyldichloroethylene DDT dichlorodiphenyltrichloroethane DEA diethylamine Dhc Dehalococcoides bacteria DHS Department of Health Services DIC Dissolved Inorganic Carbon DL Detection Limit DNAPL dense non aqueous-phase liquid DO dissolved oxygen DOC Dissolved Organic Carbon dpm disintegrations per minute


xxiv

DPT direct-push technology DQO data quality objective DTSC Department of Toxic Substances Control DUP duplicate DWR Department of Water Resources Dynes/cm dynes per centimeter EC electrical conductivity ECD electron capture detector Eco RBC Ecological risk-based concentration Eco SSL Ecological soil screening level EDB Ethylene dibromide EDD Electronic Data Deliverable EE/CA engineering evaluation/cost analysis Eh oxidation reduction potential EIA Ethylene interpolymer alloy EIR Environmental Impact Report ELAP California Environmental Laboratory Accreditation Program ENSO El Nino/La Nina southern oscillation EPA Environmental Protection Agency EPC exposure point concentration EqP equilibrium partitioning EQS Environmental Quality Standard ERA Ecological Risk Assessment ERG Environmental Restoration Group ERH Electric Resistance Heating ERI Environmental Research, Inc. ERM Environmental Resources Management. Inc. ESA Endangered Species Act ESB Equilibrium Partitioning Sediment Benchmark ESL Ecological Screening Level ESRI Environmental Systems Research Technologies ET evapotranspiration Fe(II) ferrous iron Fe(III) ferric iron Fe0 zero-valent iron FeOOH mineral hydrous ferric oxide FeS iron monosulfide FID Flame Ionization detector Final Design Report

refers to the Revised Final Pesticides Solvent Landfill Cap Design Report

FML flexible membrane liner FMR field metabolic rate FOC fraction organic carbon FOD frequency of detection FPP Former Ponds and Pads


xxv

fps feet per second FS Feasibility Study FSP field sampling plan ft feet ft/ft feet per foot ft/min feet per minute ft/yr feet per year ftbtoc feet below top of casing g/cc grams per cubic centimeter g/cm3 grams per cubic centimeter GAC granular activated carbon GC gas chromatograph GCL geosynthetic clay liner GCW Historical name of Gallery Well GHG Greenhouse Gas GIS Geographic Information System gm gram gm/mol gram-mole or gmole gpm gallons per minute GPS global positioning system GRA General response action(s) Gregg Gregg In Situ, Inc. GS Golden State Aerial Surveys GSCA Geologic Siting Criteria Assessment GST gyro steering tool GW groundwater HAR Hydrogeologic Assessment Report Hc Henrys Law constant HCSM Hydrogeologic Conceptual Site Model HDD Horizontal directional drilling HDPE High Density Polyethylene HEAST Health Effects Assessment Summary Tables HELP Hydrologic Evaluation of Landfill Performance (computer

model) HH Human health HH RBC human health risk-based concentration HHRA Human Health Risk Assessment HI Hazard Index HMW high molecular weight HNO3 nitric acid HQ hazard quotient HSA Hollow stem auger HSAA California Hazardous Substances Account Act HSCER Hydrogeologic Site Characterization and Evaluation Report HSIR Hydrogeologic Site Investigation Report


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HSR Hydrogeologic Summary Report HSU Hydrostratigraphic Unit HSWA Hazardous and Solid Waste Amendments HT hydrogen (tritium) gas HTO tritiated water vapor Hunt Hunt & Associates Biological Consultants HVAC heating, ventilation and air conditioning HVOCs halogenated volatile organic compounds Hz Hertz IC Initial Calibration ICB Initial Calibration Blank ICs Institutional Controls ICS Inference Check Samples ICV Initial Calibration Verifications ID inside diameter ILA Interim Liquids Agreement in/yr inches per year Intra Intrasearch IPR Interim Progress Report IRIS Integrated Risk Information System ISCO In-situ Chemical Oxidation ISCR in-situ chemical reduction ISTD In-situ Thermal Desorption J&E Johnson and Ettinger Vapor Intrusion Model JPEG Joint Photographic Experts Group K hydraulic conductivity Kd distribution coefficient Kdeg half-life kg kilogram(s) kg/L kilograms per liter kHz kilohertz Koc Organic carbon partition coefficient Kow octanol-water partition coefficient Kv kilovolt kW kilowatt kWh kilowatt-hours L liter(s) L/kg liters per kilogram LADD Lifetime Average Daily Dose lb pound LCRS leachate collection and recovery system LCS Laboratory Control Samples LDR Land Disposal Restrictions LF Landfill LLDPE linear-low density polyethylene


xxvii

LLTW low level threat waste LMW low molecular weight LNAPL light non aqueous-phase liquid LOAEL lowest observed adverse effect level LPGAC liquid-phase granular activated charcoal LRL Lower Explosive Limit LTA liquids treatment area LTE Long Term Effectiveness LTP liquids treatment plant LUC Land Use Controls M/S heavy metals/sludges m3 cubic meters m3/day cubic meters per day MACTEC MACTEC Engineering and Consulting, Inc. MBTA Migratory Bird Treaty Act MCL maximum contaminant level MCPA 2-methyl-4-chlorophenoxy-acetic acid MCPP 2-(4-Chloro-2-methylphenoxy) propionic acid MDL Method Detection Limit MEK Methyl ethyl ketone mg milligrams mg/kg milligrams per kilogram mg/kg bw day milligrams per kilogram of body weight per day mg/kg-day milligrams per kilogram of body weight per day mg/L milligrams per liter mg/m3 milligrams per cubic meter MH highly plastic silt (per Unified Soil Classification System) MIBK methyl isobutyl ketone MIP Membrane Interface Probe ML silt (per Unified Soil Classification System) ml milliliters ml/gm milliliter per gram ml/min milliliters per minute mm millimeters mm Hg millimeters of Mercury (pressure measurement unit) MMP Meteorological Monitoring Program Mn(II) manganese (II) Mn(IV) manganese (IV) MNA Monitored natural attenuation (the remedial alternative) MOEE Ontario Ministry of Environment and Energy Mol gram-mole MPC Maximum Permissible Concentration MPE Multi-Phase Extraction MPPE macro porous polymer extraction MS Matrix Spike


xxviii

mS/M milliSiemens per meter MSA Maintenance shed area MSD Matrix Spike Duplicate msl mean sea level MTBE Methyl tert butyl ether mV millivolts N/A, NA Not applicable NA Natural attenuation (the process) NaI sodium iodide NAPL Non-aqueous phase liquid NAWQC National Recommended Water Quality Criteria NCEA National Center for Environmental Assessment NCP National Contingency Plan ND Not Detected or Non-Detect NDMA n-nitrosodimethylamine NE non-equilibrium NFESC Naval Facilities Engineering Service Center NGVD National Geodetic Vertical Datum Ni nickel NIST National Institute of Standards and Technology NMD Normal Move Out NOAEL no observed adverse effect level NOI Notice of Intent NORCAL NORCAL Geophysical Consultants, Inc. NPDES National Pollution Discharge Elimination System NPV net present value NT Not Tested NTU Nephelometric Turbidity Unit O&M Operations and Maintenance OCDD octachlorodibenzo-p-dioxin OCDF octachlorodibenzofuran OD outside diameter OEHHA Office of Environmental Health Hazard Assessment OMM Operations and Maintenance Manual OM&M Operations Maintenance & Monitoring ORNL Oak Ridge National laboratory ORP oxidation-reduction potential (redox) OSHA Occupational Health and Safety Administration OSWER U.S. Office of Solid Waste and Emergency Response OVM organic vapor monitor P/S pesticide/solvent P/S Landfill, P/SLF

Pesticide/Solvent Landfill

PACT powder-activated carbon treatment PAHs polycyclic aromatic hydrocarbons


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Pb lead PCBs polychlorinated biphenyls pCBSA Parachlorbenzene sulfonic acid PCDD polychlorinated dibenzo p dioxin PCDF polychlorinated dibenzofuran PCE tetrachloroethylene/tetrachloroethene pcf pounds per cubic foot PCNB pentachloronitrobenzene PCT Perimeter Control Trench PE Performance Evaluation PEl Permissible Exposure Level PEST Parameter Estimation pg/g picograms per gram pg/L picograms per liter pH unit of measurement for acid/base properties PHGs Public Health Goals PID photoionization detector PLSS Public Land Survey System POC Point of Compliance PP Proposed Plan ppbv part(s) per billion by volume ppm parts per million ppmv part(s) per million by volume PPOs Poor Purging Organics ppt part(s) per trillion PRB Permeable Reactive Barriers PRG Preliminary Remediation Goal PSCT Perimeter Source Control Trench psf pounds per square foot psi pounds per square inch psig pounds per square inch gauge PTS Laboratories

Petroleum Testing Services Laboratories

PTW Principal threat wastes PUF plant uptake factor PVC polyvinyl chloride PW Pacific Western Aerial Surveys Pw pore water pressure QA/QC Quality Assurance/Quality Control QAPP Quality Assurance Project Plan QC Quality Control Qc Tip resistance QED QED Environmental Systems is a company specializing in

water quality remediation/sampling products R.G. Registered Geologist


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RA Risk Assessment RAGS Risk Assessment Guidance for Superfund RAO Remedial Action Objective RAP Remedial Action Plan RATL Reptile and Amphibian Toxicology Literature RBCs risk-based concentrations RCF Runoff Containment Facility RCRA Resource Conservation and Recovery Act RD Remedial design RDC Risk-Driving Chemical RDX nitroamine, an explosive, also known as cyclonite, hexogen,

T4, and cyclotrimethylenetrinitramine REI relative estimation interval RfC reference concentration RfD reference dose RFI Request For Information form RGMEW Routine Groundwater Monitoring Element of Work RI Remedial Investigation RI/FS Remedial Investigation/Feasibility Study RI/FS Work Plan Remedial Investigation/Feasibility Study Work Plan RICH RI Change Form RISBON Remedial Investigation soil boring onsite (soil boring

location designation e.g., RISBON-59) RME Reasonable Maximum Exposure RO Reverse osmosis ROD Record Of Decision ROI Radius Of Influence ROS Remain On-Site ROST Rapid Optical Screen Tool RPD relative percent difference RPs Responsible Parties RRF Relative Response Factors RSD Relative Standard Deviation RTMV Reduction in Toxicity, Mobility, and Volume RWQCB California Regional Water Quality Control Board S Solubility SA semiannual SA Source Area SAP Sampling Analysis Plan SARA Superfund Amendments and Reauthorization Act SB Soil boring SBCAPCD Santa Barbara County Air Pollution Control District SC sandy clay (per Unified Soil Classification System) scfm standard cubic feet per minute SDG Sample Delivery Group


xxxi

SEM simultaneously extracted metals SF Square Feet SFRWQCB San Francisco Regional Water Quality Control Board SI Surface Impoundment (the) Site the Casmalia Resources Superfund Site SIC Silty Clay SL Screening Level SOP Standard Operating Procedure SOW Scope of Work SQG Sediment Quality Guideline SS Surface soil (0 to 6 inches bgs) STE Short Term Effectiveness SVE Soil Vapor Extraction SVL snout-vent length SVOC semi-volatile organic compound SWAT Solid Waste Assessment Test SWPPP Storm Water Pollution Prevention Plan SWRs Site-wide remedial alternatives T Temperature T&E Threatened and Endangered TBA tert-butyl alcohol TBC to be considered Tc-99 technetium-99 TCA trichloroethane TCDD tetrachlorodibenzo-p-dioxin TCE trichloroethylene/trichloroethene TCLP Toxicity Characteristic Leaching Procedure TCLs Target Cleanup Levels TD Total Depth TDS total dissolved solids TEF Toxicity Equivalency Factors TEQ toxicity equivalent TI technical impracticability TIC Tentatively Identified Compound TIE technical impracticability evaluation TIN triangulated irregular network TLVs Threshold Limit Values TM Technical Memorandum TMB trimethylbenzene TOC total organic carbon TOX Total Organic Halogens TPH total petroleum hydrocarbons TPHd total petroleum hydrocarbons (as diesel) TRS Township, Range, and Section TRM turf reinforcement mats


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TRV toxicity reference value TSCA Toxic Substances Control Act TSDF treatment, storage, and disposal facility tsf tons per square foot TU tritium unit UCL upper confidence limit UCSB MIB University of California, Santa Barbara, Map and Image

Library UF Uncertainty Factor UM University of Miami (Florida) URF Inhalation Unit Risk Factors URS URS Corporation USA Underground Service Alert System USACHHPM U.S. Army Center for Health Promotion and Preventive

Medicine USCS Unified Soil Classification System USEPA United States Environmental Protection Agency USFWS United States Fish and Wildlife Service USGS United States Geological Survey UST Underground Storage Tank UTL upper tolerance limit UU/UE Unrestricted Use/Unrestricted Exposure UVIF ultraviolet induced fluorescence UVOST ultra-violet optical screening tool Vb bulk volume VC vinyl chloride VESP vibratory shear enhanced processing VETS Vapor Extraction and Treatment System VOCs volatile organic compounds Vp. VP Vapor Pressure VPGAC Vapor Phase Granular Activated Carbon WAO wet air oxidation WCC Woodward-Clyde Consultants WCCB West Canyon Catch Basin WCSA West Canyon Spray Area WDC Water Development Corporation WDR Waste Discharge Requirement WHO World Health Organization WMU Waste Management Unit Work Plan June 2004 RI/FS Work Plan WST Western spade-foot toad ybp years before present Zn zinc ZVI zero-valent iron


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EXECUTIVE SUMMARY The Feasibility Study (FS) Report for the Casmalia Resources Superfund Site evaluates a range of remedial alternatives that address various soil, soil vapor, surface water, and groundwater contamination in accordance with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) guidance for conducting Remedial Investigation/Feasibility Study (RI/FS; EPA 1988). The FS relies on the site Remedial Investigations (RI) conducted from 2004 until 2009 and the risk assessments that are summarized in the Final RI Report (2011). Together, the Final RI Report and FS Report provide EPA with the key information necessary to issue the Proposed Plan and the Record of Decision (ROD) for the site. Site Background The Casmalia Resources Superfund Site is an inactive Class I hazardous waste management facility located in the northwestern corner of Santa Barbara County, California. The site, which was owned and operated by Casmalia Resources, began accepting wastes in the early 1970s. Site operations ceased in 1991. Former waste management operations at the site were conducted within an approximate 252-acre area which included landfills, storage and evaporation ponds, evaporation pads, oil field waste spreading areas, treatment units, and disposal wells and trenches. The site lies in a rural setting approximately 4 miles from the Pacific Ocean, approximately 10 miles southwest of the city of Santa Maria, and approximately 16 miles north-northwest of the city of Lompoc. The nearest population center is the unincorporated community of Casmalia, located approximately 1.2 miles south-southeast of the site. Land use surrounding the site includes agriculture, cattle grazing, and oil field development. There has been no indication that land use, particularly land use of the historical landfill, would be likely to change within the foreseeable future. In terms of regional setting, the site is located within the Casmalia Hills, which are characterized by easily erodible clay and silt soils and rolling grassy hills that are suitable for farming, ranching, and grazing. The site sits on a ridge that separates two distinct groundwater basins. The Santa Maria River Valley basin (Santa Maria) lies to the northeast, and San Antonio Creek Valley basin (San Antonio) lies to the south. Despite its geographic proximity, there is no evidence of direct groundwater flow from the site to the town of Casmalia. Groundwater beneath the site does not serve as a drinking water source either for the town of Casmalia or other communities. The towns drinking water supply is obtained from the Santa Maria groundwater basin to the east, which is different from the groundwater underlying the site. The location of the waste disposal site was selected in large part because of its rural setting, its distance from densely populated areas, and its suitable, low permeability geological conditions that help provide containment. The waste management facility contained many closely-spaced former waste management units, disposal areas, and waste treatment and handling systems. The site has been stabilized and risks are being controlled. Figure ES-1 shows the current layout of the site, which includes the former waste management units (WMUs) operated by Casmalia Resources in the 1970s and 1980s, ponds for landfill liquids and systems for managing contaminated groundwater constructed in the 1980s, and the landfill caps and stormwater runoff control systems constructed in the late 1990s and early 2000s. The WMUs, historical and current response activities, and current site operations are summarized below.


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Casmalia Resources accepted a full range of listed and characteristic RCRA wastes as specified in Subparts C and D of 40 Code of Federal Regulations (CFR) 261 (A.T. Kearney/SAIC, 1987). These wastes are generally referred to as RCRA wastes because they are regulated under the federal Resource Conservation and Recovery Act (RCRA) as amended. The site accepted approximately 5.6 billion pounds of waste into 92 waste management or treatment facilities between 1973 and 1989. Wastes received at the site included: petroleum wastes, acids, bases, organic chemical solvents, petroleum solvents, paint sludge, pesticides, infectious wastes, septic tank pumpings, and sewage sludge.

Figure ES-1 Current Site Layout Waste disposal units at the site included:

6 landfills; 43 surface impoundments (or ponds); 15 evaporation pads; 2 non-hazardous waste spreading areas;

6 oil field waste spreading areas; 11 shallow injection wells; 7 disposal trenches; and 1 drum burial unit.

The landfills include one former landfill (the RCRA Landfill) and five existing landfills (Pesticides/Solvents, [P/S], Metals, Caustics/Cyanide, and Acids). The site also had five waste treatment units: an acid/alkaline neutralization facility, a hydrogen peroxide treatment unit, oil recovery and treatment tanks, a wet air oxidation unit, and a temporary pilot-scale powder-activated carbon treatment (PACT) unit. Surface impoundments (used for evaporation and treatment of liquid wastes or for storing stormwater), and disposal pads (used to evaporate liquid wastes and site stormwater runoff) primarily occupied the southern and central portions of the site, whereas the landfill disposal areas were positioned along the northern and northeastern margins of the site.


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EPA has been involved with the site in a variety of contexts since the 1980s and has developed a thorough understanding of site conditions as well as the nature and extent of contamination. EPA has understood for many years that remediation would involve leaving waste in place, and managing residual wastes and liquids, as part of a combined containment and treatment remedy. Early response actions and site stabilization have included successful installation of engineering controls to contain waste (i.e. landfill caps), contain groundwater contamination (i.e. GW extraction trenches), extract site liquids for treatment (i.e. extraction wells and sumps), and manage extracted site liquids (i.e. liquid collection, treatment, and disposal systems). Specifically, Casmalia Resources performed some closure and cleanup activities in the late 1980s and early 1990s that included removing wastes from some of the six former the RCRA landfills and consolidating them into the P/S Landfill, removing the liquids from the ponds, removing contaminated soils beneath and in the vicinity of the ponds and pads, and constructing landfill leachate and groundwater extraction facilities. Five ponds that exist today were created during removal of the contaminated soils. The ponds (Runoff Control Facility [RCF], A-Series Pond, Pond A-5, Pond 13, and Pond 18) are now used for the control and evaporation of stormwater and treated and untreated liquids extracted from leachate and groundwater extraction facilities. Casmalia Resources did not close or clean up RCRA Canyon, which is located in the northwestern portion of the site and contained a RCRA landfill. Although the former landfill wastes were removed, RCRA Canyon still contains soils that have been contaminated from area-wide spraying of contaminated liquids. EPA performed emergency response actions from 1992 through 1996 to stabilize the site. These actions included interim operations of the groundwater control systems and other critical site maintenance. During this time EPA negotiated the Casmalia Consent Decree with the Casmalia Steering Committee (CSC) to continue site operations, perform the RI/FS, and implement the final remedy. The CSC began performing work under the Casmalia Consent Decree in 1997. This work has included extracting, treating, and disposing landfill leachate and contaminated groundwater, designing and constructing final landfill caps, performing groundwater monitoring activities, and performing the RI/FS. The CSC constructed landfill caps on four of the five landfills between 1998 and 2002 and a stormwater collection basin to convey clean stormwater from the four capped landfills to the B-Drainage and Casmalia Creek. From north to south, contaminated groundwater is currently extracted from the Gallery Well located at the toe of the P/S Landfill, Sump 9B and the Road Sump located south of the P/S Landfill, the 2,700 foot long Perimeter Source Control Trench (PSCT) located south of the five existing landfills, and three Perimeter Capture Trenches (PCTs) located at the southern perimeter of the site at the head of the A, B, and C Drainages. Liquids extracted from the Gallery Well are the most contaminated and contain both light and dense nonaqueous phase liquids (LNAPLs and DNAPLs). Liquids from the Gallery Well and Sump 9B are temporarily stored in tanks at the liquids treatment area and then disposed at a permitted disposal facility. Liquids from the PSCT are treated at the site using granular activated carbon (GAC) and then discharged to Pond 18 for evaporation. Liquids from the PCTs are the least contaminated and are discharged directly to the RCF and A-Series pond without treatment.


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Site stormwater from the RCRA Canyon located at the western part of the site is directed to the A-Series Pond. Stormwater from the central and eastern part of the site is directed to the RCF Pond. Ponds A-5, 13, and 18 receive only minor stormwater. The total dissolved solids (TDS) and metals concentrations in the ponds are very high, approaching or exceeding concentrations of seawater, because of high concentrations of salts and metals from the extracted groundwater and evaporation. Physical Characteristics Overall the site slopes from north-to-south and is bounded to the north by a ridge (North Ridge) and to the south by the A, B, and C Drainages. The B and C Drainages flow into the perennially flowing Casmalia Creek, located immediately west of the site. Casmalia Creek flows into Shuman Creek, which empties into the Pacific Ocean. The ephemeral North Drainage is topographically separated from the site by the ridge at the northern part of the site and also flows into Shuman Creek. The site does not overlie a groundwater basin that is used for potable use. It is underlain by low permeability weathered and unweathered claystone of the Sisquoc Formation which is underlain by the Monterey Formation at a depth of approximately 1,300 feet. In addition, localized fill occurs across the site and localized alluvium occurs along Casmalia Creek and remnants of the former drainages. The underlying Monterey Formation is composed of shale and other rocks that locally produce oil and gas. The upper weathered claystone is referred to as the Upper Hydrostratigraphic Unit (Upper HSU) and the underlying deeper unweathered claystone is referred to as the Lower Hydrostratigraphic Unit (Lower HSU). Groundwater flow is controlled primarily by weathering and fracturing since the host rock is low-permeability claystone. Most groundwater flow at the site occurs in fractures within the Upper HSU that occur at a density of several fractures per foot. A minor component of groundwater flow occurs within fractures of the Lower HSU which occur at a frequency of every several feet to every several tens of feet. The Upper HSU is more permeable than the Lower HSU. The permeability of both HSUs is quite low (i.e. K = 10-5 cm/sec and 10-6 cm/second, respectively). Groundwater flow is controlled by topography, the geologic structure of the contact between the two HSUs, and the liquids extraction facilities that are operated to control the migration of landfill leachate and contaminated groundwater. A natural groundwater flow divide occurs at the North Ridge. Groundwater north of North Ridge flows northward toward the North Drainage. Groundwater south of the ridge flows southward across the site. Contaminated aqueous-phase liquids, LNAPL, and DNAPL within the P/S Landfill are extracted by the Gallery Well at the southern perimeter of the landfill. The Gallery Well is located immediately upgradient of a clay barrier at the southern limit of the P/S landfill that provides additional containment of these liquids. Groundwater in the Upper HSU flows southward through the principal contaminant sources and is intercepted by Sump 9B and the PSCT. Groundwater south of the PSCT is influenced by surface water elevations in the ponds and intercepted by the PCTs. A significant amount of groundwater pumped from the PCTs is derived from surface water from the ponds. Groundwater in the Lower HSU flows southward underneath the principal containment sources and underneath the PSCT. Groundwater flow in the Lower HSU is much less significant than the flow in the Upper HSU because of the lower permeability and less extensive fracturing of the unweathered claystone.


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RI/FS Study Areas In the FS evaluation, 5 study areas were established and evaluated based on geographical proximity and/or similar impacted media. The 5 areas are listed below and shown in Figure ES-2:

FS Area 1 PCB Landfill, Burial Trench Area, Central Drainage Area and Capped Landfills Area

FS Area 2 RCRA Canyon, West Canyon Spray Area FS Area 3 Former Ponds and Pads, Remaining Site Areas, Roadways, Liquids

Treatment Area and Maintenance Shed Area FS Area 4 Stormwater Ponds and Treated Liquid Impoundments (A-Series, RCF, A-5,

18 and 13) FS Area 5 Sitewide Groundwater and NAPL which is further divided into Groundwater

North; Groundwater South, and Groundwater West.

Figure ES-2 FS Areas (left panel shows FS Areas 1 through 4; right panel shows FS Area 5) Nature and Extent of Contamination Contamination occurs pervasively throughout the entire site, including metals, VOCs, and SVOCs in soils, surface water, groundwater, and, to a very limited degree, in soil vapor. Principal contaminant sources include the existing landfill areas, the former waste disposal areas and facilities that have not previously undergone cleanup, and residual contamination from prior site cleanup activities. Soil Soil contamination occurs pervasively throughout Areas 1 and 2 and variably within Area 3. Contamination includes many different constituents of potential concern (COPCs), such as metals, VOCs, SVOCs, and other organic compounds.


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Area 1 is by far the most contaminated part of the site, encompassing the former landfills and many other former WMUs. Surface and subsurface soils in FS Area 1 north of the PSCT are primarily contaminated with metals and organic compounds. Many of these COPCs increase in concentration with depth and serve as sources for contamination of groundwater via infiltration. The preferred remedy for the five landfills in this area is capping, and capping four of the five former landfills has been completed as part of early action work at the site. In FS Area 2, COPCs were identified in the RCRA Canyon/WCSA and contain elevated levels of residual copper, chromium, and zinc that remain from the area-wide spraying of oil field and other wastes during disposal operations. The elevated concentrations of these metals occur in the top several feet of soil and diminish with depth. In FS Area 3, several discrete soil hotspot contamination areas contain high content ratios of metals, VOCs, and other organic compounds that serve as sources for groundwater contamination. These hotspot areas included shallow soil contamination in the Liquids Treatment Area (Hotspot 1), the former Maintenance Shed Area (Hotspot 2), deeper soil contamination from former Ponds A and B that were not sufficiently cleaned up by Casmalia Resources (Hotspot 3), shallow soil contamination south of PSCT-1 (Hotspot 4), and deeper soil contamination underneath RCF Road from a former waste pond that was not cleaned up by Casmalia Resources and which was discovered while drilling soil boring RISBON-59 (Hotspot 10). Pond Surface Water The surface water storage ponds play a critical, but temporary, role in collecting and storing stormwater and treated liquids in order to prevent uncontrolled discharges. The TDS and metals concentrations in the five ponds have been generally increasing over time due to high concentration of salts and metals from the extracted groundwater that is discharged to the ponds and evaporation. In addition, low levels of organic compounds are occasionally detected in some ponds. The TDS concentrations of the ponds were low after 32 inches of rain fell during the 1997/98 El Nino winter and fresh stormwater filled the ponds. Since that time, the TDS has steadily increased and now approaches, and in some areas exceeds, the salinity of seawater. The elevated TDS and metals exceed ecological risk screening levels, including those for the California Red Legged Frog, a special status species that formerly inhabited the ponds in the 1990s and early 2000s until the ponds became too salty. Underlying pond sediments also contain elevated levels of metals, VOCs, and other organic compounds and serve as potential sources for contamination of shallow groundwater via infiltration. Groundwater Contamination Groundwater contamination is pervasive throughout the entire site ( Area 5), including a highly diverse array of several hundred COPCs, comprising metals, VOCs, SVOCs, pesticides, PCBs, and other organics. Groundwater contamination is most prominent, however, throughout Groundwater North where most of the former waste management units and buried waste materials are located. Many years of monitoring data show that groundwater contamination has been contained within the historical site boundaries through a combination of constructed engineering controls and multiple natural attenuation processes.


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Groundwater North Groundwater North contains the most heavily contaminated groundwater within the site, primarily due to the presence of former waste management units, other waste burial areas, and high volumes of NAPL. These features provide ongoing sources of contamination for groundwater that flows from north to south through Groundwater North. Contamination is most highly concentrated in the weathered and fractured upper HSU claystone, but impacts the less permeable lower HSU as well. Contamination is contained within Area 1 by both (1) the existing perimeter source control trench (PSCT) and natural attenuation processes for the Upper HSU, and (2) natural attenuation alone for the Lower HSU, since the PSCT extends only to the base of the Upper HSU. Free-phase LNAPL and DNAPL occurs in the southern part of the P/S Landfill. The thickness of DNAPL measured at the bottom of the landfill exceeds 10 feet and the annual DNAPL extraction rate from the Gallery Well has ranged between 2,000 and 4,000 gallons. The volume of free phase DNAPL is estimated to be up to approximately 100,000 gallons. The actual DNAPL volume is uncertain. The thickness of LNAPL in the landfill also exceeds 10 feet. Extraction from the Gallery Well combined with the Clay Barrier limit the migration of LNAPL and aqueous phase liquids from the landfill toward the Central Drainage Area. However, these containment features are less effective for DNAPL because it is driven by density and can penetrate fractures in the unweathered claystone that underlies the waste in the P/S Landfill. Density-driven DNAPL migration from the landfill has likely occurred into the underlying fractures of the Lower HSU as indicated by free-phase DNAPL identified in core fractures and piezometers approximately 500 feet south of the P/S Landfill. The potential sources of that DNAPL include the free phase DNAPL present in the P/S Landfill and the former Pad 9A/B area in the Central Drainage Area. The depth and horizontal extent of DNAPL are uncertain. Ongoing DNAPL migration from the P/S Landfill may occur through fractures as long as the DNAPL pool in the landfill persists since it provides a source and driving force for continued migration. Very high concentrations of TDS (approaching that of seawater), metals, and organic compounds occur in the Upper HSU throughout the Burial Trench Area and Central Drainage Area with Total VOC concentrations exceeding 1,000,000 micrograms per liter (g/L) or parts per billion (ppb). Limited amounts of free-phase LNAPL occur in the Central Drainage Area between the P/S Landfill and PSCT. The thickness of LNAPL measured in this area ranges from a sheen to slightly greater than one foot. The mobility of this LNAPL is considered to be low given the low-permeability of the Upper HSU. Residual NAPL is also likely in the Burial Trench Area based on high dissolved-phase groundwater concentrations. Dissolved-phase contaminants in the Upper HSU that move southward in groundwater are contained by the PSCT. VOCs occur in the Lower HSU beneath the Burial Trench Area, Central Drainage Area, and the North Ridge. Elevated metals occur beneath the North Ridge. VOCs beneath the Burial Trench Area occur as a result of strong downward hydraulic gradients carrying contaminants downward in this area. VOCs beneath the Central Drainage Area likely occur as a result of a combination of downward hydraulic gradients carrying contaminants downward and the free-phase DNAPL that occurs within fractures of the Lower HSU in this area. The migration of dissolved-phase contaminants in the Lower HSU moving southward through fractures is attenuated by naturally occurring mechanisms that include sorption, diffusion into the claystone matrix, and biodegradation. Although the rate of potential contaminant migration beneath the PSCT is


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uncertain, the overall mass is likely small because of the low rate of groundwater flow through the low permeability Lower HSU. A prominent surface seep periodically forms between the P/S Landfill and the PSCT due to a shallow water table that will intersect the ground surface in response to rainfall infiltrating over the area. This seep will not form if the water table is pumped down by Sump 9B. When it forms however, the seep is highly contaminated and has an LNAPL sheen. Groundwater modeling performed for the FS shows that the seep will no longer form under the remedial alternatives in which the area to the north of the PSCT is fully capped. Groundwater South Elevated concentrations of TDS, metals, and organic compounds occur in the Upper HSU south of the PSCT with total VOC concentrations ranging up to approximately 1,000 g/L immediately south of the PSCT to less than 10 g/L near the PCTs. Dissolved-phase contaminants in the Upper HSU moving southward in groundwater are contained by the A- and B-Drainage PCTs. Monitoring data demonstrate that contamination in the deeper, less permeable and less fractured Lower HSU is contained within the historical site boundaries through natural attenuation processes. Groundwater West Elevated concentrations of TDS and metals occur in the Upper HSU in the RCRA Canyon Area and to the south towards the C-Drainage PCT. Minor concentrations of organic compounds are also occasionally detected at low total VOC concentrations (generally less than 10 g/L). Dissolved-phase contaminants in the Upper HSU moving southward in groundwater are contained by the C-Drainage PCT. Monitoring data show that minor contamination in the Lower HSU is effectively contained by natural attenuation processes. A prominent surface seep seasonally forms at the south end of RCRA Canyon in the winter. The seep forms in response to a shallow water table and upward groundwater gradients at the canyon bottom that are greater in the winter in response to rainfall infiltrating over the canyon. This seep is elevated in TDS and metals, which could result in risk to amphibians if the water is allowed to pond. The seep is also important in revealing the shallowness of groundwater in this area and pointing to a need to install low-permeability capping systems to contain and lower groundwater levels. Soil Vapor Soil vapor contamination occurs primarily in Areas 1 and Area 5 in association with the most extensive buried waste materials. Concentrations of VOCs in soil vapor occur in FS Area 1 and the northern part of Area 5 (Groundwater North). These VOCs result from contamination from the landfills and residual contamination in the Burial Trench Area and Central Drainage Area. Diffusion causes these VOCs to migrate outside of these areas, including south of the PSCT and north, outside the boundaries of the waste disposal site, into the North Drainage. The soil vapor concentrations in the North Drainage, however, are relatively low and are being monitored by a cluster of three soil gas probes along the North Ridge.


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The generation of landfill gas as methane is relatively insignificant because organic rich municipal solid waste was not disposed in the landfills. Gas flux testing of the interim soil caps, before the landfills were capped by the CSC between 1998 through 2002, did not indicate significant movement of methane and other VOCs through the soil caps. Summary of Site Risks A comprehensive risk assessment was conducted as part of the RI/FS process. The risk assessment is detailed in the RI report and summarized in the FS report. Consistent with EPA guidance and policy, the risk assessment includes (1) a human health risk assessment (HHRA), and (2) an ecological risk assessment. The HHRA includes a baseline risk assessment that evaluated cancer and non-cancer risks for existing site conditions and current land and water uses. The risk assessment then qualitatively evaluates risks for reasonably anticipated future land use scenarios. The ecological risk assessment quantitatively evaluates site risks to a wide range of plant & wildlife species, for current and future use scenarios, consistent with EPA policies and practices. Human Health Risk Assessment Baseline Risk Assessment: The baseline human health risk assessment (BHHRA) evaluates risks, for each site area, under current conditions. The BHHRA studies (1) sources of contamination in different media, (2) pathways of exposure, and (3) potentially impacted populations, called receptors. Sources of contamination include contaminated media, such as buried solid and liquid wastes, soil, groundwater, DNAPL, and soil vapor. The risk assessment also considers individual site features, such as former waste management units (e.g., landfills, pits, ponds, lagoons, disposal wells, and trenches). Consistent with EPA guidance Risk Assessment Guidance for Superfund (RAGS Part A) the BHHRA addresses major components, including (1) data review & evaluation, (2) exposure assessment, (3) toxicity assessment, (4) risk characterization, and (5) uncertainty analysis. The risk assessment then considered and developed appropriate quantitative risk calculations for exposure pathways, such as direct physical contact, ingestion, inhalation, and movement of contamination through air, soil, fractured rock, surface water, and groundwater. The HHRA evaluated groundwater, but did not calculate risks for groundwater due to the lack of complete exposure pathways and receptor populations. Instead, EPA is using MCLs as risk-based cleanup goals that are relevant and appropriate in decision making for groundwater response actions. Similarly, the BHHRA does not include detailed risk calculations for site features with incomplete exposure pathways, such as the landfills, which have already been capped. Current potential exposure activities currently include site workers, occasional trespassers, and local residents, such as local ranchers and neighbors. There are no completed exposure pathways to the Town of Casmalia. EPA has established a cumulative cancer range of 10-4 to 10-6 to manage cancer risks for Superfund cleanups. Non-cancer concerns are evaluated as a hazard quotient of less than or equal to one (HQ


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The HHRA evaluated risks associated with site workers and trespassers. For future uses outside the historical site boundaries, the HHRA evaluated risks associated with ranchers, recreational users, and hy

CASMALIA SITE REMEDIATION PROJECT Resources Superfund Site Final Feasibility Study ii 4.5...

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