DRAFT FEASIBILITY STUDY AND REMEDIAL ACTION PLAN

Transcription

1 DRAFT FEASIBILITY STUDY AND REMEDIAL ACTION PLAN Emeryville Mound Parcel Emeryville, California 30 October 2009 Prepared by: Erler & Kalinowski, Inc Ogden Drive Burlingame, California EKI A

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4 Draft Feasibility Study and Remedial Action Plan Emeryville Mound Parcel Emeryville, California TABLE OF CONTENTS Executive Summary... ES Introduction Emeryville Mound Parcel Background and Current Conditions Site Development Plans Site Development-Related Documents Previous Remedial Investigations Report Organization Summary of Site Conditions and Risk Assessment Geologic and Hydrogeologic Setting Conversion of Elevation Data for this FS/RAP Chemicals of Potential Concern Scope of 2005/2006 HHRA and Modifications for the FS/RAP Analysis Scope of the HHRA Summary of HHRA Results During-Construction HHRA Results Post-Construction HHRA Results Methane-Related HHRA Results Modifications to the HHRA Methodology for the FS/RAP Analysis Remedial Action Objectives and Site Cleanup Goals Identification of Potential ARARs and TBCs Remedial Action Objectives Groundwater Use Potential Risk-Based Site Cleanup Remedial Goals for Soil and Groundwater Alternative Site Cleanup Remedial Goals for Soil Site Cleanup Remedial Goals for Groundwater Screening of Remedial Technologies General Response Actions Identification of Potential Remedial Technologies and Process Options Potential Remedial Technologies and Process Options for Soil Potential Remedial Technologies and Process Options for Groundwater Screening of Potential Remedial Technologies and Process Options Screening Criteria Potential Remedial Technologies and Process Options Soil Screening Remedial Technologies and Process Options Groundwater Screening Description of Remedial Alternatives Alternative 1: No Further Action Alternative 2: Soil Excavation for Foundation and Construction of Above- Grade Building Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal Alternative 4: Risk-Based Cleanup for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building Page i

5 Draft Feasibility Study and Remedial Action Plan Emeryville Mound Parcel Emeryville, California TABLE OF CONTENTS 5.5 Difficulties Associated with Groundwater Monitoring Post-Construction Under Alternatives 3 and Results of Risk Analysis for Evaluating Remedial Alternatives During-Construction Risk Estimate Summary Presented in the HHRA Post-Construction Risk Estimate Summary Updated in this FS/RAP Evaluation of Remedial Alternatives Remedial Alternative Evaluation Criteria NCP Criteria State of California Factors Compliance with TSCA Summary of Remedial Alternative Evaluation Results NCP Criteria Evaluation Results State Factors Evaluation Results Summary of Comparison of Alternatives Proposed Remedy Summary of Proposed Remedy Pre-Excavation Soil Sampling for PCB Congeners Targeted Additional Groundwater Characterization and In Situ Treatment Unsaturated Zone Soil Excavation Preparation of the Excavation for Building Construction Construction of SSVS Continued Function of Slurry Wall Institutional Controls Monitored Natural Attenuation Contingencies and Uncertainties Implementation Schedule Nonbinding Allocation of Responsibility References LIST OF TABLES Table 1 Identified Chemicals of Potential Concern Table 2 List of Potential ARARs and TBCs Table 3 Screening of Technologies and Process Options for Unsaturated and Saturated Zone Soil Table 4 Screening of Technologies and Process Options for Groundwater Table 5 Summary of Risk Analysis Results for Evaluating Remedial Alternatives Table 6 Analysis of Remedial Alternatives Using NCP Criteria Table 7 Summary of Estimated Relative Costs of Potential Remedial Alternatives Page ii

6 Draft Feasibility Study and Remedial Action Plan Emeryville Mound Parcel Emeryville, California TABLE OF CONTENTS LIST OF FIGURES Figure 1 Site Location Figure 2 Site Vicinity Figure 3 Site Layout with Aerial Photograph and Ground Surface Contours Figure 4 Alternative 2: Soil Excavation for Foundation and Construction of Above- Grade Building Figure 5 Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal Figure 6 Alternative 4: Risk-Based Cleanup for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building Figure 7 PCB, Lead, and Arsenic Concentrations in Soil, >12.5 feet msl (0 to 5.5 feet bgs) Figure 8 PCB, Lead, and Arsenic Concentrations in Soil, 7.5 to 12.5 feet msl (5.5 to 10.5 feet bgs) Figure 9 PCB, Lead, and Arsenic Concentrations in Soil, 3 to 7.5 feet msl (10.5 to 15 feet bgs) Figure 10 PCB, Lead, and Arsenic Concentrations in Soil, <3 Feet msl (>15 feet bgs) Figure 11 Chemical Concentrations Detected in Groundwater Figure 12 Chemical Concentrations Detected in Soil Vapor Figure 13 Alternative 2: Preliminary Soil Classification, >12.5 Feet msl (0 to 5.5 feet bgs) LIST OF APPENDICES Appendix A Summary of Analytical Results and Sample Elevation Changes Appendix B Human Health Risk Estimates and Remediation Goal Development for Alternative 4 Appendix C Preliminary Costs Estimates for Remedial Alternatives Appendix D Tables and Figures from May 2008 Annual Groundwater Sampling and Analysis Report Appendix E Letter Summarizing the Results of Groundwater Sampling in March 2009 Appendix F Application to Assess PCBs Under Section (c) of TSCA Appendix G Administrative Record List Appendix H Responsiveness Summary (prepared by DTSC after public comment period) Page iii

7 Draft Feasibility Study and Remedial Action Plan Emeryville Mound Parcel Emeryville, California ACRONYMS AND ABBREVIATIONS ARARs Applicable or Relevant and Appropriate Requirements BAAQMD Bay Area Air Quality Management District bcy bank cubic yards bgs below ground surface Cal/EPA State of California Environmental Protection Agency CBS CBS Corporation CCR California Code of Regulations CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CFR Code of Federal Regulations cm/s centimeters per second COPCs chemicals of potential concern CR cancer risk DTSC California Department of Toxic Substances Control EBMUD East Bay Municipal Utility District Emeryville City of Emeryville Redevelopment Agency EPC exposure point concentration FS/RAP Feasibility Study and Remedial Action Plan gpd gallons per day GRAs general response actions HAZWOPER Hazardous Waste Operations and Emergency Response Standard HHRA Human Health Risk Assessment HI hazard index HSC California Health and Safety Code HVAC heating, ventilation, and air conditioning LUC land use covenant MCL Maximum Contaminant Level mg/kg milligram per kilogram msl mean sea level NAVD88 North American Vertical Datum of 1988 NBAR nonbinding allocation of responsibility NCP National Oil and Hazardous Substances Pollution Contingency Plan NGVD29 National Geodetic Vertical Datum of 1929 NPDES National Pollutant Discharge Elimination System O&M operation and maintenance ORC Oxygen Release Compound OSHA Occupational Safety and Health Administration PCBs polychlorinated biphenyls POTW publicly owned treatment works PPE personal protective equipment PRB Permeable Reactive Barrier PRPs potentially responsible parties RAOs remedial action objectives Page iv

8 Draft Feasibility Study and Remedial Action Plan Emeryville Mound Parcel Emeryville, California ACRONYMS AND ABBREVIATIONS RC RSL RDIP SRRIP SSDS SSVS SVE SVOCs SWRCB TBC TEPH ug/l U.S. EPA VOCs VIMA WSP representative concentration Regional Screening Level Remedial Design and Implementation Plan Soil Removal and Remedial Implementation Plan sub-slab depressurization system sub-slab venting system soil vapor extraction semi-volatile organic compounds California State Water Resources Control Board To Be Considered total extractable petroleum hydrocarbons micrograms per liter United States Environmental Protection Agency volatile organic compounds Vapor Intrusion Mitigation Advisory WSP Environment & Energy Page v

9 EXECUTIVE SUMMARY Erler & Kalinowski, Inc. ( EKI ) has prepared this Feasibility Study and Remedial Action Plan ( FS/RAP ) on behalf of the City of Emeryville Redevelopment Agency ( Emeryville ) for the Emeryville Mound Parcel ( Site ). The Site, encompasses approximately 69,000 square feet, and is located at 59 th Street and Horton Street (formerly Landregan Street) in Emeryville, California. This Site (APN ) is located on the west side of Horton Street and is bounded by the Emeryville Amtrak Station to the south, the Union Pacific Railroad tracks to the west, and the Emeryville Post Office to the north. CBS Corporation ( CBS ), formerly Westinghouse, is the current Site land owner. Wareham Development ( Wareham ) currently leases the Site for surface parking. Emeryville is working with CBS and the developer, Wareham, to prepare the Site for redevelopment. The proposed redevelopment plan includes construction of an abovegrade building across the entire Site where the ground level will be used as a parking garage and commercial space and aboveground levels will be used as commercial space. As part of this process, EKI has prepared this FS/RAP to evaluate remedial alternatives and propose a preferred remedial action that meets the identified remedial action objectives ( RAOs ), including protection of human health and the environment; compliance with regulatory requirements; cost-effective implementation; and preference for a permanent remedy consistent with the planned future land use. The State of California Environmental Protection Agency ( Cal/EPA ), Department of Toxic Substances Control ( DTSC ) provides regulatory oversight for investigation and remediation of chemicals of concern in soil and groundwater. The United States Environmental Protection Agency ( U.S. EPA ) provides regulatory oversight for polychlorinated biphenyls ( PCBs ) pursuant to the federal Toxic Substances Control Act ( TSCA ). EKI has prepared this FS/RAP following guidance consistent with the National Oil and Hazardous Substances Pollution Contingency Plan ( NCP, U.S. EPA, 1993) and reflects the guidance for such documents published by DTSC and U.S. EPA (Cal/EPA, 1995; U.S. EPA, 1988; and U.S. EPA, 1996). In addition, EKI has followed TSCA requirements in analyzing alternatives for PCBs. Site History Westinghouse conducted operations on the Site that included maintenance and repair of electrical equipment such as transformers containing PCB fluids. In 1984, Westinghouse entered into the Consent Agreement and Final Order ( Consent Agreement ) with U.S. EPA. As required by the Consent Agreement, Westinghouse constructed a subsurface slurry wall encompassing approximately 50,000 square feet of the Site and surface cap over the entire Site (i.e., 69,000 square feet) in 1985 (WCC, 1985b and WCC, 1986). PCB-contaminated soils from areas adjacent to and outside the ES-1

10 slurry wall were placed within the slurry wall, and the composite cap was constructed over the Site consisting of a geotextile, a geomembrane, clay, aggregate baserock, and a layer of asphalt. The slurry wall was keyed into the low-permeable Old Bay Mud stratigraphic unit to a minimum depth of 5 feet (WCC, 1986). Depth to Old Bay Mud is approximately 35 feet below ground surface ( bgs ), making the total slurry wall depth approximately 40 feet bgs (-22 feet mean sea level or msl 1 ). The slurry wall and cap are intended to limit human exposure to PCBs and other chemicals in soil and limit the lateral movement of contaminated shallow groundwater into and out of the contained area. The slurry wall and surface cap remain in place. In addition, as part of the Consent Agreement, Westinghouse has performed annual groundwater monitoring for PCBs and inspection of the surface cap since Since the original work at the Site under the Consent Agreement did not address the full range of chemicals of concern in soil and groundwater, Emeryville has worked to evaluate the broader range of potential impacts associated with the Site. Historic soil, soil vapor, and groundwater monitoring data from 1981 through 2004 are summarized in EKI s Revised Human Health Risk Assessment for Proposed Transit Center/ Commercial/ Residential Redevelopment, Mound Site, Emeryville, California ( HHRA, EKI, 2005b and EKI, 2006). DTSC issued a letter on 5 May 2006 stating that DTSC had no further comment on the HHRA. Since the issuance of DTSC s 5 May 2006 letter, additional monitoring has been performed at the Site, and these additional data have been used to update the risk estimates performed in the HHRA. The updated risk estimates, including soil, soil vapor, and groundwater data collected to date, are summarized in this FS/RAP. The identified chemicals of potential concern ( COPCs ) in soil, groundwater, and soil vapor at the Site include: Soil o All volatile organic compounds ( VOCs ) and semi-volatile organic compounds ( SVOCs ) that have been detected in soil samples collected at the Site (i.e., benzene, bis(2-ethylhexyl) phthalate, n-butylbenzene, secbutylbenzene, tert-butylbenzene, chlorobenzene, chloromethane, 1,2- dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2- dichloroethane, 1,1-dichloroethene, cis-1,2-dichloroethene, trans-1,2- dichloroethene, dichloromethane (methylene chloride), ethylbenzene, fluoranthene, isopropylbenzene, 4-isopropyltoluene, 2-methylnaphthalene, naphthalene, n-propylbenzene, pyrene, 1,1,2,2-tetrachloroethane, toluene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, trichloroethene, trichlorofluoromethane, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, vinyl chloride, and xylenes); o PCBs; and, 1 Elevation presented in North American Vertical Datum of 1988 ( NAVD88 ). The elevation in National Geodetic Vertical Datum of 1929 ( NGVD29 ) is -25 feet msl. ES-2

11 o Arsenic and lead. Groundwater o All VOCs and SVOCs that have been detected in groundwater samples collected at the Site (i.e., benzene, bis(2-ethylhexyl) phthalate, butyl benzyl phthalate, tert-butylbenzene, carbon tetrachloride, chlorobenzene, chloroform, 1,4-dichlorobenzene, cis-1,2-dichloroethene, trans-1,2- dichloroethene, dichloromethane (methylene chloride), 1,2,4- trichlorobenzene, trichloroethene, vinyl chloride); and, o Arsenic and lead. Soil vapor o All chemicals detected in soil vapor samples collected at the Site (i.e., benzene, chlorobenzene, chloroethane, chloromethane, 1,3- dichlorobenzene, 1,4-dichlorobenzene, cis-1,2-dichloroethene, ethylbenzene, styrene, toluene, 1,2,4-trimethylbenzene, xylenes). Based on available Site data and proposed future redevelopment scenario, estimated cumulative human health risks exceeded acceptable levels (i.e., 1 for non-carcinogenic hazard index and 10-6 for carcinogenic risks) during theoretical future excavation activities. As a result, use of personal protective equipment ( PPE ), engineering controls, and monitoring with contingency plans will be necessary to protect on-site and off-site workers and residents during any future remedial soil excavation and soil handling activities undertaken as part of redevelopment. Except for commercial/industrial use of a building constructed directly on-grade (i.e., Alternative 2), cumulative risk estimates for the future completed redevelopment project following construction activities were below acceptable risk levels for all alternatives evaluated in this FS/RAP. Therefore, construction of a sub-slab venting system ( SSVS ) was recommended for Alternative 2 under the commercial/industrial future use scenario. 2 Summary of Remedial Alternative Analysis RAOs for the Site were developed in this FS/RAP and are intended to guide remedial actions that mitigate the identified potential threats to human health and the environment in a manner consistent with potential future uses of the Site. RAOs for the Site are listed below. Protection of human health and the environment; Compliance with applicable, relevant, and appropriate requirements; Cost-effective remediation of the Site consistent with planned future land use; and Preference for a permanent remedy whenever practicable, cost-effective, and consistent with planned future land use. 2 Residential uses of any ground-level or subterranean levels are not consistent with the development scenarios, so were not evaluated in this FS/RAP. ES-3

12 Technologies and process options that could potentially be implemented to address the RAOs for the Site were identified and grouped into the General Response Actions that included: No Action; Institutional Controls; Containment Options; and Remediation or Treatment/Disposal Options. Potential remedial technologies and process options were screened using the three criteria of effectiveness, implementability, and cost, as described in the NCP and relevant guidance documents. Remedial technologies and process options that remained viable after this screening evaluation were retained for development into four potential remedial alternatives (Alternatives 1 to 4), as discussed in detail in Section 5.0. The four potential remedial alternatives include: Alternative 1: No Further Action, Alternative 2: Soil Excavation for Foundation and Construction of Above-Grade Building, Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal, and, Alternative 4: Risk-Based Cleanup for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building. These four alternatives were subjected to detailed analysis and comparison based on the nine NCP criteria for feasibility studies (U.S. EPA, 1993) and six State of California evaluation criteria as delineated by the California Health and Safety Code (d) to identify a recommended remedial alternative for the Site. Proposed Remedy Based on the evaluation of potential remedial alternatives using the NCP criteria and the State of California criteria, Alternative 2 is recommended for implementation as the proposed remedy for the Site. An overview of Alternative 2 is summarized below and the detailed description of the proposed remedy is presented in Section 8.0. Pre-Excavation Soil Sampling for PCB Congeners. At the request of U.S. EPA, prior to soil excavation activities, soil samples will be collected and analyzed for presence of dioxin-like PCB congeners (i.e., coplanar or mono-ortho-substituted PCBs). The scope of congener monitoring is identified in a sampling work plan dated 3 September 2009 (WSP, 2009), which has been reviewed and approved by DTSC and U.S. EPA. ES-4

13 Targeted Additional Groundwater Characterization and In Situ Treatment. To further refine the area targeted for in situ treatment, an investigation using membrane interface probes ( MIP ) and hydraulic profiling tools ( HPT ) is proposed for the northeastern portion of the Site within the slurry wall. These tools can be used to further define the depth and lateral extent of VOCs in the subsurface at the Site, and therefore refine the groundwater treatment scope. Grab groundwater samples may also be collected as part of the MIP/HPT investigation. Following groundwater investigation activities, a material for in situ remediation of VOCs in groundwater will be injected into the subsurface. For the purposes of this FS/RAP evaluation, it is assumed that oxygen release compound ( ORC ) will be used to provide oxygen to native bacteria capable of aerobically degrading certain VOCs including, benzene, carbon tetrachloride, chlorobenzene, dichlorobenzene, cis-1,2-dichloroethene, and vinyl chloride. A separate in situ treatment work plan detailing the type and scope of groundwater investigation and treatment activities will be submitted to DTSC for review and approval. Unsaturated and Saturated Soil Excavation. For construction of an above-grade building, unsaturated soil will be excavated to approximately 5.5 feet bgs or 12.5 feet msl across the entire Site. The excavation may be deeper to accommodate construction activities based on the final design for the development. Excavated soil will be transported off-site to a permitted landfill for disposal. If dewatering of the excavation is performed, groundwater generated will be disposed of at Seaport Environmental or treated on-site, if needed, prior to discharge to the East Bay Municipal Utility District ( EBMUD ) sanitary sewer system. The minimum requirements for on-site treatment of groundwater generated during dewatering activities, if performed, will be specified in the contract documents. The volume of excavation dewatering water is anticipated to be relatively small given that the majority of soil excavation activities will be in the unsaturated zone. Vapor Mitigation. Following excavation of soil to the target depth, and backfilling if appropriate based upon the final development plans, an SSVS would be constructed on-site beneath the portions of the future building that (1) will be used as commercial/industrial space and (2) will be the locations for elevator shafts, stairwells, utility corridors, and other enclosed areas serving as potential preferential pathways for soil vapor migration. The intent of the SSVS is to provide a pathway to allow soil vapor to migrate or vent to the exterior of the future on-site building, rather than entering the building. The SSVS will generally consist of the following elements: o A horizontal layer of permeable venting material (e.g., sand or gravel) beneath the appropriate portion of the building footprint - the permeable venting material layer will be installed below structural grade beams and shallow sub-floor utilities that may otherwise interfere with uniform lateral venting, and thus may be approximately 2 to 4 feet below the building floor; ES-5

14 o Lengths of perforated pipe installed within the layer of permeable venting material connected to a vertical riser pipe through the building with an outlet on the building roof; o A sub-slab liner (e.g., Geo-Seal), installed either (a) directly on top of the layer of permeable material, or (b) immediately below the commercial/industrial use portion of the building floor; and, o Soil vapor sampling probes, installed within the layer of permeable material, to monitor VOC concentrations in soil vapor beneath this portion of the building. Following building construction, the vertical vent pipe will be connected to the pipe beneath the building and extended to the roof to passively vent sub-slab soil vapor. A wind-driven turbine ventilator will be provided on the vent pipe outlet to assist passive ventilation. Soil vapor samples will then be collected from the soil vapor sampling probes to assess post-construction conditions. The design details for the SSVS will be submitted to DTSC in a separate work plan for review and approval prior to SSVS construction. The SSVS will be designed so that it can be upgraded to an active sub-slab depressurization system ( SSDS ) if required by DTSC and determined necessary based on subslab soil vapor data. An SSDS is designed to function by creating a lower pressure directly underneath a building floor relative to the pressure within the building to inhibit soil vapor from migrating into the building. The lower pressure will be confirmed by measuring the pressure in the soil vapor sampling probes installed beneath the building. The sub-slab VOC concentrations for triggering an upgrade from SSVS to SSDS will be included in the SSVS design work plan submitted to DTSC for review and approval. The SSVS (and SSDS if necessary) would be designed and operated to maintain a removal efficiency for indoor air exposure scenarios to achieve an indoor air risk of 1x10-6 or below and hazard index of 1 or lower. Continued Function of Slurry Wall. The portion of the existing slurry wall below the excavation will continue to function as a barrier to lateral migration of groundwater. If additional soil is excavated below the water table, the slurry wall will be avoided so that it continues to function as a barrier to groundwater flow. Any changes to the slurry wall as a result of the construction activities will be documented in a post-remediation/pre-construction report. The report will include an analysis to demonstrate to the satisfaction of the DTSC and U.S. EPA that any changes to the slurry wall will not create conditions that will allow migration of groundwater containing chemicals of concern in the foreseeable future. Institutional Controls. DTSC and CBS will execute a land use covenant ( LUC ) entitled Covenant to Restrict Use of Property, Environmental Restriction within 120 days after DTSC approved the FS/RAP. CBS will record the executed LUC ES-6

15 with the Alameda County Assessor s Office. The LUC will restrict Site use and minimize the remaining potential for impacting human health and the environment after soil remediation. Provisions of the LUC would include, but not be limited to, the following: o Restrictions on sensitive land use (e.g., residential housing, schools, daycare facilities, hospitals, hospices, etc.) on the ground level; o Restrictions on commercial/industrial use at the ground level of the building interior where an SSVS has not been installed; o Restrictions on intruding and removing soil below 5.5 feet bgs or 12.5 feet msl except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; o Restrictions on all groundwater extraction and construction dewatering except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; o Requirements of soil and groundwater management pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; o Inspection and maintenance of subsurface portions of the building in accordance with a DTSC- and U.S. EPA-approved O&M Plan; o Requirement of annual reporting and certification; o Requirements for providing advance notification to DTSC and U.S. EPA of any planned construction or maintenance activities that may expose personnel to soil or groundwater; and o Provisions for DTSC and U.S. EPA access to the Site. The O&M Plan will be prepared after remediation is completed and will provide a framework to manage residual COPCs in soil and groundwater in a manner that is consistent with planned future land uses and is protective of human health for expected future populations. Main features of the O&M Plan are described in Section Monitored Natural Attenuation. Groundwater monitoring wells will be installed at the downgradient edge of the Site and on-site within the slurry wall. Due to the health and safety concerns associated with groundwater sampling in the future commercial/industrial portion of the building, the groundwater monitoring wells within the slurry wall will be installed in the future ventilated parking garage. Given this limitation and the pending building design, the wells may or may not be located in the area of greatest VOC concentrations in groundwater. However, DTSC prefers groundwater monitoring wells be installed close to locations with elevated VOC concentrations. For cost estimating purposes, it is assumed that each set of wells (within the slurry wall and at the downgradient edge of the Site) will consist of two wells with screen depths corresponding to the existing Site shallow wells (i.e., 10 to 25 feet bgs) and one with a screen depth corresponding to the existing Site deep wells (i.e., 25 to 40 feet bgs). The wells will not be ES-7

16 screened below the slurry wall depth because the slurry wall is keyed into an impermeable unit and it would be inadvisable to penetrate that unit on or close to the Site. A groundwater monitoring plan specifying well installation and sampling details will be submitted to DTSC and U.S. EPA for review and approval. The actual number, depths, screen lengths, and locations of groundwater monitoring wells will be decided on during DTSC and U.S. EPA s review and approval of this separate groundwater monitoring plan. Alternative 2 meets both soil and groundwater RAOs, satisfies the NCP and State of California criteria, can be implemented in a timely, safe, and cost-effective manner, and is compatible with future land uses contemplated in the City of Emeryville general plan and zoning ordinances. Identified contingencies and uncertainties as part of Alternative 2 are summarized in Section 8.2. Implementation Schedule An approximate implementation schedule to finalize the FS/RAP and to implement the soil excavation portion of the proposed remedy is provided below. Public Comment Period Mid-November 2009 to Mid-December 2009 Final FS/RAP Early-January 2010 Remedial Design and March 2009 to Late-January 2010 Implementation Plan ( RDIP ) 3 Plans and Specifications Mid-August 2009 to February 2010 Contractor Bid, Award, and Contract Period February 2010 to March 2010 Soil Excavation Work 4 April 2010 to June Timeframe for RDIP includes preparation, submittal, DTSC and U.S. EPA review, and finalization of the Draft RDIP. 4 Length of time for soil excavation subject to change based on additional information and analysis presented in the RDIP. ES-8

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18 1.0 INTRODUCTION Erler & Kalinowski, Inc. has prepared this draft Feasibility Study and Remedial Action Plan ("FS/RAP") on behalf of the City of Emeryville Redevelopment Agency ( Emeryville ) for the former Westinghouse (now CBS Corporation ["CBS"]) property, encompasses approximately 69,000 square feet, located at 59th Street and Horton Street (formerly Landregan Street) in Emeryville, California. This property (APN ) is located on the west side of Horton Street and is bounded by the Emeryville Amtrak Station to the south, the Union Pacific Railroad tracks to the west and the Emeryville Post Office to the north. This property is known as the Emeryville Mound Parcel ( Site, Figures 1 and 2). Emeryville is working with CBS (the current land owner) and Wareham Development ( Wareham ) (the developer and potential future land owner) for construction of a building across the entire Site for use as a parking garage and commercial space on the ground level with additional commercial space over the ground level parking garage/commercia1 space. As part of the redevelopment process, EKI has prepared this FS/RAP to evaluate remedial alternatives and propose a preferred remedial action that meets identified remedial action objectives ( RAOs ), including protection of human health and the environment; compliance with regulatory requirements; cost-effective implementation; and a preference for permanent remedy consistent with the planned future land use. The preferred remedial action are developed and evaluated consistent with applicable provisions of the National Oil and Hazardous Substances Pollution Contingency Plan ( NCP ) promulgated under the Comprehensive Environmental Response, Compensation, and Liability Act. The remedial alternatives will also be evaluated to confirm compliance with requirements for preparing a RAP under Section of the California Health and Safety Code. Remedial alternatives involving excavation of soil containing PCBs will follow the requirements of the federal Toxic Substances Control Act ( TSCA ). The California Department of Toxic Substances Control ( DTSC ) and the United States Environmental Protection Agency ( U.S. EPA ) provide regulatory oversight for the Site. 1.1 Emeryville Mound Parcel Background and Current Conditions Currently, CBS (the successor company of Westinghouse by acquisition) owns the Site and Wareham (the developer and potential future land owner) leases the Site for surface parking. Vehicles park on top of the surface cap constructed as part of the environmental remedial measures conducted in the 1980s. Historically, Westinghouse conducted operations on the Site that included maintenance and repair of electrical equipment such as transformers containing polychlorinated biphenyl ( PCB ) fluids. Environmental investigations conducted by EKI and others since the early 1980s have identified releases of hazardous substances in soil and groundwater at the Site. These include PCBs, volatile organic compounds ( VOCs ), Page 1 of 72

19 semi-volatile organic compounds ( SVOCs ), total extractable petroleum hydrocarbons ( TEPH ), dioxins and furans, and metals. Westinghouse entered into the Consent Agreement and Final Order ( Consent Agreement ) with U.S. EPA in As required by the Consent Agreement, Westinghouse constructed a subsurface slurry wall encompassing approximately 50,000 square feet of the Site and surface cap over the entire Site (i.e., 69,000 square feet) in 1985 (WCC, 1985b and WCC, 1986). PCB-impacted soils from areas adjacent to and outside the slurry wall were placed within the slurry wall, and the composite cap was constructed over the entire Site consisting of a geotextile, a geomembrane, clay, aggregate baserock, and a layer of asphalt (WCC, 1985b; WCC, 1986; and EKI, 2003). The slurry wall was keyed into the low-permeable Old Bay Mud stratigraphic unit to a minimum depth of 5 feet (WCC, 1986). Depth to Old Bay Mud is approximately 35 feet below ground surface ( bgs ), making the total slurry wall depth approximately 40 feet bgs (-22 feet mean sea level or msl 5 ). The cap was designed to be 2.5 feet thick (18 inches of clay, 9 inches of aggregate baserock, and 3 inches of asphalt; WCC, 1986), however, EKI encountered some variability in this thickness during Site investigations. The slurry wall and surface cap are intended to limit human exposure to PCBs and other chemicals in soil and limit the lateral movement of contaminated shallow groundwater into and out of the contained area. The slurry wall and surface cap remain in place. As required by the Consent Agreement, CBS' consultant, WSP Environment & Energy ( WSP ), currently performs annual groundwater monitoring and inspections at the Site. Monitoring activities required by the Consent Agreement consist of (1) gauging water levels in four piezometers constructed within the slurry wall and 14 monitoring wells upgradient and downgradient of the slurry wall, (2) collecting unfiltered PCB samples from the 14 monitoring wells, and (3) performing a Site inspection to assess the condition of the cap, fences, and monitoring wells at the Site. The details of annual monitoring activities are discussed in the work plan for groundwater sampling and analysis (Alta, 1997). 6 Note that the Consent Agreement does not require the piezometers within the slurry wall to be sampled for PCB analysis. As stated in the Consent Agreement, the intent of groundwater monitoring is to identify movement of PCBs off the site via ground water transport. Over the previous 10 years (i.e., since 1999), PCBs have been detected only occasionally in groundwater samples collected from wells located within the slurry wall at concentrations ranging from 0.12 micrograms per liter ( ug/l ) to 0.42 ug/l, with the exception of one detection in May 2007 at monitoring well D-5 (located outside of the slurry wall) where PCBs were detected at 4.1 ug/l (WSP, 2008). Groundwater level data are discussed in Section 2.1. Aside from occasional minor repairs, the cap, fences, and monitoring wells remain in good condition (WSP, 2008). 5 Elevation presented in North American Vertical Datum of 1988 ( NAVD88 ). The elevation in National Geodetic Vertical Datum of 1929 ( NGVD29 ) is -25 feet msl. 6 Due to the timing of the preparation of this document, results for 2009 groundwater monitoring are not included in this FS/RAP. However, EKI has reviewed the draft data to be published by WSP during fall 2009; these data are consistent with the 2008 results included in this FS/RAP. Page 2 of 72

20 1.2 Site Development Plans Emeryville is working with CBS, Wareham, and other parties to redevelop the Site for use as a parking garage and commercial space. The remedial alternatives considered in this FS/RAP contemplate human occupancy of both surface level structures (i.e., Alternative 2) and structures with one floor below ground surface (i.e., Alternatives 3 and 4). EKI understands from recent discussions with the City that Wareham has submitted a planning application for redevelopment of the Site. The planning application includes a three-level above-grade parking garage overlain by a seven-level commercial building. Planned use of the building s ground floor includes 148 parking spaces and 2,347 gross square feet of ground floor space for transit, retail and/or office uses, such as ticketbuying, travel and transit information, bike security, and car share information. For the purposes of this FS/RAP, areas used for retail or offices are considered commercial/industrial space since it is anticipated that individuals may be working in these areas for conventional 8-hour workdays and 40-hour workweeks. 1.3 Site Development-Related Documents Beginning in approximately 2002, Emeryville began assisting CBS and Wareham in evaluating the potential for a risk-based redevelopment approach for the Site that would limit remediation to those activities necessary to allow a proposed redevelopment project to proceed. As part of this process, EKI prepared a risk assessment for the proposed redevelopment project entitled, Revised Human Health Risk Assessment for Proposed Transit Center/ Commercial/ Residential Redevelopment, Mound Site, Emeryville, California, dated 7 November 2005 and a memorandum responding to comments on this document, dated 14 March 2006 ( HHRA, EKI, 2005b and EKI, 2006). DTSC issued a letter on 5 May 2006 stating that DTSC had no further comment on the HHRA. Following preparation of the HHRA, EKI prepared a document discussing remedial design and implementation plans for the soil removal action identified for the proposed redevelopment project. This document is entitled, Draft Soil Removal and Remedial Implementation Plan, Mound Parcel, Emeryville, California, and is dated 27 February 2006 ( draft SRRIP ). DTSC and U.S. EPA submitted comments on the draft SRRIP in letters dated 13 September 2006 and 5 July 2006, respectively. As a result of more recent discussions with DTSC and U.S. EPA, Emeryville, CBS, and Wareham have agreed to prepare an FS/RAP as part of the Site redevelopment process. As previously discussed, this FS/RAP establishes RAOs for the Site, evaluates remedial alternatives, and proposes a preferred remedial action that meets the RAOs, NCP, State requirements, and future redevelopment plans. Following DTSC and U.S. EPA initial review on the draft FS/RAP, Emeryville will provide a 30-day public comment period requesting the public review on the FS/RAP. Emeryville will hold a public meeting during this 30-day period to present the proposed remedial action with the public. Following the 30-day public comment period, Emeryville will prepare a Responsiveness Summary, responding to all comments for Page 3 of 72

21 DTSC s and U.S. EPA s review and approval. The Responsiveness Summary will be incorporated as Appendix G of this FS/RAP. Revisions will be made to this FS/RAP as necessary, based on the public comments and DTSC requests. Emeryville will finalize the FS/RAP for DTSC s and U.S. EPA s approval. Following regulatory agencies approval of the final FS/RAP, a remedial design and implementation plan ( RDIP ) will be prepared. Similar to the SRRIP, the RDIP will present the remedial design and implementation plans for the preferred remedial alternative identified in the final FS/RAP. The analysis of alternatives in this draft FS/RAP is based on various assumptions. However, many of the details of these assumptions (e.g., risk management during soil excavation and handling activities, and details regarding future building design and construction) will be provided in the RDIP or other future documents. 1.4 Previous Remedial Investigations Historically, soil and groundwater samples collected from the Site have been analyzed for multiple parameters including PCBs, VOCs, SVOCs, TEPH, dioxins and furans, metals, and general minerals. Available soil analytical data collected from 1981 through 2004 and groundwater analytical data collected in 2003 and 2004 for the Site are compiled in the HHRA and in Appendix A of this document. The environmental investigations from which these data were obtained are discussed in detail in the HHRA and summarized chronologically below: Brown and Caldwell, 1981 Brown and Caldwell, 1983 Woodward-Clyde Consultants, 1985 EMCON Associates, 1993 EMCON Associates, Erler & Kalinowski, Inc., Erler & Kalinowski, Inc., 2004 Additionally, during preparation of this FS/RAP, representatives from DTSC requested that additional groundwater samples collected from monitoring wells located outside the slurry wall at the Site be analyzed for VOCs to support the vapor intrusion modeling performed in this report (Appendix B). The requested sampling was performed in March 2009 in accordance with DTSC-approved work plan, dated 18 March 2009 (EKI, 2009). These data are included in the data summary tables presented in Appendix A. A summary of field activities and the analytical laboratory reports for the March 2009 groundwater sampling are included in Appendix E. 1.5 Report Organization The following list summarizes the content of each of the following sections of this report and the appendices included with this document. Section 2.0 presents a summary of the Site conditions, including the geologic and Page 4 of 72

22 hydrologic setting, the modifications made to Site elevation data to coincide with a recent survey at the Site, and chemicals of potential concern found in soil and groundwater at the Site. Section 2.0 also summarizes the scope of the HHRA and modifications made to the HHRA methodology for the risk analysis presented in this FS/RAP. Section 3.0 presents the RAOs and risk-based Site Cleanup remedial goals. Section 4.0 includes a screening of technologies for soil and groundwater remediation at the Site. Section 5.0 presents the remedial alternatives developed in this FS/RAP. Section 6.0 summarizes the results of the risk analysis for remedial alternative evaluation. Section 7.0 presents an evaluation of the remedial alternatives against RAOs, NCP criteria, State of California Factors, and TSCA. Section 8.0 includes a summary of the preferred remedial alternative. Section 9.0 presents a remedial alternative implementation schedule. Section 10.0 presents the nonbinding allocation of responsibility assigning CBS with 100% responsibility. Section 11.0 presents the references cited in this FS/RAP. Appendix A includes a summary of analytical results for soil, groundwater, and soil vapor at the Site. Appendix B presents the human health risk estimates for each remedial alternative, and the remediation goal development for the risk-based cleanup alternative (i.e., Alternative 4). Appendix C includes the preliminary cost estimates for each remedial alternative. Appendix D includes the tables and figures from the most recent groundwater monitoring report for the Site (WSP, 2008). Appendix E presents a summary of the results of groundwater sampling performed in March Appendix F includes the application to U.S. EPA for assessing PCBs under the risk-based option in TSCA (i.e., Section (c)). Appendix G includes an Administrative Record List. Appendix H is reserved for a Responsiveness Summary, which will be prepared after public review of the draft FS/RAP. Page 5 of 72

23 2.0 SUMMARY OF SITE CONDITIONS AND RISK ASSESSMENT The following sections summarize the geologic and hydrologic conditions at the Site, modifications made to the Site elevation data to coincide with a recent survey at the Site, and the chemicals of potential concern in soil and groundwater at the Site. This section also includes a summary of the scope of the HHRA and modifications made to the HHRA methodology for the risk analysis presented in this FS/RAP. 2.1 Geologic and Hydrogeologic Setting Based upon Site-specific subsurface investigations conducted by EKI in November 2002 and again in November 2004, as well as historical subsurface investigations, the Site is underlain by approximately 8 to 12 feet of fill, consisting of an engineered clay and baserock cap over imported soil and debris. The fill is itself underlain by interbedded, generally fine-grained estuarine and fluvial silts and clays with minor sands and gravels. The finer-grained sections of these deposits probably correspond to Young Bay Mud (Helley et al., 1979). Thickness of this upper unit of native (non-fill) sediments sums to approximately feet, based upon historical on-site borehole data (EMCON, 1993). Historical borehole records also indicate that a massive marine clay unit identified as "Old Bay Mud" lies below these sedimentary units (WCC, 1985a). The Old Bay Mud unit was encountered during on-site historical drilling and excavation at a depth of approximately feet below the former ground surface. Based upon Figure 5 from WCC (WCC, 1985a), the western area of the Site may have been covered by a "tidal pond or slough in the mid-1800s. Such a depositional environment typically would produce the fine-grained sediments encountered below ground surface at the Site in the shallowest zone of native sediments. As required by the Consent Agreement, Westinghouse constructed a subsurface slurry wall and surface cap on the Site in 1985 (WCC, 1985b and WCC, 1986). PCB-impacted soils from areas adjacent to and outside the slurry wall were placed in certain areas within the slurry wall, and the area was then covered with a multi-layer engineered cap (WCC, 1985b; WCC, 1986; and EKI, 2003). The slurry wall was constructed of mixed soil and bentonite backfill, and extends from a base approximately 5 feet below the top of the Old Bay Mud unit, up to the historical ground surface (WCC, 1985a). The Old Bay Mud unit is thought to represent an aquitard (EMCON, 1993). Upon completion of the slurry wall, the entire Site was covered with an engineered cap consisting of geotextile, overlain by approximately 1.5 feet of clay (although this thickness is variable, based upon EKI borehole data), which is in turn covered by a geomembrane. Several inches of baserock and asphalt were laid down over the top of the upper geomembrane to complete the cap (WCC, 1985a). Site improvements since the construction of the containment cell have added more layers of asphalt to the cap (WSP, 2008). The Site is mostly paved, with minor landscaping along the western and northwestern edge of the property (Figure 3). The current asphalt surface is highest in the center of the Site, and surface water drainage is mostly to the north and south, away from the center. Ground surface elevation contours are included on Figure 3. As shown on this figure, Page 6 of 72

24 elevations at the Site vary between approximately 17 and 19 feet msl. 7 Due to the variations in surface elevations, discussion of groundwater levels or sample depths in feet below ground surface can be confusing. Therefore, this FS/RAP generally presents this information as elevations in feet msl. To simplify discussions of depths on a Site-wide basis (e.g., when discussing excavation depths for Alternatives 2 through 4), a ground surface elevation of 18 feet msl is used for reference in estimating depths below ground surface. Along the northern property boundary, a shallow lined channel drains eastward to a storm sewer grate. Surface drainage to the south generally flows to a landscaped area adjacent to the Amtrak station building. The existing on-site monitoring wells and piezometers were originally drilled in Some wells were modified, destroyed, or replaced over time as improvements were made to the Site and adjacent properties. The wells generally were constructed in pairs, with one well of each pair screened at more shallow depths (approximately 9.5 to 24.5 feet bgs), and one well screened at deeper depths (approximately 25 to 40 feet bgs) (WSP, 2008). The shallow piezometers P-1 and P-3 and the deep piezometers P-2 and P-4 are located inside the slurry wall (Figure 3). The remaining wells are all located outside the slurry wall. Table A-1 of Appendix A summarizes the construction details for the existing monitoring wells at the Site. Construction of the slurry wall, which is a mixture of soil and bentonite approximately 3 feet thick and keyed into the low-permeable Old Bay Mud stratigraphic unit (WCC, 1986), was intended to hydraulically isolate PCB-impacted soil from groundwater flow occurring in saturated sediments (WCC, 1985a). In October 1985, shortly after construction of the slurry wall, nine slurry wall samples were collected by drilling within the wall. Laboratory horizontal permeability tests of the samples indicated that the horizontal hydraulic conductivity of the slurry wall ranged from 0.9 x 10-8 centimeter per second ( cm/s ) to 3.5 x 10-8 cm/s, based upon the samples tested (WCC, 1986). In situ hydraulic pumping tests of the slurry wall were conducted in 1986 by WCC. WCC concluded that the slurry wall cutoff was acting as an effective hydraulic barrier and the remediation work was in compliance with U.S. EPA Consent Agreement (WCC, 1985b). Historical piezometric head measurements for the Site wells indicate that groundwater flows generally west, toward San Francisco Bay (WSP, 2008), which is located approximately 700 feet downgradient from the Site. Groundwater contours based on the piezometric head measurements recorded by WSP in May 2008 are presented in Appendix D. Groundwater elevations measured in shallow and deep wells outside the slurry wall in May 2008 range from 9.76 feet msl at well S-1 to feet msl at well S-4. 8 Groundwater elevations measured in shallow and deep piezometers within the 7 As discussed in further detail in Section 2.2, elevation data at the Site have been adjusted from the NGVD29 datum to the NAVD88 datum, resulting in a Site-wide elevation increase of approximately 2.7 feet. 8 The measured depth to groundwater ranged from approximately 4.3 feet bgs at well D-5 to 8 feet bgs at well S-1. These locations do not necessarily correspond to the locations listed above for the maximum Page 7 of 72

25 slurry wall in May 2008 are fairly consistent at approximately 12.5 feet msl, which corresponds to approximately 6 feet bgs in this area of the Site (WSP, 2008) Conversion of Elevation Data for this FS/RAP The locations of existing monitoring wells were resurveyed on 30 August 2008 by PLS Survey Inc (WSP, 2008). The elevation datum used for surveying these locations was North American Vertical Datum of 1988 ( NAVD88 ), whereas the previous elevation data available for the Site is based on the National Geodetic Vertical Datum of 1929 ( NGVD29 ). Therefore, for consistency, existing elevation data available for the sample locations at the Site were converted from NGVD29 to NAVD88 using the MS Windows-based program published by the U.S. Army Corps of Engineers called Corpscon (Version 6.0). Due to the relatively small area of the Site, the vertical adjustment approximated by Corpscon is equivalent for all locations, namely an elevation increase of approximately 2.7 feet. This elevation adjustment is consistent with the difference in historical and current (i.e., August 2008) elevations of the existing monitoring wells, with the exception of three monitoring wells (WSP, 2008). However, it is likely that the elevation of these three monitoring wells (D-1, S-1, and S-6) had changed since they were last surveyed due to repaving or repair activities related to the Site cap, as the current elevations of these monitoring wells are now more consistent with elevations of nearby wells. A summary of the historical and current elevations for the samples referenced in this report is provided in Appendix A. 2.3 Chemicals of Potential Concern Chemicals of potential concern ( COPCs ) in soil and groundwater were established in the HHRA. These same COPCs, which are summarized in Table 1, are included in the updated risk analysis presented in this FS/RAP (Appendix B). All organic chemicals detected in soil or groundwater samples collected at the Site were retained as COPCs for the Site. The selected COPCs for soil include the following: All VOCs and SVOCs that have been detected in soil samples collected at the Site (i.e., benzene, bis(2-ethylhexyl) phthalate, n-butylbenzene, sec-butylbenzene, tertbutylbenzene, chlorobenzene, chloromethane, 1,2-dichlorobenzene, 1,3- dichlorobenzene, 1,4-dichlorobenzene, 1,2-dichloroethane, 1,1-dichloroethene, cis- 1,2-dichloroethene, trans-1,2-dichloroethene, dichloromethane (methylene chloride), ethylbenzene, fluoranthene, isopropylbenzene, 4-isopropyltoluene, 2- methylnaphthalene, naphthalene, n-propylbenzene, pyrene, 1,1,2,2- range in groundwater elevations since depth to groundwater is dependent on ground surface elevations. Note that these groundwater level ranges exclude wells S-6 and D-6, which are located over 200 feet upgradient of the Site on the east side of the Emerystation North building across Horton Street (see Figures 2 and 3 in Appendix D). Groundwater in these upgradient wells is generally shallower than in wells on and near the Site. 9 Groundwater elevations measured in May 2009 are consistent with the previous years data. The results for May 2009 groundwater sampling will be published in a report by WSP in early October Page 8 of 72

26 tetrachloroethane, toluene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, trichloroethene, trichlorofluoromethane, 1,2,4-trimethylbenzene, 1,3,5- trimethylbenzene, vinyl chloride, and xylenes); PCBs; Polychlorinated Dibenzodioxins and Polychlorinated Dibenzofurans; and Arsenic and lead. The selected COPCs for groundwater include the following: All VOCs and SVOCs that have been detected in groundwater samples collected at the Site (i.e., benzene, bis(2-ethylhexyl) phthalate, butyl benzyl phthalate, tertbutylbenzene, carbon tetrachloride, chlorobenzene, chloroform, 1,4- dichlorobenzene, cis-1,2-dichloroethene, trans-1,2-dichloroethene, dichloromethane (methylene chloride), 1,2,4-trichlorobenzene, trichloroethene, vinyl chloride); and Arsenic and lead. Although PCBs were detected in historical groundwater samples, PCBs are not considered COPCs for groundwater in the HHRA or in this FS/RAP. During more recent sampling events where groundwater samples were collected using low-flow sampling techniques, PCBs have only been detected sporadically and at low concentrations (Appendix D; WSP, 2008). Low-flow sampling minimizes entrained sediment in groundwater samples. Additionally, PCBs were not detected in any of the 15 field filtered groundwater samples collected during the 2004 field investigation (EKI, 2005b). These results suggest that detections of PCBs in historical groundwater samples resulted from PCBs sorbed to particulates entrained in the groundwater samples. This finding is not surprising given the hydrophobic nature of PCBs. Therefore, because previous PCB detections in groundwater are likely due to entrained sediment in the samples, PCBs are retained as a soil COPC only. While PCBs are not retained as COPCs in groundwater, the potential presence of PCBs in groundwater extracted for dewatering purposes must still be considered in the management and disposal of that extracted groundwater. TEPH is not retained as a COPC in soil or groundwater in the HHRA or in this FS/RAP because: TEPH results were found to significantly overestimate the concentrations of TEPH in the presence of high concentrations of PCBs; and The form of TEPH at the Site (i.e., transformer oil) is considered to be of low toxicity. These points are discussed in further detail in Appendix B of the HHRA (EKI, 2005b). Page 9 of 72

27 Two metals (lead and arsenic) are also retained as COPCs in soil and groundwater. Other metals detected in soil and groundwater were at concentrations below the applicable residential Regional Screening Level ( RSL ) published by the U.S. EPA for soil (U.S. EPA, 2008) and Maximum Contaminant Level ( MCL ) for drinking water, respectively. 10 Additionally, the risk estimates presented in Appendix B include soil vapor results for assessing potential risks associated with the current Site use (i.e., the "no further action" alternative, see Section 5.1). Therefore, available soil vapor data collected at the Site were also considered in this FS/RAP. These data were not applicable to the HHRA assessment, or to the other remedial alternatives assessed in this FS/RAP because, as discussed in further detail below, these scenarios include excavation of the soil above the water table where the soil vapor samples were collected. Therefore, available soil vapor data for the Site are not relevant to the future redevelopment scenarios. The selected COPCs for soil vapor include the following: All chemicals detected in soil vapor samples collected at the Site (i.e., benzene, chlorobenzene, chloroethane, chloromethane, 1,3-dichlorobenzene, 1,4- dichlorobenzene, cis-1,2-dichloroethene, ethylbenzene, styrene, toluene, 1,2,4- trimethylbenzene, xylenes). The COPCs for soil, groundwater, and soil vapor are summarized in Table 1. Appendix A includes tables summarizing COPC concentrations in soil, groundwater, and soil vapor at the Site. Additionally, detected PCB, lead, and arsenic concentrations in soil are illustrated on Figures 7 through 10, and all COPCs detected in groundwater and soil vapor are illustrated on Figures 11 and 12, respectively. The potential human health risks post-construction due to the presence of the COPCs retained for soil, groundwater, and soil vapor at the Site are evaluated in Appendix B for each alternative assessed in this FS/RAP. 2.4 Scope of 2005/2006 HHRA and Modifications for the FS/RAP Analysis The following sections summarize the scope and results of the HHRA, as well as the modifications made to the HHRA methodology for the risk analysis presented in this FS/RAP. 10 The representative concentration calculated in the HHRA using ProUCL Version 3.0 for total chromium in groundwater is 54 ug/l, which exceeds the MCL for total chromium of 50 ug/l. However, chromium was not retained as a COPC in groundwater because the exceedance of the MCL is minor and use of MCLs in screening for COPCs in groundwater at the Site is conservative since groundwater at the Site will not be used as a drinking water source. As shown in Table B-11, the representative concentration calculated using the current version of ProUCL (Version 4.0) is 50.6 ug/l, which is even closer to the MCL. Additionally, chromium was only detected in one groundwater sample above the MCL (i.e., 53.8 ug/l at location P-1, which is within the limits of the slurry wall). Page 10 of 72

28 2.4.1 Scope of the HHRA As previously discussed, EKI prepared the HHRA on behalf of Emeryville (EKI, 2005b and EKI, 2006). DTSC issued a letter on 5 May 2006 stating that DTSC had no further comment on the HHRA. The future redevelopment scenario evaluated in the HHRA for the Site was a parking garage with one below-grade floor across the entire Site and two above-grade levels covering approximately the western two-thirds of the Site. Additionally, residential and/or commercial development was planned for the floors above the parking garage. The HHRA considered conditions of the Site during and following redevelopment. The HHRA did not consider human health risks under current conditions. The scope of the HHRA was limited to chemicals found within the boundaries of the Site (i.e., the Emeryville Mound Parcel) and the soil excavation and other construction activities related to the proposed redevelopment. Therefore, potential exposures of on- and off-site populations to chemicals found in soil and groundwater outside of the boundaries of the Site were not considered. Potential exposures to on- and off-site populations due to future emissions from the activities associated with the planned development (e.g., gasoline and diesel fumes in the parking structure and public transit facility) were also not evaluated in the HHRA. In addition, the potential effects of construction activities and planned redevelopment at the Site on the remediation strategies and physical systems previously implemented at the Site (i.e., the slurry wall and cap) were not evaluated in the HHRA. Remedial goals were not developed in the HHRA because the redevelopment scenario evaluated was based on soil removal for a planned future Site use. Remedial goals for soil and groundwater are established in this FS/RAP for development of the Site remedial alternative only (i.e., Alternative 4). These goals, which are discussed in Section 3.4, are not applicable to the other alternatives assessed in this FS/RAP because these alternatives are also based on soil removal for a planned future Site use where the planned structures at the Site would provide barriers to soil exposures, and land use controls would be established Summary of HHRA Results The following sections summarize the results of the HHRA During-Construction HHRA Results Using the assumptions described in the HHRA, estimated human health risks during excavation activities exceed regulatory benchmarks for acceptable risk levels (i.e., 1 for non-carcinogenic hazard index and 10-6 for carcinogenic risks). These results indicate that use of personal protective equipment ( PPE ), engineering controls, and monitoring with contingency plans would be necessary to protect on-site workers and off-site workers and residents during the soil excavation and handling phase of the project. Some of these engineering controls may include: Wetting or foaming of soil during construction activities to reduce volatilization of COPCs and emission of dust particulates containing COPCs; Page 11 of 72

29 Construction of a fabric-covered fence around the Site to inhibit the movement of dust particulates containing COPCs to off-site areas directly adjacent to the site and to induce greater dispersion of volatile COPCs as they leave the Site; and Monitoring for airborne dusts and COPCs to determine actual airborne COPC concentrations and to monitor the effectiveness of engineering controls and any contingent response actions Post-Construction HHRA Results As discussed above, the future redevelopment scenario evaluated in the HHRA for the Site was a parking garage with one below-grade floor across the entire Site. Therefore, risks were estimated for potentially volatile chemical exposures to individuals using a sub-surface parking garage (i.e., one hour of exposure per day with the high parking garage ventilation rates required by building codes). The post-construction risk estimates calculated in the HHRA were below regulatory benchmarks for acceptable risk levels. Therefore, no additional controls or remediation were recommended in the HHRA. However, the proposed remedy in this FS/RAP includes both in situ groundwater treatment activities and construction of a vapor mitigation system to protect future populations at the Site (Section 8.1) Methane-Related HHRA Results As discussed in the HHRA, methane was detected at elevated concentrations in soil vapor samples, in some cases exceeding its lower flammability limit in air. These data on subsurface occurrence of methane at the Site indicate that precautions are warranted during soil excavation and in design of structures to reduce the risk of fire and explosion hazards. Since methane is not considered chemically toxic to humans, methane was not retained as a COPC in the HHRA. However, DTSC requested that indoor air concentrations of methane post-construction be assessed in the HHRA to verify that concentrations would be below levels of concern. The results of vapor intrusion modeling in the HHRA indicate that methane concentrations in indoor air post-construction are not expected to be of concern. However, the HHRA acknowledged that monitoring for methane gas in any non-ventilated facilities (e.g., utility vaults) located outside the future on-site structure may be prudent and would be discussed in the Operation and Maintenance ( O&M ) Plan Modifications to the HHRA Methodology for the FS/RAP Analysis The future redevelopment scenario evaluated in the HHRA is equivalent to Alternative 3 of this FS/RAP, except that commercial/industria1 space is now included as a potential use of the sub-grade floor. 11 As discussed in additional detail below, the during- 11 Due to the modifications in Site elevations (see Section 2.2), the excavation depths included in Alternative 3 of this FS/RAP vary slightly (i.e., approximately 0.5 feet) from the excavation depths for the redevelopment scenario evaluated in the HHRA. Page 12 of 72

30 construction risk estimates presented in the HHRA are not updated in this FS/RAP, however, the post-construction risk estimates have been modified to correspond to the remedial alternatives assessed herein. Appendix B of this FS/RAP presents the key elements of the HHRA and the modifications made to prepare the post-construction risk estimates for this FS/RAP. These modifications are summarized below: Toxicity criteria were revised based on reference documents updated since preparation of the HHRA, including: o "All OEHHA Acute, 8-hour and Chronic Reference Exposure Levels (chrels) as on December 18, 2008", available at o OEHHA Toxicity Criteria Database, available at (website last updated 17 December 2008); o U.S. EPA Integrated Risk Information System ( IRIS ), available at: (website last updated February 2009); and o U.S. EPA's RSLs (U.S. EPA, 2008). Commercial/Industrial Worker breathing rate was revised to be consistent with the Cal/EPA document, Human Health Risk Assessment (HHRA) Note, HERD HHRA Note Number 1, (Cal/EPA, 2005c). Representative concentrations are established using ProUCL Version 4.0 methodology versus Version 3.0 methodology. ProUCL Version 4.0 was published in To improve correspondence with the Site conceptual model, the model for estimating VOC flux into indoor air in the below-grade floor was adjusted by: o estimating the maximum vertical diffusive flux of VOCs from groundwater through soil to the ground surface assuming the equilibrium soil vapor concentration at the groundwater interface, and no chemicals in soil vapor at ground surface (i.e., the maximum gradient); o assuming the area of chemicals fluxing is a "halo" around the building perimeter, from 0 to 5 feet from the building wall; o assuming all of the chemicals fluxing from this area of groundwater adjacent to the building (i.e., vapors migrating upward within 5 feet of the building wall) are pulled into the building through below-grade cracks in the building sidewalls; 13 and 12 Table B-37 of Appendix B presents a comparison of the representative concentrations established in the HHRA (using ProUCL Version 3.0 methodology) versus Alternative 3 of this FS/RAP (using ProUCL Version 4.0 methodology). 13 A distance of 5 feet was chosen for modeling since the depth to groundwater at the perimeter of the Site is approximately 5 feet. Therefore, for locations further than 5 feet from the building, the shortest pathway for vapor migration is to the ground surface. However, for locations within 5 feet of the building wall, there is a greater potential for the vapors to be captured by a potential soil vapor leak through the building wall to the building interior, if the interior is at a lower pressure than soil vapor. Page 13 of 72

31 o Estimating chemical concentration in indoor air of below grade level by dividing the VOC flux by the volume of fresh air entering building through ventilations system. 14 Groundwater data for samples collected from monitoring wells outside the slurry wall in March 2009 are utilized in risk estimates. Risk associated with use of the first floor (i.e., ground-level floor for Alternative 2 and sub-grade floor for Alternatives 3 and 4) include both the potential future uses of a parking garage and commercial/industria1 space. During-construction risk estimates from the HHRA are not updated in this FS/RAP. As discussed in Section , the human health risks estimated in the HHRA for the excavation phase exceeded regulatory benchmarks for acceptable risk levels. Since these risk estimates are conservative with respect to the recommended alternative (Section 8.0), the during-construction risk estimates are not updated in this FS/RAP. Rather, the assumption is made that the use of PPE, engineering controls, and monitoring with contingency plans will be necessary to protect on-site workers and off-site workers and residents during the soil excavation and handling phase of the project. Some of the above-listed modifications to the HHRA methodology apply to the duringconstruction risk estimates (i.e., updating certain toxicity criteria and exposure parameters, using ProUCL Version 4.0 methodology to establish representative concentrations, and including additional data collected at the Site since preparation of the HHRA), however, these modifications would not impact the conclusion of the HHRA risk estimates, namely, that use of PPE, engineering controls, and monitoring with contingency plans will be necessary to protect on-site workers and off-site workers and residents during excavation and soil handling activities. As part of the RDIP, an air monitoring plan will be developed that will detail the specific procedures to be put in place for monitoring airborne dusts and COPCs to determine actual airborne COPC concentrations and to monitor the effectiveness of engineering controls and any contingent response actions during soil excavation and handling activities. The action levels developed in the air monitoring plan will be risk-based, and will consider additional data collected at the Site (e.g., PCB congener data; see Section 8.1.1) and modifications made to the HHRA methodology discussed above. 15 Therefore, recalculating risk estimates during construction is not warranted in this FS/RAP. A more detailed description of the plans to be implemented to protect the health of remedial construction workers and other on and off-site personnel will be provided in the RDIP. 14 Section B of Appendix B discusses the difference in attenuation coefficients between soil vapor and indoor air calculated using the HHRA methodology and this FS/RAP methodology (for Alternative 3). 15 As discussed in the description of remedial alternatives (Section 5.0), during a conference call on 5 March 2009; representatives from US. EPA requested that additional soil samples be collected at the Site for congener-specific PCB analysis to determine whether "dioxin-like" congeners are present. These data will also be incorporated into the development of risk-based action levels in air during construction activities. Page 14 of 72

32 3.0 REMEDIAL ACTION OBJECTIVES AND SITE CLEANUP GOALS This section outlines RAOs, which are statements of the overarching goals of a cleanup, and provide a basis for evaluating whether a remedial action is necessary or if no further actions are required. RAOs are developed to meet the objective of protecting human health and the environment. RAOs can address both chemical concentrations and potential exposure pathways. Protection can be achieved by reducing the mass, volume, toxicity, or mobility of chemicals of interest, by reducing potential exposures, or by a combination of these approaches. This section also summarizes proposed remedial goals for the risk-based cleanup alternative (Alternative 4) as a method or component of methods to achieving RAOs. 3.1 Identification of Potential ARARs and TBCs RAOs are developed by considering, among other things, Applicable or Relevant and Appropriate Requirements ( ARARs ). ARARs are defined in the NCP, 40 Code of Federal Regulations ( CFR ) Part (e)(2)(i), as follows: Applicable Requirements: Cleanup standards, standards of control, and other substantive requirements, criteria, or limitations promulgated under federal environmental or state environmental or facility siting laws that specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance found at a Comprehensive Environmental Response, Compensation, and Liability Act ( CERCLA ) site. Relevant and Appropriate Requirements: Cleanup standards, standards of control, and other substantive environmental protection requirements, criteria, or limitations promulgated under federal environmental or state environmental or facility siting laws that, while not applicable to a hazardous substance, pollutant, contaminant, remedial action, location, or other circumstance at CERCLA site, address problems or situations sufficiently similar to those encountered at the site that their use is well-suited to the particular site. ARARs typically are separated into three categories: 1. Chemical-specific ARARs: These are health-based or risk-based standards that define the allowable limits of specific chemical constituents found in or discharged to the environment. They can provide cleanup and discharge levels that can determine site remedial goals. Most chemical-specific ARARs are applicable to water sources potentially used for drinking water; few are available for ambient air or soil. MCL for drinking water are examples of potential chemical-specific ARARs. 2. Location-specific ARARs: These requirements can apply to natural site features, such as wetlands, flood plains, or the presence of endangered species, and to manmade features and institutional factors, including landfills, zoning Page 15 of 72

33 requirements, and places of historical or archaeological significance. Locationspecific ARARs restrict the types of remedial actions that can be implemented based on site-specific characteristics or location. 3. Action-specific ARARs: These ARARs are technology-based or activity-based limitations that can set performance and design restrictions. They specify permit requirements and engineering controls that must be instituted during site activities, or restrict particular activities. Federal and state non-promulgated standards, policies, or guidance documents, and local requirements, are not ARARs. However, according to the NCP guidance, these items are also to be considered when evaluating and selecting removal actions necessary to protect human health and the environment. These non-promulgated, non-binding factors are designated "To Be Considered," or "TBCs." Potential chemical-, location-, and action specific ARARs and TBCs for the Site are identified, listed, and described on Table Remedial Action Objectives The RAOs for remedial alternatives considered for the Site include: Protection of human health and the environment; Compliance with applicable, relevant, and appropriate requirements; Cost-effective remediation of the Site consistent with planned future land use; and Preference for a permanent remedy whenever practicable, cost-effective, and consistent with planned future land use. RAOs for protection of human health and the environment are generally quantitative or semi-quantitative and are judged by comparison to applicable cleanup levels and assessment of potential risks. For the purposes of this analysis, target risk levels are established as 1 for non-carcinogenic hazard index and 10-6 for carcinogenic risks. These target risk levels are discussed in greater detail in Appendix B. Other RAOs are qualitative and are evaluated during the analysis of remedial alternatives. As described by the fourth RAO listed above, the draft FS/RAP will consider the practicality of achieving permanent remedy at the Site. The benefits of permanent remedy are an increased reliability in protecting human health and the environment, elimination of the requirements for land use controls and oversight by U.S. EPA, and reduction in oversight by DTSC. These benefits are discussed further in evaluation of the risk-based cleanup alternative (i.e., Alternative 4, Section 7.0). 3.3 Groundwater Use Potential California State Water Resources Control Board ( SWRCB ) Resolution indicates that all surface and ground waters of the State are considered to be suitable, or potentially suitable, for municipal or domestic water supply. However, Resolution provides an exception for groundwater use as a drinking water source where sustained well yields are less than 200 gallons per day ( gpd ) per well. Page 16 of 72

34 During the November 2004 sampling event, groundwater monitoring wells located outside of the slurry wall, presumed to be representative of naturally-occurring Site groundwater conditions, were purged at a rate of 0.11 to 0.16 gallons per minute (i.e., 160 to 230 gpd), which resulted in drawdown of 0.4 to 5.1 feet (EKI, 2005b). 16 The drawdown caused by purging at approximately 200 gpd over short well purging time periods suggests that the sustained groundwater extraction at rates at or greater than the 200 gpd SWRCB exception criterion may be infeasible. The low well yield suggests that Site groundwater would meet the exception criteria under Resolution and is not likely to actually be used as a drinking water resource. Further, the California Regional Water Quality Control Board, San Francisco Bay Region s East Bay Plain Groundwater Basin Beneficial Use Evaluation Report (RWQCB, 1999; "East Bay Plan") states that Site groundwater is "unlikely to be used as a drinking water resource." The Site is located within "Zone B" and the "Emeryville Brownfield Groundwater Management Zone," where groundwater is not currently used for any municipal, domestic, industrial, agricultural purposes; 17 and no extraction beneficial uses are planned in the future. As stated in the East Bay Plan, Remedial strategies [in Zone B] should reflect the low probability that groundwater in this zone will be used as a source of drinking water in the foreseeable future. However, other beneficial uses/exposure pathways 18 exist and should be protected. Zone B areas should utilize risk based correction action in establishing groundwater cleanup standards. Passive remediation to restore municipal beneficial uses as a long-term goal is recommended. As stated in the East Bay Plan, the beneficial use of groundwater for domestic and municipal supply has not been de-designated at the Site. Therefore, based on the groundwater use potential and beneficial use designation of Site groundwater, Site cleanup remedial goals for groundwater include active treatment to attain acceptable human health risk levels, and passive long-term remediation to attain MCLs. 16 Less drawdown was observed during the March 2009 groundwater sampling event (i.e., between 0.1 and 2.5 feet), however, the pumping rate for this event was generally lower than in November 2004 (i.e., between 85 and 160 gpd). 17 As stated in the HHRA, "all water used at the Site will be municipal water supplied by East Bay Municipal District ("EBMUD"). 18 Of all of the beneficial uses or exposure pathways identified in the East Bay Plan, only the human health exposure pathway by vapor intrusion potential is considered to be complete. The other beneficial uses or exposure pathways that are not complete at the Site are described in this note. As concluded in EKI s DTSC-approved HHRA, the domestic irrigation exposure pathway (including incidental ingestion from back yard wells) was found to be potentially incomplete. Due to the low well yield, industrial process supply is not considered to be a likely exposure pathway. The exposure pathway to ecological receptors is considered to be incomplete due to distance between the Site and San Francisco Bay, where Site groundwater is presumed to discharge to surface water. Page 17 of 72

35 3.4 Risk-Based Site Cleanup Remedial Goals for Soil and Groundwater Alternative 4 Remedial goals for soil and groundwater are established as benchmarks for developing the Site cleanup alternative (i.e., Alternative 4; see Section 5.4). Remedial goals do not apply to other alternatives because the other alternatives are based on soil removal for a planned future Site use, rather than soil removal to specific concentration goals. Therefore, the limits of soil excavation under Alternatives 1 through 3 are pre-determined and potential future human health risks will be managed through engineering and institutional controls (as is currently done for the Site). Conversely, for the Site cleanup alternative (Alternative 4), the limits of soil excavation and, if necessary, the extent of groundwater remediation will be primarily determined by the objective of achieving chemical concentrations in soil and groundwater that, without institutional controls, engineering controls, ongoing maintenance or oversight, result in potential future human health risks below target levels Site Cleanup Remedial Goals for Soil As discussed in further detail in Section 5.4, Alternative 4 includes excavation of soil to at least 15 feet bgs or 3 feet msl across the entire Site (with deeper excavations in some areas) and construction of a building with one below-grade floor. Since all soil at the Site above the water table will be excavated, there is no pathway for volatile chemicals in unsaturated soil to migrate into indoor air, and VOCs in saturated soil below the water table elevation would be reflected in the measured VOC concentrations in groundwater (see Section for volatile COPC remedial goals for groundwater). Therefore, remedial goals for soil are developed for the non-volatile COPCs in soil, namely, PCBs, bis(2-ethylhexyl)phthalate, fluoranthene, arsenic, and lead. These remedial goals are based on estimating risks for potential future direct exposures to the soil. Given the presence of a building above the soil left in place, it is difficult to predict the potentially complete exposure pathways and parameters applicable to a future exposure of on-site populations to COPCs in soil. It is unlikely that future on-site populations would regularly perform maintenance of utilities beneath the building because the proposed building for this alternative would be constructed below the water table (i.e., the base of the building submerged). However, there is potential for future on-site construction worker populations to directly contact soil below the building if the building were to be demolished and a new, deeper structure was constructed at the Site. Given the very limited and unpredictable nature of potential future exposures to on-site soil, Site-specific risk-based remedial goals for COPCs in soil are not developed in this FS/RAP. For the purposes of this analysis, the Site cleanup remedial goals for soil for non-volatile COPCs are established as the greater of (1) commercial/industrial screening criteria published by DTSC and U.S. EPA (Cal/EPA, 2005a and U.S. EPA, 2008) and (2) background levels for metals published by the Lawrence Berkeley National Laboratory (LBNL, 2002). Table B-35 of Appendix B presents the summary of Site cleanup remedial goals for soil. The screening criteria developed by DTSC and U.S. EPA are based on commercial/industrial exposure parameters that likely over-estimate Page 18 of 72

36 future exposure levels at the Site, and thus are considered conservative (health protective) screening levels for the Site. To assess whether soil remedial goals are met under the Site cleanup alternative, representative concentrations would be compared to remedial goals based on screening criteria (i.e., for PCBs, bis(2-ethylhexy1)phthalate and fluoranthene). However, for COPCs with remedial goals based on published background levels, each detection in soil would be compared to the goal because background levels are based on statisticallyderived upper bound values for naturally occurring background conditions Site Cleanup Remedial Goals for Groundwater As discussed in Appendix B, remedial goals for groundwater for Alternative 4 were calculated two ways, (1) using the same methodology used to estimate risks due to vapor intrusion for Alternatives 3 and 4 (i.e., assuming VOCs fluxing from a groundwater "halo'' around the building perimeter, from 0 to 5 feet from the building wall, are captured by soil vapor leaking into the building) and (2) assuming groundwater leaks into the sub-grade floor and the leak is not repaired, allowing VOCs in groundwater to volatilize directly into indoor air. Considering that the risk estimates for the On-Site Commercial/Industria1 Worker in the sub-grade floor were greater than the estimates for the On-Site Resident utilizing a sub-grade parking structure (Section 6.1.2), the Site cleanup remedial goals for groundwater were only calculated for the On-Site Commercial/Industrial Worker. The methodology used to estimate Site cleanup groundwater remedial goals is described in greater detail in Appendix B. Table B-36 of Appendix B presents the summary of Site cleanup remedial goals for groundwater under Alternative 4. However, as discussed in Section 5.4, because the RCs for volatile chemicals in groundwater are below the Site cleanup remedial goals, no additional remediation to achieve these goals under Alternative 4 is anticipated. Note that this analysis assumes that the engineering controls (i.e., vapor barrier/ waterproofing system) fail and that no management protocols are in place for repairing leaks in the sub-grade floor. Therefore, this analysis considers the most conservative (i.e., health-protective) scenario, and is therefore applicable to all alternatives. Based on this analysis, it can be concluded that risk levels associated with human health concerns from the vapor intrusion pathway are within acceptable risk levels (i.e., below 1 for noncarcinogenic hazard index and 10-6 for carcinogenic risks). Page 19 of 72

37 4.0 SCREENING OF REMEDIAL TECHNOLOGIES The purpose of this FS/RAP is to develop and evaluate remedial alternatives that are consistent with the NCP requirements and state requirements, and that comply with the Site RAOs developed above. In accordance with NCP guidance (U.S. EPA, 1993), this section: (1) develops general response actions ( GRAs ) for impacted media that may be taken to satisfy the RAOs for the Site, (2) identifying potential technologies and process options for impacted media, and (3) screening the identified potential technologies and process options against the NCP-mandated criteria of effectiveness, implementability, and cost. 4.1 General Response Actions GRAs are broad categories of remedial alternatives, some of which may clearly not be pertinent to the site-specific conditions and goals. The NCP provides that a combination of methods may be used to achieve protection of human health and the environment. The soil and groundwater GRAs developed for the Site are: No Further Action: The NCP requires that a no action alternative be developed within an FS/RAP as a baseline for comparing alternatives. However, as remedial actions have been implemented (i.e., soil consolidation activities in 1985) and remain in place (i.e., slurry wall and engineering cap), this no action alternative has been renamed to no further action to account for past and ongoing remedial actions at the Site. Institutional Controls: Institutional controls, such as land use controls, water use restrictions, or deed restrictions, can be used to supplement engineering controls to limit exposure to hazardous substances. With the exception of "No Action" approach, all alternatives developed and evaluated in this FS/RAP will be assumed to incorporate some measure of institutional controls after remediation to be protective of human health and the environment. Containment Options: Soil containment options may include specific technologies or options to physically restrict exposure to COPCs in soil or to physically minimize leaching of chemicals to the environment. Groundwater containment options may include specific technologies or options to restrict human exposure to impacted groundwater, to limit migration of impacted on-site groundwater by constructing physical barriers or by controlling the local hydraulic gradient in impacted areas. Remediation or Treatment/Disposal Options: Soil and groundwater remedial options may include a range of media specific technologies or options to reduce human exposure to impacted soil and groundwater by removing and destroying or disposing of contaminants. These remediation or treatment options may be performed in situ or ex situ. Page 20 of 72

38 Each GRA has a number of associated technologies and process options to be considered for incorporation into remedial alternatives that are identified and discussed in the following subsections. 4.2 Identification of Potential Remedial Technologies and Process Options The following sections discuss potential remedial technologies and process options for soil and groundwater Potential Remedial Technologies and Process Options for Soil Identified potential technologies and process options for soil, grouped by GRAs, are listed below and are described in Table 3 (Screening of Technologies and Process Options for Unsaturated and Saturated Zone Soil). No Further Action Institutional Controls Soil Vapor Monitoring Soil Containment o New or Replacement Engineered Cap o New or Replacement On-site Land Containment Unit Soil Remediation and Treatment Options o Bioventing o Soil Vapor Extraction o Multiple Phase Extraction o Electrokinetic Treatment o Excavation o Chemical Stabilization o Enhanced Bioremediation o Chemical Oxidation o Chemical Dechlorination o Soil Washing o Thermal Desorption Off-Site Soil Treatment and/or Disposal Options o Off-site Landfill Disposal o Incineration o In Situ Vitrification Potential Remedial Technologies and Process Options for Groundwater Identified potential technologies and process options for groundwater, grouped by GRAs, are listed below and are briefly described in Table 4 (Screening of Technologies and Process Options for Groundwater). No Further Action Institutional Controls Groundwater Monitoring Soil Vapor Monitoring Groundwater Containment Options Page 21 of 72

39 o Slurry Wall o Sheet Piling o Soil Cement Columns o Permeable Reactive Barrier ( PRB ) o Engineered Cap o Groundwater Extraction Wells and Ex Situ Groundwater Treatment o Groundwater Extraction Trenches and Ex Situ Groundwater Treatment o Excavation Dewatering On-site Groundwater Treatment Options o Enhanced Reductive Dechlorination o Enhanced Aerobic Degradation o Chemical Oxidation o Natural Attenuation o Dual-Phase Extraction o Air Stripping o Filtration Off-site Groundwater Treatment and/or Disposal Options o Publicly Owned Treatment Works ( POTW ) o Off-site Disposal o Temescal Creek under National Pollutant Discharge Elimination System ( NPDES ) Permit. 4.3 Screening of Potential Remedial Technologies and Process Options In the following sections, potential remedial technologies and process options for soil and groundwater are screened against the NCP-mandated criteria of effectiveness, implementability, and cost Screening Criteria Potential remedial technologies and process options were screened using the three criteria, summarized below, as described in the NCP and relevant guidance documents. 1. Effectiveness: The technical effectiveness criterion was used to determine which remedial technologies would be effective at the Site in protecting human health and the environment, attaining ARARs and the RAOs established in Section 3.0, and reducing chemical mass and mobility based upon the site conditions and other engineering considerations. 2. Implementability: The implementability criterion was used to evaluate the technical and administrative feasibility of implementing remedial technologies at the Site. Implementability also considers the potential disruption of off-site property uses. 3. Cost: The cost criterion was used to evaluate the probable life-cycle financial costs of implementing a particular remedial technology at the Site and to generally identify alternatives that are significantly more costly than other approaches achieving the same degree of chemical management or mass reduction Page 22 of 72

40 or that have costs which would be grossly excessive compared with their overall effectiveness Potential Remedial Technologies and Process Options Soil Screening Table 3 evaluates potential remedial technologies and process options for soil using the three screening criteria outlined in Section Based on this evaluation, the following remedial technologies and process options were retained for assemblage into potential remedial alternatives. No Further Action Institutional Controls Soil Vapor Monitoring Soil Containment Options o New or Replacement Engineered Cap Soil Remediation and Treatment Options o Excavation of soil from the unsaturated and saturated zone Off-Site Soil Treatment and/or Disposal Options o Off-Site Landfill Disposal o Incineration Remedial Technologies and Process Options Groundwater Screening Table 4 evaluates potential remedial technologies and process options for groundwater using the three screening criteria outlined in Section Based on this evaluation, the following remedial technologies and process options were retained for assemblage into potential remedial alternatives. No Further Action Institutional Controls Groundwater Monitoring Soil Vapor Monitoring Groundwater Containment Options o Slurry Wall o Sheet Piling (only for short-term use during soil excavation) o Soil Cement Columns (only for short-term use during soil excavation) o Engineered Cap o Excavation Dewatering On-Site Groundwater Treatment Options o Natural Attenuation o Filtration (only for short-term use during soil excavation) Off-site Groundwater Treatment and/or Disposal Options o POTW o Off-Site Disposal. Page 23 of 72

41 5.0 DESCRIPTION OF REMEDIAL ALTERNATIVES 5.1 Alternative 1: No Further Action Alternative 1 includes: Ongoing maintenance of existing cap and slurry wall system (see Section 1.1); and Ongoing DTSC and U.S. EPA oversight. The components of Alternative 1 are described below. Ongoing maintenance of existing cap and slurry wall system and agency oversight: As required by the Consent Agreement, annual groundwater monitoring and inspections of the Site are assumed to continue under this alternative. Due to the sporadic and low PCB detections in groundwater, CBS may request U.S. EPA to amend the Consent Agreement to allow for a cessation of groundwater monitoring activities. For cost estimating purposes, it is assumed that groundwater monitoring would only continue for the next five years. However, annual inspections of the Site cap and reporting of Site conditions to DTSC and U.S. EPA on an annual basis is assumed to continue into the foreseeable future. 5.2 Alternative 2: Soil Excavation for Foundation and Construction of Above-Grade Building Alternative 2 includes: Pre-excavation soil sampling for PCB congeners; Targeted additional groundwater characterization and in situ treatment; Excavation across the entire Site to approximately 5.5 feet bgs (12.5 feet msl) for utilities and foundation system for above-grade structure; 19 Preparation of the excavation for building construction; Construction of a sub-slab venting system ( SSVS ); Continued function of slurry wall; Institutional controls; Monitored natural attenuation of COPCs in groundwater to MCLs; and 19 As discussed in Section 1.2, EKI understands from recent discussions with the City that the planned use of the building s ground floor includes 2,347 gross square feet of ground floor space for transit, retail and/or office uses, such as ticket-buying, travel and transit information, bike security, and car share information.. For the purposes of this FS/RAP, areas used for retail or offices are considered commercial/industrial space. Page 24 of 72

42 Ongoing monitoring of the future building as a Site cap and DTSC and U.S. EPA oversight. As discussed in further detail below and in Section 6.1.2, the risk estimate for the On-Site Commercial/Industrial Worker population in the first floor of an above-grade building is greater than As a result, Alternative 2 includes construction of an SSVS to mitigate risk. However, risk estimates for on-site residential populations utilizing a first floor parking garage in an above-grade building are below target levels. Therefore, the portion of the first floor of the future above-grade building used for parking does not require additional controls to meet the target risk levels. The components of Alternative 2 are described below. Pre-Excavation Soil Sampling for PCB Congeners: As discussed in the data tables included in Appendices A and B, and in accordance with the current standard of practice, PCB analysis at the Site was performed on an Aroclor-basis. Aroclors are made up of mixtures of PCB congeners. PCB analysis can also be performed on a congener-basis. Some PCB congeners are coplanar or mono-ortho-substituted congeners, also referred to as dioxin-like chemicals due to their similarity in structure (CDC, 2005). Although no guidance requiring analysis for or assessment of risks associated with PCB congeners has been published by U.S. EPA or Cal/EPA, representatives from U.S. EPA requested during a conference call on 5 March 2009 that additional soil samples be collected at the Site for congener-specific PCB analysis to determine whether dioxin-like congeners are present. If these compounds are present, these data will be considered as part of the development of risk-based action levels for COPCs in air during construction activities. It may be, considering the non-standard laboratory method employed to evaluate the presence of dioxin-like congeners, that the action-levels will be part of the overall dust standard for the project and not a specific numerical goal that will necessitate specialized laboratory testing. Consistent with the sampling work plan reviewed and approved by the DTSC and U.S. EPA (WSP, 2009), it was assumed for cost estimating purposes that 5, 4-point composite soil samples will be collected at the Site to assess the presence of dioxin-like PCB congeners. For the purposes of this FS/RAP evaluation, it is assumed that all soil excavated from the Site, with the exception of the cap material, contains concentrations of PCBs above 50 mg/kg. Making this assumption classifies the soil as TSCA hazardous waste, which can only be disposed of at a Class I hazardous waste disposal facility. Based on discussions with representatives from U.S. EPA, no additional disposal characterization sampling would be required if all material is assumed to contain PCBs above 50 mg/kg. For cost estimating purposes, a distinction is made for soil containing greater than 1,000 mg/kg PCBs because of higher fees associated with disposal of such contaminated soil. Targeted Additional Groundwater Characterization and In situ Treatment: The DTSC has requested that a one-time injection of material for in situ treatment be Page 25 of 72

43 considered to reduce VOC concentrations in groundwater and jump start the natural attenuation processes. VOCs in groundwater at the Site are generally detected at higher concentrations in the northeastern portion of the area contained within the slurry wall (an area of approximately 10,800 square feet). For the purposes of this FS/RAP, it is assumed that an investigation using membrane interface probes ( MIP ) and hydraulic profiling tools ( HPT ) would be performed in this area to further refine the area targeted for in situ treatment. However, a separate in situ treatment work plan would be submitted to DTSC for review and approval. This work plan may propose a different type or scope of groundwater investigation and treatment activities. MIP is a screening tool which acts as an interface between chemicals in the subsurface and gas phase detectors at the surface. HPT allows for real-time profiling of soil hydraulic properties in the subsurface. These tools can be used to further define the depth and lateral extent of VOCs in the subsurface at the Site, and therefore refine the potential groundwater treatment scope. Grab groundwater samples may also be collected as part of the MIP/HPT investigation. For cost estimating purposes, it is assumed that MIP and HPT probes would be advanced to an elevation of approximately -12 feet msl at 24 locations for MIP and 12 locations for HPT. Additionally, for cost estimating, it is assumed that these groundwater investigation activities would reduce the area targeted for in situ treatment by approximately 30 percent (i.e., from 10,800 square feet to 7,600 square feet) by better defining the extent of VOCs in groundwater. For the purposes of this FS/RAP evaluation, following groundwater investigation activities, it is assumed that oxygen release compound ( ORC ) would be injected into the subsurface. ORC would provide oxygen to native bacteria capable of aerobically degrading certain VOCs including, benzene, carbon tetrachloride, chlorobenzene, dichlorobenzene, cis-1,2-dichloroethene, and vinyl chloride. For cost estimating purposes, it is assumed that ORC would be injected at approximately 134 locations in a 7,600 square foot treatment area over a 24-foot vertical interval in the groundwater, across an elevation range of approximately 12 to -12 feet msl. However, as mentioned above, a separate in situ treatment work plan would be submitted to DTSC for review and approval. This work plan may propose a different type or scope of groundwater investigation and treatment activities. Soil Excavation Activities: Soil excavation activities performed under Alternative 2 would include excavation of unsaturated zone soil across the entire Site. The intent would be to remove soil for installation of utilities and a shallow foundation system for construction of an above-grade building across the entire Site. The depth of the excavation would be to the approximate level of the groundwater potentiometric surface measured within the slurry wall during the most recent groundwater monitoring event (i.e., 12.5 feet msl measured in May 2008, which corresponds to a depth of 5.5 feet bgs assuming the average ground surface elevation at the Site is 18 feet msl; WSP, 2008). The planned excavation layout for Alternative 2 is Page 26 of 72

44 shown on Figure 4. However, the total depth of the excavation may be extended in the RDIP (e.g., approximately 3 to 6 feet deeper) to meet the specifications for the final development at the Site. There may also be additional soil excavated in defined areas to allow for the placement of elevator shafts, piles, pile caps, and grade beams in accordance with the final design of the development. If additional soil is excavated, the human health risks estimated for Alternative 3 would remain a representative estimate of during-construction risks for this alternative because (1) the maximum detected chemical concentrations in soil and the risks associated with excavating this material are accounted for in the Alternative 3 risk estimates and (2) additional PCB-impacted soil would be removed, thereby removing additional chemical mass and reducing potential exposures for future on-site populations. Informational soil sampling would be performed at the base of the excavation to document soil conditions remaining below the future building. However, because the excavation plan applies to a specific redevelopment scenario (i.e., as opposed to a riskbased removal action), the results of soil sampling would not prompt additional soil excavation activities. Preparation of the Excavation for Building Construction: A synthetic liner, plastic sheeting or other barrier would be installed inside the excavation walls and floor (protected with a minimum 6-inch gravel cover, or similar suitable material) prior to building construction to reduce the risk of construction workers contacting impacted soil or groundwater. The liner and gravel cover would also serve as a working surface for foundation construction. The remediation contractor and the development contractor would reach an agreement as to the specific type of barrier that would be installed inside the excavation floor and walls prior to building construction. The SSVS piping and additional gravel bedding, would be installed after the foundations and major utilities are installed to prevent damage to the piping and conflict between the two installations. The liner and clean fill at the base of the excavation and the barrier on the sidewalls of the excavation would provide a significant barrier between chemicals in underlying soil and construction workers building the foundation. However, because estimated risks for construction workers during excavation activities (i.e., populations with direct soil contact) are above acceptable levels (see Alternative 3 results in Table 5), any contractor working in the excavation prior to the placement of the working surface and perimeter barriers on the excavation sidewalls, or performing any other type of construction work that might expose workers to chemical contaminants, would be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE. If elevator shafts, piles, and pile caps/grade beam systems are constructed in soil below the working surface at the base of the excavation, the workers would be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE. As discussed above, a barrier (e.g., flexible synthetic liner) would be placed immediately on the PCB-contaminated soil, to reduce the risk of contact with impacted soil and groundwater during foundation construction. This barrier would also reduce vapor intrusion potential into the fill placed on top of the liner. However, the installation of Page 27 of 72

45 piles that puncture the barrier and subsequent construction activities may reduce the liner s effectiveness. In addition to this synthetic liner, an SSVS would be constructed, as discussed in further detail below. Construction of SSVS: Soil excavation under this alternative, as described above, may reduce VOC mass beneath the future building and subsequently reduce VOC concentrations in soil vapor beneath the future building. However, there remains the potential for VOC concentrations to exceed target levels for vapor intrusion concerns. Thus, following excavation activities and as part of the redevelopment construction, an SSVS would be constructed on-site beneath the portions of the future building that (1) would be used as commercial/industrial space and (2) would be the locations for elevator shafts, stairwells, utility corridors, and other enclosed areas serving as potential preferential pathways for soil vapor migration. The intent of the SSVS would be to provide a pathway to allow soil vapor to migrate or vent to the exterior of the future on- Site building, rather than entering the building. The SSVS would generally consist of the following elements: A horizontal layer of permeable venting material (e.g., sand or gravel) beneath the appropriate portion of the building footprint - the permeable venting material layer would be installed below structural grade beams and shallow sub-floor utilities that may otherwise interfere with uniform lateral venting, and thus may be approximately 2 to 4 feet below the building floor; 20 Lengths of perforated pipe installed within the layer of permeable venting material connected to a vertical riser pipe through the building with an outlet on the building roof; A sub-slab liner (e.g., Geo-Seal) installed either (a) directly on top of the layer of permeable material, or (b) immediately below the commercial/industrial use portion of the building floor; and Soil vapor sampling probes, installed within the layer of permeable material, to monitor VOC concentrations in soil vapor beneath this portion of the building. Following building construction, the vertical vent pipe would be connected to the pipe beneath the building and extended to the roof to passively vent sub-slab soil vapor. A wind-driven turbine ventilator would be provided on the vent pipe outlet to assist passive ventilation. Soil vapor samples would then be collected from the soil vapor sampling probes to assess post-construction conditions. The objective of sub-slab soil vapor monitoring would be to measure VOC concentrations in soil vapor beneath the building that are less than 100 times the indoor 20 Since this permeable layer may be installed at a depth that could intercept groundwater, the SSVS design details submitted under separate cover will discuss the potential effects of groundwater infiltration into this layer and related design specifications. For example, the design details may specify that the perforated piping (discussed in the next bullet) be installed above the highest measured groundwater (i.e., approximately 15.5 feet msl; WSP, 2008). Page 28 of 72

46 air target risk levels. The factor of 100 is based on the DTSC recommended default attenuation factor for VOC migration from sub-slab soil vapor to indoor air (Cal/EPA, 2005b). If VOC concentrations in soil vapor exceed 100 times the indoor air target risk levels, DTSC may require that the SSVS be upgraded to an active SSDS. The process and trigger levels for upgrading from SSVS to SSDS are discussed below. The design details for the SSVS would be submitted to DTSC in a separate work plan for review and approval prior to SSVS construction. In accordance with DTSC s Vapor Intrusion Mitigation Advisory ( VIMA, Cal/EPA, 2009), the SSVS would be designed so that it could be upgraded to an active SSDS, if required by DTSC and determined necessary based on sub-slab soil vapor data. The upgrade would involve connecting the SSVS to a blower on the roof of the future on-site building to allow for active depressurization beneath the building. The blower would be designed and operated to allow the SSDS to create a lower pressure directly underneath the building floor relative to the pressure within the building to inhibit soil vapor from migrating into the building. The lower pressure would be confirmed by measuring the pressure in the soil vapor sampling probes installed beneath the building. The sub-slab VOC concentrations for triggering an upgrade from SSVS to SSDS would be included in the SSVS design work plan submitted to DTSC for review and approval. The time required to modify the SSVS to an SSDS is anticipated to be relatively minor (i.e., two to three months) as the key activities would be (1) submitting the design details for upgrading to an SSDS to DTSC for review and approval and (2) obtaining a Bay Area Air Quality Management District ( BAAQMD ) permit (if necessary) and installing a blower on the roof. As discussed at the end of this section, a BAAQMD permit may not be required if estimated and/or measured emissions from the SSDS are determined to be below BAAQMD s permitting thresholds. The SSDS would effectively mitigate vapor intrusion by reducing pressure below the building and/or further reducing VOC concentrations in sub-slab soil vapor, due to higher sub-slab ventilation rates provided by the blower (i.e., enhanced SSVS ). Thus, effectiveness of the SSDS can be demonstrated by either (a) measuring reduced pressure in the soil vapor sampling probes, or (b) demonstrating that VOC concentrations in soil vapor samples are reduced to less than 100 times the risk-based target levels for indoor air. Achieving either goal would indicate effective vapor intrusion mitigation, and it is likely that both goals would be achieved by an active SSDS. The capital and operation and maintenance costs associated with an SSDS (e.g., installation of a blower and ongoing electricity costs) are included in the cost estimate for Alternative 2 presented in Appendix C (i.e., it is conservatively assumed for cost estimating purposes that the system would be upgraded to SSDS). The need to upgrade the SSVS to an SSDS would be determined following collection of soil vapor data from the layer of permeable material post-construction and discussions with DTSC. The dimensions and materials assumed for constructing an SSVS are presented in the cost estimates included in Appendix C. As mentioned above, CBS would provide the SSVS design details and the sub-slab VOC concentrations for triggering an upgrade from Page 29 of 72

47 SSVS to SSDS in a separate work plan submitted to DTSC for review and approval prior to construction of the SSVS. Continued Function of Slurry Wall: Under the proposed remedy, the portion of the existing slurry wall below the excavation would continue to function as a barrier to lateral migration of groundwater contained within the slurry wall. Since the base of the excavation would generally be above the potentiometric surface, with the exception of potential locations of deeper excavations into the saturated zone for elevator shafts, piles, pile caps, and grade beams, excavation activities are not anticipated to affect the slurry wall s ability to limit off-site migration of groundwater. If additional soil is excavated below the water table, the slurry wall would be avoided so that it continues to function as a barrier to groundwater flow. Any changes to the slurry wall as a result of the construction activities would be documented in a post-remediation/pre-construction report. The report would include an analysis to demonstrate to the satisfaction of the DTSC and U.S. EPA that any changes to the slurry wall will not create conditions that will allow migration of groundwater containing chemicals of concern in the foreseeable future. Institutional Controls: DTSC and CBS will execute a land use covenant ( LUC ) entitled Covenant to Restrict Use of Property, Environmental Restriction within 120 days after DTSC approved the FS/RAP. CBS will record the executed LUC with the Alameda County Assessor s Office. The LUC will restrict Site use and minimize the remaining potential for impacting human health and the environment after soil remediation. Provisions of the LUC will include, but not be limited to, the following: Restrictions on sensitive land use (e.g., residential housing, schools, day-care facilities, hospitals, hospices, etc.) on the ground level; Restrictions on commercial/industrial use at the ground level of the building interior where an SSVS has not been installed; Restrictions on intruding and removing soil below 5.5 feet bgs or 12.5 feet msl except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Restrictions on all groundwater extraction and construction dewatering except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Requirements of soil and groundwater management pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Inspection and maintenance of subsurface portions of the building in accordance with a DTSC- and U.S. EPA-approved O&M Plan; Requirement of annual reporting and certification; Page 30 of 72

48 Requirements for providing advance notification to DTSC and U.S. EPA of any planned construction or maintenance activities that may expose personnel to soil or groundwater; and Provisions for DTSC and U.S. EPA access to the Site. DTSC and CBS will enter into an O&M Agreement within 60 days following the submittal date of the draft remedy implementation report. The O&M Plan would be prepared after soil removal is completed and would provide a framework to manage residual COPCs in soil and groundwater in a manner that is consistent with planned future land uses and is protective of human health for expected future populations. Main features of the O&M Plan would include, but not be limited to, the following: A summary of conditions, based on informational soil sampling performed after excavation; Requirements for a Site-specific environmental health and safety plan to be protective of future maintenance/construction workers performing subsurface activities at the Site (if necessary) and may also specify certain types of work to be performed by 40-hour OSHA HAZWOPER trained personnel; Requirements for management of water collected during draining of any sub-grade structures; Requirements for monitoring for methane in non-ventilated subsurface facilities until the determination can be made that methane gas in non-ventilated facilities is not a concern; and Long-term SSVS (or SSDS) operations and monitoring program. Monitored Natural Attenuation of COPCs in Groundwater: The risk estimates for Alternative 2, under unmitigated conditions, are presented in Table 5. Because the risk estimates for the On-Site Commercial/Industrial Worker population are above 10-6, an SSVS would be installed, as discussed above.. As discussed in the HHRA and Section 3.3, the groundwater beneficial use of domestic and municipal supply has not been de-designated at the Site. However, the East Bay Plan recommends passive remediation to restore municipal beneficial uses as a long-term goal for groundwater at the Site. Over time, COPC concentrations in groundwater are expected to reach drinking water standards by natural attenuation. Additionally, the onetime injection of material for in situ treatment is anticipated to jump start the natural attenuation processes. Empirical data in the form of observed COC concentrations at collocated groundwater sampling locations collected over time suggest natural attenuation of COCs in groundwater is occurring at the Site. Examples of observed COC attenuation at the Site Page 31 of 72

49 are discussed below for the two risk-driving chemicals under Alternative 2: carbon tetrachloride and vinyl chloride. Carbon Tetrachloride: Historically, carbon tetrachloride was detected in groundwater at two locations on or near the Site. Between 1991 and 1994, carbon tetrachloride was detected in the four groundwater samples collected from monitoring well D-1 (northwestern portion of the Site, outside the slurry wall) and the five groundwater samples collected from monitoring well D-5 (northeast of the Site, within Horton Street; Figure 3). The average concentration of carbon tetrachloride detected in D-1 and D-5 between 1991 and 1994 was 4.0 and 12.4 ug/l, respectively (EKI, 2005a). During the groundwater sampling performed in March 2009, carbon tetrachloride was not detected (<0.50 ug/l) in monitoring well D-1 and detected at 0.79 ug/l in monitoring well D-5. Biodegradation through reductive dehalogenation of carbon tetrachloride is possible under anaerobic, reducing conditions. However, measurements of oxidationreduction potential ( ORP ) during groundwater sampling indicates neutral to aerobic, oxidizing conditions in these wells. 21 Therefore, it is likely that the historical, relatively low concentrations of carbon tetrachloride at these locations are being naturally attenuated through the mechanisms of dilution and/or dispersion. Vinyl Chloride: At monitoring well S-7, which is located outside the slurry wall in the northern portion of the Site, significant reductions in chlorinated VOCs (including vinyl chloride) have been observed. The average concentration of vinyl chloride detected in the five samples collected from this well between 1991 and 1994 was 15.6 ug/l (EKI, 2005a). Vinyl chloride was not detected (<0.5 ug/l) in the November 2004 or March 2009 groundwater samples collected from this monitoring well. Similar concentration trends were observed in monitoring well S-7 for cis-1,2-dce and trans-1,2-dce. A similar reduction in chlorinated VOC concentrations was not observed in off-site monitoring well S-5 (northeast of the Site, within Horton Street). However, chlorinated VOCs measured in nearby on-site locations W-3 (historical groundwater well) and EKI-4 (location of 2002 grab groundwater sample) did show such a reduction. In 1983, the concentration of vinyl chloride measured in monitoring well W-3 was 44 ug/l. In 2002, vinyl chloride was not detected (<2.5 ug/l) in the grab groundwater sample collected from boring EKI-4 (EKI, 2005a). These data, in conjunction with the data from S-7 also located in the northern portion of the Site, suggest the chemical concentrations detected in groundwater near monitoring well S-5 are not impacting groundwater on-site. Long-term monitoring for COCs except for PCBs has not occurred for groundwater located within the slurry wall. However, chlorinated VOC concentrations detected in 1983 in historical groundwater wells W-20 and W-22 are significantly higher 21 During groundwater sampling in March 2009, ORP was measured at -35 millivolts ( mv ) in monitoring well D-1 and 89 mv in monitoring well D-5. Page 32 of 72

50 than those measured in grab groundwater samples collected in 2004 at EKI-9 and EKI-12 in the vicinity of these historical wells. Locations W-20, W-22, EKI-9, and EKI-12 are all located in the northern portion of the Site within the slurry wall where the highest concentrations of chlorinated VOCs have generally been detected. In 1983, the concentration of vinyl chloride measured in monitoring wells W-20 and W-22 was 120 and 540 ug/l, respectively. In 2004, vinyl chloride was detected at 2.63 ug/l at borehole EKI-9 and at 10.9 ug/l at borehole EKI-12. A similar concentration trend was observed at these locations for trans-1,2-dce. Biodegradation of vinyl chloride through reductive dehalogenation is possible under both aerobic, oxidizing conditions and anaerobic, reducing conditions. However, the reaction is more energetically favorable under oxidizing conditions. Measurements of ORP during groundwater sampling in March 2009 indicate slightly oxidizing conditions exist in monitoring well S-7 (i.e., ORP of 94 mv). Information regarding the oxidizing/reducing conditions in groundwater in the northern portion of the Site within the slurry wall is not available. However, it is likely that the vinyl chloride concentrations in groundwater outside the slurry wall are decreasing due to dilution, dispersion and/or biodegradation and that vinyl chloride concentrations in groundwater within the slurry wall are decreasing due to biodegradation. In addition to the Site observations regarding natural attenuation, potential chemical migration would continue to be limited by the slurry wall, which would remain in place at the Site following completion of soil excavation activities. However, even without the slurry wall, the low groundwater gradients and the long distance to any potential receptors (i.e., San Francisco Bay, see Section 3.3) indicate the potential for COPCs in groundwater to create a risk to human health and the environment is low. In summary, monitored natural attenuation for groundwater is proposed under Alternative 2 because: Groundwater concentrations are expected to attain drinking water standards over the long-term by natural attenuation; and Potential for groundwater migration is limited by the slurry wall and naturally occurring low groundwater gradient. At DTSC s request, groundwater monitoring is included as part of the ongoing natural attenuation under Alternative 2. The proposed future development includes construction of a building over the entire Site property. Therefore, on-site groundwater monitoring wells would have to be installed within the footprint of the future development. Further, any groundwater sampling performed within the future building may present health and safety concerns. Potential ongoing vapor intrusion concerns would be managed through monitoring and maintenance of the SSVS (discussed below). However, DTSC is requiring ongoing monitoring of groundwater within and downgradient of the slurry wall. Therefore, due to the health and safety concerns Page 33 of 72

51 associated with groundwater sampling in the future commercial/industrial portion of the building, this alternative includes installation of three groundwater monitoring wells within the slurry wall installed in the future ventilated parking garage. Given this limitation and the pending building design, the wells may or may not be located in the area of greatest VOC concentrations in groundwater. However, DTSC prefers groundwater monitoring wells be installed close to locations with elevated VOC concentrations. Additionally under this alternative, another three groundwater monitoring wells would be installed outside of the slurry wall on the downgradient edge of the Site. It is assumed that each set of wells (within the slurry wall and at the downgradient edge of the Site) would consist of two wells with screen depths corresponding to the existing Site shallow wells (i.e., 10 to 25 feet bgs) and one with a screen depth corresponding to the existing deep wells (i.e., 25 to 40 feet bgs). However, screen depths would be decided on during DTSC and U.S. EPA s review and approval of a separate groundwater monitoring plan. Although the shallowest groundwater is most relevant for vapor intrusion concerns, installing groundwater wells with screen depths corresponding to the existing Site wells would allow for comparability between historical and future groundwater data. Additionally, vapor intrusion potential would be monitored through sub-slab soil vapor data. The wells would not be screened below the slurry wall depth because the slurry wall is keyed into an impermeable unit and it would be inadvisable to penetrate that unit on or close to the Site. Under this alternative, a groundwater monitoring plan specifying well installation and sampling details would be submitted to DTSC and U.S. EPA for review and approval. The actual number, depths, screen lengths, and locations of groundwater monitoring wells would be decided on during DTSC and U.S. EPA s review and approval of this separate groundwater monitoring plan. Ongoing Monitoring of the Future Building as a Site Cap and DTSC and U.S. EPA Oversight: It is anticipated that both DTSC and U.S. EPA would continue to oversee Site activities, as necessary. Due to PCBs remaining in soil at the Site under Alternative 2 at concentrations above risk-based direct contact criteria (see Section 3.4.1), the Site building would be acting as a barrier to direct contact with impacted material. Therefore, annual inspections of the building condition are anticipated. Under this alternative, it is assumed that an annual report would be submitted to DTSC and U.S. EPA documenting the condition of the building and 5-year review reports would be submitted summarizing the status of this remedial alternative. Additionally, ongoing monitoring would be taking place as part of SSVS operation and maintenance. The effectiveness of SSVS is evaluated by measuring VOC concentrations in sub-slab soil vapor and SSDS is evaluated by monitoring blower operation and subslab pressure. In the cost estimates included in Appendix C, it is assumed that ongoing sub-slab pressure monitoring would take place and that sub-slab soil vapor sampling within the layer of permeable material would be performed semi-annually for the first two years. Page 34 of 72

52 However, if measured sub-slab vapor concentrations are consistently low, a request to reduce the frequency of monitoring will be submitted to DTSC. The BAAQMD currently regulates active SSDS under the soil vapor extraction ( SVE ) regulation (Regulation 8, Rule 47). The need for obtaining a BAAQMD permit to regulate stack emissions from an SSDS at the Site has yet to be determined. A permit may not be required if estimated and/or measured emissions from the SSDS are determined to be below BAAQMD s permitting thresholds. However, for cost estimating purposes, it is assumed that a BAAQMD permit will be required. Therefore, it is assumed that stack emissions would be sampled monthly for the first 6-months and quarterly thereafter as part of BAAQMD permit requirements. If the SSVS is not upgraded to an SSDS, monitoring of soil vapor within the layer of permeable material would continue and stack emission sampling would either not occur or be limited in scope. 5.3 Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal Alternative 3 includes: Pre-excavation soil sampling for PCB congeners; Excavation across the entire Site to approximately 15 feet bgs (3 feet msl) for below-grade parking and/or office space and additional targeted soil excavation in pre-defined areas to remove known hot spots ; Preparation of the excavation for building construction, including construction of waterproof and vapor proof below-grade floor; Continued function of slurry wall; Institutional controls; Monitored natural attenuation of COPCs in groundwater to MCLs; and Ongoing monitoring of the future building as a Site cap and DTSC and U.S. EPA oversight. The components of Alternative 3 are described below. Pre-Excavation Soil Sampling for PCB Congeners: Refer to the discussion under Alternative 2. Soil Excavation Activities: Soil excavation activities performed under Alternative 3 would include excavation of unsaturated and saturated zone soil. The intent would be to remove soil for construction of a building across the entire Site with one story belowgrade. For the purposes of this FS/RAP evaluation, it is assumed that the bottom of the Page 35 of 72

53 excavation would be approximately 15 feet bgs or 3 feet msl across the entire Site, with two areas excavated deeper to remove additional PCB-impacted soil (discussed below). However, the total depth of the excavation may be extended in the RDIP (e.g., approximately 3 to 6 feet deeper) to meet the specifications for the final development at the Site. There may also be additional soil excavated in defined areas to allow for the placement of piles, pile caps, and grade beams in accordance with the final design of the development. If additional soil is excavated, the human health risks estimated for Alternative 3 would remain applicable (and likely be conservative) because (1) the maximum detected chemical concentrations in soil and the risks associated with excavating this material are already accounted for in the shallower soil that would be removed under this alternative and (2) additional PCB-impacted soil would be removed, thereby removing additional chemical mass and reducing potential exposures for future on-site populations. As mentioned above, the bottom elevation of the excavation assumed for this alternative is 15 feet bgs or 3 feet msl across the entire Site. Additionally, two areas would be excavated deeper to remove additional PCB-impacted soil: (1) an additional one foot of soil would be excavated in an area on the eastern portion of the Site (i.e., to an elevation of 16 feet bgs or 2 feet msl) and (2) an additional 4 feet of soil would be excavated in the area surrounding sampling location EKI-4 (i.e., to an elevation of 19 feet bgs or -1 foot msl). The planned excavation layout for Alternative 3 is shown on Figure 5. Note that the slurry wall would be avoided during the additional excavation activities in the vicinity of sampling location EKI-4, and only soil outside of the slurry wall would be excavated. Since the excavation would extend below the groundwater potentiometric surface, dewatering is anticipated both inside and outside the slurry wall during excavation activities. Informational soil sampling would be performed at the base of the excavation. However, because the excavation plan applies to a specific redevelopment scenario (i.e., as opposed to a risk-based removal action), the results of soil sampling would not prompt additional soil excavation activities. Preparation of the Excavation for Building Construction: After excavation of soil to the target depth, and backfilling if appropriate based upon the final development plans, a working surface would be constructed by the remediation contractor at the base of the excavation to facilitate building construction activities. This working surface, minimum 6 inches thick, may consist of clean fill (e.g., gravel), a concrete mud slab (working mat), or other suitable working surface to be described in the RDIP. After transfer of the property to the development owner, the development contractor might then excavate soil for elevator shafts and/or drive piles and construct a pile cap/grade beam system below the working surface within the clean backfill. A vapor barrier/waterproofing system would be installed inside the walls and on the floor of the excavation as a prelude to, or as a part of, the foundation construction for the building, leaving the remediation shoring and working surface in place. The vapor barrier/waterproofing system is a normal part of building construction to keep water and Page 36 of 72

54 water vapor from migrating through the floor and walls of the future building. Following application of the vapor barrier/waterproofing system, construction of the below-grade portion of the building would commence. If elevator shafts, piles and pile caps/grade beam systems are constructed in soil below the clean fill, the workers would be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE. The working surface constructed at the base of the excavation would provide a significant barrier between chemicals in underlying soil and on-site workers applying the vapor barrier/waterproofing to the base and walls of the excavation. However, some chemically-impacted soil may adhere to and remain on the inside of the shoring on the excavation sidewalls. Because estimated risks for on-site worker populations during excavation activities (i.e., populations with direct soil contact) are above acceptable levels (Table 5), any contractor working in the excavation prior to the completion of the vapor barrier/waterproofing on the excavation floor and sidewalls would be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE. Following application of vapor barrier/waterproofing material to the base and sidewalls of the excavation, there would be no complete exposure pathway for on-site worker populations to the underlying soil or soil on the excavation sidewalls. Under this scenario it is assumed that no or minimal groundwater or chemical vapors are entering the excavation from the dewatered floor or sidewalls of the excavation, given that the floor and sidewalls would be covered with shoring and vapor barrier/waterproofing material. Potential risks to the on-site worker populations during excavation activities, which include the vapor barrier/waterproofing contractor, were assessed in the HHRA for a future redevelopment scenario equivalent to Alternative 3 and are summarized in Table 5. Post-construction risk estimates for Alternative 3 are also summarized in Table 5. Continued Function of Slurry Wall: As in the case of Alternative 2, the portion of the existing slurry wall below the excavation would continue to function as a barrier to lateral migration of groundwater contained within the slurry wall. Under Alternative 3 however, the base of the excavation would be below the potentiometric surface. Therefore, the excavation and future construction would need to allow for "sealing" between the bottom of the future building or its foundation and the top of slurry wall. The details of this connection would be provided in the RDIP. Institutional Controls: DTSC and CBS will execute a LUC entitled Covenant to Restrict Use of Property, Environmental Restriction within 120 days after DTSC approved the FS/RAP. CBS will record the executed LUC with the Alameda County Assessor s Office. The LUC will restrict Site use and minimize the remaining potential for impacting human health and the environment after soil remediation. Provisions of the LUC would include, but not be limited to, the following: Page 37 of 72

55 Restrictions on sensitive land use (e.g., residential housing, schools, day-care facilities, hospitals, hospices, etc.) on the below-ground levels; Restrictions on intruding and removing soil below 15 feet bgs or 3 feet msl except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Restrictions on all groundwater extraction and construction dewater except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Requirements of soil and groundwater management pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Inspection and maintenance of subsurface portions of the building in accordance with a DTSC- and U.S. EPA-approved O&M Plan; Requirement of annual reporting and certification; Requirements for providing advance notification to DTSC and U.S. EPA of any planned construction or maintenance activities that may expose personnel to soil or groundwater; and Provisions for DTSC and U.S. EPA access to the Site. DTSC and CBS will enter into an O&M Agreement within 60 days following the submittal date of the draft remedy implementation report. The O&M Plan would be prepared after soil removal is completed and would provide a framework to manage residual COPCs in soil and groundwater in a manner that is consistent with planned future land uses and is protective of human health for expected future populations. Main features of the O&M Plan would include, but not be limited to, the following: A summary of conditions, based on informational soil sampling performed after excavation; Requirements for a Site-specific environmental health and safety plan to be protective of future maintenance/construction workers performing subsurface activities at the Site (if necessary); the O&M Plan may also specify certain types of work to be performed by 40-hour OSHA HAZWOPER trained personnel; Requirements for management of water collected during draining of any sub-grade structures; and Requirements for monitoring for methane in non-ventilated subsurface facilities until a determination can be made that methane gas in non-ventilated facilities is not a concern. Page 38 of 72

56 Monitored Natural Attenuation of COPCs in Groundwater: Following completion of soil excavation activities, monitored natural attenuation for groundwater is proposed under Alternative 3 because: COPCs in groundwater do not contribute to unacceptable risk levels under the redevelopment scenario proposed for Alternative 3 (Table 5); Groundwater concentrations are expected to attain drinking water standards over the long-term by natural attenuation (refer to discussion of observed COC degradation in Section 5.2); and, Potential for groundwater migration is limited by the slurry wall and naturally occurring low groundwater gradient. Under Alternative 3, the future building constructed on-site would contain a below-grade floor that would be used for commercial/industrial occupied space or as a parking structure. This floor would extend below the water table (see description above). As such, if a monitoring well were constructed within the building footprint, the well would have a tendency to overflow the top of the well into the below-grade floor of the building. Therefore, construction of a groundwater monitoring well within the future building, especially if the bottom most floor is below the water table, is considered technically impracticable. The concerns associated with constructing groundwater monitoring wells within a future building extending below the water table are discussed in further detail in Section 5.5. However, DTSC is requiring ongoing monitoring of groundwater downgradient of the slurry wall. Therefore, this alternative includes installation of three monitoring wells on the downgradient edge of the Site. Two of the wells would be screened at depths corresponding to the existing Site shallow wells (i.e., 10 to 25 feet bgs) and one would be screened at a depth corresponding to the existing Site deep wells (i.e., 25 to 40 feet bgs). Under this alternative, a groundwater monitoring plan specifying well installation and sampling details would be submitted to DTSC for review and approval. The actual number, depths, screen lengths, and locations of groundwater monitoring wells would be decided on during DTSC and U.S. EPA s review and approval of this separate groundwater monitoring plan. Ongoing Monitoring of the Future Building as a Site Cap and DTSC and U.S. EPA Oversight: It is anticipated that both DTSC and U.S. EPA would continue to oversee Site activities, as necessary. Due to PCBs remaining in soil at the Site under Alternative 3 at concentrations above risk-based direct contact criteria (see Section 3.4.1), the Site building would be acting as a "cap" over impacted material. Therefore, annual inspections of the building condition are anticipated. Under this alternative, it is assumed that an annual report would be submitted to DTSC and U.S. EPA documenting the condition of the building and 5-year review reports would be submitted summarizing the status of this remedial alternative. Page 39 of 72

57 5.4 Alternative 4: Risk-Based Cleanup for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building Alternative 4 includes: Pre-excavation soil sampling for PCB congeners; Excavate across the entire Site to approximately 15 feet bgs (3 feet msl) for belowgrade parking and/or office space with additional targeted soil excavation to remove soil where COPCs are present above remedial goals; Preparation of the excavation for building construction, including construction of waterproof and vapor proof below-grade floor; Continued function of slurry wall; Institutional controls; Natural attenuation of COPCs in groundwater to MCLs; and, Limited DTSC oversight and no additional U.S. EPA oversight. The components of Alternative 4 are described below. Pre-Excavation Soil Sampling for PCB Congeners: Refer to the discussion under Alternative 2. Soil Excavation Activities: Soil excavation activities performed under Alternative 4 include excavation of unsaturated and saturated zone soil. The intent would be to remove soil (a) for construction of a building across the entire Site with one story below-grade and (b) to aid in achieving future Site cleanup. For the purposes of this FS/RAP evaluation, it is assumed that the bottom of the excavation would be approximately 15 feet bgs or 3 feet msl across the entire Site with seven areas excavated deeper to achieve risk-based criteria (Figure 6). As discussed under Alternatives 2 and 3, the total depth of the excavation may be extended in the RDIP (e.g., approximately 3 to 6 feet deeper) to meet the specifications for the final development at the Site. There may also be additional soil excavated in defined areas to allow for the placement of piles, pile caps, and grade beams in accordance with the final design of the development. If additional soil is excavated, the human health risks estimated for Alternative 4 would remain applicable (and likely be conservative) because (1) the maximum detected chemical concentrations in soil and the risks associated with excavating this material are already accounted for in the shallower soil that would be removed under this alternative and (2) additional PCB-impacted soil would be removed, thereby removing additional chemical mass and reducing potential exposures for future on-site populations. As mentioned above, the bottom elevation of the excavation assumed for this alternative is 15 feet bgs or 3 feet msl across the entire Site. Additionally, seven areas would be excavated deeper in an effort to achieve the risk-based remedial goals for Site cleanup discussed in Section 3.4. The planned excavation layout for Alternative 4 is shown on Page 40 of 72

58 Figure 6. Since the excavation would extend below the groundwater potentiometric surface, dewatering is anticipated both inside and outside the slurry wall during excavation activities. Existing data associated with soil remaining at the Site below the excavation and data associated with confirmation soil samples collected from the base of the excavation would be compared to the remedial goals developed in Section 3.4. If these criteria are not achieved following the initial soil excavation, additional soil would be excavated. Note that due to a lack of deeper soil data for SVOCs and metals, the additional excavation areas proposed for this alternative are driven by PCB detections. As such, there is significant uncertainty associated with the final depth of the excavation. It is difficult to excavate very deep soil at the Site given its placement between occupied buildings and adjacent to operating railroad tracks. Thus, to achieve Site cleanup, a maximum excavation limit of -17 feet msl (approximately 35 feet bgs) would be established (i.e., approximate depth of the Old Bay Mud geologic unit). Soil below 35 feet bgs or -17 feet msl would not be excavated even if data associated with soil remaining at the Site did not meet the risk-based criteria for Site cleanup. The available PCB results for soil samples collected at or below 35 feet bgs or -17 feet msl range from non-detect to 0.08 mg/kg, suggesting that PCB concentrations are very low at this depth. Potentially leaving low levels of chemicals at depths greater than 35 feet bgs or -17 feet msl should not affect the ability to close the Site given that (1) the potential for human contact with soil at this depth is very low, and (2) potential migration of chemicals in soil and groundwater in an Old Bay Mud unit is very slow due to the low permeability of Old Bay Mud and higher organic content (i.e., greater affinity for hydrophobic compounds like PCBs). As shown on Figure 6, under Alternative 4, soil for the seven deeper excavations (i.e., below 15 feet bgs or 3 feet msl) would be excavated from both inside and outside of the slurry wall. Since this alternative involves ongoing natural attenuation of chemicals in groundwater to achieve MCLs, the continued function of the slurry wall (i.e., limiting lateral migration of COPCs in groundwater) is desired. Therefore, if this alternative was implemented, the RDIP would address how the effectiveness of the slurry wall would be retained (e.g., by excavating soil in these deeper excavation areas from either side of the slurry wall leaving the slurry wall intact or reconstructing the excavated portion of the slurry wall). Preparation of the Excavation for Building Construction: Refer to the discussion under Alternative 3. As in the case of Alternative 3, the portion of the existing slurry wall below the excavation would continue to function as a barrier to lateral migration of groundwater contained within the slurry wall, and the base of the excavation would be below the potentiometric surface. Therefore, the bottom of the excavation would need to allow for "sealing" between the bottom of the excavation and the top of slurry wall. The details of this connection would be provided in the RDIP. Institutional Controls: Refer to the discussion under Alternative 3. Page 41 of 72

59 Monitored Natural Attenuation of COPCs in Groundwater: Similar to Alternative 3, following completion of soil excavation activities, natural attenuation of groundwater is proposed under Alternative 4 because: COPCs in groundwater do not contribute to unacceptable risk levels under the redevelopment scenario proposed for Alternative 4 (Table 5); Groundwater concentrations are expected to attain drinking water standards over the long-term by natural attenuation (refer to discussion of observed COC degradation in Section 5.2); and, Potential for groundwater migration is limited by the slurry wall and naturally occurring low groundwater gradient. Similar to Alternative 3, the redevelopment scenario under Alternative 4 includes construction of a below-grade floor that would be used for commercial/industrial occupied space or as a parking structure. Under this alternative, construction of a groundwater monitoring well within the future building, especially if the bottom most floor is below the water table, is technically impracticable. The concerns associated with constructing groundwater monitoring wells within a future building extending below the water table are discussed in further detail in Section 5.5. Additionally, under Alternative 4, it is anticipated that all potential on-site sources of chemicals in soil will be excavated. Therefore, no ongoing groundwater monitoring would be necessary. Limited DTSC Oversight and No Additional U.S. EPA Oversight: It is anticipated that under this alternative, U.S. EPA would have no further oversight activities as PCBs would have been removed to below the risk-based criteria (see Section 3.4.1), and DTSC's oversight activities would be limited to submittal of the final completion report for this remedial alternative. 5.5 Difficulties Associated with Groundwater Monitoring Post-Construction Under Alternatives 3 and 4 With the soil excavation and engineering controls that are part of Alternatives 3 and 4, including the slurry wall and engineered cap, risk-based exposure to COPCs in groundwater are expected to be below 10-6 (Appendix B). As discussed in further detail below, on-site groundwater monitoring is not proposed under either of these scenarios due to the technical impracticability and health and safety concerns for future on-site populations associated with installing and sampling on-site groundwater monitoring wells. Under Alternatives 3 and 4, a building would be constructed across the entire Site. As such, a "typical" groundwater well installed on-site (i.e., a vertical well with a screen through the entire groundwater aquifer) would have to be constructed through the floor of the building. Construction of such a well presents the following concerns: (1) creates a potential exposure pathway for on-site populations to COPCs in groundwater given that the top of the monitoring well would be inside the building; (2) requires additional Page 42 of 72

60 construction considerations to mitigate potential exposures (e.g., top of well should be within a dedicated utility room with exhaust air to be vented outside the building and not circulated in the HVAC system); and (3) creates locations for potential breaches in the vapor barrier/waterproof system applied to the foundation of the building. Additionally, under the Alternative 3 and 4 redevelopment scenarios, the building constructed on-site would have one below-grade story that is below the piezometric surface at the Site. As discussed above, construction of a "typical" on-site groundwater monitoring well is likely to be technically impracticable and create unacceptable health and safety concerns for future on-site populations. Given that the building constructed under Alternatives 3 and 4 would also be below the potentiometric surface amplifies these concerns (see "Option 1" below). A second option for well installation under Alternatives 3 and 4 is also presented below, however, is limited in its ability to effectively monitor groundwater. Option 1: Installation of a "typical" groundwater monitoring well (i.e., a vertical well with a screen through the entire groundwater aquifer). The advantages of such a well include the ability to (1) sample groundwater within the slurry wall, where some of the highest concentrations of COPCs have been detected; and (2) collect an integrated groundwater sample across the vertical thickness of the aquifer, which is considered representative of groundwater conditions. The disadvantages associated with installation of an on-site groundwater monitoring well following excavation and redevelopment activities are discussed above. Additionally, because the redevelopment scenario associated with Alternatives 3 and 4 includes construction of one-story below the potentiometric surface at the Site, groundwater in a portion of the well within the below-grade story will be under pressure (i.e., artesian), further increasing the risks to future on-site populations. Due to likely difficulty of well installation and additional construction and HVAC requirements to accommodate a groundwater monitoring well inside the building, installation of a vertical well is considered to be technically impractical. The cost to install a vertical groundwater monitoring well and associated engineering controls would be determined by the ability to conform to building plans; however, cost is likely to be high. Due to the technical impracticability of installing a vertical well, no detailed cost estimate has been prepared. Option 2: Installation of a horizontal groundwater monitoring well underneath the future building. Unlike a vertical well, the top of the well would be constructed outside the building, with the horizontal screened interval within a trench underneath the foundation of the building. The horizontal well trench would be excavated upon completion of soil excavation activities. The screened interval would be connected to a horizontal casing running to the Site perimeter, and then to a vertical riser pipe that extends above the piezometric surface and finished at grade in a well box located outside the footprint of the future building. The future building would be constructed on top of the trench. The advantages associated with a horizontal groundwater monitoring well include (1) the ability Page 43 of 72

61 to sample groundwater underneath the building, and (2) with the top of the groundwater monitoring well located outside of the building, the potential for exposure of future on-site populations to COPCs in groundwater is reduced. Disadvantages associated with a horizontal groundwater monitoring well include (1) the well is only capable of sampling at one discrete depth within the groundwater aquifer, and as such, the groundwater sample may not be representative of aquifer conditions; (2) a horizontal groundwater monitoring well is difficult to develop and is likely to become filled with fine-grained soils and become impossible to sample; (3) a horizontal groundwater monitoring groundwater well may be damaged during construction of the building; and (4) the horizontal portion of the well casing would have to puncture the slurry wall to be connected to a riser pipe outside the building footprint, potentially creating a pathway for groundwater into or out of the slurry wall. Given the likelihood of silting and difficult well development, a horizontal well may only be viable for several years after construction. Page 44 of 72

62 6.0 RESULTS OF RISK ANALYSIS FOR EVALUATING REMEDIAL ALTERNATIVES The results of the during-construction risk analysis performed in the HHRA and postconstruction risk analysis performed in this FS/RAP are summarized in the following sections. As discussed in Appendix B, a non-carcinogenic hazard index ( HI ) less than or equal to one represents a condition for assumed exposures that is unlikely to cause adverse non-cancer health effects, even for sensitive populations (U.S. EPA, 1989). Consistent with the NCP (40 CFR 300), an HI less than or equal to one is considered to be associated with an acceptable exposure level and is established as the target noncancer risk level in this FS/RAP. The NCP (40 CFR 300) provides a definition of an acceptable incremental cancer risk ( CR ) range of 10-6 through 10-4 for the selection of remedial actions that protect human health and the environment. U.S. EPA (U.S. EPA, 1991b) has stated that remediation is generally not warranted for contaminated property if the cumulative cancer risk is less than If remediation is undertaken at a property, U.S. EPA has expressed a preference for cleanups that achieve the lower end of this target risk range. However, U.S. EPA acknowledges that remedial actions that achieve reductions in site risk anywhere within the 10-6 through 10-4 risk range may be acceptable after considering sitespecific conditions (U.S. EPA, 1991b). The State of California has adopted 10-5 as the no significant risk level for protecting persons from exposure to chemicals in consumer products and commercial establishments under The Safe Drinking Water and Toxic Enforcement Act, which is commonly referred to as Proposition 65. Additionally, in DTSC s VIMA document (Cal/EPA, 2009), the following risk management guidance is established for sites with vapor intrusion concerns: Cumulative CR 10-6 or HI 1: No Further Action 10-4 Cumulative CR 10-6 or HI >1: Monitoring, Possible Mitigation, Possible Source Remediation Cumulative CR > 10-4 : Vapor Intrusion Mitigation System, Source Remediation Therefore, a cumulative CR less than or equal to 10-6 is considered to be associated with an acceptable exposure level and is established as the target cancer risk level in this FS/RAP. For estimated cumulative CRs between 10-4 and 10-6, monitoring, possible mitigation, and possible source remediation will be considered in this FS/RAP During-Construction Risk Estimate Summary Presented in the HHRA As previously discussed, the redevelopment scenario assessed in the HHRA is equivalent to Alternative 3 in this FS/RAP, except that commercial/industria1 space is included as a potential use of the sub-grade floor. Therefore, the during-construction risk estimates are applicable to Alternative 3. Risk estimates for the during-construction phase of Alternative 2 would likely be lower (due to a shorter construction period and less impacted soil disturbed) and risk estimates for the during-construction phase of Page 45 of 72

63 Alternative 4 would likely be somewhat higher (due to a longer construction period). The potential hazards and risks associated with construction at the Site estimated in the HHRA are presented in Attachment 1 of Appendix B and summarized below: Earthwork/Remediation Construction Workers: Potential hazards and risks exceed the target risk levels of 1 and 10-6, respectively. Risks due to potential exposure to lead in soil are below levels of concern. 22 Off-Site Commercial/Industrial Workers: Potential hazards and risks exceed the target risk levels of 1 and 10-6, respectively. Risks due to potential exposure to lead in soil are below levels of concern. 22 Off-Site Residents: Potential hazards and risks exceed the target risk levels of 1 and 10-6, respectively. Risks due to potential exposure to lead in soil are below levels of concern. 22 Note that these risk estimates were calculated assuming no PPE is used and that no engineering controls or health and safety measures are implemented Post-Construction Risk Estimate Summary Updated in this FS/RAP The potential hazards and risks associated with the post-construction scenario are calculated for each remedial alternative using the methodology, equations, and input parameters presented in Appendix B. The risk estimates are summarized in Table 5 and in the following sections. Except for commercial/industrial use of a building constructed directly on-grade (i.e., Alternative 2), the results of the post-construction risk analysis indicate that potential hazards and risks are below the target risk levels. Alternative 1 Risk Estimate Summary Off-Site Commercial/Industrial Workers (Surface Parking Lot Exposures): The human health risk estimates are as follows: HI = and CR = 2x10-8 (based on vapor intrusion modeling using soil vapor data). 23 These potential hazards and risks are below the target risk levels of 1 and 10-6, respectively. Alternative 2 Risk Estimate Summary On-Site Commercial/Industrial Workers (First Floor Occupancy): The human health risk estimates are as follows: HI = 0.01 and CR = 2x10-6. Therefore, potential non-carcinogenic hazards are below the target risk level of 1; however, the estimated carcinogenic risk for this population and alternative is above the target risk level As discussed above, DTSC s VIMA document recommends 22 Using the LeadSpread model, the level of concern reflects the environmental exposure to lead will that will cause blood lead levels in an individual to be greater than 10 micrograms per deciliter 1% of the time (i.e., at the 99 th percentile). 23 For Alternative 1, human health risks were estimated based on vapor intrusion modeling using groundwater data and soil vapor data. The more conservative results (i.e., modeling results using soil vapor data) are presented herein. Page 46 of 72

64 monitoring, possible mitigation, and possible source remediation for CR estimates between 10-4 and On-Site Residents (First Floor Parking Garage Exposures): 24 The human health risk estimates are as follows: HI = and CR = 3x Therefore, potential hazards and risks are below the target risk levels of 1 and 10-6, respectively. Alternative 3 Risk Estimate Summary On-Site Commercial/Industrial Workers (Sub-Grade Floor Occupancy): The human health risk estimates are as follows: HI = and CR = 1x10-6. Therefore, potential hazards and risks are at or below the target risk levels of 1 and 10-6, respectively. On-Site Residents (Sub-Grade Parking Garage Exposures): 25 The human health risk estimates are as follows: HI = and CR = 1x Therefore, potential hazards and risks are below the target risk levels of 1 and 10-6, respectively. Alternative 4 Risk Estimate Summary On-Site Commercial/Industrial Workers (Sub-Grade Floor Occupancy): The human health risk estimates are as follows: HI = and CR = 1x Therefore, potential hazards and risks are at or below the target risk levels of 1 and 10-6, respectively. On-Site Residents (Sub-Grade Parking Garage Exposures): 25 The human health risk estimates are as follows: HI = and CR = 1x Therefore, potential hazards and risks are below the target risk levels of 1 and 10-6, respectively. 24 Note that the in the current development plans, upper floors of the future on-site building will not be used for residential purposes. However, risks estimates were conservatively calculated for the first floor (Alternative 2) and below-grade (Alternatives 3 and 4) parking garage scenario assuming residential exposure assumptions. 25 For this scenario, human health risks were estimated for both adult and child populations. The more conservative results (i.e., child HI and adult CR) are presented herein. Page 47 of 72

65 7.0 EVALUATION OF REMEDIAL ALTERNATIVES This section provides a description of the developed remedial alternatives based on viable remedial technologies and process options, as identified in Section 4.0, and evaluates remedial alternatives against criteria set forth in the NCP (U.S. EPA, 1993) and California Health and Safety Code Section (d). 7.1 Remedial Alternative Evaluation Criteria The following sections describe the nine federal criteria in the NCP and the six State of California factors used to evaluate remedial alternatives NCP Criteria The nine federal criteria in the NCP, listed below, are divided into three general categories: a) threshold criteria, b) primary balancing criteria, and c) modifying criteria. Threshold criteria are actually requirements, and the selected remedy must protect human health and the environment and must comply with identified ARARs. The primary balancing criteria determines how the alternatives compare with one another and identifies tradeoffs between them. The modifying criteria take into account acceptance by the State and by the local community. a. Threshold Criteria 1. Overall protection of human health and the environment: This criterion addresses whether a remedial alternative is protective of human health and the environment in the long-term and short-term. 2. Compliance with ARARs: The selected remedy must comply with ARARs unless a waiver is appropriate pursuant to 40 CFR Paragraph (f)(1)(ii)(c). b. Primary Balancing Criteria 3. Long-term effectiveness and permanence: This criterion addresses how well a remedy maintains protection of human health and the environment after RAOs have been initially met and the degree of certainty that the alternative will continue to meet RAOs. Components to be addressed include the magnitude of residual risk and the adequacy and long-term reliability of management controls. 4. Reduction of toxicity, mobility, or volume: This criterion assesses the anticipated amount of target chemical destroyed or treated and the amount remaining at the site along with the degree of expected reduction in chemical mobility, toxicity, or volume. 5. Short-term effectiveness: This criterion concerns protection of human health and the environment during construction and implementation of remedial actions. To be considered are the length of time required to achieve protection, the short-term reliability of remedial technologies, protection of Page 48 of 72

66 workers and the community during construction, and potential disruptions to nearby commercial and residential neighborhoods. 6. Implementability: This criterion is meant to assess implementability considering the technical and administrative feasibility of each alternative, as well as the availability of needed goods and services to perform the remedy. Other implementability considerations include the ability to construct and operate remedial facilities, ease of undertaking additional remedial actions, ability to monitor remedial effectiveness, and ability to obtain approvals and permits. 7. Cost: This criterion evaluates the cost of remedial alternatives, including both total long-term and short-term costs. c. Modifying Criteria Typically, these two criteria are evaluated based on formal comments received during the project comment period. However, a formal comment period has not yet occurred. Issues and concerns of the agencies and community will be addressed after the public comment period on the draft FS/RAP. 8. State acceptance: This criterion considers the acceptability of remedial alternatives to State and local agencies. 9. Community acceptance: This criterion considers the acceptability of remedial alternatives to the local residents and community State of California Factors A brief outline of the six State of California factors as delineated by California Health and Safety Code (d) are listed below. These State factors, although similar to the nine NCP criteria, are considered separately. 1. Health and safety risks: This factor considers health and safety risks posed by site conditions. 2. Effect of contamination upon beneficial uses of resource: This factor considers the effect of contamination upon present, future, and probable beneficial uses of contaminated, polluted, or threatened resources. 3. Effect on groundwater resources: This factor considers the effect of remedial alternatives on the availability of groundwater resources for present, future, and probable beneficial uses and the extent to which remedial alternatives use treatment to reduce the volume, toxicity, or mobility of hazardous substances. 4. Site-specific characteristics: This factor considers site-specific characteristics, including the potential for off-site migration of hazardous substances, surface or subsurface soil conditions, hydrogeologic conditions, and pre-existing background chemicals levels. Page 49 of 72

67 5. Cost effectiveness: This factor considers the cost-effectiveness of remedial alternatives, including both total long-term and short-term costs. 6. Potential environmental impacts of remedial action: This factor considers potential environmental impacts of remedial alternatives, including land disposal and treatment issues Compliance with TSCA Remedial alternatives involving excavation of soil containing PCBs will follow the requirements of TSCA. The three parts of TSCA under which PCB-impacted material may be remediated are: 40 CFR (a), Self-implementing on-site cleanup and disposal of PCB remediation waste; 40 CFR (b), Performance-based disposal; and, 40 CFR (c), Risk-based disposal approval. Soil removal activities for Alternatives 2 through 4 are proposed to be performed under (c). Under this section, any person wishing to sample, cleanup, or dispose of PCB-impacted material in a manner other than as prescribed in (a) or (b), must apply in writing to the U.S. EPA Regional Administrator in the Region where the site is located. Pursuant to (c) of TSCA, each application to assess PCBs under this section must contain the information described in the notification requirements of (a)(3). Following review of the application, U.S. EPA may issue a written decision on the request for risk-based remediation of PCBs. According to TSCA requirements, U.S. EPA will approve a risk-based remediation of PCBs if it finds that the remediation method will not pose an unreasonable risk of injury to health or the environment (40 CFR (c)). As discussed in further detail in Appendix F, this FS/RAP serves as the written application to U.S. EPA to assess and remediate PCBs under (c) for the recommended alternative. Including the application to U.S. EPA with this draft FS/RAP allows U.S. EPA to review and comment on the application in the draft phase, and approve the application with the final FS/RAP document. Thus, in accordance with the requirements of Section (c) of TSCA, and as discussed in Appendix F, this FS/RAP serves as the written application to U.S. EPA to assess and remediate PCBs under (c) for the recommended alternative (Section 8.0). Pursuant to (c) of TSCA, this FS/RAP contains the information described in the notification requirements of (a)(3). The location of information required by (a)(3) is described in Appendix F. Including the application to U.S. EPA with this draft FS/RAP allows U.S. EPA to review and comment on the application in the draft phase, and to approve the application with the final FS/RAP document. Page 50 of 72

68 Since all alternatives assessed in this draft FS/RAP would be implemented in compliance with TSCA, an evaluation of alternatives against TSCA requirements is not included in Section Summary of Remedial Alternative Evaluation Results The following sections summarize the results of the analysis of remedial alternatives against NCP criteria and State of California factors NCP Criteria Evaluation Results Table 6 includes a detailed analysis of the four remedial alternatives using the NCP criteria. The analysis is summarized below. Threshold Criteria Overall Protection of Human Health and the Environment: Alternatives 1 through 4 are protective of human health and the environment for the land use included for each alternative. All four alternatives are protective of human health from direct exposure to COPCs in soil and groundwater, and from COPCs in groundwater migrating to outdoor air (Alternative 1) and indoor air (Alternatives 2 through 4). Post-construction risk estimates for each alternative are summarized in Section 6.0 and Table 5. Because the estimated CR for On-Site Commercial/Industrial Workers under Alternative 2 is between 10-4 and 10-6, this alternative includes targeted groundwater treatment and construction of an SSVS to mitigate potential future risks. Compliance with ARARs: Alternatives 1 through 4 are expected to comply with ARARs. For all four Alternatives, groundwater is expected to attain drinking water-related ARARs over the long-term by natural attenuation. Attenuation under Alternative 2 is anticipated to be enhanced for certain risk-driving VOCs due to the injection of ORC (or other material for in situ treatment) prior to excavation activities. Primary Balancing Criteria Long-term Effectiveness and Permanence: All four alternatives are expected to provide long-term effectiveness and permanence at addressing protection of human health and the environment. For Alternative 1, chemicals in soil remain on-site above risk-based levels of concern (assuming no engineering controls); and as such, long-term effectiveness depends on maintenance of the existing cap and slurry wall. Therefore, Alternative 1 provides the least long-term reliability. Under Alternatives 2 through 4, impacted soil would be excavated, followed by backfill with clean soil and/or construction of a building on-site. As such, Alternatives 2 through 4 may be more reliable at protecting human health and the environment than Alternative 1. Additionally, Alternative 2 includes construction of an SSVS with ongoing monitoring of sub-slab soil vapor and/or stack emissions. Therefore, this alternative provides additional control and knowledge of the future conditions at the Site with respect to protecting human health. Under Alternative 4, to the extent practicable, Page 51 of 72

69 soil will be removed to attain risk-based Site cleanup, thus most reliably protects human health and environment. Under Alternatives 2 through 4, the building that is constructed following soil excavation will limit potential leaching of COPCs to groundwater. For Alternatives 2 and 3, where representative concentrations of COPCs in soil (e.g., PCBs) may be present at levels above risk-based goals developed for the Site cleanup alternative (i.e., Alternative 4), protection of human health will depend on long-term maintenance of the on-site structure, which will be acting as a physical barrier between on-site populations and the underlying soil. Reduction of Toxicity, Mobility, or Volume: No active treatment is associated with Alternative 1, and as such, it does not provide reduction of toxicity, mobility, or volume of COPCs. Alternative 2 provides the most reduction of toxicity and volume of COPCs through treatment, given the in situ groundwater treatment prior to excavation activities. Additionally, Alternatives 2 through 4 provide varying degrees of reduction in mobility and volume of COPCs by removing and disposing of soil off-site. Short-term Effectiveness: Alternative 1 is considered most effective in the short-term as no exposure to COPCs is associated with implementation of Alternative 1. For Alternatives 2 through 4, short-term exposures to COPCs and potential off-site impacts from dust, odor, and traffic would need to be addressed by available mitigation measures during excavation activities. Alternatives 3 and 4 may have a greater potential for off-site impacts due to longer excavation period and higher concentrations of some COPCs (e.g., PCBs) in soil to be excavated. Due to limited deeper soil data, the excavation period associated with Alternative 4 has a significant potential to increase from additional excavation activities required based on the results of confirmation soil sampling. Additional soil excavation under Alternative 4 would increase the potential for off-site impacts due to a longer excavation period. Alternative 2 has less potential to generate off-site impacts from dust, odor, and traffic than Alternatives 3 and 4 because significantly less soil will be removed from the Site under this alternative. Implementability: Alternative 1 is most implementable. Alternatives 2 through 4 are implementable, but may require extensive control measures to reduce on- and off-site exposures, potential noise, dust, and odor impacts during excavation activities. With the additional volumes of soil to be excavated, including excavation of saturated soil, Alternatives 3 and 4 are expected to be more difficult to implement than Alternatives 1 and 2. As discussed in Section 5.4, it may be technically infeasible to excavate soil in order to achieve the risk-based criteria for Site cleanup (Alternative 4). Therefore, a maximum excavation base elevation is established at 35 feet bgs or -17 feet msl. However, even at this depth, permanent tiebacks may be required which would reduce the developable area at the Site, making this alternative less implementable. Page 52 of 72

70 Cost: Capital costs and annual ongoing costs were estimated for Alternatives 1 to 4 based on descriptions of alternatives provided in Section 5.0 (Table 7). Appendix C presents cost estimates for components of alternatives and the basis and assumptions for these estimates. Modifying Criteria State Acceptance: State acceptance will be evaluated after the public comment period and incorporated into the final FS/RAP. Community Acceptance: Community acceptance will be evaluated after the public comment period and incorporated into the final FS/RAP State Factors Evaluation Results The evaluation results of State factors are summarized below. Health and Safety Risks: As stated in Section 6.1.2, based on current land use, health and safety risks posed by current Site conditions are below noncarcinogenic and carcinogenic the target risk levels of 1 and 10-6, respectively, and would remain at this level under Alternative 1. However, Alternative 1 would not address the inherent risks associated with leaving COPCs in soil at the Site. Under Alternatives 2 through 4, varying amounts of impacted soil would be removed from the Site. Potential risks during construction would be mitigated by through use of PPE, engineering controls, and monitoring with contingency plans. Under Alternative 2, if CR remains above the 10-6 target level following groundwater treatment and soil excavation, potential risk due to vapor intrusion would be managed through operation and maintenance of an SSVS. Risk estimates for Alternatives 3 and 4 are below non-carcinogenic and carcinogenic the target risk levels of 1 and 10-6, respectively (Table 5). Both Alternatives 2 and 3 include long-term institutional controls to limit exposure to soil. Under Alternative 4, to the extent practicable, soil will be excavated to meet risk-based cleanup requirements, so this alternative presents the least health and safety risks to future on-site populations. Effect of Contamination upon Beneficial Uses of Resource: Alternative 1 would not result in substantial reduction of COPC concentrations in soil, and would therefore, have little effect on the beneficial uses of the Site. Alternatives 2 through 4 include removal of COPC-impacted soil, which would substantially improve potential beneficial use, including allowing construction of commercial use buildings at the Site. For Alternatives 1 through 4, groundwater may attain ARARs over the long-term by natural attenuation. Effect on Groundwater Resources: As discussed in Section 6.1.2, risk estimates for the vapor intrusion pathway based on COPCs in groundwater at the Site are below non-carcinogenic and carcinogenic the target risk levels of 1 and 10-6, respectively for Alternatives 3 and 4. Additionally, representative concentrations of COPCs in groundwater are below risk-based goals developed for the most Page 53 of 72

71 conservative (i.e., health-protective) alternative (i.e., Alternative 4; Section 3.4.2). Therefore, there is currently no impact on groundwater resources with respect to human health concerns from the vapor intrusion pathway under Alternatives 3 and 4. Although representative concentrations of COPCs in groundwater are below riskbased goals developed for Alternative 4, due to the conservative assumptions regarding future fill soil used at the Site and shallow depth to groundwater, vapor intrusion modeling results estimate a greater than 10-6 CR to future On-Site Commercial/Industrial Workers occupying the first floor of an above-grade building (i.e., Alternative 2 scenario). Therefore, Alternative 2 includes preexcavation groundwater treatment and post-construction vapor mitigation measures (see Section 5.2). As discussed in Section 3.3, the probability of using Site groundwater for domestic and municipal supply is low, however, the domestic use beneficial use has not been de-designated at the Site. Alternatives 3 through 4 would have a positive impact on this beneficial use because under these alternatives, COPCimpacted saturated zone soils would be removed and disposed of off-site. As mentioned above, in situ groundwater treatment under Alternative 2 would also have a positive impact on this beneficial use. For all alternatives, groundwater concentrations are expected to attain drinking water-related ARARs over time by natural attenuation. A discussion of the empirical evidence supporting ongoing natural attenuation of the risk-driving chemicals under Alternative 2 (i.e., carbon tetrachloride and vinyl chloride) is provided in Section 5.2. Site-Specific Characteristics: The Site-specific characteristics include existing engineering controls (cap and slurry wall), the mixture of inorganic and organic COPCs in soil and groundwater, current and future Site use and development plans, and space limitations of the Site. These Site-specific characteristics were considered during the evaluation and development of remedial technologies and alternatives for the Site. Cost Effectiveness: Cost estimates for the four alternatives are summarized in Table 7. The cost associated with Alternative 1 is low, but this alternative is not considered cost effective because the Site use under Alternative 1 is not consistent with future development plans. The cost of Alternative 2 is moderate, and Alternative 2 is cost effective if future development plans are consistent with the development proposal under this alternative. The cost of Alternative 3 is higher than Alternative 2, but is cost effective if future development is consistent with the development proposal under Alternative 3. The cost to implement Alternative 4 is the highest and reflects the cost to remove soil to attain risk-based cleanup. Alternative 4 is not considered to be cost effective because the incremental protectiveness to human health and environment is not justified by the significantly higher costs and uncertainty associated with soil excavation to attain risk-based cleanup. Page 54 of 72

72 Potential Environmental Impacts of Remedial Action: Alternative 1 would have no new environmental impacts because remedial actions would not be implemented. Alternatives 2 through 4 include off-site disposal of soil containing COPCs and would result in the reduction of chemical volume, toxicity, and mobility in on-site soil. Excavated soils would be trucked to off-site permitted land disposal facilities that manage wastes containing COPCs in a manner that restricts mobility and toxicity in accordance with standards promulgated by the relevant regulatory authorities in the facilities operating permits. Potential environmental impacts from soil remediation activities include traffic impacts, near the Site and along selected transportation routes, from the estimated 20 to 40 trucks per day entering and leaving the Site. These excavation and truck loading activities would have associated potential air quality impacts from dust, vapor, and odor generation during soil excavation, and potential stormwater quality impacts, which will be monitored and controlled in accordance with project plans approved by the pertinent governmental agencies. Alternative 4 has the greatest potential for off-site impacts due to a longer excavation period and greater number of truck trips. Alternatives 2 through 4 include mitigation measures and plans to be implemented such that soil remediation activities would not adversely impact the surrounding community. Additionally, DTSC and U.S. EPA have expressed a preference for implementing green technologies and practices in remediation projects, where feasible. According to DTSC s green remediation website 26, remediation technologies and practices may be considered green if they are less disruptive to the environment, generate less waste, include recycling, and/or emit fewer pollutants and greenhouse gases to the atmosphere than other options. The use of excavators, other machinery, and the truck traffic associated with the excavation and off-site disposal of soil under Alternatives 2 through 4 will result in emission of greenhouse gasses to the atmosphere related to fuel consumption. These greenhouse gas emissions will be proportionately greater for remedial actions of longer duration and with more truck trips. Alternative 2 would be expected to have the least emission of green house gases, and Alternative 4 would have the most. Hence, Alternatives 2 and 3 may be considered the more green remedial alternatives compared with Alternative 4 because overall less soil would be excavated and transported off-site. Alternatives 2 and 3 would have more reliance given to the use of on-site engineered barriers and institutional controls that are compatible with future Site development and provide protection of human health and the environment with fewer greenhouse emissions Summary of Comparison of Alternatives This subsection presents a summary of the comparative analysis of each of the remedial alternatives described in Section 5.0. This analysis focuses on the relative performance of each alternative against the NCP criteria. The consideration of State factors is incorporated into these summary conclusions and judgments of relative performance. 26 Information from DTSC s green remediation website was obtained from the following location: Page 55 of 72

73 Based on the future land use scenarios proposed in Alternatives 1 through 4, all four alternatives meet the threshold criteria. However, the future land use scenario associated with Alternative 1 is not consistent with future development plans as it does not include construction of a building on-site. Therefore, Alternative 1 is eliminated from further consideration. Alternatives 2 through 4 meet the threshold criteria based on future development plans. Alternative 2 includes excavation to 5.5 feet bgs or 12.5 feet msl (i.e., unsaturated zone soil) for construction of an above-grade building. Alternatives 3 and 4 include excavation to 15 feet bgs or 3 feet msl for construction of a building with one floor below ground. For Alternative 4, additional soil would be excavated to attain risk-based goals. The greatest potential for short-term exposures to COPCs, and potential off-site impacts from dust, odor, and traffic, are associated with Alternatives 3 and 4. Additionally, due to limited deeper soil data, the excavation period associated with Alternative 4 has a significant potential to increase from additional excavation activities required based on the results of confirmation soil sampling. While the additional excavation under Alternatives 3 and 4 provides some enhanced reliability in protecting human health and the environment because more impacted soil is removed, the incremental protectiveness to human health and the environment is not justified by the higher costs and possible short-term effects associated with additional soil excavation. Alternative 2 includes in situ treatment of VOCs in groundwater. Additionally, vapor mitigation under Alternative 2 allows for additional control and knowledge of the future conditions at the Site with respect to protecting human health. Therefore, as it is protective of human health and the environment under the future development plans while minimizing the potential for short-term adverse effects and providing additional control and knowledge of future Site conditions, Alternative 2 has been selected as the proposed alternative. Page 56 of 72

74 8.0 PROPOSED REMEDY Based on the evaluation of potential remedial alternatives using the NCP criteria and the State of California factors from the California Health and Safety Code, Alternative 2 is recommended for implementation as the remedial action for the Site (Figure 4). This alternative meets the RAOs, protects human health and the environment, satisfies the NCP and State of California criteria, can be implemented in a timely, safe, and costeffective manner, and is compatible with future development plans for the Site. As compared to the Alternatives 1, 3, and 4, this preferred alternative (i.e., Alternative 2) provides for a high degree of certainty in protection of human health and the environment, long-term and short-term effectiveness, is implementable, and it is more likely to receive State and community acceptance than the no action alternative due to the desired redevelopment of the Site. The recommended excavation and off-site disposal approach can be accomplished relatively quickly and efficiently with conventional means and methods. Alternative 4 is the highest level of protection of human health and environment and may be worthwhile if the additional costs could be absorbed by the project. Although a LUC, O&M Agreement, and O&M Plan would be required, it is assumed that such specific institutional constraints would not significantly impact redevelopment based on foreseeable future land use as parking and commercial space. This land use is consistent with the surrounding City of Emeryville community. 8.1 Summary of Proposed Remedy The components of Alternative 2 are described in the sections below Pre-Excavation Soil Sampling for PCB Congeners As discussed in the data tables included in Appendices A and B, and in accordance with the current standard of practice, PCB analysis at the Site was performed on an Aroclorbasis. Aroclors are made up of mixtures of PCB congeners and PCB analysis can also be performed on a congener-basis. Some PCB congeners are coplanar or mono-orthosubstituted congeners, also referred to as dioxin-like chemicals due to their similarity in structure (CDC, 2005). Although no guidance requiring analysis for or assessment of risks associated with PCB congeners has been published by U.S. EPA or Cal/EPA, representatives from U.S. EPA requested during a conference call on 5 March 2009 that additional soil samples be collected at the Site for congener-specific PCB analysis to determine whether dioxinlike congeners are present. If these compounds are present, these data will be considered as part of the development of risk-based action levels for COPCs in air during construction activities. It may be, considering the non-standard laboratory method employed to evaluate the presence of dioxin-like congeners, that the action-levels will be part of the overall dust standard for the project and not a specific numerical goal that will necessitate specialized laboratory testing. Page 57 of 72

75 Consistent with the sampling work plan reviewed and approved by the DTSC and U.S. EPA (WSP, 2009), it was assumed for cost estimating purposes that 5, 4-point composite soil samples will be collected at the Site to assess the presence of dioxin-like PCB congeners. For the purposes of this FS/RAP evaluation, it is assumed that all soil excavated from the Site, with the exception of the cap material, contains concentrations of PCBs above 50 mg/kg. Making this assumption classifies the soil as TSCA hazardous waste, which can only be disposed of at a Class I hazardous waste disposal facility. Based on discussions with representatives from U.S. EPA, no additional disposal characterization sampling would be required if all material is assumed to contain PCBs above 50 mg/kg. For cost estimating purposes, a distinction is made for soil containing greater than 1,000 mg/kg PCBs because of higher fees associated with disposal of such contaminated soil Targeted Additional Groundwater Characterization and In Situ Treatment To further refine the area targeted for in situ treatment, it is assumed that an investigation using MIP and HPT will be performed in the northeastern portion of the Site within the slurry wall. These tools can be used to further define the depth and lateral extent of VOCs in the subsurface at the Site, and therefore refine the groundwater treatment scope. Grab groundwater samples may also be collected as part of the MIP/HPT investigation. However, a separate in situ treatment work plan will be submitted to DTSC for review and approval. This work plan may propose a different type or scope of groundwater investigation and treatment activities. For cost estimating purposes, it is assumed that MIP and HPT probes will be advanced to an elevation of approximately -12 feet msl at 24 locations for MIP and 12 locations for HPT. For cost estimating, it is assumed that these groundwater investigation activities will reduce the area targeted for in situ treatment by approximately 30 percent (i.e., from 10,800 square feet to 7,600 square feet) by better defining the extent of VOCs in groundwater. For the purposes of this FS/RAP evaluation, following groundwater investigation activities, it is assumed that ORC will be injected into the subsurface. ORC will provide oxygen to native bacteria capable of aerobically degrading certain VOCs including, benzene, carbon tetrachloride, chlorobenzene, dichlorobenzene, cis-1,2-dichloroethene, and vinyl chloride. For cost estimating purposes, it is assumed that ORC will be injected at approximately 134 locations in a 7,600 square foot treatment area over a 24-foot vertical interval in the groundwater, across an elevation range of approximately 12 to -12 feet msl. However, as mentioned above, a separate in situ treatment work plan will be submitted to DTSC for review and approval. This work plan may propose a different type or scope of groundwater investigation and treatment activities. Page 58 of 72

76 8.1.3 Unsaturated Zone Soil Excavation The proposed remedy includes excavation of unsaturated zone soil for construction of an above-grade building across the entire Site. For the purposes of this FS/RAP evaluation, it is assumed that the bottom of the excavation will be approximately 5.5 feet bgs or 12.5 feet msl across the entire Site. However, the total depth of the proposed excavation may be extended in the plans presented in the RDIP (e.g., approximately 3 to 6 feet deeper) to meet the specifications for the final development at the Site. There may also be proposals for additional soil to be excavated in defined areas to allow for the placement of elevator shafts, piles, pile caps, and grade beams in accordance with the final design of the development. If additional soil is excavated, the human health risks estimated for Alternative 3 would remain a conservative estimate of during-construction risks for this alternative because (1) the maximum detected chemical concentrations in soil and the risks associated with excavating this material are accounted for in the Alternative 3 risk estimates and (2) additional PCB-impacted soil would be removed, thereby removing additional chemical mass and reducing potential exposures for future on-site populations. Figure 4 presents the estimated excavation extent for the proposed remedy. The estimated unsaturated soil volume to be excavated during implementation of the remedy is approximately 7,400 bank cubic yards ( bcy ) of cap material and 5,700 bcy of soil beneath the cap material. However, as discussed above, additional soil may be excavated to meet the specifications for the final development at the Site (e.g., for placement of piles and pile cap/grade beam systems). 27 It is assumed that all soil excavated from the Site, with the exception of the cap material, contains concentrations of PCBs above 50 mg/kg. Making this assumption classifies the soil as PCB remediation waste, which can only be disposed of at a Class I waste disposal facility that has been approved by U.S. EPA under TSCA for PCB disposal. Excavated soil will be loaded into trucks and transported to an appropriately permitted off-site facility for disposal. As necessary (e.g., for soil also identified as RCRA or California hazardous waste due to lead toxicity characteristic), stabilization treatment prior to disposal will be performed. The preliminary soil classifications for disposal are presented graphically on Figure 13. Informational soil sampling will be performed at the base of the excavation. However, because the excavation plan applies to a specific redevelopment scenario (i.e., as opposed to a risk-based removal action), the results of such soil sampling will not prompt additional soil excavation activities. Since the excavation is not anticipated to extend below the groundwater potentiometric surface, dewatering may not be necessary during excavation activities. However, it will 27 For example, using the following design assumptions for a building constructed on a different Site: (1) one pile with an area of 49 square feet (i.e., 7 feet by 7 feet) is installed for approximately every 2,500 square feet of building floor to a depth of 3 feet bgs and (2) an area of 78 square feet is excavated to a depth of 5 feet bgs for each elevator shaft, and assuming six elevators are installed in the future building, approximately 6,500 cubic feet of additional soil would be excavated. Page 59 of 72

77 be required if development plans require saturated soil excavation in limited areas of the Site for placement of elevator shafts, piles, pile caps, and grade beams. If dewatering is performed, excavation dewatering water will be disposed of at Seaport Environmental or treated on-site (if needed) prior to discharging to the East Bay Municipal Utility District ( EBMUD ) sanitary sewer system. The minimum requirements for on-site treatment of groundwater generated during dewatering activities will be specified in the contract documents. If treated water is discharged to EBMUD, the system must be capable of satisfying the EBMUD discharge criteria. Initially, it is anticipated that treated water will be stored on-site in temporary storage tanks until analytical results confirm that the EBMUD permit requirements have been achieved. Conceptually, the temporary groundwater treatment system may include settling tanks to remove particulates, filtering, and/or contact with activated carbon. A permit would be required to discharge treated water to the EBMUD sanitary sewer system, however, permits for the treatment system itself are not anticipated to be necessary. The volume of excavation dewatering water is anticipated to be relatively small given that the majority of soil excavation activities will be in the unsaturated zone. As previously discussed, prior to implementation of soil excavation activities, an RDIP will be prepared and approved by DTSC and U.S. EPA. The RDIP will include, but not be limited to, plans for implementing soil remediation and for employing safety measures during soil remedial activities to protect human health and the environment such as: (1) Health and Safety Plan, (2) Traffic Control and Waste Transportation Plan, (3) Decontamination Plan, (4) Dust, Vapor, and Odor Control Plan, (5) Perimeter Air Monitoring Plan, (6) Storm Water Pollution Prevention Plan, (7) Sampling and Analysis Plan, (8) Shoring Plan, (9) Remedial Design, and (10) Quality Assurance Project Plan. The design details for the SSVS and the sub-slab VOC concentrations for triggering an upgrade from SSVS to SSDS will be submitted to DTSC in a separate work plan for review and approval prior to SSVS construction. Additionally, the minimum requirements for on-site treatment of groundwater generated during dewatering activities, if performed, will be specified in the contract documents Preparation of the Excavation for Building Construction If a dewatering system is installed during the soil removal, it may remain in place during this phase of the project to allow for removal of any groundwater that may seep into the excavation and for the removal of any rainfall that may accumulate in the excavation. The water will be handled as described above for the primary excavation work. Plastic sheeting or other barrier will be installed inside the excavation walls and floor (protected with a minimum 6-inch gravel cover, or similar suitable material) prior to building construction to reduce the risk of construction workers contacting impacted soil or groundwater. The liner and gravel cover will also serve as a working surface for foundation construction. The remediation contractor and the development contractor will reach an agreement as to the specific type of barrier that will be installed inside the excavation floor and walls prior to building construction. Page 60 of 72

78 The liner and clean fill at the base of the excavation and the barrier on the sidewalls of the excavation will provide a significant barrier between chemicals in underlying soil and construction workers building the foundation. However, because estimated risks for construction workers during excavation activities (i.e., populations with direct soil contact) are above acceptable levels (see Alternative 3 results in Table 5), any contractor working in the excavation prior to the placement of working surface and perimeter barriers on the excavation sidewalls, or performing any other type of construction work that might expose workers to chemical contaminants, will be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE. If elevator shafts, piles and pile caps/grade beam systems are constructed in soil below the working surface at the base of the excavation, the workers will be required to be 40-hour OSHA HAZWOPER-trained and use appropriate engineering controls and PPE Construction of SSVS Soil excavation, as described above, may reduce VOC mass beneath the future building and subsequently reduce VOC concentrations in soil vapor. Additionally, the liner placed immediately on the PCB-contaminated soil to reduce the risk of contact with impacted soil and groundwater during foundation construction (discussed above) will also reduce vapor intrusion potential into the fill placed on top of the liner. However, there remains the potential for VOC concentrations to exceed target levels for vapor intrusion concerns Thus, following excavation of soil to the target depth, and backfilling if appropriate based upon the final development plans, an SSVS will be constructed on-site beneath the portions of the future building that (1) will be used as commercial/industrial space and (2) will be the locations for elevator shafts, stairwells, utility corridors, and other enclosed areas serving as potential preferential pathways for soil vapor migration. The intent of the SSVS is to provide a pathway to allow soil vapor to migrate or vent to the exterior of the future on-site building, rather than entering the building. The SSVS will generally consist of the following elements: A horizontal layer of permeable venting material (e.g., sand or gravel) beneath the appropriate portion of the building footprint - the permeable venting material layer will be installed below structural grade beams and shallow sub-floor utilities that may otherwise interfere with uniform lateral venting, and thus may be approximately 2 to 4 feet below the building floor; 28 Lengths of perforated pipe installed within the layer of permeable venting material connected to a vertical riser pipe through the building with an outlet on the building roof; 28 Since this permeable layer may be installed at a depth that could intercept groundwater, the SSVS design details submitted under separate cover will discuss the potential effects of groundwater infiltration into this layer and related design specifications. For example, the design details may specify that the perforated piping (discussed in the next bullet) be installed above the highest measured groundwater (i.e., approximately 15.5 feet msl; WSP, 2008). Page 61 of 72

79 A sub-slab liner (e.g., Geo-Seal), installed either (a) directly on top of the layer of permeable material, or (b) immediately below the commercial/industrial use portion of the building floor; and, Soil vapor sampling probes, installed within the layer of permeable material, to monitor VOC concentrations in soil vapor beneath this portion of the building. Following building construction, the vertical vent pipe will be connected to the pipe beneath the building and extended to the roof to passively vent sub-slab soil vapor. A wind-driven turbine ventilator will be provided on the vent pipe outlet to assist passive ventilation. Soil vapor samples will then be collected from the soil vapor sampling probes to assess post-construction conditions. The objective of sub-slab soil vapor monitoring will be to measure VOC concentrations in soil vapor beneath the building that are less than 100 times the indoor air target risk levels. The factor of 100 is based on the DTSC recommended default attenuation factor for VOC migration from sub-slab soil vapor to indoor air (Cal/EPA, 2005b). If VOC concentrations in soil vapor exceed 100 times the indoor air target risk levels, DTSC may require the SSVS be upgraded to an active SSDS. The process and trigger levels for upgrading from SSVS to SSDS are discussed below. The design details for the SSVS will be submitted to DTSC in a separate work plan for review and approval prior to SSVS construction. The SSVS will be designed so that it can be upgraded to an active SSDS, if required by DTSC and determined necessary based on sub-slab soil vapor data. The upgrade would involve connecting the SSVS to a blower on the roof of the future on-site building to allow for active depressurization beneath the building. The blower would be designed and operated to allow the SSDS to create a lower pressure directly underneath the building floor relative to the pressure within the building to inhibit soil vapor from migrating into the building. The lower pressure would be confirmed by measuring the pressure in the soil vapor sampling probes installed beneath the building. The sub-slab VOC concentrations for triggering an upgrade from SSVS to SSDS will be included in the SSVS design work plan submitted to DTSC for review and approval. The SSVS (and SSDS if necessary) would be designed and operated to maintain a removal efficiency for indoor air exposure scenarios to achieve an indoor air risk of 1x10-6 or below and hazard index of 1 or lower. The time required to modify the SSVS to an SSDS is anticipated to be relatively minor (i.e., two to three months) as the key activities would be (1) submitting the design details for upgrading to an SSDS to DTSC for review and approval and (2) obtaining a Bay Area Air Quality Management District ( BAAQMD ) permit (if necessary) and installing a blower on the roof. As discussed at the end of this section, a BAAQMD permit may not be required if estimated and/or measured emissions from the SSDS are determined to be below BAAQMD s permitting thresholds. The SSDS will effectively mitigate vapor intrusion by reducing pressure below the building, and/or further reducing VOC concentrations in sub-slab soil vapor, due to higher sub-slab ventilation rates provided by the blower (i.e., enhanced SSVS ). Thus, Page 62 of 72

80 effectiveness of the SSDS can be demonstrated by either (a) measuring reduced pressure in the soil vapor sampling probes, or (b) demonstrating that VOC concentrations in soil vapor samples are reduced to less than 100 times the risk-based target levels for indoor air. Achieving either goal will indicate effective vapor intrusion mitigation, and it is likely that both goals will be achieved by an active SSDS. The capital and operation and maintenance costs associated with an SSDS (e.g., installation of a blower and ongoing electricity costs) are included in the cost estimate for Alternative 2 presented in Appendix C (i.e., it is conservatively assumed for cost estimating purposes that the system will be upgraded to SSDS). 29 The need to upgrade the SSVS to an SSDS will be determined following collection of soil vapor data from the layer of permeable material post-construction. The dimensions and materials assumed for constructing an SSVS are presented in the cost estimates included in Appendix C. The plans for this portion of the project, at a minimum, will be conceptually described in the RDIP based on typical construction drawings and descriptions. The specific plans will be prepared by CBS and submitted to DTSC for approval prior to the commencement of the building project Continued Function of Slurry Wall Under the proposed remedy, the portion of the existing slurry wall below the excavation will continue to function as a barrier to lateral migration of groundwater contained within the slurry wall. Since the base of the excavation will generally be above the potentiometric surface, with the exception of potential locations of deeper excavations into the saturated zone for elevator shafts, piles, pile caps, and grade beams, excavation activities are not anticipated to affect the slurry wall s ability to limit off-site migration of groundwater. If additional soil is excavated below the water table, the slurry wall will be avoided so that it continues to function as a barrier to groundwater flow. Any changes to the slurry wall as a result of the construction activities will be documented in a postremediation/pre-construction report. The report will include an analysis to demonstrate to the satisfaction of the DTSC and U.S. EPA that any changes to the slurry wall will not create conditions that will allow migration of groundwater containing chemicals of concern in the foreseeable future Institutional Controls DTSC and CBS will execute a LUC entitled Covenant to Restrict Use of Property, Environmental Restriction within 120 days after DTSC approved the FS/RAP. CBS will record the executed LUC with the Alameda County Assessor s Office. The LUC will restrict Site use and minimize the remaining potential for impacting human health and the environment after soil remediation. Provisions of the LUC will include, but not be limited to, the following: Restrictions on sensitive land use (e.g., residential housing, schools, day-care facilities, hospitals, hospices, etc.) on the ground level; 29 Vapor mitigation option B discussed below would also include some ongoing operation and maintenance costs. However, these costs are anticipated to be less than either an SSVS or an SSD system. Page 63 of 72

81 Restrictions on commercial/industrial use at the ground level of the building interior where an SSVS has not been installed; Restrictions on intruding and removing soil below 5.5 feet bgs or 12.5 feet msl except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Restrictions on all groundwater extraction and construction dewatering except as conducted pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Requirements of soil and groundwater management pursuant to the DTSC- and U.S. EPA-approved RDIP, O&M Plan, and other specific DTSC and U.S. EPA concurrences; Inspection and maintenance of subsurface portions of the building in accordance with a DTSC- and U.S. EPA-approved O&M Plan; Requirement of annual reporting and certification; Requirements for providing advance notification to DTSC and U.S. EPA of any planned construction or maintenance activities that may expose personnel to soil or groundwater; and Provisions for DTSC and U.S. EPA access to the Site. DTSC and CBS will enter into an O&M Agreement within 60 days following the submittal date of the draft remedy implementation report. The O&M Plan will be prepared after soil removal is completed and will provide a framework to manage residual COPCs in soil vapor, soil, and groundwater in a manner that is consistent with planned future land uses and is protective of human health for expected future populations. Main features of the O&M Plan will include, but not be limited to, the followings: A summary of conditions, based on informational soil sampling performed after excavation; Requirements for a Site-specific environmental health and safety plan to be protective of future maintenance/construction workers performing subsurface activities at the Site (if necessary) and may also specify certain types of work to be performed by 40-hour OSHA HAZWOPER trained personnel; Requirements for management of water collected during draining of any sub-grade structures; Page 64 of 72

82 Requirements for monitoring for methane in non-ventilated subsurface facilities until the determination can be made that methane gas in non-ventilated facilities is not a concern; and Long-term SSVS (or SSDS) operations and monitoring program Monitored Natural Attenuation This alternative includes installation of three groundwater monitoring wells within the slurry wall and three groundwater monitoring wells on the downgradient edge of the Site. Due to the health and safety concerns associated with groundwater sampling in the future commercial/industrial portion of the building, the groundwater monitoring wells within the slurry wall will be installed in the future ventilated parking garage. Given this limitation the pending building design, the wells may or may not be located in the area of greatest VOC concentrations in groundwater. However, DTSC prefers groundwater monitoring wells be installed close to locations with elevated VOC concentrations. It is assumed that each set of wells (within the slurry wall and at the downgradient edge of the Site) will consist of two wells with screen depths corresponding to the existing Site shallow wells (i.e., 10 to 25 feet bgs) and one with a screen depth corresponding to the existing Site deep wells (i.e., 25 to 40 feet bgs). The wells will not be screened below the slurry wall depth because the slurry wall is keyed into an impermeable unit and it would be inadvisable to penetrate that unit on or close to the Site. Under this alternative, a groundwater monitoring plan specifying well installation and sampling details will be submitted to DTSC and U.S. EPA for review and approval. The actual number, depths, screen lengths, and locations of groundwater monitoring wells will be decided on during DTSC and U.S. EPA s review and approval of this separate groundwater monitoring plan. 8.2 Contingencies and Uncertainties The proposed remedy is based upon proven technologies that can be successfully applied at the Site. However, several items were identified in the process of developing this FS/RAP that could alter the total estimated costs. Although a 25 percent contingency factor is added to the total capital costs for the proposed remedy, a change in some of the following assumptions could significantly alter calculations that arrived at the remedial alternative costs. In Situ Treatment Area: To potentially reduce the area targeted for in situ treatment, this FS/RAP proposes an investigation using MIP and HPT be performed in the northeastern portion of the Site within the slurry wall. The cost estimates in Appendix C assume that, following these investigations, the area defined for treatment will be approximately 7,600 square feet. If investigation activities result in a smaller treatment area, costs will be less than those estimated in Appendix C. Additionally, a separate in situ treatment work plan will be submitted to DTSC for review and approval. This work plan may propose a different type or scope of Page 65 of 72

83 groundwater investigation and treatment activities, which may affect the costs of these activities. Dust and Odor Control: Dust and odor control at the Site will likely be a major concern to the local community. Dust and odor control measures will include conventional and effective measures to be identified in the selected contractor s Dust and Odor Control Plan; these measures will include, but not be limited to, using watering trucks, using an odor suppressant, stockpile covering, limiting vehicle speed on-site, limiting the rate of excavation (if necessary), limiting excavation in odorous areas (if necessary) to certain hours of the day, decontaminating vehicles and equipment as they leave contaminated areas, as well as dust monitoring and air sampling. Estimated costs for these items are incorporated in the cost estimates in Appendix C. However, if additional dust and odor control measures are found necessary to meet permit requirement, to protect the health of neighbors, or to limit nuisance odor issues, additional costs could be incurred. Shoring Design: The excavation boundary is expected to extend to the Site boundary (Figure 5) and may be stabilized by shoring. Materials and how the shoring will be installed (if used) will be specified in the selected contractor s excavation plan. Estimated costs for shoring are assumed to be based on surface area of exposed shoring, as incorporated in the cost estimates in Appendix C. However, if the selected contractor s excavation plan does not agree with the cost estimate assumptions, or, during shoring installation, unanticipated challenges are encountered, additional costs could be incurred. Landfill Acceptance: Prior to and following soil excavation, no additional soil confirmation sampling will be performed, and soil is expected to be transported off- Site for landfill disposal based on soil data from previous investigations. However, if additional soil characterization sampling is required prior to disposal, additional costs could be incurred. At a minimum, these additional costs will include field time to collect and manage samples, and costs for laboratory analytical services. However, significant increased costs may be incurred if additional sampling data lead to additional soil excavation, or changes to the disposal criteria that were assumed for cost estimates in Appendix C. Quantity and Disposal of Groundwater: Alternative 2 does not include excavation of saturated soil, that is, soil below the groundwater table. As such, cost estimates assume that the excavation area will not require dewatering, treatment of extracted groundwater, or disposal/discharge of extracted groundwater. Additional costs may be encountered if dewatering is required due to deeper soil excavation or rainfall during excavation activities. Maintenance of Existing Slurry Wall: Because Alternative 2 does not include excavation below the water table, excavation activities are not anticipated to affect the slurry wall s ability to limit off-site migration of groundwater. If it is necessary to excavate soil below the water table during implementation of Alternative 2 Page 66 of 72

84 (e.g., for placement of elevator shafts, piles and pile cap/grade beam systems), the slurry wall will be avoided. If building plans require impacting the slurry wall during construction activities, a detailed plan for how the integrity of the hydraulic barrier will be restored will be submitted to DTSC and U.S. EPA for review and approval. Estimated costs in Appendix C do not include these costs. Page 67 of 72

85 9.0 IMPLEMENTATION SCHEDULE An approximate implementation schedule to finalize the FS/RAP and to implement the soil excavation portion of the proposed remedy is provided below Public Comment Period Mid-November 2009 to Mid-December 2009 Final FS/RAP Early-January 2010 RDIP 30 March 2009 to Late-January 2010 Plans and Specifications Mid-August 2009 to February 2010 Contractor Bid, Award, and Contract Period February 2010 to March 2010 Soil Excavation Work 31 April 2010 to June Timeframe for RDIP includes preparation, submittal, DTSC and U.S. EPA review, and finalization of the Draft RDIP. 31 Length of time for soil excavation subject to change based on additional information and analysis presented in the RDIP. Page 68 of 72

86 10.0 NONBINDING ALLOCATION OF RESPONSIBILITY The California Health and Safety Code ( HSC ) section (e) requires DTSC to prepare a preliminary nonbinding allocation of responsibility (the NBAR ) among all identifiable potentially responsible parties ( PRPs ). HSC section (a) allows PRPs with an aggregate allocation in excess of 50% to convene an arbitration proceeding by submitting to binding arbitration before an arbitration panel. If PRPs with over 50% of the allocation convene arbitration, then any other PRP wishing to do so may also submit to binding arbitration. The sole purpose of the NBAR is to establish which PRPs will have an aggregate allocation in excess of 50% and can therefore convene arbitration if they so choose. The NBAR, which is based on the evidence available to DTSC, is not binding on anyone, including PRPs, DTSC, or the arbitration panel. If a panel is convened, its proceedings are de novo and do not constitute a review of the provisional allocation. The arbitration panel's allocation will be based on the panel's application of the criteria spelled out in HSC section (c) to the evidence produced at the arbitration hearing. Once arbitration is convened, or waived, the NBAR has no further effect, in arbitration, litigation or any other proceeding, except that both the NBAR and the arbitration panel's allocation are admissible in a court of law, pursuant to HSC section for the sole purpose of showing the good faith of the parties who have discharged the arbitration panel's decision. DTSC sets forth the following preliminary nonbinding allocation of responsibility for the Emeryville Mound Parcel: CBS Corporation is allocated 100% responsibility. Page 69 of 72

87 11.0 REFERENCES Alta, Work Plan, Groundwater Sampling and Analysis, Westinghouse Emeryville Site, Emeryville, California, Alta Geosciences, Inc., October Cal/EPA, Supplemental Guidance for Human Health Multimedia Risk Assessments of Hazardous Waste Sites and Permitted Facilities, California Environmental Protection Agency, Department of Toxic Substances Control, July Cal/EPA, Remedial Action Plan Policy, State of California Environmental Protection Agency, Department of Toxic Substances Control, Document Number EO PP, 16 November Cal/EPA, 2005a. Use of California Human Health Screening Levels (CHHSLs) in Evaluation of Contaminated Properties, California Environmental Protection Agency, January Cal/EPA, 2005b. Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air - Interim Final, California Environmental Protection, Department of Toxic Substances Control, Sacramento, California, revised February Cal/EPA, 2005c. Human Health Risk Assessment (HHRA) Note, HERD HHRA Note Number 1, California Environmental Protection Agency, Department of Toxic Substance Control, Human and Ecological Risk Division, issued 27 October 2005 Cal/EPA, Vapor Intrusion Mitigation Advisory, California Environmental Protection Agency, Department of Toxic Substance Control, Human and Ecological Risk Division, April 2009 (revised 8 May 2009). CDC, Third National Report on Human Exposure to Environmental Chemicals, United States Centers for Disease Control and Prevention, Atlanta, Georgia, EKI, Results of Investigations, Mound Parcel Site, Emeryville, California, Erler & Kalinowski, Inc., 12 February EKI, 2005a. Additional Investigations Report, Mound Parcel, Emeryville, California, Erler & Kalinowski, Inc., March EKI, 2005b. Revised Draft Human Health Risk Assessment for Proposed Transit Center/Commercial/Residential Redevelopment, Mound Parcel, Emeryville, California, Erler & Kalinowski, Inc., 7 November EKI, Response to DTSC Comment Letter dated, 28 February 2006 on the Revised Draft Human Health Risk Assessment for Proposed Transit Center/Commercial/ Residential Development, Erler & Kalinowski, Inc., 14 March Page 70 of 72

88 EKI, Final Work Plan for Groundwater Sampling on the Emeryville Mound Parcel, Emeryville, California, Erler & Kalinowski, Inc., 18 March EMCON, Westinghouse Emeryville Data Summary Report, Emeryville, California, EMCON Associates, 13 October Helley et al., Flatland Deposits of the San Francisco Bay Region, California; Their Geology and Engineering Properties, and Their Importance to Comprehensive Planning, U.S.G.S. Professional Paper 943, U.S.G.S., Reston, VA, 88 p, by Helley, E.J., K.R. LaJoie, W.E.Spangle, and M.L. Blair, LBNL, Analysis of Background Distributions of Metals in the Soil at Lawrence Berkeley National Laboratory, Lawrence Berkeley National Laboratory, Environmental Restoration Program, June RWQCB, East Bay Plain Groundwater Basin Beneficial Use Evaluation Report, California Regional Water Quality Control Board, San Francisco Bay Region, June Singh et al., The Lognormal Distribution in Environmental Applications, U.S. EPA/600/R-97/006, Singh, A.K., Singh, Anita, and Engelhardt, M., December U.S. EPA, Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA: Interim Final, U.S. Environmental Protection Agency Document No. EPA/540/G-89/004, October U.S. EPA, Risk Assessment Guidance for Superfund, Volume 1- Human Health Evaluation Manual, U.S. Environmental Protection Agency, December U.S. EPA, 1991b. Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions, Memorandum from Don R. Clay, Assistant Administrator, United States Environmental Protection Agency, Office of Solid Waste and Emergency Response, OSWER Directive No , 22 April U.S. EPA, National Contingency Plan, Nine Criteria for Evaluation, 40 CFR 300, U.S Environmental Protection Agency, 22 September U.S. EPA, The Role of Cost in the Superfund Remedy Selection Process, U.S. Environmental Protection Agency, Document No. EPA/540/F-96/018, September U.S. EPA, Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites, United States Environmental Protection Agency, Office of Solid Waste and Emergency Response, OSWER , December Page 71 of 72

89 U.S. EPA, ProUCL Version 3.0 Users Guide, U.S. EPA, Las Vegas, Nevada, April U.S. EPA, ProUCL Version 4.0 Technical Guide, U.S. Environmental Protection Agency, Office of Research and Development, Las Vegas, Nevada, April U.S. EPA, Regional Screening Levels for Chemical Contaminants at Superfund Sites, U.S. Environmental Protection Agency, September 2008 WCC, 1985a. Report on Investigations and Recommended Remedial Measures, Westinghouse Property, Emeryville, California, Woodward-Clyde Consultants, 8 April WCC, 1985b. Exterior Remedial Action Plan, Specifications and Procedures, Westinghouse Property, Emeryville, California, Woodward-Clyde Consultants, 9 July WCC, Implementation of Exterior Remedial Action Plan, Westinghouse Property, Emeryville, California, Deviations from Original Construction Plan, Woodward-Clyde Consultants, 13 January WSP, May 2008 Annual Groundwater Sampling and Analysis Report, Prepared for CBS Corporation, Former Westinghouse Site, Emeryville, California, WSP Environment & Energy, 19 September WSP, Workplan to Perform Pre-Excavation Soil Sampling for PCB Congeners for the Emeryville Mound Parcel in Emeryville, California, WSP Environment & Energy, 1 October Page 72 of 72

90 TABLE 1 IDENTIFIED CHEMICALS OF POTENTIAL CONCERN Emeryville Mound Parcel, Emeryville, California Identified COPCs (a) Matrix Soil Groundwater Soil Vapor PCBs X - - PCDDs and PCDFs as 2,3,7,8-TCDD (b) X - - VOCs and SVOCs Benzene X X X bis(2-ethylhexyl) Phthalate X X - Butyl Benzyl Phthalate - X - n-butylbenzene X - - sec-butylbenzene X - - tert-butylbenzene X X - Carbon Tetrachloride - X - Chlorobenzene X X X Chloroethane - - X Chloroform - X - Chloromethane X - X 1,2-Dichlorobenzene X - - 1,3-Dichlorobenzene X - X 1,4-Dichlorobenzene X X X 1,2-Dichloroethane X - - 1,1-Dichloroethene X - - cis-1,2-dichloroethene X X X trans-1,2-dichloroethene X X - Dichloromethane (Methylene Chloride) X X - Ethylbenzene X - X Fluoranthene X - - Isopropylbenzene X Isopropyltoluene X Methylnaphthalene X - - Naphthalene X - - n-propylbenzene X - - Pyrene X - - A Page 1 of 2 October 2009 Erler & Kalinowski, Inc.

91 TABLE 1 IDENTIFIED CHEMICALS OF POTENTIAL CONCERN Emeryville Mound Parcel, Emeryville, California Identified COPCs (a) Matrix Soil Groundwater Soil Vapor VOCs and SVOCs (continued) Styrene - - X 1,1,2,2-Tetrachloroethane X - - Toluene X - X 1,2,3-Trichlorobenzene X - - 1,2,4-Trichlorobenzene X X - Trichloroethene X X - Trichlorofluoromethane X - - 1,2,4-Trimethylbenzene X - X 1,3,5-Trimethylbenzene X - - Vinyl Chloride X X - Xylenes X - X Metals Lead X X - Arsenic X X - Abbreviations: COPCs = chemicals of potential concern ITEF = International Toxic Equivalent Factors PCBs = polychlorinated biphenyls PCDDs = polychlorinated dibenzodioxins PCDFs = polychlorinated dibenzofurans SVOC = semi-volatile organic compound TEQ = toxic equivalent quotient VOC = volatile organic compound A dash (-) indicates that the chemical is not a COPC in that matrix Notes: (a) The process for identifying COPCs is described in the FS/RAP text. (b) The laboratory reported the analytical data expressed as a minimum 2,3,7,8-TCDD toxic equivalent quotient ("TEQ") for each sample. TEQs are based on International Toxic Equivalent Factors ("ITEFs"). A Page 2 of 2 October 2009 Erler & Kalinowski, Inc.

92 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC Resource Conservation and Recovery Act ("RCRA") Identification and Listing of Hazardous Waste (40 Code of Federal Regulations ["CFR"] Part 261) POTENTIAL CHEMICAL-SPECIFIC ARARs AND TBCs These regulations define RCRA hazardous waste if listed or characteristically hazardous. Toxicity Characteristic Leaching Procedure ("TCLP") criteria classify RCRA hazardous wastes for on-site or off-site disposal of excavated Site soil and extracted groundwater. ARAR RCRA Land Disposal Restrictions (40 CFR Part 268) RCRA hazardous wastes are potentially subject to land disposal restrictions. Land disposal restrictions can set performance requirements on treatment of the wastes for identified chemical constituents before land disposal. If chemical-specific universal treatment standards are exceeded, material must be treated prior to land disposal. ARAR Total Threshold Limit Concentrations ( TTLCs ) and Soluble Threshold Limit Concentrations ( STLCs ) (22 California Code of Regulations ["CCR"] Section ) Toxic Substances Control Act ("TSCA") (40 CFR Part 761 & 763) Title 22 of CCR lists TTLC and STLC values for classification of "hazardous" and "extremely hazardous" wastes. TTLC and STLC criteria for classifying California hazardous wastes are ARARs for on-site or off-site disposal of soil excavated from the Site. The TSCA PCB regulations specify treatment, storage, and disposal requirements for PCBs based on their form and concentration. TSCA Subpart D (storage and disposal) sets for cleanup and disposal option for sites with PCBs greater than 1 milligram per kilogram ("mg/kg"). More specifically, TSCA Subpart D (a) includes a prescriptive self-implementing cleanup program, TSCA Subpart D (b) provides for more flexibility in the cleanup program so long as the PCBs are remediated to a concentration less than 1 mg/kg, and TSCA Subpart D (c) provides for alternate risk-based remediation approaches under United States Environmental Protection Agency ("U.S. EPA") oversight. In addition, if PCBs are to be capped and managed in place, TSCA Subpart D contains the specific capping requirements. ARAR ARAR Federal Drinking Water Standards (40 CFR Part 141) and California Drinking Water Standards (22 CCR Section 64431, 64444, & 64449). National Pretreatment Standards (40 CFR Part 403) Chemical-specific drinking water standards are promulgated under the federal Safe Drinking Water Act as Maximum Contaminant Levels ( MCLs ). California has also promulgated drinking water standards, California MCLs. Shallow groundwater in the vicinity of the Emeryville Mound Parcel is not currently used for potable water supply and is not likely to be used as a drinking water source in the future. National Pretreatment Standards are implemented to control pollutants which pass through or interfere with treatment processe in Publicly Owned Treatment Works ("POTWs"). The remedial alternatives evaluated may include discharge of COCimpacted water to a POTW for treatment and/or disposal. ARAR ARAR A Page 1 of 8 October 2009 Erler & Kalinowski, Inc.

93 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC POTENTIAL CHEMICAL-SPECIFIC ARARs AND TBCs California State Water Resources Control These promulgated State policies address water quality objectives for the State of California. Board - 1) Sources of Drinking Water Resolution 88-63, 2) Nondegradation Policy Resolution 68-16, and 3) ARAR Containment Zone Policy Resolution Safe Drinking Water and Toxic Enforcement Act of 1986 ( Proposition 65 ) San Francisco Bay Basin Water Quality Control Plan ("Basin Plan") Proposition 65 prohibits the discharge, into a source of drinking water, of chemicals listed in 22 CCR Section et seq. The statute also requires that a reasonable warning be given to individuals who may be exposed to listed substances at levels posing an unacceptable risk. The Basin Plan outlines surface water quality objectives for selected toxic pollutants and quantifies concentrations of chemical constituents in amounts that adversely affect any designated beneficial use. ARAR ARAR Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California (40 CFR Section ) Lawrence Berkeley National Laboratory ("LBNL") background metal study The Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California (40 CFR Section ) ("California Toxics Rule") promulgates criteria for priority toxic pollutants in the State of California for inland surface waters and enclosed bays and estuaries. LBNL, located in Berkeley, California, conducted an evaluation of naturally occurring metals in soils to establish local background concentrations. These published background metal concentrations have been cited by Department of Toxic Substances Control ("DTSC") as applicable to the local area. ARAR TBC California Human Health Screening Levels ("CHHSLs") The CHHSLs were developed by the Office of Environmental Health Hazard Assessment ("OEHHA") on behalf of California EPA ("Cal-EPA") and are soil or soil gas concentrations that Cal-EPA considers to be below thresholds of concern for risks to human health. TBC U.S. EPA Regional Screening Levels for Chemical Contaminants at Superfund Sites ("RSLs") Porter Cologne Water Quality Control Act, California Water Code, Division 7, Section et seq. RSLs published by the U.S. EPA combine current U.S. EPA toxicity values with standardized exposure factors to estimate constituent concentrations in soil, groundwater, and ambient air that are protective of humans, including sensitive groups, over a lifetime on a screening-level basis. The Porter-Cologne Act is the basic water quality control law for California and is implemented by the State Water Resource Control Board ("SWRCB") and the Regional Water Quality Control Boards ("RWQCBs"). This law requires that anyone who is discharging waste or proposing to discharge waste which could affect the quality of the state s water must file a report of waste discharge with the appropriate RWQCB under the requirements of an issued National Pollutant Discharge Elimination System ("NPDES") permit. TBC TBC A Page 2 of 8 October 2009 Erler & Kalinowski, Inc.

94 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC POTENTIAL LOCATION-SPECIFIC ARARs AND TBCs San Francisco RWQCB ("SFRWQCB") This report presents a comprehensive evaluation of the beneficial uses of groundwater in the East Bay Plain Groundwater Groundwater Committee - East Bay Plain Basin in which Emeryville, California is located. This report classifies Emeryville as Zone B, where groundwater is unlikely t Groundwater Basin Beneficial Use be used as a drinking water resource, and states that remedial strategies should focus on protecting potential aquatic receptors Evaluation Report dated 21 April 2001 and potential future irrigation or industrial uses. TBC Requirements for Land Use Covenants (CCR Title ) Financial Assurance Requirement (California Health and Safety Code ) Regulatory Oversight - Soil Excavation and Handling (California Health and Safety Code and ) RCRA Treatment Standards (40 CFR ) POTENTIAL ACTION-SPECIFIC ARARs AND TBCs Requirement to establish a land use covenant to provide for long-term management at a site with residual chemicals at levels of concern. The regulation also specifies the procedures that must be followed when entering into a land use covenant. If operation and maintenance activities are required as part of the selected remedy, financial assurance must be provided throughout the time necessary to complete all required operation and maintenance activities. Addresses permitting and oversight regarding excavation and handling of soil. Section of the Health and Safety Code excludes on-site work from certain hazardous waste facility permitting requirements if the work is being conducted pursuant to a removal action plan or remedial action plan approved the DTSC and the cleanup complies with all applicable laws, rules, regulations, standards, and requirements. RCRA treatment standards for disposal of hazardous waste (soil and groundwater) include total waste standards, waste extract standards, and treatment technology standards. ARAR ARAR ARAR ARAR Federal Clean Air Act (42 United States Code ["USC"] Section ) Implementation of Federal Clean Air Act requirements has been delegated, in part, to California. The Bay Area Air Quality Management District ("BAAQMD") is the local implementing agency. Where BAAQMD requirements have been incorporated into the State Implementation Plan ("SIP") and approved by EPA, they are federally-enforceable. Where BAAQMD requirements have not been incorporated into the SIP and approved by EPA, they are not federally-enforceable. ARAR A Page 3 of 8 October 2009 Erler & Kalinowski, Inc.

95 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC POTENTIAL ACTION-SPECIFIC ARARs AND TBCs BAAQMD Rules and Regulations Applicable BAAQMD rules and regulations for remedial actions may include: a) Particulate Matter and Visible Emissions (Regulation 6) - limits the quantity of particulate matter in the atmosphere by controlling emission rates, concentration, visible emissions and opacity; b) Odorous Substances (Regulation 7) - establishes general limitations on odorous substances and specific emission limitations on certain odorous compounds; c) Aeration of Contaminated Soil and Removal of Underground Storage Tanks (Regulation 8, Rule 40) - limits the emission of organic compounds from soil that has been contaminated by organic chemical or petroleum chemical leaks or spills and describes an acceptable procedure for controlling emissions from underground storage tanks during removal or replacement; and, d) Hazardous Pollutants such as lead, vinyl chloride, and benzene (Regulation 11) - sets emission and/or performance standards for hazardous pollutants to limit the emissions of volatile organic. ARAR Regulation 8 Rules 15 & 40 are SIP-approved and are federally enforceable requirements. Federal Clean Water Act (33 USC 1251 et seq. and 40 CFR Parts ) Hazardous Waste Manifest System, Recordkeeping, and Reporting (40 CFR Parts 262, 263, & 264 and 22 CCR Sections 66262, 66263, & 66264, California Health and Safety Code ["CHSC"] Sections ) Hazardous Materials Transportation Regulations (49 CFR Parts 107, ) Includes requirements applicable to obtaining NPDES permit. Applicable for RCRA, non-rcra, and TSCA classified hazardous waste that may be transported off-site for treatment and disposal. Standards applicable to generators and transporters of hazardous waste and owners and operators of hazardous waste treatment, storage, and disposal facilities that include manifest, transport, recordkeeping, and reporting requirements. Federal regulations were established for the safe and secure transportation of hazardous materials in commerce under the federal hazardous materials transportation law (49 USC 5101 et seq.). These regulations are applicable to those who cause hazardous materials to be transported and to those who manufacture or maintain a packaging or a component of a packaging qualified for use in the transportation of a hazardous material. ARAR ARAR ARAR California Hazardous Waste Haulers Act (CHSC Sections ) State regulations concerning the transportation of hazardous waste, including all inspection, licensing, and registration of trucks, trailers, semi trailers, vacuum tanks, cargo tanks, and containers used to transport all types of hazardous wastes. No state or local agency, including, but not limited to, a chartered city or county, shall adopt or enforce any ordinance or regulation which is inconsistent with the rules and regulations adopted by the Department of Toxic Substances Control, the Department of the California Highway Patrol, or the State Fire Marshal pursuant to this article. ARAR A Page 4 of 8 October 2009 Erler & Kalinowski, Inc.

96 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC Soil Stockpiling Regulations (California Health and Safety Code (b)(4)(B)) POTENTIAL ACTION-SPECIFIC ARARs AND TBCs Stockpiles containing non-rcra hazardous waste may be accumulated on-site for off-site disposal without first obtaining a storage facility permit if specific conditions are met. If excavated soil that is classified as a non-rcra hazardous waste is stockpiled on-site prior to transportation to an off-site disposal facility, the requirements of this section would need to be met. ARAR TSCA (40 CFR (c)(9)) Occupational Safety and Health Administration (29 CFR Part ) and Hazardous Waste Operations and Emergency Response (CCR Title ) Requirements for the storage of bulk PCB remediation waste. Requirements for health and safety for on-site workers involved in hazardous waste operations and emergency response that are applicable to clean-up operations at sites recognized by governmental bodies as hazardous waste sites. ARAR ARAR California Environmental Quality Act ("CEQA") (Public Resources Code, Division 13, Section et seq.) Requirements for Land Use Restrictions (22 CCR ) Unless an exemption applies, CEQA requires completion of an Environmental Impact Report ( EIR ) or issuance of a Negative or Mitigated Negative Declaration before implementation of a project (such as redevelopment or remedial actions) that have the potential to have a physical impact on the environment. The purpose of an EIR is to provide State and local agencies and the general public with detailed information on the potentially significant environmental effects which a proposed project is likely to have and to list ways which the significant environmental effects may be minimized and indicate alternative to the project. Requires the execution and recording of a land use covenant imposing appropriate limitations on the use of the property when hazardous materials or substances will remain on the property at levels not suitable for unrestricted use of the property. ARAR ARAR Alameda County Public Works Agency - Wells Standard Program Regulations of groundwater wells and exploratory holes, as required by California Water Code Sections , for Emeryville, California are administered and enforced by the Alameda County Public Works Agency ("ACPWA") through the Well Standards Program. Applicable for well permits, installation, and destruction. TBC Porter Cologne Water Quality Control Act, California Water Code, Division 7, Section et seq. Establishes authority of SWRCB and RWQCB, and requires provisions to protect groundwater and surface water during remedial activities. California State Water Resources Control This resolution, the Antidegradation policy, applies to both surface water and groundwater. It may apply to cleanup activities Board - Nondegradation Policy that lead to discharge of pollutants into State waters, e.g., the San Francisco Bay, including groundwater. Under this Resolution resolution, discharge of contaminated groundwater is not permitted to high quality groundwater, unless it is in the public interest to allow such a discharge. TBC TBC A Page 5 of 8 October 2009 Erler & Kalinowski, Inc.

97 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC Reuse Policy (Resolution No ) by SFRWQCB POTENTIAL ACTION-SPECIFIC ARARs AND TBCs Resolution No urges dischargers of extracted groundwater from site cleanup projects to reclaim effluent, and when reclamation is not technically and/or economically feasible, to discharge to a POTW. If neither reclamation nor discharge to a POTW is technically or economically feasible and if beneficial uses of the receiving water are not adversely affected, the RWQCB can issue a NPDES permit authorizing discharge to surface waters. TBC East Bay Municipal Utility District ( EBMUD ) - Permit Program and Discharge Limitations Establishes permitting requirements for and limits on the quantity and quality of water that may be discharged to the local POTW via the sanitary sewer collection system. EBMUD is the local POTW that may potentially be utilized to discharge chemical of concern ("COC")-impacted water for treatment and/or disposal. The remedial alternatives evaluated may include discharge of COC-impacted water to the POTW for treatment and/or disposal. TBC Basin Plan Basin Plan, Pages 4-8 to 4-11, 4-13 to 4-14 Basin Plan, Pages 4-17 to 4-18; Table 4-1 Chapter 4 of the Basin Plan sets forth discharge prohibitions throughout the San Francisco Bay region. For alternatives involving a discharge, Pages 4-8 to 4-11 set forth effluent limitations for discharges to ocean waters and discharges to the San Francisco Bay. Pages 4-1 to 4-14 set forth requirements for the implementation of effluent limitations. In addition, Pages 4-14 to 4-15 of the Basin Plan affirm that the Regional Board regulates construction stormwater discharges through NPDES permits and requires the use of controls to reduce pollutants in stormwater. Remediation efforts may include groundwater extraction, and thus, the need for proper disposal of treated groundwater. The Basin Plan requires the discharger to minimize the discharge of toxic substances. Table 4-1 more broadly describes discharge prohibitions, e.g., with respect to toxic substances, solid wastes, silt, sediments, oil, and petroleum byproducts. Page 4-17 of the Basin Plan refers to SWRCB Resolution No , Disposal of Extracted Groundwater from Clean-up Projects, which urges dischargers of groundwater extracted from site clean-up projects to reclaim their effluent. It states that when reclamation is not feasible, discharges must be piped to a POTW. If neither reclamation nor discharge to a POTW is feasible, the RWQCB will issue NPDES permits authorizing discharge from these sites. Page 4-32 states that an NPDES permit will be required for the discharge of stormwater from construction activities involving disturbance of five acres or greater total land area or that are part of a larger common plan of development that disturbs greater than five acres of total land area. Pages 4-40 to 4-41 state that the RWQCB may impose further conditions, restrictions, or limitations on waste disposal or other activities that might degrade water quality. TBC TBC TBC Municipal Code of the City of Emeryville (Title 7, Chapter 5: Public Works - Grading) Requires that excavations and fills and construction in and around watercourses and public rights-of-way be performed in accordance with good engineering practices, thereby reducing to a minimum the hazards and damages to public and private property from such work. A grading permit will likely be required if remedial actions require removal or replacement of soil. TBC A Page 6 of 8 October 2009 Erler & Kalinowski, Inc.

98 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Requirement Description ARAR or TBC Municipal Code of the City of Emeryville (Title 6, Chapter 13: Sanitation and Health - Stormwater Management and Discharge Control Program) POTENTIAL ACTION-SPECIFIC ARARs AND TBCs Ensures the future health, safety, and general welfare of the public by: a) eliminating non-stormwater discharges to the municipal separate storm sewer, b) controlling the discharge to municipal separate storm sewers from spills, dumping or disposal of materials other than stormwater, and c) reducing pollutants in stormwater discharges to the maximum extent practicable. Protects and enhances the water quality of watercourses, water bodies, and wetlands in a manner pursuant to and consistent with the Clean Water Act. TBC Abbreviations: ARARs - Applicable or Relevant and Appropriate Requirements ACPWA - Alameda County Public Works Agency BAAQMD - Bay Area Air Quality Management District Basin Plan - San Francisco Basin Water Quality Control Plan Cal-EPA - California Environmental Protection Agency CCR - California Code of Regulations CEQA - California Environmental Quality Act CFR - Code of Federal Regulations CHHSLs - California Human Health Screening Levels CHSC - California Health and Safety Code COCs - chemicals of concern DTSC - California Department of Toxic Substances Control EBMUD - East Bay Municipal Utility District LBNL - Lawrence Berkeley National Laboratory MCLs - Maximum Contaminant Levels mg/kg - milligrams per kilogram NPDES - National Pollutant Discharge Elimination System OEHHA - Office of Environmental Health Hazard Assessment PCB - polychlorinated biphenyl POTWs - publicly owned treatment works Proposition 65 - Safe Drinking Water and Toxic Enforcement Act of 1986 RCRA - Resource Conservation and Recovery Act RSLs - United States Environmental Protection Agency Regional Screening Levels for Chemical Contaminants at Superfund Sites RWQCB - Regional Water Quality Control Board SFRWQCB - San Francisco Bay Regional Water Quality Control Board SIP - State Implementation Plan STLCs - Soluble Threshold Limit Concentrations SWRCB - State Water Resource Control Board TBC - To Be Considered A Page 7 of 8 October 2009 Erler & Kalinowski, Inc.

99 TABLE 2 LIST OF POTENTIAL ARARs AND TBCs Emeryville Mound Parcel, Emeryville, California Abbreviations (continued): TCLP - Toxicity Characteristic Leaching Procedure TSCA - Toxicy Substances Control Act TTLCs - Total Threshold Limit Concentrations USC - United States Code USEPA - U.S. Environmental Protection Agency A Page 8 of 8 October 2009 Erler & Kalinowski, Inc.

100 Technology or Process Option No Further Action Description No further remedial or investigative activity. Under this option, the existing slurry wall and asphalt cap would remain in place and on-going monitoring would continue. TABLE 3 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR UNSATURATED AND SATURATED ZONE SOIL (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Effectiveness Implementability Pros Cons Pros Cons NO ACTION - Effective at restricting populations utilizing the - Not effective at addressing requirements for the - Implementable for existing use. - Restricts Site use, no other use possible. Site for surface parking from direct exposure to Site closure remedial action objective ("RAO"). - Requires long-term maintenance. chemicals of concern ("COC") in soil. - No reduction in mobility, toxicity, or volume is - Effective for reducing the potential for leaching associated with this alternative. COCs from the unsaturated zone to groundwater - May not provide significant benefits due to low by reducing the area where COC concentrations concentrations of leachable COCs in vadose zone exceed leaching goals. (i.e., arsenic [potentially leachable due to - Effective at restriction groundwater migration. chemical conditions at the Site] and VOCs). - Not effective at reducing COC concentrations in groundwater and soil. Cost - No additional capital costs. - Low ongoing operation and maintenance ("O&M") costs associated with implementing the existing remedy. Conclusion Retain Institutional Controls Record Land Use Covenant ("LUC"), including well permit and- Effective for restricting exposure to COCs in excavation restrictions. Implement a long-term risk soil and groundwater. management plan that may include requirements for vapor control systems for future developments to cut off vapor intrusion of volatile organic compounds ("VOCs"). Can also include site fencing, security, land cover requirements. Varying degrees of institutional controls are likely appropriate as part of any remedial alternative, except "No Further Action", to reduce the potential for exposure to Site COCs in soil. Noninstitutional controls associated with the current remedy are already in place. INSTITUTIONAL CONTROLS - Not effective at addressing requirements for the Site closure RAO. - Not effective for addressing VOCs in soil vapor. - No reduction in mobility, toxicity, or volume is associated with this alternative. - Implementable. - Requires long-term enforcement of institutional controls. - Low to moderate capital cost for development of LUCs and risk-management plan. - Moderate capital costs and O&M costs for vapor control systems for future buildings (if necessary). - Costs of controls difficult to assess. Retain Soil Vapor Monitoring New or Replacement Engineered Cap Install soil vapor probes and monitor VOCs periodically. Consistent with regulatory agency recommendations, soil vapor data may be used preferentially in evaluating vapor intrusion risks. - Effective for monitoring vapor intrusion risk. - Not effective for addressing RAOs Installation of on-site soil vapor probe would not implementable if (1) future development is expected to utilize the entire Site property, and (2) future development is expected to include underground components will be below the groundwater table, and as such, the future development will not contain any soil in the vadose zone. Cover impacted areas of soil with a low-permeability barrier (such as existing Site cap), buildings, or pavement to limit human exposures to impacted soil and to reduce potential leaching of COCs from the unsaturated zone to groundwater. Requires ongoing O&M. - Effective for restricting direct exposure to COCs in soil. - Potentially effective at reducing potential leaching of COCs from the unsaturated zone to groundwater. SOIL CONTAINMENT OPTIONS - May not provide significant benefits due to low - Implementable. Currently, an engineered cap concentrations of leachable COCs in vadose zone exists at the Site. (i.e., arsenic [potentially leachable due to chemical conditions at the Site] and VOCs). - Not effective at reducing COC concentrations in groundwater. - Potentially low capital cost for soil vapor probe installation, but capital costs may be higher if limited by development. - Moderate O&M cost. - Requires long-term maintenance. - Moderate capital costs for installation or no capital cost if existing Site cap is utilized. - Low O&M costs. Retain Retain New or Replacement On- Site Land Containment Unit Excavate soil, potentially treat soil, consolidate, and place in an engineered cell. The engineered cell would be designed to limit exposure to and migration of COCs, and may include caps, liners, and leachate collection. May require formal creation of a hazardous waste landfill or a corrective action management unit ("CAMU") designation. Requires on-going maintenance and monitoring to verify effectiveness of the cell. - Effective for restricting exposure to COCs and reducing the potential for leaching COCs from the unsaturated zone to groundwater by reducing the area where COC concentrations exceed leaching goals. - Not effective for removing or reducing COC concentrations in soil. - Once implemented, potentially less restrictions on future development. - Not easily implementable because of the occurrence of COCs in soil across the Site. -Not easily implementable due to long-term maintenance and monitoring requirements, and extensive engineering standards. - High capital and permitting costs. - High O&M costs. Reject A Page 1 of 4 October 2009 Erler & Kalinowski, Inc.

101 TABLE 3 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR UNSATURATED AND SATURATED ZONE SOIL (a) Emeryville Mound Parcel, Emeryville, California Technology or Process Option Bioventing Soil Vapor Extraction Dual-Phase Extraction ("DPE") Electrokinetic Treatment Description In Situ Treatment Option: Vent the unsaturated zone to the atmosphere to volatilize or enhance aerobic biodegradation of COCs. Volatilized compounds may require treatment prior to discharge. Not applicable for saturated zone soils. In Situ Treatment Option: Apply vacuum to the unsaturated zone soil to volatilize COCs into soil vapor extracted for treatment Simultaneous extraction of soil vapor and groundwater to lower the water table and to remove VOCs and SVOCs from the unsaturated and saturated zone soils. May require treatment of extracted groundwater and soil vapor prior to discharge or disposal. In Situ Treatment Option: Place electrodes in the subsurface, which applies an electric field to attract and concentrate polar COCs to electrodes. Requires subsequent in situ treatment or removal of concentrated COCs near electrodes. Applicable for saturated or partially saturated soils. Screening Criteria Effectiveness Implementability Pros Cons Pros Cons SOIL REMEDIATION AND TREATMENT OPTIONS - Not effective for treating polychlorinated - Potentially implementable if bioventing biphenyls ("PCBs"), the most prevalent COC, infrastructure can be incorporated into future and metal COCs (arsenic and lead) which are not development. volatile and biodegradable - Not effective for treating COCs in the saturated zone. - Effectiveness limited by longer timeframe required for remediation. - Potentially effective for treatment of volatile and biodegradable COCs (VOCs and semivolatile organic compounds ("SVOCs")). - Potentially effective for removal of volatile COCs in the unsaturated soil. - Potentially effective at reducing concentrations of volatile COCs in soil, soil vapor, and groundwater. - Potentially effective for dissolved metal COCs (arsenic) in soil. - May be difficult to implement if proposed bioventing infrastructure is located within the area for future development. - Not effective for treating PCBs, the most - Potentially implementable if soil vapor - May be difficult to implement if proposed soil prevalent COC, and metal COCs (arsenic and extraction infrastructure can be incorporated into vapor extraction infrastructure is located within lead), which are not volatile. - Not effective for treating COCs in the saturated zone. - Effectiveness limited by potentially longer timeframe required for remediation, however, could be used to control vapor migration into overlying building (as a sub-slab depressurization system) the future development. the area for future development. - Effectiveness may be limited by low extraction rates through tight soils. - Not effective for treating PCBs, the most prevalent COC, and lead, which are not volatile or soluble. - Not effective for non-polar COCs (including PCBs, the most prevalent COC, other organic COCs, and lead). - Effectiveness limited by longer timeframe required for remediation. - Potentially implementable, especially if DPE wells and infrastructure can be incorporated into the future development. Cost - Moderate capital cost. - Moderate O&M costs. - Moderate capital cost. - Moderate O&M costs. - May be difficult to implement depending on the - Moderate capital costs. location of DPE wells and infrastructure with - Potentially high O&M costs for long-term respect to the area for future development. treatment. - Potentially implementable if electrodes and - May be difficult to implement if proposed applied electric field can be incorporated into the electrodes and electric field is located within the future development. area for future development. - High capital costs. - High O&M costs. Conclusion Reject Retain for longterm control, Reject as a remediation option Reject Reject Excavation Excavate soil containing COCs from the unsaturated zone. Excavated soil is transported off-site for disposal. - Effective for removing on-site COC mass, reducing potential exposure to COCs in soil, and reducing long-term threat to groundwater quality. - Likely most effective remediation for reducing PCBs in soil. - Following soil excavation from the unsaturated zone, VOCs from groundwater may diffuse into excavation backfill. - Likely implementable for unsaturated zone soils. - May require extensive control measures to reduce potential noise, dust, odor, and traffic impacts to the local community. - High capital cost. Retain Chemical Stabilization Excavate soil containing COCs from the saturated zone. Excavated soil is transported off-site for disposal. In Situ Treatment or Ex Situ Treatment with No Off-site Disposal Option: Mix soil in situ with solidifying and fixative agents to reduce the mobility of chemicals, then leave amended soil on-site. May require CAMU designation. Requires ongoing groundwater monitoring to evaluate effectiveness of stabilization. May impact geotechnical properties of soil and impact future development. - Effective for removing on-site COC mass, reducing potential exposure to COCs in soil, and reducing long-term threat to groundwater and surface water quality. - Likely most effective process option for reducing PCBs in soil. - Potentially effective for reducing leachable COC concentrations in soil and reducing potential for leaching to groundwater. - Some COCs at deeper depths may not be excavated due to implementability considerations and will therefore remain on-site. - May be difficult to stabilize arsenic and lead due to different stabilization requirements. - Though leachable concentrations may be reduced by stabilization, this process option does not remove COCs from soil. - Effectiveness limited by delivery and mixing of amendments into low-permeability soils. - Likely implementable for saturated zone soils. - Excavation dewatering water may require treatment prior to disposal. - May require extensive control measures to reduce potential noise, dust, odor, and traffic impacts to the local community. - High capital cost. Retain -- - Not likely implementable because of difficulty associated with in situ mixing and may have potential impacts to geotechnical soil properties that may impact future development. - Not easily implementable due to potential CAMU designation requirement. - On-Site ex situ chemical stabilization is not implementable because of limited space for an on site ex situ treatment system. - Moderate to high capital costs. - Moderate O&M costs. Reject Ex Situ Treatment Option with Off-Site Disposal: Requires - Potentially effective for reducing leachable excavation to be selected as a remedial technology. Mix COC concentrations in soil to meet lower criteria excavated soil with solidifying and fixative agents to reduce the for off-site disposal. mobility of COCs. Stabilization could be performed on-site or at an off-site facility. Treated soil will be taken off-site for disposal. - May be difficult to stabilize arsenic and lead - Chemical stabilization may only be due to different stabilization requirements. implementable off-site because of limited on-site - Though leachable concentrations may be space for a treatment system to occupy. reduced by stabilization, this process option does not remove COCs from soil. - Chemical stabilization may not provide significant benefit with respect to off-site disposal criteria for COCs. - On-site ex situ chemical stabilization is not implementable because of limited space for an on Site ex situ treatment system. - Moderate to high capital cost. - Low to no O&M costs. Reject A Page 2 of 4 October 2009 Erler & Kalinowski, Inc.

102 TABLE 3 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR UNSATURATED AND SATURATED ZONE SOIL (a) Emeryville Mound Parcel, Emeryville, California Technology or Process Option Enhanced Bioremediation Description In Situ Treatment with No Off-Site Disposal Option: Inject amendment, nutrients, and/or microorganisms to promote or enhance biological treatment of COCs. Screening Criteria Effectiveness Implementability Pros Cons Pros Cons SOIL REMEDIATION AND TREATMENT OPTIONS - Potentially effective for reducing concentrations - Treatability studies will be necessary to - Potentially implementable in a limited area. - May not be implementable over the entire Site of COCs that are biodegradable. demonstrate concentration reductions can be due to the varying concentrations of different achieved. COCs in soil. - Not effective for unsaturated soil. - Implementability may be limited by low - Not effective for PCBs, the most prevalent permeability soils which may limit uniform COC, or for metal COCS (arsenic and lead) distribution of injected amendment. which are not biodegradable. - For reductive bioremediation, effectiveness may be limited if concentrations of undesirable daughter products accumulate and if undesirable byproducts (e.g., methane and hydrogen sulfide) are produced. - Effectiveness may be limited if groundwater conditions are not conducive for bioremediation. - Effectiveness limited by longer timeframe required for remediation. Cost - Moderate capital costs associated with number and density of injection points due to the extent of impacted area, but may be higher cost if follow-up injections are necessary. - Moderate O&M costs. Conclusion Reject Ex Situ Treatment Option with Off-Site Disposal: Requires excavation to be selected as a remedial technology. Mix excavated soil with amendment, nutrients, and/or microorganisms for biological treatment. Treated soil will be taken off-site for disposal. - Potentially effective for reducing concentrations - Treatability studies will be necessary to of COCs that are biodegradable. demonstrate concentration reductions can be achieved. - Not effective for PCBs, the most prevalent COC, or for metal COCs (arsenic and lead), which are not biodegradable. Enhanced bioremediation may not provide significant benefit with respect to meeting off-site disposal criterion. - Effectiveness may be limited if concentrations of undesirable daughter products accumulate. - Effectiveness limited by longer timeframe required for remediation. - Enhanced bioremediation may only be - Not implementable because of limited space for - Moderate to high capital cost. Reject implementable off-site because of limited on-site an on-site ex situ treatment system. space for a treatment system to occupy. Chemical Oxidation In Situ Treatment with No Off-Site Disposal Option: Inject oxidant such as permanganate, hydrogen peroxide, sodium persulfate, and ozone to oxidize COC to non-toxic products. - Potentially effective for COCs susceptible to oxidation (i.e., some VOCs and SVOCs). - Treatability studies will be necessary to - May be implementable within a limited area of demonstrate concentration reductions can be saturated soil. achieved. - Not effective for treatment of unsaturated soil. - Not effective for PCBs, the most prevalent COC, which are not susceptible to oxidation. Limited effectiveness for metal COCs (arsenic and lead). - Effectiveness may be limited due to low permeability soil which may complicate delivery of injected oxidant. - Effectiveness may be limited if reducing conditions are present in saturated soil. - Potentially limited implementability because low permeability soils may limit uniform delivery of injected oxidant. - Moderate capital costs associated with number and density of injection points due to the extent of impacted area, but may be higher cost if follow-up injections are necessary. - Moderate O&M costs. Reject Ex Situ Treatment with Off-Site Disposal Option: Requires excavation to be selected as a remedial technology. Mix excavated soil with oxidants to treat organic COCs by oxidation. Treated soil will be taken off-site for disposal. - Potentially effective for COCs susceptible to oxidation (i.e., some VOCs and SVOCs). - Not effective for PCBs, the most prevalent - Chemical oxidation may only be implementable - Not implementable because of limited space for - Moderate to high capital cost. Reject COC, which are not susceptible to oxidation. Limited effectiveness for metal COCs (arsenic and lead). - Chemical oxidation may not provide significant benefit with respect to meeting off-site disposal criterion. - Effectiveness limited by longer timeframe required for remediation. off-site because of limited on-site space for a treatment system to occupy. an on-site ex situ treatment system. A Page 3 of 4 October 2009 Erler & Kalinowski, Inc.

103 TABLE 3 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR UNSATURATED AND SATURATED ZONE SOIL (a) Emeryville Mound Parcel, Emeryville, California Technology or Process Option Chemical Dechlorination Description Ex Situ Treatment with No Off-Site Disposal Option: Requires excavation to be selected as a remedial technology. Excavated soil containing PCBs is reacted with two liquid reagents: base (e.g., potassium hydroxide) and polyethylene glycols. The mixture is agitated and heated to 300 F. The reaction dechlorinates PCBs to a non-toxic product. The resulting soil is neutralized using a strong acid, which then is disposed of off- Site. The resulting solution may require further treatment (e.g., sorption of organic compounds by granular activated carbon) before discharge. Screening Criteria Effectiveness Implementability Pros Cons Pros Cons SOIL REMEDIATION AND TREATMENT OPTIONS - Potentially effective for reducing PCBs - Treatability studies will be necessary to concentrations to meet lower criterion for off-site demonstrate concentration reductions can be disposal. achieved on a consistent basis. - Not effective for reducing concentrations of metal COCs. - Chemical dechlorination may only be implementable off-site because of the need for complex series of reaction and regents, and limited on-site space for a treatment system to occupy. - Not implementable because of limited space for an on-site ex situ treatment system. - Implementation at example sites has occurred in drum-size reactors, as such, implementability of chemical dechlorination for large quantities of soil, such as the volume expected during the Site excavation, likely to be limited. Cost - Likely high cost because of complex nature of reactions, quantity of reagents, and need to treat resulting waste solution. Conclusion Reject Soil Washing Ex Situ Treatment with Off-Site Disposal Option: Requires excavation to be selected as a remedial technology. Extracted soil washed with a solution to extract COCs. Capture and treat extracted COCs in rinseate. Requires additional treatment or off-site disposal of rinseate and resulting slurry containing COCs. Treated soil will be disposed of off-site. - Potentially effective for removal of COCs from excavated soil to meet lower criteria for off-site disposal. - Extraction of PCBs from excavated soil likely not effective or may be difficult and require high volumes of wash solution. - Requires additional treatment or off-site disposal of rinseate and resulting slurry containing COCs Not easily implementable due to limited space for an on-site ex situ treatment system and potentially extended treatment time due to multiple soil washings to treat complex mixture of COCs. - Likely high cost because of the large volume of solution required to extract PCBs from soil. Reject Off-Site Landfill Disposal Transport excavated soil for land disposal at a permitted offsite disposal facility. Additional treatment such as off-site ex situ chemical stabilization or incineration may be required. - Effective for disposal of directly excavated soil or treated soil that qualifies for landfill disposal. OFF-SITE SOIL TREATMENT AND/OR DISPOSAL OPTIONS -May require treatment or stabilization before disposal. - Implementable. - Potential impacts to traffic. - Potentially high unit costs, in particular, if requiring treatment prior to disposal. Retain Incineration In Situ Vitrification Incinerate excavated soil at a permitted off-site facility at high temperatures to reduce concentrations of organic compounds prior to off-site landfill disposal. May be necessary if soil is identified as a RCRA hazardous waste and contains underlying hazardous constituents. Construct electrodes in the ground and apply electricity to melt soils containing COCs. Thermally destroy organic COCs, and produce a glass or crystalline structure with very low leaching characteristics. - Effective for reduction of organic COC concentrations, including PCBs, to meet off-site disposal criteria. - Effective for reducing organic COC concentrations, including PCBs, and reduce potential for leaching. - Not effective for metal COCs (arsenic and lead), which are not destroyed by incineration. Additional treatment for metals COCs may be required. - Effectiveness may be limited by migration of volatile COCs caused by heating soils. - Due to the likely large volume of soil to be vitrified, this option may be technically infeasible. - Implementable because incineration can be performed at an off-site facility and not occupy limited on-site space with a treatment system High unit cost. - Based on soil analytical data, no or limited need for incineration is likely. Retain (if needed) -- - Difficult to implement due to need to collect off-gas High capital cost. Reject generated. Notes: (a) Technologies and process options presented in this table are assessed considering the current remedial measures in place at the Site (i.e., a cap and slurry wall system). Abbreviations: CAMU - Corrective Action Management Unit COCs - Chemicals of Concern LUC - land use control O&M - operation and maintenance PCBs - polychlorinated biphenyls RAO - Remedial Action Objective SVOCs - semi-volatile organic compounds VOCs - Volatile Organic Compounds A Page 4 of 4 October 2009 Erler & Kalinowski, Inc.

104 TABLE 4 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR GROUNDWATER (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Technology or Process Option Description Effectiveness Implementability Pros Cons Pros Cons Cost Conclusion No Further Action No further remedial or investigative activity. Under this option, the existing remedial measures (i.e., cap and slurry wall system) and on-going monitoring would continue. - Effective at mitigating risks to potentially exposed populations utilizing the Site for surface parking. - Effective for reducing the potential for leaching chemicals of concern ("COCs") from the unsaturated zone to groundwater by reducing the area where COC concentrations exceed leaching goals. - Effective at restriction groundwater migration. NO ACTION - Not effective at addressing requirements for the Site closure remedial action objective ("RAO"). - No reduction in mobility, toxicity, or volume is associated with this alternative. - May not provide significant benefits due to low concentrations of leachable COCs in vadose zone (i.e., arsenic [potentially leachable due to chemical conditions at the Site] and VOCs). - Not effective at reducing COC concentrations in groundwater and soil. - Implementable No additional capital costs. - Low ongoing operation and maintenance ("O&M") costs associated with implementing the existing remedy. Retain Institutional Controls Groundwater Monitoring Soil Vapor Monitoring Slurry Wall Sheet Piling Record Land Use Covenant ("LUC") and Deed Restriction prohibiting use of groundwater for drinking water until drinking water standards are attained. Implement a long-term risk-management plan that may include requirements for vapor control systems for future developments to cut off vapor intrusion of volatile organic compounds ("VOCs") from groundwater. Install groundwater monitoring wells within the existing slurry wall and monitor COC concentrations periodically. Install soil vapor probes and monitor VOCs periodically. Consistent with regulatory agency recommendations, soil vapor data may be used preferentially in evaluating vapor intrusion risks. Maintain existing passive low permeability vertical walls around areas with impacted groundwater. The existing slurry wall was installed in 1985 to limit off-site migration of potentially-impacted groundwater. INSTITUTIONAL CONTROLS - Effective for restricting exposure to COCs. - Not effective at addressing requirements for the Site closure RAO. - Effective for monitoring groundwater concentrations with respect to risk levels and the Site closure RAO. - Implementable. - Requires long-term enforcement of institutional controls. - Not effective for addressing RAOs. - Potentially implementable if groundwater monitoring well locations can be incorporated into future development. - May be difficult to implement if proposed groundwater monitoring well locations are within the future development footprint. Installation of groundwater monitoring wells may be made more difficult, if, due to development limitations, the top of the monitoring well is below the piezometric surface at the Site. Within the slurry wall, the piezometric surface is estimated to be between approximately 10 and 12.5 feet mean sea level ("msl"), and between approximately 7.5 and 14 feet msl in the shallow wells outside the slurry wall (b). - Effective for monitoring vapor intrusion risk. - Not effective for addressing RAOs Installation of on-site soil vapor probe would not implementable if (1) future development is expected to utilize the entire Site property, and (2) future development is expected to include underground components will be below the groundwater table, and as such, the future development will not contain any soil in the vadose zone. - Effective at limiting off-site migration of groundwater based on available monitoring data. Construct vertical wall of interlocking steel sheet piling, - Effective for short-term use to reduce possibly with sealed joints. May be used in the short-term to groundwater inflow into an open excavation. reduce groundwater inflow into an open excavation. For longterm use, may be used to limit off-site migration of groundwater. GROUNDWATER CONTAINMENT ACTIONS - No active treatment of COCs. - Slurry wall has been constructed. No further implementation necessary. - Over the long-term, not effective in providing groundwater containment in addition to the existing slurry wall (see "Slurry Wall" above). - Implementable for short-term excavation shoring by driving sheet piling prior to excavation. - Low to moderate capital cost for development of LUC, Deed Restriction, and risk-management plan. - Moderate capital cost and ongoing O&M costs for vapor mitigation systems on future buildings (if necessary). - Moderate capital cost for groundwater monitoring well installation, but capital costs may be higher if limited by development. - Moderate ongoing O&M cost. - Low capital cost for soil vapor probe installation, but capital costs may be higher if limited by development. - Moderate ongoing O&M cost. Retain Retain Retain -- - Low ongoing O&M costs. Retain -- - High capital cost due to extent of shoring needed during the short-term. Retain for shortterm use, reject for long-term use A Page 1 of 5 October 2009 Erler & Kalinowski, Inc.

105 TABLE 4 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR GROUNDWATER (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Technology or Process Option Description Effectiveness Implementability Pros Cons Pros Cons Cost Conclusion GROUNDWATER CONTAINMENT ACTIONS Soil Cement Columns Construct in situ vertical wall of interlocking columns of soil and cement. May be used in the short-term to reduce groundwater inflow into an open excavation. For long-term use, may be used to limit off-site migration of groundwater. - Effective for short-term use to reduce groundwater inflow into an open excavation. - Over the long-term, not effective in providing groundwater containment in addition to the existing slurry wall (see "Slurry Wall" above). - Implementable for short-term excavation shoring by installing soil cement columns prior to excavation. - Chemically-impacted soil may be entrained in columns. - High capital cost due to extent of shoring needed during the short-term. Retain for shortterm use, reject for long-term use Permeable Reactive Barrier Install a subsurface passive treatment wall across the flow (PRB) path of groundwater impacted by COCs. The PRB would consist of a reactive substance (such as zero valent iron, chitin, or mulch) that would create conditions conducive for treatment, which would occur when groundwater flowed through the PRB. Engineered Cap Cover impacted areas of soil with a low-permeability barrier (such as existing Site cap), buildings, or pavement to limit human exposures to impacted soil and to reduce potential leaching of COCs to from the unsaturated zone to groundwater. Requires ongoing O&M. - Potentially effective at reducing some COC concentrations. - Potentially most effective if the PRB were installed in an area where the highest concentrations were detected, within the existing slurry wall. - Potentially effective at reducing leaching of COCs from the unsaturated zone to groundwater. - May not be effective at reducing all primary COCs in groundwater (i.e., arsenic, chlorinated VOCs, and benzene compounds) due to different chemical conditions needed for treatment. - Potentially implementable, especially if PRB is installed outside the footprint of the development. - Groundwater outside the slurry wall may not require treatment due to low COC concentrations (i.e., generally less than 10-times drinking water standards). - May not provide significant benefits due to - Implementable. Currently, an engineered cap low concentrations of leachable COCs in vadose exists at the Site. zone (i.e., arsenic [potentially leachable due to chemical conditions at the Site] and VOCs). - Not effective at reducing COC concentrations in groundwater. - May be difficult to implement the PRB within the existing slurry wall because the slurry wall would have to be removed to allow relative stagnant groundwater to flow through the PRB. - High capital costs for installation and likely high re-occurring capital costs to rejuvenate PRB. - Likely high O&M costs. - Requires long-term maintenance. - Moderate capital costs for installation or no capital cost if existing Site cap is utilized. - Low O&M costs. Reject Retain Groundwater Extraction Wells and Ex Situ Groundwater Treatment Extract groundwater from the shallow groundwater zone for hydraulic containment. Extracted groundwater may require treatment prior to disposal. - Potentially effective at reducing COC concentrations and providing localized hydraulic control. - Effectiveness of groundwater extraction - Potentially implementable, especially if system may be limited by potential for low groundwater extraction wells can be groundwater flowrate or dewatering, especially incorporated into the future development. if groundwater is pumped from within the slurry wall. - Over the long-term, not effective in providing hydraulic control in addition to the existing slurry wall (see "Slurry Wall" above). - May not be implementable for long-term use - Moderate to high capital costs. due to likelihood of dewatering, especially if - Potentially high O&M costs for long-term groundwater is pumped from within the existing treatment and disposal. slurry wall. May have to remove slurry wall to achieve acceptable pumping rates. - May be difficult to implement depending on the location of subsurface or aboveground features for the future redevelopment plans. Reject Groundwater Extraction Trenches and Ex Situ Groundwater Treatment Construct long-term trenches to intercept shallow groundwater flow for hydraulic containment. Extracted groundwater may require treatment prior to disposal. - Potentially effective at reducing COC concentrations and providing localized hydraulic control. - Effectiveness of groundwater extraction - Potentially implementable, especially if system may be limited by potential for low groundwater extraction wells can be groundwater flowrate or dewatering, especially incorporated into the future development. if groundwater is pumped from within the slurry wall. - Over the long-term, not effective in providing hydraulic control in addition to the existing slurry wall (see "Slurry Wall" above). - May not be implementable for long-term use - Moderate to high capital costs. due to likelihood of dewatering especially if - Potentially high O&M costs for long-term groundwater is pumped from within the existing treatment and disposal. slurry wall. May have to remove slurry wall to achieve acceptable pumping rates. - May be difficult to implement depending on the location of subsurface or aboveground features for the future redevelopment plans. Reject Excavation Dewatering Conduct short-term dewatering to intercept shallow - Effective for short-term excavation groundwater flow during soil excavation activities. Extracted dewatering. groundwater may require treatment prior to disposal. - May be effective for reducing COC mass in groundwater. - May not be effective at reducing Site-wide COC concentrations in groundwater. - Implementable for short-term use during excavation and may also be required to allow for excavation in the saturated zone Low to moderate capital and O&M costs. Retain A Page 2 of 5 October 2009 Erler & Kalinowski, Inc.

106 TABLE 4 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR GROUNDWATER (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Technology or Process Option Description Effectiveness Implementability Pros Cons Pros Cons Cost Conclusion ON-SITE GROUNDWATER TREATMENT OPTIONS Enhanced Reductive Dechlorination ("ERD") In Situ Treatment Option: Inject electron donor to promote or enhance microbial growth and biological breakdown of chlorinated ethenes. Externally cultured bacteria could be added to augment the activity of indigenous bacteria. -Potentially effective to reduce chlorinated ethenes concentrations in groundwater. ERD will likely be effective as indications of naturally occurring reductive dechlorination have been observed at the Site. - Likely effective if dechlorination processes proceed to the non-toxic end product of ethene. - Distribution of chlorinated ethenes in groundwater is limited at the Site. Additionally, concentrations of chlorinated ethenes may be reducing naturally, so ERD may not be necessary. - Potential to increase concentrations of undesirable daughter products (at least in the short term). - Less effective for reducing concentrations of total petroleum hydrocarbon ("TPH") compounds and benzene compounds. - Potential production of undesirable byproducts (e.g., methane and hydrogen sulfide). - Not effective for reducing concentrations of some COCs (e.g., phthalates, arsenic) Potentially limited implementability because low permeability soils may limit uniform delivery of injected electron donor. - Occurrence of elevated chlorinated ethene concentrations is limited. Therefore, capital cost for ERD will likely be low. Additional capital costs may be higher if follow-up injections are necessary. - Potentially moderate O&M costs. Reject Enhanced Aerobic Degradation ("EAD") In Situ Treatment Option: Inject oxygen release compound ("ORC") to promote or enhance microbial growth and biological breakdown of contaminants by aerobic processes. - Potentially effective for reduction of benzene and TPH concentrations in groundwater. - Potentially effective for reducing arsenic concentration in groundwater by converting arsenic to the less soluble +5 state. - Effectiveness may be limited if groundwater conditions are currently reducing. - Limited effectiveness for reducing chlorinated ethene concentrations. - EAD may not be effective at treating some COCs (e.g., phthalates). - Site-wide implementation may be limited given potential reducing conditions in groundwater; however, within a limited area of groundwater, EAD may be more implementable. - Potentially limited implementability because low permeability soils may limit uniform delivery of injected ORC. - Cost to implement EAD in a limited area, is likely to be low, but may be moderate to high if implemented over the entire Site. - Potentially moderate O&M costs. Retain Chemical Oxidation In Situ Treatment Option: Inject oxidant such as permanganate, hydrogen peroxide, sodium persulfate, and ozone into groundwater to destroy VOCs and TPH and immobilize metals by oxidation. - Potentially effective for reducing chlorinated ethenes concentrations without the formation of undesirable daughter products. - Potentially effective for reduction of benzene and TPH concentrations in groundwater. - Potentially effective for reducing arsenic concentrations by converting arsenic to the less soluble +5 state. - Effectiveness may be limited if reducing conditions are present in groundwater at the Site. - Effectiveness may be limited due to low permeability soil which may complicate delivery of injected oxidant. - Chemical oxidation may not be effective for some COCs (e.g., phthalates). - Likely implementable within a limited area of groundwater. - Potentially limited implementability because low permeability soils may limit uniform delivery of injected oxidant. - Site-wide implementation of chemical oxidation may be difficult given potential reducing conditions in groundwater. - Cost to implement chemical oxidation in a limited area is likely to be low, but may be moderate to high if implemented over the entire Site. - Moderate O&M costs. Reject Natural Attenuation Dual-Phase Extraction ("DPE") In Situ Treatment Option: Allow natural processes to attenuate or remediate COCs in groundwater. Simultaneous extraction of soil vapor and groundwater to remove VOCs and semi-volatile organic compounds ("SVOCs") from vadose zone, dissolved phase, and controlling groundwater migration by vacuum-enhanced groundwater extraction. May require treatment of extracted soil vapor and groundwater. prior to discharge or disposal. - Potentially effective to attenuate or remediate - Effectiveness of natural attenuation may be - Implementable as natural attenuation COCs by biological and physical processes over limited by production of harmful daughter processes are already occurring at the Site as the long-term to meet the Site closure RAO. Based on available data, COC concentrations have decreased naturally in groundwater at the Site. - No accumulation of undesirable daughter products from reductive dechlorination of PCE and TCE has been observed at the Site. products such as vinyl chloride, that, may increase in the short-term, but decrease over the long-term. evidenced by decreasing COC concentrations. - Potentially effective at reducing COC concentrations and providing hydraulic control. - Effectiveness may be limited by low extraction rates through tight soils. - Over the long-term, not effective in controlling groundwater migration in addition to the existing slurry wall (see "Slurry Wall" above). - Potentially implementable, especially if DPE wells can be incorporated into the future development. - May be difficult to implement if groundwater monitoring wells are within the future development footprint (see "Groundwater Monitoring" above) - May be difficult to implement depending on the location of subsurface or aboveground features for the future redevelopment plans. - Moderate capital costs associated with installation of groundwater monitoring wells at the Site, but capital costs may be higher if limited by development. - Moderate O&M costs. - Moderate to high capital costs. - Potentially high O&M costs for long-term treatment and disposal. Retain Reject A Page 3 of 5 October 2009 Erler & Kalinowski, Inc.

107 TABLE 4 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR GROUNDWATER (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Technology or Process Option Description Effectiveness Implementability Pros Cons Pros Cons Cost Conclusion ON-SITE GROUNDWATER TREATMENT OPTIONS Air Stripping Ex Situ Treatment Option: Extract groundwater then remove VOCs from extracted groundwater by aeration. May require treatment and monitoring of off-gas. - Potentially effective for reducing COC concentrations and providing hydraulic control. - In addition to air stripping to remove VOCs from extracted groundwater, additional treatment of extracted groundwater may be necessary to meet discharge requirements. - Over the long-term, not effective in controlling groundwater migration in addition to the existing slurry wall (see "Slurry Wall" above). - Potentially implementable, especially if groundwater extraction wells can be incorporated into the future development. - May not be implementable for long-term use - Moderate capital costs. due to likelihood of dewatering especially if - Moderate O&M costs. groundwater is pumped from within the existing slurry wall. May have to remove slurry wall to achieve acceptable pumping rates. - May be difficult to implement depending on the location of subsurface or aboveground features for the future redevelopment plans. Reject Filtration Ex Situ Treatment Option: Filtration of groundwater extracted - Effective for removing particulates and during construction and excavation dewatering to remove soil suspended solids, likely carrying sorbed metal particulates and suspended solids potentially containing metal COCs (lead) and PCBs, from extracted COCs (lead) and polychlorinated biphenyls ("PCBs"). groundwater. Ex Situ Treatment Option: Membrane filtration, such as reverse osmosis or nanofiltration, for removal of dissolved phase metal COCs. Removes metal COCs by passing extracted groundwater through a semi-permeable barrier or membrane. - Potentially effective for removal of dissolved metal COCs (arsenic). - Potentially effective if used as part of a treatment process train. - Not effective for treatment of COCs unless sorbed onto particulates. - Effectiveness may be limited by ability to remove COCs that are sorbed onto small (i.e., one micron or less) size solids. - Not effective for treatment of organic COCs. - Presence of organics and other inorganic compounds may foul the membrane. - Potentially implementable depending on particle size distribution, and concentrations of sorbed concentrations compared to discharge limits. - Spent filters may potentially need to be managed as a hazardous waste Not easily implementable due to high pressure requirements to force water through membrane and additional treatment and disposal of resultant concentrate. - Moderate capital cost. - Moderate to high O&M costs depending on frequency of filter changeout. - High capital cost. - Potentially high O&M costs. Retain Reject Publicly Owned Treatment Works ("POTW") Discharge extracted groundwater directly to sanitary sewer system for off-site treatment and disposal at the local POTW. Transport groundwater, via truck, to the local POTW for offsite treatment and disposal. OFF-SITE GROUNDWATER TREATMENT AND/OR DISPOSAL OPTIONS FOR WATER GENERATED DURING EXCAVATION DEWATERING - Effective for soil excavation below the groundwater table and disposal of extracted groundwater generated during dewatering. - Available groundwater data indicates that COC concentrations may be below applicable discharge limits, and as such, on-site treatment of groundwater may not be required prior to disposal. - Effectiveness of excavation below the water table may be limited by discharge restrictions to POTW during and 24-hours following a significant rainfall (defined during a call with East Bay Municipal District as greater than a drizzle). During such a time, generated groundwater needs to be stored on-site and discharged 24-hours after the significant rainfall. - If COC concentrations in groundwater detected during excavation exceed discharge limits, groundwater treatment may be needed prior to discharge. - Effective for soil excavation below the - Effectiveness of excavation below the groundwater table and disposal of extracted groundwater table may be limited by storage groundwater generated during dewatering in the capacity for generated groundwater and ability short-term. to transport generated groundwater to the - Available groundwater data indicates that POTW. COC concentrations may be below applicable - If COC concentrations in groundwater discharge limits, and as such, on-site treatment detected during excavation exceed discharge of groundwater may not be required prior to limits, groundwater treatment may be needed disposal. prior to discharge. - Likely implementable. - If COC concentrations in extracted groundwater meet the POTW's allowable limits (as expected based on available groundwater data), extracted groundwater may be discharged without treatment. - Discharge of groundwater directly to sanitary is more implementable than trucking the generated groundwater to the POTW. Discharge limits for VOCs may be higher for directly discharging to the sanitary sewer than for trucking to POTW and may require less extensive additional treatment. - Likely implementable for smaller volumes of groundwater generated from short-term dewatering as trucking does not impact capacity of the sewer system. - POTW located fairly close to the site. - Not likely implementable if discharge rate exceeds 100 gallons per minute. - If excavation activities occur during the rainy season, will need to account for potential need for storage of extracted groundwater generated during and 24-hours after the significant rainfall. - May require treatment prior to discharge if groundwater concentrations exceed POTW discharge limits. - May require traffic management plan to avoid impacting traffic in surrounding streets. - POTW establishes VOC specific discharge limits for trucked waste that May require more extensive treatment prior to disposal than directly discharging to the sanitary sewer. - Implementability may be limited if large volumes of groundwater are generated during excavation. - May require treatment prior to discharge if groundwater concentrations exceed POTW discharge limits. - Short-term Use: Moderate capital cost, however, may be higher if extensive treatment of extracted groundwater is required prior to discharge to POTW. Additional costs would be incurred during permitting process. Moderate to high ongoing costs, depending on groundwater volume generated. - Long-term Use: High cost for long-term disposal - Short-term Use: Moderate capital cost, however, may be higher if extensive treatment of extracted groundwater is required prior to discharge to POTW. Additional costs would be incurred during permitting process. Moderate to high costs, depending on groundwater volume generated. Long-term Use: High O&M costs for longterm disposal. Retain Retain A Page 4 of 5 October 2009 Erler & Kalinowski, Inc.

108 TABLE 4 SCREENING OF TECHNOLOGIES AND PROCESS OPTIONS FOR GROUNDWATER (a) Emeryville Mound Parcel, Emeryville, California Screening Criteria Technology or Process Option Description Effectiveness Implementability Pros Cons Pros Cons Cost Conclusion Off-Site Disposal Dispose of extracted groundwater at a permitted disposal facility. Temescal Creek under Discharge treated groundwater to Temescal Creek. National Pollutant Discharge Elimination System ("NPDES") Permit OFF-SITE GROUNDWATER TREATMENT AND/OR DISPOSAL OPTIONS FOR WATER GENERATED DURING EXCAVATION DEWATERING - Effective for soil excavation below the groundwater table and disposal of extracted groundwater generated during dewatering. COC concentrations in extracted groundwater may meet the disposal facility's allowable limits without additional treatment. - Effective as a disposal option for groundwater if NPDES permit standards for organics and inorganics can be met. - Not effective because Temescal Creek is located significantly south of the Site such that discharge to Temescal Creek would require construction of additional piping and infrastructure Likely implementable for very limited volumes - Not easily implementable for larger volumes of short-term excavation dewatering. of water or for long-term disposal. - Most likely implementable if longer-term groundwater treatment is deemed necessary. - Not easily implementable in short-term as the NPDES permit application process will likely be lengthy and expensive for discharge to shallow surface waters. - Treatment of groundwater to NPDES permit discharge standards may be difficult to meet. - Discharge to Temescal Creek cannot be implemented without additional construction of infrastructure. - Short-term Use: Moderate capital cost. - Long-term Use: High cost for long-term disposal - Short-term Use: Moderate capital cost, however, may be higher if extensive treatment of extracted groundwater is required prior to discharge to surface water. High costs would be incurred during permitting process. Moderate to high costs, depending on groundwater volume generated. - Long-term Use: High cost for long-term disposal Retain Reject Notes: (a) Technologies and process options presented in this table are assessed considering the current remedial measures in place at the Site (i.e., a cap and slurry wall system). (b) Elevation of piezometric surface estimated based on groundwater elevations measured over the previous five years (i.e., 2004 to 2008; WSP, 2008) Abbreviations: COCs - chemicals of concern EAD - enhanced aerobic degradation ERD - enhanced reductive dechlorination LUC - land use controls msl - mean sea level NPDES permit - National Pollutant Discharge Elimination System permit. A NPDES permit must be issued by the local Regional Water Quality Control Board prior to discharge of treated water to surface waters in the State of California, including discharge to a storm drain. O&M - operations and maintenance PCBs - polychlorinated biphenyls POTW - publicly owned treatment works PRB - permeable reactive barrier RAO - Remedial Action Objective TPH - total petroleum hydrocarbons VOCs - volatile organic compounds A Page 5 of 5 October 2009 Erler & Kalinowski, Inc.

109 TABLE 5 SUMMARY OF RISK ANALYSIS RESULTS FOR EVALUATING REMEDIAL ALTERNATIVES Emeryville Mound Parcel, Emeryville, California During Excavation Activities (a) Post-Construction (b) Remedial Alternative Earthwork/ Off-Site Commercial/ Child Off-Site Adult Off-Site Off-Site Commercial/ On-Site Commercial/ Child On-Site Resident Adult On-Site Resident Remediation Workers Industrial Worker Resident Resident Industrial Worker Industrial Worker (in Parking Garage) (c) (in Parking Garage) (c) HI CR HI CR HI CR HI CR HI CR HI CR HI CR HI CR Alternative 1: No Further Action na na na na na na na na 5E-05(d) 2E-08(d) na na na na na na Alternative 2: Soil Excavation for Foundation and Construction of Above-Grade Building Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal Alternative 4: Risk-Based Closure for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building - (e) na na 1E-02 2E-06 3E-04 2E-08 1E-04 3E-08 1E+03 2E-04 3E+02 4E-05 2E+02 3E-05 8E+01 1E-05 na na 9E-04 1E-06 2E-05 6E-09 1E-05 1E na na 9E-04 1E-06 2E-05 6E-09 1E-05 1E-08 Abbreviations: - = not calculated (see Note (d)) CR = Cancer Risk na = not applicable HHRA = Human Health Risk Assessment (EKI, 2005 and 2006) HI = Hazard Index Notes: (a) Risks during excavation activities were estimated in the HHRA prepared in 2005 and 2006 for a redevelopment scenario generally equivalent to Alternative 3 of this FS/RAP (EKI, 2005 and EKI, 2006). (b) Risks post-construction were estimated in Appendix B of this FS/RAP for each remedial alternative. (c) In the current development plans, upper floors will not be used for residential purposes. Therefore, estimating risks for this scenario using residential exposure assumptions is conservative. (d) For Alternative 1, human health risks were estimated based on vapor intrusion modeling using groundwater data and soil vapor data. The more conservative results (i.e., modeling results using soil vapor data) are presented in this table. (e) As discussed in the text, since the during construction risk estimates from the HHRA are conservative with respect to the recommended alternative (i.e., Alternative 2), these risk estimates are not updated in this FS/RAP. References: EKI, Revised Draft Human Health Risk Assessment for Proposed Transit Center/Commercial/Residential Redevelopment, Mound Parcel, Emeryville, California, Erler & Kalinowski, Inc., 7 November EKI, Response to DTSC Comment Letter dated, 28 February 2006 on the Revised Draft Human Health Risk Assessment for Proposed Transit Center/Commercial/ Residential Development, Erler & Kalinowski, Inc., 14 March A Page 1 of 1 October 2009 Erler & Kalinowski, Inc.

110 TABLE 6 ANALYSIS OF REMEDIAL ALTERNATIVES USING NCP CRITERIA Emeryville Mound Parcel, Emeryville, California REMEDIAL Alternative 1 Alternative 2 Alternative 3 Alternative 4 Description (a) 1) Maintenance of existing asphalt cap and slurry wall 2) Ongoing DTSC and U.S. EPA oversight 3) No further action 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately to 12.5 feet msl 4) Construction of sub-slab venting system 5) Construction of above-ground building 6) Institutional controls (Land Use Covenant, Operation and Maintenance Plan) 7) Slurry wall below 12.5 feet msl to remain on-site 8) Ongoing groundwater monitoring 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately 1 foot msl, and targeted "hot spot" soil excavation 4) Construction of sub-slab venting system 5) Construction of water-tight below-ground parking structure and/or office space 6) Institutional controls (Land Use Covenant, Operation and Maintenance Plan) 7) Slurry wall below 1 foot msl to remain on-site 8) Ongoing groundwater monitoring 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately 1 foot msl with additional soil excavation to attain remediation goals 4) Construction of sub-slab venting system 5) Construction of water-tight below-ground parking structure and/or office space 6) Institutional controls (Land Use Covenant) 7) Slurry wall below 1 foot msl to remain on-site 8) No ongoing groundwater monitoring THRESHOLD CRITERIA PRIMARY BALANCING CRITERIA Overall Protection of Human Health/ Environment Compliance with ARARs Long-Term Effectiveness Reduce Mobility, Toxicity, Volume Short-Term Effectiveness This alternative is protective of human health from direct This alternative protects human health from direct exposure to exposure to COPCs in soil and groundwater, and from exposure to COPCs in soil and groundwater, and from exposure to chemicals chemicals in groundwater via outdoor air. This alternative is in groundwater via indoor air. This alternative is protective of the protective of the environment because the potential for COPCs environment because the potential for COPCs leaching to leaching to groundwater is limited by a low-permeability cap (i.e., groundwater is limited with a low-permeability cap (i.e., future existing asphalt cap). Potential for COPC migration is limited by building). Potential for COPC migration is limited by the existing slurry wall, hydrophobicity of COPCs (e.g., PCBs), and remainder of the existing slurry wall following excavation, no on-site or nearby ecological receptors. hydrophobicity of COPCs (e.g., PCBs), and no on-site or nearby ecological receptors. Similar to Alternative 2. Similar to Alternative 2. Complies with ARARs. Similar to Alternative 1. Similar to Alternative 1. Similar to Alternative 1. This alternative is effective at protecting human health and the environment based on current land use. Long-term effectiveness depends on maintenance of the existing asphalt cap and slurry wall, and provides less reliability at protecting human health and the environment than the soil excavation alternatives (Alternatives 2 through 4). Under Alternative 1, chemicals in soil will remain on-site above risk-based levels of concern (assuming no engineering controls), and as such, this alternative provides the least long-term reliability. Additionally, Alternative 1 limits Site use to a surface parking lot. No reduction in mobility, toxicity, or volume is associated with this alternative. Effective - no short-term exposures to COPCs associated with implementation of this alternative. Alternative 2 is effective at protecting human health and the environment. Based on the likely long-term nature of the proposed development, potential for exposure to COPCs and leaching COPCs to groundwater is limited by the building proposed for future development. As such, this alternative is expected to be effective at protecting human health and the environment in the long-term. Ongoing groundwater monitoring will also provide long-term control and knowledge regarding COPC concentrations in groundwater. However, despite removal of soil above 12.5 feet MSL, chemicals in soil will remain on-site above risk-based levels of concern (assuming no engineering controls). Therefore, the effectiveness at protecting human health for exposures to COPCs in the subsurface depends on long-term maintenance of institutional controls and engineering controls (i.e., physical barriers between on-site populations and COPCs in soil). Alternative 3 is effective at protecting human health and the environment. Based on the likely long-term nature of the proposed development, potential for exposure to COPCs and leaching COPCs to groundwater is limited by the building proposed for future development. As such, this alternative is expected to be effective at protecting human health and the environment in the long-term. Ongoing groundwater monitoring will also provide long-term control and knowledge regarding COPC concentrations in groundwater. As part of this alternative, more PCB-impacted soil will be removed than Alternative 2, however, PCBs in soil above risk-based concentrations (assuming no engineering controls) will remain on-site. Therefore, the effectiveness at protecting human health for exposures to COPCs in the subsurface depends on long-term maintenance of engineering controls (i.e., physical barriers between on-site populations and COPCs in soil). Soil containing PCBs at levels exceeding the TSCA disposal Similar to Alternative 2. Similar to Alternative 2. criterion of 1,000 mg/kg will be incinerated. Soil characterized as a RCRA hazardous waste will undergo stabilization. Partially Effective. During excavation, short-term exposures to COPCs and potential off-site impacts from dust, odor, and traffic would be addressed by available mitigation measures. Following soil excavation, this alternative effectively reduces COPC concentrations in soil in the short-term for protection of human health. Under Alternative 4, to the extent practicable, soil will be removed to attain risk-based closure. As such, this alternative provides the greatest reliability in protecting human health and the environment. Similar to Alternative 2 with a greater potential for off-site Similar to Alternative 3, with a greater potential for off-site impacts due to longer excavation period and higher concentrations impacts due to longer excavation period. of some COPCs (e.g., PCBs) in soil to be excavated. A Page 1 of 2 October 2009 Erler & Kalinowski, Inc.

111 TABLE 6 ANALYSIS OF REMEDIAL ALTERNATIVES USING NCP CRITERIA Emeryville Mound Parcel, Emeryville, California REMEDIAL Alternative 1 Alternative 2 Alternative 3 Alternative 4 Description (a) 1) Maintenance of existing asphalt cap and slurry wall 2) Ongoing DTSC and U.S. EPA oversight 3) No further action 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately to 12.5 feet msl 4) Construction of sub-slab venting system 5) Construction of above-ground building 6) Institutional controls (Land Use Covenant, Operation and Maintenance Plan) 7) Slurry wall below 12.5 feet msl to remain on-site 8) Ongoing groundwater monitoring 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately 1 foot msl, and targeted "hot spot" soil excavation 4) Construction of sub-slab venting system 5) Construction of water-tight below-ground parking structure and/or office space 6) Institutional controls (Land Use Covenant, Operation and Maintenance Plan) 7) Slurry wall below 1 foot msl to remain on-site 8) Ongoing groundwater monitoring 1) Pre-excavation soil sampling for PCB congeners 2) Targeted additional groundwater characterization and in situ treatment 3) Excavation of soil to approximately 1 foot msl with additional soil excavation to attain remediation goals 4) Construction of sub-slab venting system 5) Construction of water-tight below-ground parking structure and/or office space 6) Institutional controls (Land Use Covenant) 7) Slurry wall below 1 foot msl to remain on-site 8) No ongoing groundwater monitoring PRIMARY BALANCING CRITERIA MODIFYING CRITERIA Implementability Readily implementable. Implementable. May require extensive control measures to reduce Similar to Alternative 2. on- and off-site exposures, potential noise, dust, and odor impacts Similar to Alternative 2. during excavation activities. Additional soil excavation, including excavation of saturated soil, Additional soil excavation, including excavation of saturated soil, is expected under Alternative 3, thus this Alternative may be more is expected under Alternative 4, thus this Alternative may be more difficult to implement than Alternative 2. difficult to implement than Alternatives 2 and 3. Costs See Table 6 See Table 6 See Table 6 See Table 6 State Acceptance Alternative may be acceptable. Likely to be acceptable. Likely to be acceptable. Most likely to be acceptable. Community Acceptance Alternative may be acceptable. Alternative likely to be acceptable. Alternative likely to be acceptable. Alternative likely to be acceptable. CONCLUSION The current Site use associated with Alternative 1 is not consistent with future development plans. Recommended alternative. The Site use associated with Alternative 3 is not consistent with future development plans. Incremental protectiveness to human health and environment is not justified by significantly higher costs and uncertainty associated with soil excavation to attain risk-based closure. Abbreviations: ARARs = Applicable or Relevant and Appropriate Requirements COPC = chemicals of potential concern DTSC = Department of Toxic Substances Control mg/kg = milligram per kilogram msl = mean sea level NCP = National Contingency Plan PCB = polychlorinated biphenyl TSCA = Toxic Substances Control Act U.S. EPA = United States Environmental Protection Agency A Page 2 of 2 October 2009 Erler & Kalinowski, Inc.

112 TABLE 7 SUMMARY OF ESTIMATED COSTS OF POTENTIAL REMEDIAL ALTERNATIVES Emeryville Mound Parcel, Emeryville, California Remedial Alternative Estimated Cost (2009 dollars) (a) Present Worth Present Worth Present Worth of Estimated of Estimated of Total Remedial Alternative Capital Costs Annual Costs (b) Estimated Costs (c) Alternative 1: No Further Action $20,000 $110,000 $130,000 Alternative 2: Groundwater Investigation and Treatment; and Soil Excavation for Foundation and Construction of Above-Grade Building (d) Alternative 3: Soil Excavation for Construction of One Below-Grade Floor and Overlying Building with Additional Targeted Soil Removal (d) Alternative 4: Risk-Based Closure for Future Commercial/Industrial Land Use and Construction of One Below-Grade Floor and Overlying Building (d) $5,000,000 $339,000 $5,300,000 $13,000,000 $151,000 $13,000,000 $16,000,000 $0 $16,000,000 Notes: (a) Backup tables for capital and annual costs are provided in Appendix C. (b) Consistent with U.S. EPA's A Guide to Developing and Documenting Cost Estimates During the Feasibility Study, dated July 2000, present worth of total estimated costs assume that annual costs will be experienced for 30 years. Present worth of estimated annual costs includes cap inspection for Alternatives 1 through 3, five years of groundwater monitoring for Alternative 1, on-going groundwater monitoring for Alternatives 2 and 3, and operation and maintenance of an active sub-slab vent system for Alternative 2. (c) Totals may not sum exactly due to rounding. (d) Excavation associated with Alternatives 2 through 4 is assumed to occur in A Page 1 of 1 October 2009 Erler & Kalinowski, Inc.

113 SITE LOCATION G:\A \Oct09\Fig01 - Site Location.dwg Layout1 Reference: Thomas Bros. Maps, San Francisco, Alameda and Contra Costa Counties, Notes: 1. All locations are approximate. (Approximate Scale in Feet) Erler & Kalinowski, Inc. Site Location Emeryville Mound Parcel Emeryville, CA October 2009 EKI A Figure 1

114 62nd STREET SHELLMOUND STREET POST OFFICE OFFICES RAILROAD TRACKS EMERYVILLE MOUND PARCEL HORTON STREET EMERYVILLE STATION NO. 1 59th STREET OFFICES HOLLIS STREET OFFICES AMTRAK STATION PELADEAU STREET HORTON STREET EMERYVILLE STATION NO. 2 CONDOMINIUMS POWELL STREET Reference: Pacific Aerial Surveys - Oakland, CA, August 24, Notes: 1. All locations are approximate. Erler & Kalinowski, Inc. Site Vicinity (Approximate Scale in Feet) Emeryville Mound Parcel Emeryville, CA October 2009 EKI A Figure 2

115 WCC-8 S-7 17 WCC-1 SS-5 EKI-4 W-3 B-5 S-5 D-5 Legend: (Approximate Scale in Feet) Soil Vapor Sampling Location W W-22 B-14 B-7 WCC-4 B EKI Soil Borehole Location 2004 EKI Soil Borehole Location Groundwater Monitoring Well Location G:\A \Oct09\Fig03 - Site Layout with Aerial Photo.dwg Railroad Tracks Amtrak Platform Overhead Pedestrian Bridge Railroad Tracks W-1 S-2R D-2R S-2 D-2 WCC-9 WCC-9A D-3 S-3 WCC-10 D-1 S-1 P-1 P-2 B-10 WCC-6 B-21 B-37 EKI-6 B-40 W-2 B-32 B-35 WCC-13B-26 B-36 B-16 EKI-2 B-11 B-44 W-20 B B-38 W-17 W-18 EKI-5 B-27 B-39 B-30 B-43 B-31 WCC-12 WCC-12A W-45 WCC-7 W B-34 WCC-11 WCC-14 B-41 S-8 B EKI-1 17 B-13 B-9 B-12 B-28 B-23 B-15 WCC-5 B-25 EKI-3 P-3 P-4 B-8 WCC-2 WCC-3 S-4 D-4 HORTON STREET 59TH STREET Notes: Existing Piezometer for Groundwater Sampling Borehole/Soil Sample Location for Previous Investigation by Others Abandoned Monitoring Well Location Slurry Wall Existing Fence Railroad Tracks Ground Surface Contour in Feet Mean Sea Level (NAVD88) (Note 4) All locations are approximate. Borehole locations were surveyed by MacLeod & Associates, November 2002 and December 2004 and groundwater monitoring locations were re-surveyed by PLS Surveys Inc. in August Pacific Aerial Surveys, Oakland, California, 24 August Elevations from topographic survey map provided by the City of Emeryville. Erler & Kalinowski, Inc. Site Layout with Aerial Photograph and Ground Surface Contours Emeryville Mound Parcel Emeryville, CA October 2009 EKI A Figure 3