Acronyms and Abbreviations... v. 1.0 Introduction Chemical Use Areas, Chemical Use Area Clusters, and Corrective Measures Study Areas...

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2 Contents Section Page Acronyms and Abbreviations... v 1.0 Introduction Chemical Use Areas, Chemical Use Area Clusters, and Corrective Measures Study Areas Comprehensive Data Quality Objectives Evaluation CUA Confirmation and Conditional NFA Area Documentation EEL Media specific DQO Evaluation DQO Evaluation for Surficial Media and Vadose Zone DQO Evaluation for Groundwater and Seeps Response to DTSC Comments on Draft RFI Reports Sampling and Analysis Plan Schedule References... 6 Appendices A EEL RFI Site Comprehensive Data Quality Objectives Evaluation B Responses to DTSC Comments Relevant to the EEL RFI Site C EEL RFI Site Data Gap Sampling and Analysis Plan D Vadose Zone Mass Flux to Groundwater Evaluation Tables 1 Chemical Use Summary for the EEL RFI Site 2a Current Status of DQO Evaluation for EEL RFI Site Soil, Sediment, Soil Vapor, and Surface Water 2b Data Summary Table for Exceedances for Detected Results 2c Data Summary Table for Exceedances for Nondetect Results 3 Corrective Measure Study Areas and Chemical Risk Drivers 4 Current Status of DQO Evaluation for EEL RFI Site Groundwater and Seeps 5 Summary of Proposed Samples by Matrix for the EEL RFI Site 6 Schedule for EEL RFI Site Data Gap Work Plan Activities Figures 1 Boeing RFI Subareas for Data Gap Categorization 2 EEL RFI Site CUAs and CUA Clusters ES BAO COPYRIGHT 2013 BY CH2M HILL, INC. III

3 Acronyms and Abbreviations Boeing BTV CMS CUA DCE DQO DTSC EEL GCL GSU mg/kg MWH RBSL RCRA RFI SAP SMOU SSFL TCE The Boeing Company background threshold value corrective measures study chemical use area dichloroethene data quality objective California Environmental Protection Agency, Department of Toxic Substances Control Environmental Effects Laboratory groundwater characterization level Geological Services Unit milligrams per kilogram MWH International, Inc. risk based screening level Resource Conservation and Recovery Act RCRA facility investigation sampling and analysis plan Surficial Media Operable Unit Santa Susana Field Laboratory trichloroethene ES BAO COPYRIGHT 2013 BY CH2M HILL, INC. V

4 Addendum to Master RCRA Facility Investigation Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California 1.0 Introduction This addendum to the Master Resource Conservation and Recovery Act Facility Investigation Data Gap Work Plan, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California Master RFI Data Gap Work Plan) was prepared for The Boeing Company Boeing) CH2M HILL, 2013a) and relates to the Environmental Effects Laboratory EEL) Resource Conservation and Recovery Act RCRA) facility investigation RFI) site also known as the Hydrogen Laboratory) in Boeing RFI Subarea 5/9 South at the Santa Susana Field Laboratory SSFL) in Ventura County, California. This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site located within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site that are located within Administrative Area IV are being characterized by the United States Department of Energy. As presented in Figure 1, Boeing RFI Subarea 5/9 South includes: The eastern portion of Group 5 in Administrative Area III, which includes the Systems Test Laboratory IV RFI site, Area III Sewage Treatment Plant RFI site, Compound A RFI site, and the southeast portion of the EEL RFI site. The southern portion of Group 9 located between Administrative Areas II and IV and south of Administrative Areas II, III, and IV. Other addenda to the Master RFI Data Gap Work Plan address the remaining portions of Boeing RFI Subarea 5/9 South. The Master RFI Data Gap Work Plan presents the overall framework and procedures to complete characterization of the nature and extent of contamination and to obtain necessary data to support a corrective measures study CMS) and conditional no further action recommendations 1 for all portions of SSFL that are not subject to either the December 6, 2010 United States Department of Energy Administrative Order on Consent for Remedial Action or the December 6, 2010 National Aeronautics and Space Administration Administrative Order on Consent for Remedial Action. The purpose of this addendum to the Boeing Master RFI Data Gap Work Plan is to: Summarize the chemical use areas CUAs) and CUA clusters that have been identified in the EEL RFI site to date. Document the comprehensive data quality objectives DQOs) evaluation for the EEL RFI site in Appendix A). Respond to California Environmental Protection Agency, Department of Toxic Substances Control DTSC) comments DTSC, 2009, 2010a, 2010b, and 2012) on the Draft Group 5 Central Portions of Areas III and IV RCRA Facility Investigation Report, Santa Susana Field Laboratory, Ventura County, California Group 5 RFI Report) CH2M HILL, 2008) that pertain to the EEL RFI site in Appendix B). Present the proposed data gap work plan for the EEL RFI site, which presents the plan for addressing data gaps identified through the DQO evaluation and response to comment processes in Appendix C). 1 A CNFA recommendation is based on current site information and weight of evidence documentation but is considered conditional pending resolution of Senate Bill 990, findings from future building demolition, and determination of background concentrations, analytical method reporting limits, and final regulatory requirements. ES BAO 1 COPYRIGHT 2013 BY CH2M HILL, INC.

5 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA 2.0 Chemical Use Areas, Chemical Use Area Clusters, and Corrective Measures Study Areas The EEL RFI site was investigated during previous site investigations conducted between 1993 through To date, 14 CUAs have been identified at EEL, as presented in Table 1 and on Figure 2. For the purposes of evaluation, CUAs were renumbered from what was presented in the CH2M HILL 2008 Group 5 RFI Report such that each individual CUA was allocated an individual number for identification. In addition, CUAs have been combined into CUA clusters based on similarities in operational history, geographic proximity, lithologic features, analytical data, and previous CMS recommendations. Every location where a chemical has been detected above a corresponding characterization level 2 has also been included in a CUA cluster. One CUA cluster has been identified at the EEL RFI site. Table 1 and Figure 2 present the CUAs and CUA cluster that have been identified to date at the EEL RFI site. Table 2a presents a summary of the nature and extent of contamination and contaminant fate and transport evaluations that have been performed to date for CUA cluster 1 at the EEL RFI site. Tables 2b and 2c present summaries of exceedances for detected and nondetect results, respectively. The Group 5 RFI Report CH2M HILL, 2008) presented the areas of the EEL RFI site that were recommended for CMS. These CMS areas were revisited during preparation of this data gap work plan to differentiate the areas that are recommended for CMS based on soil contamination from the areas that are recommended for CMS based on soil vapor contamination. During this process, the concentrations of the risk driving chemicals identified for EEL in the Group 5 RFI Report were compared to the most recent soil characterization levels and soil vapor characterization levels. The locations of samples with risk driving chemical concentrations that exceed the corresponding, most recent soil characterization levels or soil vapor characterization levels are included in the soil or soil vapor CMS areas. The resulting soil and soil vapor CMS areas are presented on Figure 2. The risk driving chemicals for each CMS area are presented in Table 3. Consistent with the DQO Report, these CMS areas were considered in identifying the data gaps for the EEL RFI site. These CMS areas are interim and subject to change following additional data collection and additional risk assessment. Final CMS areas will be presented in forthcoming Boeing RFI data summary and findings reports. 3.0 Comprehensive Data Quality Objectives Evaluation Data gaps for the EEL RFI site were identified by evaluating the DQOs identified in Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California DQO Report) CH2M HILL, 2013b) relative to the data and information specific to the EEL RFI site. The data gaps that were identified for the EEL RFI site through this process are presented in Appendix A. 3.1 CUA Confirmation and Conditional NFA Area Documentation In accordance with the DQO Report CH2M HILL, 2013b) and the Master RFI Data Gap Work Plan CH2M HILL, 2013a), Tables A 1 and A 2 in Appendix A contain the Conditional No Further Action Area Weight of Evidence Documentation for the Surficial Media Operable Unit SMOU) and the CUA Confirmation Status for newly identified features at the EEL RFI site. Table A 1 presents a comprehensive summary of the weight of evidence 2 With the exception of the vadose zone mass flux to groundwater and groundwater and seeps evaluations, the soil characterization levels used in preparing this work plan are the 2005 background levels, the suburban residential risk-based screening levels RBSLs) included in the May 2012 Gold Copy hard-drive deliverable, and the low-trv-based ecological RBSLs for soil included in the May 2012 Gold Copy hard-drive deliverable. The background levels and select RBSLs were updated in 2012 while this work plan was in development. The updated background levels and RBSLs will be used in future evaluations of data gaps for the EEL RFI site in accordance with the comprehensive DQO process. The background levels for aluminum, arsenic, and orthophosphate have changed significantly since Consequently, the most recent background levels for these three chemicals 37,900 milligrams per kilogram [mg/kg], 24.2 mg/kg, and mg/kg, respectively) were considered during the evaluation of soil data gaps. The 2012 background levels and RBSLs were used in the vadose zone mass flux to groundwater and groundwater and seeps evaluations presented in this work plan. The soil vapor characterization levels used in preparing this work plan are the residential soil vapor characterization levels presented in Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RFI Project, Santa Susana Field Laboratory, Ventura County, California CH2M HILL, 2013c) and the low-trv-based ecological RBSLs for soil vapor included in the May 2012 Gold Copy hard-drive deliverable CH2M HILL, 2012). 2 ES BAO COPYRIGHT 2013 BY CH2M HILL, INC.

6 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA assessment of any release or potential release of any chemical previously used, stored, handled, or disposed within the EEL RFI site for each of the activities listed in DQO Report Figure 2. Any release or potential release that has not already been identified, investigated, and documented in the CH2M HILL 2008 Group 5 RFI Report is identified in Table A 1 highlighted yellow or blue in Table A 1) and carried forward into Table A 2. The information presented in Table A 1 for portions of the EEL RFI site where a release or potential release of any chemical is not identified highlighted magenta in Table A 1) will be used to support a future conditional no further action recommendation for those portions of EEL. Table A 2 presents specific information on the newly identified releases or potential releases within the EEL RFI site and the planned approach for addressing these releases. In accordance with DQO Report Figure 2, each newly identified release or potential release identified in Table A 2 is either: 1) added to an existing CUA, 2) identified as a new CUA if there is clear documentation a release of chemicals to the environment has occurred, or 3) subjected to a screening level investigation in accordance with DQO Report Table 2 for suspect features). As presented in Table A 2, two potential CUAs A and B) have been identified since submittal of the Group 5 RFI Report that require investigation to determine if a newly identified release or potential release 3 should be carried forward as a new CUA in the media specific DQO tables for the EEL RFI site. In addition, Table A 2 identifies if new information has been obtained that should be added to the site conceptual model and carried forward into the media specific DQO tables for the EEL RFI site for an existing CUA. Appendix A also includes Figure A 1, which presents the locations of newly identified releases or potential releases and the potential CUAs identified for the EEL RFI site. Proposed samples to investigate the newly identified releases or potential releases are identified in Table C 1, EEL RFI Site Data Gap Sampling and Analysis in Appendix C. 3.2 EEL Media-specific DQO Evaluation DQO Evaluation for Surficial Media and Vadose Zone Consistent with the organization of DQO Report CH2M HILL, 2013b), Appendix A to this document includes the following media specific tables for the EEL RFI site SMOU and vadose zone: Table A 3: Data Quality Objectives for Surface Water Bodies at the EEL RFI Site Table A 4: Data Quality Objectives for Soil and Sediment at the EEL RFI Site Table A 5: Data Quality Objectives for the Vadose Zone at the EEL RFI Site These tables list the data gaps identified for each study question for surface water bodies, soil and sediment, and the vadose zone for CUA Cluster 1 through the DQO process. To complement these tables, Table 2a summarizes the current status of nature and extent and fate and transport evaluations performed for soil, sediment, soil vapor, and surface water at EEL RFI site CUA Cluster 1 to date. Tables 2b and 2c, which are provided electronically on the CD that accompanies this data gap work plan, presents details on the detect results and nondetect results, respectively, that exceed above characterization levels. Figures A 2, A 3, A 4, A 5, and A 6 in Appendix A present high level summaries of the soil and soil vapor characterization that has been performed to date at the EEL RFI site. These tables and figures are intended to represent the current status of investigations and evaluations only and will be revised as additional data are collected. Complete analytical, lithologic, and spatial data associated with the EEL RFI site are presented in the May 2012 SSFL Sitewide Gold Copy GIS Mapping and Analytical Geodatabase System CH2M HILL, 2012). The plan to address the data gaps identified in Appendix A is presented in the EEL RFI Site Data Gap SAP in Appendix C. 3 A newly identified release or potential release is one that has not already been identified, investigated, and documented in the CH2M HILL 2008 Group 5 RFI Report. A newly identified release or potential release can result in identification of a new CUA or can represent a newly identified source and/or newly identified chemicals) associated with an existing CUA. ES BAO 3 COPYRIGHT 2013 BY CH2M HILL, INC.

7 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA Vadose Zone Mass Flux to Groundwater Evaluation Available soil, soil vapor, and rock core vadose zone data were evaluated for the single EEL RFI site CUA cluster to determine whether any chemicals in the vadose zone pose a potential threat to groundwater. The compiled data were compared to background threshold values BTVs), if available, or groundwater characterization levels GCLs) if BTVs were not available. If the vadose zone concentration of a chemical in the environmental sample exceeded the BTV or GCL, further analysis was conducted. If the compiled analytical results did not exceed the BTV or GCL, the vadose zone to groundwater evaluation is considered complete for that location and CNFA, with respect to this evaluation, was recommended. Chemicals that exceeded BTVs or GCLs in the vadose zone were further evaluated against groundwater data for wells along the flow path to determine whether a particular chemical would be recommended for CMS for groundwater protection or whether transport modeling is required. To evaluate the chemical exceedances, data from existing monitoring wells were compared to GCLs. Monitoring wells within approximately 300 feet of the sample location or CUA cluster were selected through reviewing forward and backward particle tracks generated by the three dimensional groundwater flow model FEFLOW) under pumping and non pumping conditions, as presented in the Site Wide Groundwater Remedial Investigation Report MWH International, Inc. [MWH], 2009). Monitoring wells located downgradient under pumping and/or non pumping conditions include PZ 50, RS 15, and RS 17. Once these wells were identified, groundwater data for the wells were reviewed for chemicals that exceeded the GCLs in the vadose zone. If sampling results for these chemicals were available within the last 3 years for that well, the most recent data were used for comparison against the GCLs. If concentrations in the groundwater were above the GCLs, CMS for groundwater protection was recommended since the evaluation demonstrates that the CUA cluster has already impacted groundwater. If the concentrations in groundwater were below the GCLs, transport modeling was recommended to evaluate whether the CUA cluster would impact groundwater above GCLs within the next 50 years. The findings from this evaluation are presented in Appendix D. Based on this evaluation: CNFA with respect to vadose zone mass flux to groundwater is recommended for CUA cluster 1 for a subset of chemicals because there were no chemical exceedances detected in the environmental samples collected from this CUA cluster. CMS for groundwater protection is recommended at CUA cluster 1 for trichloroethene [TCE]. This list may be expanded following collection of additional samples. Additional groundwater samples are proposed for collection at three existing monitoring wells PZ 50, RS 15 and RS 17) to support completion of the vadose zone mass flux to groundwater evaluation. These samples will be analyzed for semivolatile organic compounds, total petroleum hydrocarbons, and metals. Fate and transport modeling is recommended for CUA cluster 1 to evaluate whether transport of contaminants from the vadose zone to groundwater at levels above GCLs will occur within the next 50 years for 1,1 dichloroethene DCE) and trans 1,2 DCE. This list may be expanded following collection of additional vadose zone samples at EEL and additional groundwater samples from monitoring wells PZ 50, RS 15 and RS 17. The transport modeling will be conducted as part of the data gap work plan implementation process, and the outcome will be used to complete the DQO process to support a CNFA or CMS recommendation for the CUA cluster. Additional details related to the vadose zone mass flux to groundwater evaluation performed at EEL RFI site are presented in Appendix D DQO Evaluation for Groundwater and Seeps Consistent with the organization of the DQO Report CH2M HILL, 2013b), Appendix A includes the following EEL RFI site media specific table for groundwater and seeps: Table A 6: Data Quality Objectives for Groundwater and Seeps at the EEL RFI Site 4 ES BAO COPYRIGHT 2013 BY CH2M HILL, INC.

8 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA This table lists the data gaps identified through the DQO process for each study question for groundwater and seeps in the EEL RFI site. To complement this table, Table 4 summarizes the current status of nature and extent of contamination and contaminant fate and transport evaluations performed for groundwater and seeps at the EEL RFI site to date. Table 4 is intended to represent the current status of investigations and evaluations only. This table will be revised as additional data are collected. Data were queried over the period January 1, 1984 through December 31, 2012 during analysis of available groundwater characterization data, and a review of data sufficiency and statistical trends was conducted. The results show the following: Source Zone Evaluation. Groundwater samples were collected at the water table from well PZ 50 at EEL in 2003, and additional sampling of this location is recommended. RS 15, northeast of EEL, has a sampling history spanning over 25 years. Existing and planned vadose zone sample results, coupled with sampling results from these wells, are used to characterize the sources at EEL. Adequacy of Existing Monitoring Well Network to Evaluate Flow Paths. As depicted on Figure A 7 in Appendix A, existing monitoring wells intercept groundwater sourced from the EEL RFI site. This evaluation is based on the forward particle tracks from the 3 dimensional SSFL groundwater flow model, as presented in the 2009 Site wide Groundwater Remedial Investigation Report MWH, 2009), coupled with backward particle tracks from monitoring wells. At this time, no additional wells are recommended to further evaluate potential impacts to groundwater of chemicals in soil. Adequacy of Existing Monitoring Well Network to Define Plume Nature and Extent. The existing monitoring well network defines the nature and extent of impacts from the EEL RFI site, in consideration of impacts to groundwater from adjacent RFI sites that include Compound A to the east and southeast, ECL to the eastnortheast, and STL IV to the south. As depicted on Figure A 7 in Appendix A, groundwater from the EEL site generally flows to the southwest under current, non pumping conditions), where some commingling may occur with groundwater from Compound A and STL IV. TCE impacted groundwater is laterally bounded by wells with concentrations less than GCLs, including RS 17 to the southwest and PZ 28 to the east/northeast, as shown in Figure A 7 in Appendix A. Although there are no vertically discrete sampling locations within EEL, sampling results from the vertical clusters to the west and southwest near STL IV RD 55B and RD 58B and C) and to the south of the Burro Flats fault SP 882G) show that VOCs have been characterized to below or near GCLs. The TCE concentrations in RD 55B 5.7 µg/l in July 2012) are very near the GCL of 5 µg/l, and vinyl chloride concentrations in RD 58C 0.56J µg/l in July 2012) are very near the GCL of 0.5 µg/l. At this time, no additional wells are recommended to further define the nature and extent of groundwater impacts from the EEL RFI site. Plume Stability Evaluation. The Boeing Environmental Data Management System for SSFL was queried for chemical concentration data from five wells ES 23, ES 28, ES 30, RS 15, and RS 17) associated with the EEL RFI site for the period ending December 31, The evaluation was conducted for TCE and cis 1,2 DCE. Trends in the data were analyzed using the Mann Kendall test at a 99 percent confidence level using a commercially available software package. This method for trend analysis is consistent with the alternatives identified in the DQO Report. Based on this plume stability evaluation, data indicate that the extent of impacted groundwater related to releases from EEL is not increasing laterally or vertically. As depicted on Figure A 7 in Appendix A, these wells within and at the boundaries of the EEL RFI site show decreasing or stable trends. At this time, no additional wells are recommended to evaluate plume stability for the EEL RFI site. 4.0 Response to DTSC Comments on Draft RFI Reports DTSC Geological Services Unit GSU) comments on the Group 5 RFI Report CH2M HILL, 2008; DTSC, 2009, 2010a, 2010b, and 2012) that pertain to the EEL RFI site and the corresponding responses to those comments are provided in Appendix B. Specifically, Appendix B includes the following tables: ES BAO 5 COPYRIGHT 2013 BY CH2M HILL, INC.

9 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA Table B 1: Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report Table B 2: Response to DTSC GSU Comments on the Groundwater evaluation portions of the 2008 EEL RFI Site Report Table B 1 presents the specific DTSC GSU comments and associated responses that pertain to the EEL RFI site. This Master RFI Data Gap Work Plan Addendum presents the responses to the general DTSC comments on the Group 5 RFI Report CH2M HILL, 2008). Other specific DTSC GSU Group 5 comments that pertain to other RFI sites in Boeing RFI Subareas 5/9 North or 5/9 South will be included in the future Master RFI Data Gap Work Plan addenda for those RFI sites. Table B 2 presents the DTSC GSU comments and associated responses that pertain to groundwater at the EEL RFI site. DTSC comments on all the Boeing RFI Reports Groups 1A, 1B, 5, 9, and 10) were reviewed and 19 general comment categories were identified. The 19 general comment categories were further separated into specific comment categories that are reiterated and found to be common to all Boeing RFI group and site reports. The recapitulated DTSC comments on the Boeing RFI reports and Boeing s responses to these comments were presented in Appendix A to the Master RFI Data Gap Work Plan CH2M HILL, 2013a). These responses are referred to, as appropriate, within the detailed response to each DTSC comment in Tables B 1 and B 2 in Appendix B. For each comment and response, Appendix B also lists the samples that are proposed to address DTSC s comment where applicable), other proposed data collection activities that are intended to address DTSC s comment where applicable), and the specific DQOs that the proposed samples and other data collection activities are intended to satisfy. Each recommendation for sample collection or other data collection activity is also carried forward into the EEL RFI Site Data Gap SAP in Appendix C. 5.0 Sampling and Analysis Plan This data gap work plan consists of a field sampling and analysis plan SAP) to address the RFI analytical data gaps that have been identified for the EEL RFI site. The EEL RFI Site Data Gap SAP to address the data gaps identified in Appendices A and B DQO evaluations and response to DTSC comments, respectively) is presented in Appendix C. Appendix C includes a table that lists the sample media, sample depth, and analytical groups for each proposed sample Table C 1) and a table that presents the analytical method proposed for each analytical group Table C 2). In addition, the rationale, the specific DQOs that the proposed sample are intended to satisfy, and the DTSC comments) that the proposed sample is intended to address where applicable) are identified in Table C 1 for each sample. Figure C 1 in Appendix C presents the locations of the proposed samples. A summary of the samples proposed for collection at the EEL RFI site is presented in Table Schedule The schedule for implementing the EEL RFI Site Data Gap Work Plan is presented in Table 6. The table also presents the activities and associated performance periods that are anticipated to collect all data necessary to support the final CMS area and no further action area conclusions for the EEL RFI site. 7.0 References California Environmental Protection Agency, Department of Toxic Substances Control DTSC) Memorandum from Laura Rainey/DTSC to Gerard Abrams/DTSC. Comments on Group 5 Central Portion of Areas III and IV RCRA Facility Investigation Report, Santa Susana Field Laboratory, Ventura County, California. December 9. California Environmental Protection Agency, Department of Toxic Substances Control DTSC). 2010a. Memorandum from Thomas M. Seckington/DTSC to Gerard Abrams/DTSC. Group 5 RFI Report. January ES BAO COPYRIGHT 2013 BY CH2M HILL, INC.

10 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA California Environmental Protection Agency, Department of Toxic Substances Control DTSC). 2010b. Memorandum from Brian Faulkner/DTSC to Gerard Abrams/DTSC. Partial Review of the Group 5 RFI Report for Santa Susana Field Laboratory, Ventura County, CA. May 17. California Environmental Protection Agency, Department of Toxic Substances Control DTSC) Memorandum from Don Greenlee/DTSC to Laura Rainey/DTSC and Roger Paulson/DTSC. HERO Comments on Group 5 Building 65 Metals Clarifier for the Santa Susana Field Laboratory SSFL) Project, Ventura County, California. February 21. CH2M HILL Group 5 Central Portions of Areas III and IV RCRA Facility Investigation Report, Santa Susana Field Laboratory, Ventura County, California. November. CH2M HILL SSFL Sitewide Gold Copy GIS Mapping and Analytical Geodatabase System hard drive deliverable). May. CH2M HILL. 2013a. Master Resource Conservation and Recovery Act Facility Investigation Data Gap Work Plan. March. CH2M HILL. 2013b. Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California. March. CH2M HILL. 2013c. Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RFI Facility Investigation Project, Santa Susana Field Laboratory, Ventura County, California. Appendix A to the DQO Report). March. MWH International, Inc. MWH) Site wide Groundwater Remedial Investigation Report, Santa Susana Field Laboratory, Ventura County, California. December. ES BAO 7 COPYRIGHT 2013 BY CH2M HILL, INC.

11 Tables

12 TABLE 1 Chemical Use Summary for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Chemical Use Area Types and Typical Target Analytical Suites Chemical Use Area Number a Potential Chemicals Used, Stored, EEL CUA Solvents Petroleum Fuels Gasoline Range Petroleum Fuels TPH, VOCs Diesel/ Motor Oil Range Petroleum Fuels TPH, SVOCs Hydrazine related Compounds VOCs, SVOCs Formaldehyde, NDMA) b Oil related Materials SVOCs, TPH, PCBs, Metals Waste Oils SVOCs, TPH, PCBs, Metals Metal and Inorganics exclusive of debris areas) Fluoride, Chloride, Nitrate, Sulfate, Bromide Debris Areas/ Fill Energetic Constituents Transformers Leach Field d Other TPH, Metals, VOCs, SVOCs, PCBs, Dioxins, Asbestos c Energetics, Metals Perchlorate PCBs Chemical Use Area Name Handled, or Disposed Cluster VOCs Metals, ph Perchlorate 1 EEL Cryogenic Test Cell Building 3271) Solvents, metals, oil, IPA 1 X X X X X X X e 2 EEL Storage Buildings 3109 and 3908) Solvents, metals, oil, IPA 1 X X X X X X X e 3 EEL Mechanics Workshop Buildings 3227, 3264) Solvents, metals, oil, IPA 1 X X X X X X X e 5 Tanks Hydraulic oil, gases hydrogen, nitrogen, helium) 1 X X 6 Transformers PCBs, SVOCs 1 X 7 Hazardous Materials Storage Pad VOCs, metals, oil 1 X X X X 8 TPH Soil Excavation Area TPH 1 X 9 Transformers PCBs, SVOCs 1 X 10 EEL Cryogenic Test Cell Building 3108) Solvents, metals, oil 1 X X X X 11 Tanks Hydraulic oil, gases hydrogen, 1 X X nitrogen, helium) 12 Tanks Hydraulic oil, gases hydrogen, 1 X X nitrogen, helium) 13 Tanks Hydraulic oil, gases hydrogen, 1 X X nitrogen, helium) 14 EEL Cryogenic Laboratory Building 3268) Solvents, metals, oil, PCBs, IPA 1 X X X X X X X X e Notes: a CUA 4 is an office building Building 3905, but also referenced as Building 3805 in some historical documents) that did not have any chemical uses. b Potential hydrazine impacts are evaluated by analyzing for hydrazine breakdown products: formaldehyde and n nitrosodimethylamine NDMA). c SVOCs and dioxins are sampled for if burned materials are observed or suspected. Asbestos are sampled for if potentially asbestos containing materials are observed. d The chemical groups associated with leach fields do not represent chemical groups used, stored, or released at the leach fields themselves. The chemical groups associated with the buildings that the leach fields serviced are considered in the review of leach field characterization for completeness. e Isopropyl alcohol Acronyms: COPC = chemical of potential concern CUA = chemical use area EEL = Environmental Effects Laboratory IPA = isopropanol PCB = polychlorinated biphenyl RFI = RCRA facility investigation SVOC = semivolatile organic compound TPH = total petroleum hydrocarbons VOC = volatile organic compound

13 TABLE 2a Current Status of DQO Evaluation for EEL RFI Site Soil, Sediment, Soil Vapor, and Surface Water Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California EEL CUA Cluster a Chemical Use Area Number 1 CUAs 2, 3, 8 through 14, and portions of CUAs 1 and 7 Study Question #1: Are all potential sources and chemicals identified in soil and sediment within CUAs? Sources, Operational History, and Physical Characteristics Yes. To be confirmed upon completion of processes presented in Figure 2 of the DQO Report and all activities listed in Table A 1 are complete. A summary of the CUA sources, operational history, and physical characteristics based on currently available information is provided below. CUA 1: EEL Cryogenic Test Cell Building 3271): Identified as SWMU 6.9 in the RFA. Used for testing various materials including carbon and stainless steel under high pressure hydrogen conditions from 1968 through One ton and 20 ton metal cooling towers where KP 1 was used were also located near or at Building CUA 2: EEL Storage Buildings 3109 and 3908): EEL equipment and material storage. It also contained one structure feature near Building CUA 3: EEL Mechanics Workshop Buildings 3227 and 3264): Mechanics workshop. It also contained one undefined feature south of Building CUA 7: Hazardous Materials Storage Pad: Hazardous materials were stored in drums on a concrete pad east of the cryogenic laboratory. CUA 8: TPH Soil Excavation Area: A removal action was conducted east of the cryogenic laboratory and south of the hazardous materials storage pad where 2 to 3 cubic yards of soil were removed and disposed of offsite. CUA 9: Transformers: Located south of the hazardous materials storage pad and at Building CUA 10: EEL Cryogenic Test Cell Building 3108): Contained a test cell associated with Building Used for testing various materials including carbon and stainless steel under high pressure hydrogen conditions from 1968 through CUA 11: Tanks: Small ASTs primarily used to store hydraulic oil for the vacuum pumps and several hydrogen and helium gas tanks. CUA 12: Tanks: Small ASTs primarily used to store hydraulic oil for the vacuum pumps and several hydrogen and helium gas tanks. CUA 13: Tanks: Small ASTs primarily used to store hydraulic oil for the vacuum pumps and several hydrogen and helium gas tanks. CUA 14: EEL Cryogenic Laboratory Building 3268): Identified as SWMU 6.9 in the RFA. Used for testing various materials including carbon and stainless steel under high pressure hydrogen conditions from 1968 Potential Chemicals Used/ Stored VOCs SVOCs TPH PCBs Study Question #2: Are the nature and extent of chemical distributions characterized to required characterization levels, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? b, c No. As described in Tables A 2, A 4, and A 5 in Appendix A and as detailed in Appendix C, additional soil vapor sampling is proposed to define the extent of VOCs to required SVCLs, to address elevated MRLs, and to evaluate newly identified features. A summary of the nature and extent of VOCs in soil and soil vapor based on currently available information is below. Refer to Tables 2b and 2c for details on the detect results and nondetect results, respectively, that exceed SCLs and SVCLs. Soil Vapor: Thirteen soil vapor samples were collected at 8 locations from 4 to 10 feet bgs between 1997 and 2008 and were analyzed for VOCs. Benzene, toluene, and TCE in soil vapor samples exceeded the SVCLs. The highest benzene and toluene concentrations were detected at the southern end of historical operations at the site. The lateral extent of benzene and toluene is defined by samples with results below SVCLs except to the east where concentrations are decreasing with distance, and the vertical extent is not defined. The highest TCE concentration was detected southwest of the former hazardous materials storage pad CUA 7). The lateral extent of TCE detected is defined by samples with results below SVCLs to the north and east, and concentrations are decreasing to the southwest and southeast with distance. Extent has not been defined to the west. The vertical extent is defined by bedrock. MRLs for multiple VOCs were greater than SVCLs. Soil: Thirty three soil samples were collected at 16 locations from 0 to 10.5 feet bgs between 1993 and 2008 and were analyzed for VOCs. No VOCs were detected above their SCLs. MRLs for 2 chloroethylvinylether were greater than its SCL. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to evaluate newly identified features. A summary of the nature and extent of SVOCs in soil based on currently available information is below. Soil: Twenty nine soil samples were collected at 14 locations from 0 to 10.5 feet bgs in 2008 and were analyzed for SVOCs. No SVOCs were detected above their SCLs. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to evaluate newly identified features. A summary of the nature and extent of TPH in soil based on currently available information is below. Soil: Twenty eight soil samples were collected at 20 locations from 0 to 10.5 feet bgs between 1993 and 2012 and were analyzed for TPH. The highest TPH concentration detected was TPH as diesel located south of CUA 14 at 1 foot bgs. SCLs have not been developed for TPH. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to address elevated MRLs and to evaluate newly identified features. A summary of the nature and extent of PCBs in soil based on currently available information is below. Refer to Tables 2b and 2c for details on the detect results and nondetect results, respectively, that exceed SCLs. Soil: Five soil samples were collected at four locations from 0 to 10.5 feet bgs between 2003 and 2012 and analyzed for PCBs. No PCBs were detected in any of the soil samples for which it was analyzed. However, MRLs for Aroclor 1242, Study Question #3: Are data adequate to understand the fate and transport of chemicals, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? No. As described in Table A 4, additional metals data are needed to define fate and transport of metals in soil at the site. A summary of the fate and transport of chemicals in soil and soil vapor based on currently available information is summarized below. Migration to Air: Migration of VOCs to air during operational use of solvents is not included in air dispersion modeling since these chemicals volatilize rapidly and do not result in residues/particulates. Air dispersion modeling is currently being performed for sources identified in the Air Dispersion Technical Memorandum CH2M HILL, 2013). The need to model potential sources in EEL RFI site CC1 will be determined after this modeling is complete. Migration of VOCs in soil to air will be evaluated. Based on existing soil vapor data targeting known operations, VOC source areas are considered generally defined for purposes of evaluating future migration of VOCs in soil vapor for risk assessment; however, the full extent of VOCs will be defined to the SVCLs as described in Study Question #2. Migration to Surface Water: VOCs, SVOCs, TPH, and PCBs were detected at concentrations below SCLs or low concentrations for TPH) in the surface soil sample collected from EEL CC 1; therefore, significant concentrations of these constituents in soil are not expected to migrate from EEL CC 1 via surface water runoff. In addition, migration of VOCs to surface water is not considered since VOCs volatilize rapidly and do not persist in the environment. Metals have been detected in surface soil samples from CUA 8 at concentrations that exceed SCLs. As described in Tables A 4 and C 1, samples are proposed downstream of CUA 8 to assess potential transport of metals from areas with exceedances toward the southern areas via surface water runoff. Migration to Vadose Bedrock and Mass Flux to Groundwater: VOCs, SVOCs, metals, and TPH were detected in soil or soil vapor at concentrations that exceed background or groundwater characterization levels. 1,1 DCE and trans 1,2 DCE were not detected in groundwater sampled from nearby monitoring wells along the flow path at concentrations that exceed the groundwater characterization levels. Vadose zone fate and transport modeling is recommended to evaluate future potential impacts of 1,1 DCE and trans 1,2 DCE to groundwater. Study Question #4: Do concentrations of chemicals within CUA Cluster exceed action levels? RFI recommendation: CNFA or CMS Assessment Yes. CMS areas were identified for TCE in soil vapor and arsenic in soil in the 2008 RFI Report CH2M HILL, 2008). The extent of the CMS areas will be further defined based on results from proposed sampling presented in this work plan. CMS areas were not previously identified for any additional constituents in the 2008 RFI Report CH2M HILL, 2008). Study Question #5: Are existing data sufficient to perform remedial planning? No. Remedial planning will be required for EEL CC 1. However, additional data collection efforts are recommended to support estimation of impacted soil volume within a tolerance of +50% / 30%. In addition, the volume of soil requiring corrective measures will be refined following reassessment of human health and ecological risks. ES BAO 1

14 TABLE 2a Current Status of DQO Evaluation for EEL RFI Site Soil, Sediment, Soil Vapor, and Surface Water Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California EEL CUA Cluster a Chemical Use Area Number Study Question #1: Are all potential sources and chemicals identified in soil and sediment within CUAs? Sources, Operational History, and Physical Characteristics through Contained multiple transformers, one of which showed staining around the valve. There were 1 ton and 30 ton metal cooling towers near Building 3268 that used KP 1. Documented historical releases of 2.5 to 80 gallons of water paint, aluminum powder and water, coolant, and hydraulic fluid occurred between 1975 and The site is located on the border between Administrative Areas III and IV. All structures at the site have been demolished, and all tanks have been removed. The site is currently unpaved due to demolition activities performed in Historically, areas near the buildings were paved. Topography in the central portion of the site slopes to the south and east. Throughout most of the site, soil is generally thin, typically ranging from less than 3 feet to 7 feet thick. Soil in the undisturbed areas of the site consists of weathered Chatsworth Formation materials, which are primarily fine grained, silty sands and clayey silts. Surface water exists intermittently at the site as the result of seasonal precipitation events. Surface water runoff flows generally south to the STP 3 RFI site, then through the Compound A Facility RFI site, and ultimately to the R 2 Discharge Ponds in Administrative Area II. Potential Chemicals Used/ Stored Dioxins and Furans Energetics and Perchlorate Metals and Inorganics Study Question #2: Are the nature and extent of chemical distributions characterized to required characterization levels, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? b, c Aroclor 1248, Aroclor 1254,and Aroclor 1260 were greater than SCLs. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to evaluate newly identified features. A summary of the nature and extent of dioxins and furans in soil based on currently available information is below. Refer to Tables 2b and 2c for details on the detect results and nondetect results, respectively, that exceed SCLs. Soil: Two soil samples were collected at one location from 5.5 to 10.5 feet bgs in 2008 and were analyzed for dioxins and furans. No dioxins and furans were detected above their SCLs. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to evaluate newly identified features. A summary of the nature and extent of energetics and perchlorate in soil based on currently available information is below. Refer to Tables 2b and 2c for details on the detect results and nondetect results, respectively, that exceed SCLs. Soil: Two soil samples were collected at one location from 5.5 to 10.5 feet bgs in 2008 and were analyzed for energetics and perchlorate. No energetics or perchlorate were detected above their SCLs. No. As described in Tables A 2 and A 4 in Appendix A and as detailed in Appendix C, additional soil sampling is proposed to define the extent of arsenic, barium, lithium, silver, and selenium to its SCL and to evaluate newly identified features. A summary of the nature and extent of metals and inorganics in soil based on currently available information is below. Refer to Tables 2b and 2c for details on the detect results and nondetect results, respectively, that exceed SCLs. Soil: Fifty six soil samples were collected at 30 locations from 0 to 10.5 feet bgs between 1993 and 2008 and were analyzed for metals or inorganics. The primary metal of concern at EEL CC1 is arsenic. Arsenic was detected in 49 of the 52 samples for which it was analyzed. Arsenic was detected above SCL in five samples. The five samples with exceedances are located within the historical TPH soil excavation area CUA 8), southeast of the transformer area CUA 6), and southwest of Building 3109 CUA 2). The lateral extent of arsenic was defined to below SCLs for all five samples except to the north of sample ELBS1014, where a sample was not collected. The vertical extent of arsenic is defined to below SCLs for all five samples except the vertical extent at sample locations ELBS1014 and ELSS01. Study Question #3: Are data adequate to understand the fate and transport of chemicals, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? Additional groundwater sampling is recommended for SVOCs, metals, and TPH at RS 15, RS 17, and PZ 50 to determine if vadose zone mass flux to groundwater modeling is required. Study Question #4: Do concentrations of chemicals within CUA Cluster exceed action levels? RFI recommendation: CNFA or CMS Assessment Study Question #5: Are existing data sufficient to perform remedial planning? Notes: a This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site located within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site that are located within Administrative Area IV are being characterized by the United States Department of Energy. b Refer to the Comprehensive SSFL GIS Mapping and Analytical Geodatabase System CH2M HILL, 2012) for the analytical data associated with all samples listed in this table. c Only primary samples are counted for purposes of calculating the number of samples, number of detections, or number of detections that exceed characterization levels in this table duplicate and split samples are not counted as separate samples). Conversely, all analytical results for primary, duplicate, and split samples that exceed characterization levels are shown in Tables 2b and 2c for detect and non detect results, respectively. Acronyms: AST = aboveground storage tank bgs = below ground surface CC = CUA cluster CMS = corrective measures study 2 ES BAO

15 TABLE 2a Current Status of DQO Evaluation for EEL RFI Site Soil, Sediment, Soil Vapor, and Surface Water Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California EEL CUA Cluster a Chemical Use Area Number Study Question #1: Are all potential sources and chemicals identified in soil and sediment within CUAs? Sources, Operational History, and Physical Characteristics Potential Chemicals Used/ Stored Study Question #2: Are the nature and extent of chemical distributions characterized to required characterization levels, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? b, c Study Question #3: Are data adequate to understand the fate and transport of chemicals, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? Study Question #4: Do concentrations of chemicals within CUA Cluster exceed action levels? RFI recommendation: CNFA or CMS Assessment Study Question #5: Are existing data sufficient to perform remedial planning? CUA = chemical use area EEL = Environmental Effects Laboratory MRL = method reporting limit PCB = polychlorinated biphenyl RFA = RCRA facility assessment SCL = soil characterization limit SVCL = soil vapor characterization limit SVOC = semivolatile organic compound SWMU = solid waste management unit TCE = trichloroethene TPH = total petroleum hydrocarbons VOC = volatile organic compound Sources: CH2M HILL Group 5 Central Portions of Areas III and IV RCRA Facility Investigation Report, Santa Susana Field Laboratory, Ventura County, California. November. CH2M HILL Recommended Approach for Air Dispersion Modeling, Boeing RCRA Facility Investigation Project, Santa Susana Field Laboratory. Appendix B to DQO Report). March. ES BAO 3

16 TABLE 2b Data Summary Table for Exceedances for Detected Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Stats Residential Characterization Level Comparisons 1 CUA Cluster EEL CC 1 EEL CC 1 EEL CC 1 EEL CC 1 EEL CC 1 EEL CC 1 EEL CC 1 Chem > Characterization Level # samples analyzed # samples detected Excavation Status Collection Date Sample ID for detects > Res RBSL Concentration Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for detects > Sample ID for detects > Concentration Eco Low Depth ft Concentration Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL VOCs - Soil Vapor ug/l) Trichloroethene 13 4 # Samples > Res # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL Res RBSL BTV RBSL RBSL BTV RBSL RBSL BTV In Place 7/17/1997 ELSV02S ELSV02S ELSV02S In Place 7/17/1997 ELSV03S ELSV03S In Place 7/11/1997 ELSV01S ELSV01S In Place 7/17/1997 ELSV03S Benzene 13 3 # Samples > Res RBSL Res RBSL BTV In Place 3/26/2008 ELSV1003S Toluene 13 6 # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL RBSL BTV RBSL RBSL BTV In Place 3/26/2008 ELSV1003S ELSV1003S In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S VOCs - Soil ug/kg) - No exceedances for detected results SVOCs - Soil ug/kg) - No exceedances for detected results PCBs - Soil ug/kg) - None detected Energetics - Soil ug/kg) - None detected Dioxin_Furans - Soil pg/g) - No exceedances for detected results Metals - Soil mg/kg) Arsenic # Samples > Res # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV Res RBSL BTV RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 12/5/1997 ELBS05S ELBS05S ELBS05S In Place 3/26/2008 ELBS1018D ELBS1018D ELBS1018D In Place 11/11/1997 ELBS02S ELBS02S ELBS02S In Place 5/23/1996 ELSS01S ELSS01S ELSS01S In Place 3/24/2008 ELBS1014S ELBS1014S ELBS1014S In Place 5/23/2008 ELBS1409S ELBS1409S In Place 3/24/2008 ELBS1016S ELBS1016S In Place 3/27/2008 ELBS1028S ELBS1028S In Place 3/26/2008 ELBS1021S ELBS1021S Aluminum # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 3/27/2008 ELBS1028X ELBS1028X In Place 3/26/2008 ELBS1027S ELBS1027S In Place 5/30/2008 ELBS1402X ELBS1402X In Place 3/26/2008 ELBS1021S ELBS1021S In Place 3/24/2008 ELBS1016S ELBS1016S In Place 3/24/2008 ELBS1029X ELBS1029X Barium # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 3/24/2008 ELBS1016S ELBS1016S Bottom Depth ft bgs) EEL CC 1 Detects Page 1 of 2

17 TABLE 2b Data Summary Table for Exceedances for Detected Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Stats Residential Characterization Level Comparisons 1 CUA Cluster EEL CC 1 Chem > Characterization Level # samples analyzed # samples detected Lithium Selenium Silver Cadmium Zinc Inorganics - Soil mg/kg) Phosphate 18 6 Excavation Status Collection Date Sample ID for detects > Res RBSL Concentration Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for detects > Sample ID for detects > Concentration Eco Low Depth ft Concentration Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 3/27/2008 ELBS1019S ELBS1019S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 3/24/2008 ELBS1016S In Place 3/24/2008 ELBS1014S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 9/16/2008 SWBS1006S In Place 9/16/2008 SWBS1006S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 3/27/2008 ELBS1019S In Place 3/27/2008 ELBS1028X # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV Excavated 2/17/1993 D D # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV Excavated 2/17/1993 D # Samples > Eco Low RBSL Eco Low RBSL BTV # Samples > Eco High RBSL Eco High RBSL BTV In Place 3/24/2008 ELBS1016S ELBS1016S In Place 3/26/2008 ELBS1011S ELBS1011S In Place 3/24/2008 ELBS1017S ELBS1017S In Place 3/24/2008 ELBS1014S ELBS1014S In Place 3/24/2008 ELBS1014D ELBS1014D In Place 3/26/2008 ELBS1012S ELBS1012S For Residential and Ecological screening, chemicals with a DTSC-approved background value undergo a two-tiered screening. Each result is first screened against the background threshold value BTV) to identify data potentially related to site operations, and then those data are compared to RBSLs. The ratio is calculated as the data result divided by the RBSL. 2 Low and High Ecological RBSLs are used for data comparison. Low ecological comparisons are based on low toxicity reference value TRV) RBSLs and are used for data gap analysis and sampling recommendations; high ecological comparisons are based on high TRV RBSLs and are used in conjunction with other lines of evidence for CMS and remedial planning recommendations Bottom Depth ft bgs) EEL CC 1 Detects Page 2 of 2

18 TABLE 2b Data Summary Table for Exceedances for Detected Results-No CC Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Stats Residential Characterization Level Comparisons 1 CUA Cluster No CC No CC Chem > Characterization Level # samples analyzed # samples detected VOCs - Soil Vapor ug/l) - No exceedances for detected results Metals - Soil mg/kg) - No exceedances for detected results Excavation Status Collection Date Sample ID for detects > Res RBSL Concentration Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for detects > Sample ID for detects > Concentration Eco Low Depth ft Concentration Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL Bottom Depth ft bgs) 1 For Residential and Ecological screening, chemicals with a DTSC-approved background value undergo a two-tiered screening. Each result is first screened against the background threshold value BTV) to identify data potentially related to site operations, and then those data are compared to RBSLs. The ratio is calculated as the data result divided by the RBSL. 2 Low and High Ecological RBSLs are used for data comparison. Low ecological comparisons are based on low toxicity reference value TRV) RBSLs and are used for data gap analysis and sampling recommendations; high ecological comparisons are based on high TRV RBSLs and are used in conjunction with other lines of evidence for CMS and remedial planning recommendations No CC Detects Page 1 of 1

19 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster EEL CC 1 Chem w/ Result > Characterization Level VOCs - Soil Vapor ug/l) Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Vinyl chloride FALSE FALSE 1,1,2,2-Tetrachloroethane FALSE FALSE Carbon Tetrachloride FALSE FALSE Benzene TRUE TRUE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL # Samples > Res RBSL Res RBSL BTV # Samples > Eco Low RBSL Eco Low RBSL BTV In Place 7/11/1997 ELSV01S ELSV01S In Place 7/17/1997 ELSV02S ELSV02S In Place 7/17/1997 ELSV03S ELSV03S In Place 7/17/1997 ELSV03S ELSV03S In Place 9/29/1999 ELSV08S ELSV08S In Place 3/26/2008 ELSV1003S In Place 3/26/2008 ELSV1004D In Place 3/26/2008 ELSV1004S In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S In Place 5/16/2008 ELSV1402S In Place 9/25/2008 SWSV1006S In Place 9/25/2008 SWSV1006S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S In Place 3/26/2008 ELSV1003S In Place 3/26/2008 ELSV1004D In Place 3/26/2008 ELSV1004S In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S In Place 5/16/2008 ELSV1402S In Place 9/25/2008 SWSV1006S In Place 9/25/2008 SWSV1006S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S In Place 3/26/2008 ELSV1003S In Place 3/26/2008 ELSV1004D In Place 3/26/2008 ELSV1004S In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S In Place 5/16/2008 ELSV1402S # Samples > Res # Samples > Eco Low Eco Low RBSL Res RBSL BTV RBSL RBSL BTV In Place 7/11/1997 ELSV01S ELSV01S In Place 7/17/1997 ELSV02S ELSV02S In Place 7/17/1997 ELSV03S ELSV03S Bottom Depth ft bgs) EEL CC 1 Non-detects Page 1 of 6

20 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster Chem w/ Result > Characterization Level Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Methylene chloride FALSE FALSE 1,1,1,2-Tetrachloroethane FALSE FALSE 1,1,2-Trichloroethane FALSE FALSE 1,2-Dichloroethane FALSE FALSE Chloroform FALSE FALSE Ethylbenzene TRUE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 7/17/1997 ELSV03S ELSV03S In Place 9/29/1999 ELSV08S ELSV08S In Place 3/26/2008 ELSV1004D In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S # Samples > Res RBSL Res RBSL BTV In Place 9/29/1999 ELSV08S In Place 3/26/2008 ELSV1003S In Place 3/26/2008 ELSV1004D In Place 3/26/2008 ELSV1004S In Place 3/26/2008 ELSV1004S In Place 5/16/2008 ELSV1402S In Place 5/16/2008 ELSV1402S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 7/11/1997 ELSV01S In Place 7/17/1997 ELSV02S In Place 7/17/1997 ELSV03S Bottom Depth ft bgs) EEL CC 1 Non-detects Page 2 of 6

21 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster EEL CC 1 EEL CC 1 Chem w/ Result > Characterization Level Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Trichloroethene 13 9 TRUE TRUE Toluene 13 7 TRUE TRUE VOCs - Soil ug/kg) 2-Chloroethylvinyl ether FALSE FALSE SVOCs - Soil ug/kg) Benzoa)anthracene TRUE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 7/17/1997 ELSV03S In Place 9/29/1999 ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 9/29/1999 ELSV08S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL RBSL BTV RBSL RBSL BTV In Place 7/11/1997 ELSV01S ELSV01S In Place 7/17/1997 ELSV02S ELSV02S In Place 7/17/1997 ELSV03S ELSV03S In Place 7/17/1997 ELSV03S ELSV03S In Place 9/29/1999 ELSV08S ELSV08S # Samples > Res RBSL Res RBSL BTV In Place 11/11/1997 ELBS02S In Place 11/11/1997 ELBS02S In Place 3/24/2008 ELBS1016S In Place 3/26/2008 ELBS1027S In Place 3/24/2008 ELBS1017S In Place 3/26/2008 ELBS1021S In Place 3/26/2008 ELBS1018S In Place 3/26/2008 ELBS1011S In Place 3/26/2008 ELBS1027S In Place 3/24/2008 ELBS1017S In Place 3/24/2008 ELBS1014D In Place 3/24/2008 ELBS1014S In Place 3/24/2008 ELBS1016S In Place 3/26/2008 ELBS1018S In Place 3/24/2008 ELBS1014S In Place 3/26/2008 ELBS1018D In Place 3/26/2008 ELBS1011S In Place 3/26/2008 ELBS1012S In Place 4/8/2008 ELBS1015S In Place 4/8/2008 ELBS1015S In Place 3/27/2008 ELBS1026S In Place 4/1/2008 ELBS1020S In Place 3/27/2008 ELBS1019S In Place 3/27/2008 ELBS1026S In Place 3/27/2008 ELBS1019S In Place 3/27/2008 ELBS1024S In Place 3/27/2008 ELBS1024S In Place 4/11/2008 ELBS1013S In Place 4/11/2008 ELBS1013S # Samples > Res RBSL Res RBSL BTV In Place 3/26/2008 ELBS1012S Bottom Depth ft bgs) EEL CC 1 Non-detects Page 3 of 6

22 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster EEL CC 1 EEL CC 1 Chem w/ Result > Characterization Level Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Indeno1,2,3-cd)pyrene TRUE FALSE n-nitrosodimethylamine FALSE FALSE Acenaphthylene TRUE FALSE bis2-ethylhexyl) phthalate TRUE FALSE Di-n-butyl phthalate TRUE FALSE PCBs - Soil ug/kg) Aroclor FALSE FALSE Aroclor FALSE FALSE Aroclor FALSE FALSE Aroclor FALSE FALSE Energetics - Soil ug/kg) 2,4,6-Trinitrotoluene 2 2 FALSE FALSE 2-Amino-4,6-Dinitrotoluene 2 2 FALSE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL # Samples > Res RBSL Res RBSL BTV In Place 3/26/2008 ELBS1012S # Samples > Res RBSL Res RBSL BTV In Place 3/26/2008 ELBS1012S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 3/26/2008 ELBS1012S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 3/26/2008 ELBS1012S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 3/26/2008 ELBS1012S # Samples > Eco Low RBSL Eco Low RBSL BTV In Place 9/17/2003 ELBS13S In Place 9/17/2003 ELBS14S In Place 9/16/2008 SWBS1006S In Place 9/16/2008 SWBS1006S In Place 5/22/2012 STBS1019S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 9/17/2003 ELBS13S In Place 9/17/2003 ELBS14S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 9/17/2003 ELBS13S In Place 9/17/2003 ELBS14S # Samples > Eco Low Eco Low RBSL RBSL BTV In Place 9/17/2003 ELBS13S In Place 9/17/2003 ELBS14S # Samples > Eco Low RBSL Eco Low RBSL BTV In Place 9/16/2008 SWBS1006S In Place 9/16/2008 SWBS1006S # Samples > Eco Low Eco Low RBSL RBSL BTV Bottom Depth ft bgs) EEL CC 1 Non-detects Page 4 of 6

23 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster EEL CC 1 EEL CC 1 Chem w/ Result > Characterization Level Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? RDX 2 2 FALSE FALSE Dioxin_Furans - Soil pg/g) - No exceedances for non-detected results Metals - Soil mg/kg) Thallium 39 7 TRUE FALSE Hexavalent Chromium 3 3 FALSE FALSE Selenium TRUE TRUE Zirconium 36 6 TRUE FALSE Mercury TRUE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 9/16/2008 SWBS1006S In Place 9/16/2008 SWBS1006S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL RBSL BTV RBSL RBSL BTV In Place 9/16/2008 SWBS1006S SWBS1006S In Place 9/16/2008 SWBS1006S SWBS1006S # Samples > Res RBSL and BTV Res RBSL BTV # Samples > Eco Low RBSL and BTV Eco Low RBSL BTV Excavated 2/17/1993 D D In Place 2/17/1993 D D # Samples > Res # Samples > Eco Low Eco Low RBSL Res RBSL BTV RBSL RBSL BTV In Place 1/29/1998 ELBS02S ELBS02S In Place 9/16/2008 SWBS1006S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV Excavated 2/17/1993 D D In Place 2/17/1993 D D In Place 3/26/2008 ELBS1018X ELBS1018X In Place 3/24/2008 ELBS1029X ELBS1029X In Place 3/27/2008 ELBS1028X ELBS1028X In Place 4/11/2008 ELBS1013S In Place 4/8/2008 ELBS1015X In Place 4/8/2008 ELBS1015S In Place 4/11/2008 ELBS1013S In Place 3/27/2008 ELBS1026S In Place 3/27/2008 ELBS1019S In Place 4/1/2008 ELBS1020S In Place 4/8/2008 ELBS1015S In Place 3/27/2008 ELBS1024S In Place 3/27/2008 ELBS1028D In Place 3/27/2008 ELBS1028S In Place 3/27/2008 ELBS1019S In Place 3/27/2008 ELBS1026S In Place 3/27/2008 ELBS1024S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 3/24/2008 ELBS1014D In Place 3/24/2008 ELBS1016S In Place 3/24/2008 ELBS1017S In Place 3/24/2008 ELBS1014S In Place 3/24/2008 ELBS1029S In Place 3/24/2008 ELBS1017S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV Bottom Depth ft bgs) EEL CC 1 Non-detects Page 5 of 6

24 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-CC 1 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster EEL CC 1 Chem w/ Result > Characterization Level Inorganics - Soil mg/kg) Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Phosphate TRUE TRUE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 4/8/2008 ELBS1015X In Place 3/26/2008 ELBS1018X In Place 3/27/2008 ELBS1028X In Place 3/24/2008 ELBS1029X # Samples > Eco Low RBSL Eco Low RBSL BTV # Samples > Eco High RBSL Eco High RBSL BTV In Place 3/26/2008 ELBS1011S ELBS1011S In Place 9/16/2008 SWBS1006S SWBS1006S In Place 9/16/2008 SWBS1006S SWBS1006S In Place 3/26/2008 ELBS1027S ELBS1027S In Place 3/26/2008 ELBS1027S ELBS1027S In Place 4/8/2008 ELBS1015S ELBS1015S In Place 3/27/2008 ELBS1026S ELBS1026S In Place 4/11/2008 ELBS1013S ELBS1013S In Place 3/27/2008 ELBS1024S ELBS1024S In Place 4/11/2008 ELBS1013S ELBS1013S In Place 3/27/2008 ELBS1026S ELBS1026S In Place 3/27/2008 ELBS1024S ELBS1024S For Residential and Ecological screening, chemicals with a DTSC-approved background value undergo a two-tiered screening. Each result is first screened against the background threshold value BTV) to identify data potentially related to site operations, and then those data are compared to RBSLs. The ratio is calculated as the data result divided by the RBSL. 2 Low and High Ecological RBSLs are used for data comparison. Low ecological comparisons are based on low toxicity reference value TRV) RBSLs and are used for data gap analysis and sampling recommendations; high ecological comparisons are based on high TRV RBSLs and are used in conjunction with other lines of evidence for CMS and remedial planning recommendations Bottom Depth ft bgs) EEL CC 1 Non-detects Page 6 of 6

25 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-No CC Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster No CC No CC Chem w/ Result > Characterization Level VOCs - Soil Vapor ug/l) # samples analyzed # samples not detected Detected? Detected > RBSLs? 1,1,2,2-Tetrachloroethane 7 7 FALSE FALSE Carbon Tetrachloride 7 7 FALSE FALSE Methylene chloride 7 7 FALSE FALSE Vinyl chloride 7 7 FALSE FALSE Benzene 7 5 TRUE FALSE Metals - Soil mg/kg) Stats Thallium 1 1 FALSE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) # Samples > Res RBSL Res RBSL BTV In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1401D In Place 4/28/2008 ELSV1401S In Place 4/28/2008 ELSV1401S In Place 5/16/2008 ELSV1403S In Place 5/16/2008 ELSV1403S # Samples > Res RBSL Res RBSL BTV In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1401D In Place 4/28/2008 ELSV1401S In Place 4/28/2008 ELSV1401S In Place 5/16/2008 ELSV1403S In Place 5/16/2008 ELSV1403S # Samples > Res RBSL Res RBSL BTV In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1401D In Place 4/28/2008 ELSV1401S In Place 4/28/2008 ELSV1401S In Place 5/16/2008 ELSV1403S In Place 5/16/2008 ELSV1403S # Samples > Res RBSL Res RBSL BTV In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1400S In Place 4/28/2008 ELSV1401D In Place 4/28/2008 ELSV1401S In Place 4/28/2008 ELSV1401S In Place 5/16/2008 ELSV1403S In Place 5/16/2008 ELSV1403S # Samples > Res RBSL Res RBSL BTV In Place 4/28/2008 ELSV1400S In Place 5/16/2008 ELSV1403S In Place 5/16/2008 ELSV1403S In Place 4/28/2008 ELSV1401D In Place 4/28/2008 ELSV1401S # Samples > Res # Samples > Eco Low Eco Low RBSL and BTV Res RBSL BTV RBSL and BTV RBSL BTV Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL Bottom Depth ft bgs) No CC Non-detects Page 1 of 2

26 TABLE 2c Data Summary Table for Exceedances for Non-Detect Results-No CC Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CUA Cluster Chem w/ Result > Characterization Level Stats # samples analyzed # samples not detected Detected? Detected > RBSLs? Antimony 1 1 FALSE FALSE Boron 1 1 FALSE FALSE Mercury 1 1 FALSE FALSE Molybdenum 1 1 FALSE FALSE Selenium 1 1 FALSE FALSE Excavation Status Collection Date Residential Characterization Level Comparisons 1 Sample ID for MRL > Res RBSL MRL Ratio to Res RBSL Bottom Depth ft bgs) Ecologic Characterization Level Comparisons 2 Ecological CMS Level Comparisons 2 Ratio to Bottom Ratio to Sample ID for MRL > Sample ID for MRL > MRL Eco Low Depth ft MRL Eco High Eco Low RBSL Eco High RBSL RBSL bgs) RBSL In Place 9/22/1999 ELBS10S ELBS10S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 9/22/1999 ELBS10S ELBS10S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 9/22/1999 ELBS10S # Samples > Eco Low Eco Low RBSL and BTV RBSL BTV In Place 9/22/1999 ELBS10S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 9/22/1999 ELBS10S ELBS10S # Samples > Eco Low Eco Low # Samples > Eco High Eco High RBSL and BTV RBSL BTV RBSL and BTV RBSL BTV In Place 9/22/1999 ELBS10S ELBS10S For Residential and Ecological screening, chemicals with a DTSC-approved background value undergo a two-tiered screening. Each result is first screened against the background threshold value BTV) to identify data potentially related to site operations, and then those data are compared to RBSLs. The ratio is calculated as the data result divided by the RBSL. 2 Low and High Ecological RBSLs are used for data comparison. Low ecological comparisons are based on low toxicity reference value TRV) RBSLs and are used for data gap analysis and sampling recommendations; high ecological comparisons are based on high TRV RBSLs and are used in conjunction with other lines of evidence for CMS and remedial planning recommendations Bottom Depth ft bgs) No CC Non-detects Page 2 of 2

27 General Notes for Tables 2b and 2c: This table only lists chemicals for which a characterization level exists. The soil characterization levels used in preparing these summary tables are the 2005 background levels, the suburban residential RBSLs included in the May 2012 Gold Copy hard drive deliverable, and the low toxicity reference value based ecological RBSLs for soil included in the May 2012 Gold Copy hard drive deliverable. The background levels and select RBSLs were updated in 2012 while this work plan was in development. The updated background levels and RBSLs will be used in future evaluations of data gaps for the STL IV RFI site, in accordance with the comprehensive DQO process. The background levels for aluminum, arsenic, and orthophosphate have changed significantly since Consequently, the most recent background levels for these three chemicals 37,900, 24.2, and milligrams per kilogram, respectively) were considered during the evaluation of soil data gaps. The SVCLs used in preparing this work plan are the residential SVCLs presented in Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RFI Project, SSFL CH2M HILL, 2013c) and the low toxicity reference value based ecological RBSLs for soil vapor included in the May 2012 Gold Copy hard drive deliverable. Chemicals listed as VOC in Vapor Screens represent the total VOCs concentration measured using a field screening method. For non detect results, chemical characterization levels are compared against the practical quantification limits PQL) as the method reporting limits. If PQL values were not available, the method detection limits were used for the comparisons.

28 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA TABLE 3 Corrective Measure Study Areas and Chemical Risk Drivers Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Soil CMS Areas a Chemical Risk Driver EEL CMS S1 EEL CMS S2 EEL CMS S3 Arsenic Arsenic Arsenic Soil Vapor EEL CMS SV1 EEL CMS SV2 TCE TCE Notes: CMS = corrective measure study a The CMS areas presented in the Group 5 RFI Report CH2M HILL, 2008) were revisited during preparation of this data gap work plan to differentiate the areas that are recommended for CMS based on soil contamination from the areas that are recommended for CMS based on soil vapor contamination. During this process, the concentrations of the risk driving chemicals identified for the EEL RFI site in the Group 5 RFI Report were compared to the soil characterization levels and soil vapor characterization levels used during preparation of this data gap work plan. The locations of samples with risk driving chemical concentrations that exceed the corresponding, updated soil characterization levels or soil vapor characterization levels are included in the soil or soil vapor CMS areas. The resulting soil and soil vapor CMS areas are presented on the figures in this data gap work plan. These CMS areas are subject to change pending additional data collection and additional risk assessment. Final CMS areas will be presented in forthcoming Boeing RFI data summary and findings reports. COPYRIGHT 2013 BY CH2M HILL, INC.

29 TABLE 4 Current Status of DQO Evaluation for EEL RFI Site - Groundwater and Seeps Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Group VOCs Study Question #2: Are the nature and extent of chemicals characterized to required characterization levels in groundwater, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? TBD. The response to this study question will be reevaluated following collection of additional data and following vadose zone fate and transport modeling. VOCs were analyzed in groundwater samples collected at RS-15 and RS-17 in the last three years 2010, 2011, and 2012) and VOCs have not been analyzed at PZ-50 and PZ-51 in the Study Question #3: Are data adequate to understand the fate and transport of chemicals in groundwater, including volatilization of chemicals from groundwater to the vadose zone and migrations of chemicals to seeps and off-site wells, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? last 10 years. VOCs were below GCLs in groundwater samples collected from RS-15 and RS- SSFL, Ventura County, California CH2M HILL, 2013). One VOC was detected above soil 17 with exceptions of cis-1,2-dce and TCE at RS-15. Samples from wells within the vapor characterization levels in soil vapor above groundwater plumes containing the adjacent Compound A RFI site and south of RS-15 also contain cis-1,2-dce and TCE at same VOCs. concentrations above its GCL. The lateral extent of VOCs in groundwater at EEL is currently defined by RS-17 to the southwest, PZ-28 to the east/northeast and wells in southwest drainage to the south that is, SP-882 and RD-6). Based on 3-dimensional groundwater flow model particle tracking, historically, when groundwater was being extracted from water supply or interim remedial wells, the groundwater from EEL primarily flows northeast along strike towards the ECL RFI site and appears intercepted by wells PZ-50, PZ-51, and RS-15, with a component of flow toward the southeast and the Compound A and STL-IV RFI sites. Under non-pumping conditions, groundwater from EEL flows primarily southwest along strike and appears intercepted by well RS-17. Although there are no vertically discrete sampling locations within EEL, sampling results from the vertical clusters to the west and southwest near STL-IV RD-55 and RD-58 clusters) and to the south of the Burro Flats fault SP-882G) show that VOCs have been characterized to below or near GCLs. Groundwater samples should be collected at PZ-50 and -51 and analyzed for VOCs. Results will be evaluated when available. TBD. The response to this study question will be reevaluated following collection of additional data and following vadose zone fate and transport modeling. In addition, as part of the fate and transport evaluation, groundwater will be evaluated as a potential source of VOCs to indoor air through the vapor intrusion pathway in accordance with Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RFI Project, Several RFI sites are in close proximity within this portion of SSFL. There are other nearby source areas at other RFI sites beyond EEL that have impacted groundwater and resulted in commingling of contaminant plumes in this area i.e., Compound A, STL-IV). The evaluation of groundwater fate and transport in Study Question #3 requires a review of the downgradient extent of a plume sourced from an RFI site, or from the larger plume if there is commingling from more than one RFI site. Therefore, the extent of groundwater impacts from EEL are defined by the collective monitoring system for the commingled plume; this monitoring system includes downgradient wells within STL-IV, and the seeps well clusters installed along the southwest drainage in Any potential VOC groundwater plume sourced from EEL is not expanding based on analysis of existing data from RS-15 and ES-23 south of RS-15), which show decreasing concentration trends. VOC concentrations in downgradient wells are defined to below characterization levels at locations expected to be far down the flow path, including the SP-882 cluster, and there is a statistically significant downward or stable/indeterminate) trend in concentrations at existing wells. Onsite seeps FDP-890, -881 and -882 have shown VOC concentrations above the groundwater characterization levels, but concentrations in samples collected from seeps further down the drainage for example, FDP-882E and S-22) have been non-detect, as well as samples collected from seep cluster SP-22 and offsite seep FDP-835. Offsite wells and seeps are not impacted by VOC plumes sourced from EEL. Study Question #4: Do concentrations of chemicals in groundwater exceed action levels and/or do concentrations of chemicals present significant risk to current or future receptors indoor air, seeps, or off-site wells)? TBD. The response to this study question will be re-evaluated following collection of additional data and following vadose zone fate-and-transport modeling. Preliminary RFI recommendation: Conditional NFA or CMS Assessment CMS Assessment. TCE exceeded both the soil vapor characterization level and the GCL and is recommended for CMS assessment. The need for performing a CMS for groundwater has been previously recommended in the draft groundwater RI report. Chemicals in groundwater at EEL are present at concentrations that exceed GCLs. This evaluation will be updated following review of data from proposed vadose zone and groundwater samples. SVOCs Metals Petroleum Hydrocarbons TBD. The response to this study question will be verified following collection of SVOC groundwater data. Analysis of SVOCs in samples from wells along flow paths from EEL is nearly 30 years old. Wells RS-15 and -17 are recommended for sampling and SVOC analysis, as noted in the vadose zone evaluation. Additionally, it is recommended that PZ-50 also be sampled and analyzed for SVOCs. TBD. The response to this study question will be verified following collection of metals groundwater data. Analysis of metals in samples from wells along flow paths from EEL is nearly 25 years old. Wells RS-15 and -17 are recommended for sampling and metals analysis as noted in the vadose zone evaluation. Additionally, it is recommended that PZ-50 also be sampled and analyzed for metals. TBD. The response to this study question will be verified following collection of groundwater samples. Analysis of petroleum hydrocarbons in samples from wells along flow paths from EEL are nearly 25 years old. Wells RS-15 and -17 are recommended for sampling and gasoline-, diesel-, and motor-oil-range hydrocarbon analysis as noted in the vadose zone evaluation. Additionally, it is recommended that PZ-50 also be sampled and analyzed for the same constituents. Notes: CMS = corrective measures study TBD. The response to this study question will be reevaluated following collection of additional data and following vadose zone fate-and-transport modeling. Samples have not been detected collected and analyzed for SVOCs at on- or offsite seeps, as comprehensive sampling to date have not shown SVOCs to be a prevalent contaminant in SSFL groundwater. TBD. The response to this study questions will be reevaluated after additional data are collected, fate and transport evaluations are performed, and groundwater action levels are confirmed. TBD. The response to this study questions will be reevaluated after additional data are collected, fate and transport evaluations are performed, and groundwater action levels are confirmed. TBD. The response to this study questions will be re-evaluated after additional data are collected, fate-and-transport evaluations are performed, and groundwater action levels are confirmed. TBD. TBD. TBD. TBD. TBD. ES BAO Page 1 of 2

30 TABLE 4 Current Status of DQO Evaluation for EEL RFI Site - Groundwater and Seeps Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Group Study Question #2: Are the nature and extent of chemicals characterized to required characterization levels in groundwater, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? Study Question #3: Are data adequate to understand the fate and transport of chemicals in groundwater, including volatilization of chemicals from groundwater to the vadose zone and migrations of chemicals to seeps and off-site wells, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? Study Question #4: Do concentrations of chemicals in groundwater exceed action levels and/or do concentrations of chemicals present significant risk to current or future receptors indoor air, seeps, or off-site wells)? Preliminary RFI recommendation: Conditional NFA or CMS Assessment CUA = chemical use area DQO = data quality objective GCL = groundwater comparison level NFA = no further action ES BAO Page 2 of 2

31 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA TABLE 5 Summary of Proposed Samples by Matrix for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California RFI Site No. Soil Samples including samples on hold) No. Soil Vapor Samples No. Rock Samples No. Groundwater Samples Total No. Proposed Samples EEL RFI Site Notes: It is proposed that groundwater samples be collected from monitoring wells PZ 50, PZ 51, RS 15, and RS 17 during a minimum of one groundwater monitoring event to support the vadose zone mass flux to groundwater evaluation for the EEL RFI Site. COPYRIGHT 2013 BY CH2M HILL, INC.

32 ADDENDUM TO MASTER RCRA FACILITY INVESTIGATION DATA GAP WORK PLAN, BOEING RFI SUBAREA 5/9 SOUTH, EEL RFI SITE, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA TABLE 6 Schedule for EEL RFI Site Data Gap Work Plan Activities Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activity Submittal of Master RFI Data Gap Work Plan Addendum for EEL March 2013 DTSC Review/Comment on Draft Master RFI Data Gap Work Plan Addendum for EEL April 2013 Boeing revises Draft Master RFI Data Gap Work Plan Addendum for EEL in response to DTSC comments April 2013 Conduct Public Meeting for Draft Master RFI Data Gap Work Plan Addendum for EEL May 2013 Boeing prepares Final Master RFI Data Gap Work Plan Addendum for EEL and submit to DTSC for final review/approval Estimated Performance Period May 2013 DTSC approves Final Master RFI Data Gap Work Plan Addendum for EEL June 2013 EEL RFI Site Data Gap Work Plan Implementation Field Work and Data Validation Boeing prepares Draft Boeing RFI Group 5/9 South Data Summary and Findings Report; submits to DTSC for review June 2013 December 2013 a December 2013 April 2014 Notes: a Boeing will confer with DTSC during this period to verify that all outstanding data gaps have been identified and filled, and to verify that all DQOs have been achieved. COPYRIGHT 2013 BY CH2M HILL, INC.

33 Figures

34 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV UNDEVELOPED LAND UNDEVELOPED LAND UNDEVELOPED LAND AREA IV EEL STP-3 Compound A STL-IV ECL AREA III Boeing RFI Subarea 5/9 North Silvernale AREA II Boeing RFI Subarea 1B North CTL-V CTL-III R-1 Pond LF AREA I Bowl Area A1 AF APTF Impoundment 1 CN Boeing RFI Group 1A North HVN BS IL HVS B1 Boeing RFI Group 1A South Boeing RFI Subarea 1A South Boeing RFI Subarea 1A North Boeing RFI Subarea 1A Central LEGEND DOE AOC Boundary NASA AOC Boundary RFI Group Boundary Administrative Boundary Ponds Boeing RFI Site Paved Road Dirt Road Unpaved trail Boeing RFI Subarea 5/9 South Area I Burn Pit Boeing RFI Subarea 1B Southwest Perimeter Pond Boeing RFI Subarea 1B Southeast UNDEVELOPED LAND Boeing RFI Subarea 10 $ ,500 Feet 1 in = 1,500 ft FIGURE 1 Boeing RFI Subareas for Data Gap Characterization Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGURE1_SUBAREAS.MXD RANHORN 5/22/ :02:09 AM

35 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 UNDEVELOPED LAND 6 EEL-CMS-S EEL-CMS-S EEL CC 1 EEL-CMS-SV EEL-CMS-S3 EEL-CMS-SV BASEMAP LEGEND Boeing RFI Site RFI Group Boundary Administrative Boundary EEL RFI Site Reporting Area Chemical Use Area CUA) Dirt Road Paved Road Rock Outcrop Pond Transformer Pad Structure 1 CUA Reference Number CUA Cluster CC) Soil CMS Area Soil Vapor CMS Area Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Features Debris Area ' Debris Point Disturbed Soil Transformer Pole Pipeline Leach Field Line Debris Line Drainage Channel Operational Channel Vegetation Clearing Excavation Area U U U U U U U U Undefined Feature U U U U Spray Field Leach Field Area Septic Tank Sumps Former Ranch House Note: 1) CMS areas are interim and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 2) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE. $ Feet 1 in = 60 ft Western Eastern Forming Pit FIGURE 2 EEL RFI Site CUAs and CUA Clusters Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGURE2_CUAAREAS.MXD RANHORN 5/16/2013 5:01:37 PM

36 Appendix A EEL RFI Site Comprehensive DQO Evaluation

37 Appendix A Contents CUA Confirmation and Conditional NFA Area Weight of Evidence Documentation Table A 1: Conditional NFA Area Weight of Evidence for the EEL RFI Site Reporting Area Table A 2: CUA Confirmation and Supplemental Conditional NFA Area Weight of Evidence Documentation for the SMOU, EEL RFI Site Figure A 1: Newly Identified Features and Potential CUAs at EEL RFI Site DQO Evaluation for Surficial Media Vadose Zone Table A 3: Data Quality Objectives for Surface Water Bodies at the EEL RFI Site Table A 4: Data Quality Objectives for Soil and Sediment at the EEL RFI Site Table A 5: Data Quality Objectives for the Vadose Zone at the EEL RFI Site Figure A 2: Comparison of Analytical Results to Characterization Levels for Soil from 0 to 2 Feet Below Ground Surface, EEL RFI Site Figure A 3: Comparison of Analytical Results to Characterization Levels for Soil from 2 to 10 Feet Below Ground Surface, EEL RFI Site Figure A 4: Comparison of Analytical Results to Characterization Levels for Soil Greater Than 10 Feet Below Ground Surface, EEL RFI Site Figure A 5: Comparison of Analytical Results to Characterization Levels for VOCs Soil and Soil Vapor) from 0 to 10 Feet Below Ground Surface, EEL RFI Site Figure A 6: Comparison of Analytical Results to Characterization Levels for VOCs Soil and Soil Vapor) Greater Than 10 Feet Below Ground Surface, EEL RFI Site DQO Evaluation for Groundwater and Seeps Table A 6: Data Quality Objectives for Groundwater and Seeps at the EEL RFI Site Figure A 7: Summary Evaluation of Groundwater Assessment at EEL A-1 COPYRIGHT 2013 BY CH2M HILL, INC.

38 TABLE A 1 Conditional NFA Area Weight of Evidence Documentation for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a Method 1: SSFL Document and Record Review RCRA Facility Assessment Assessment and documentation supporting recommendation that no release or potential release of any chemical previously used, stored, handled or disposed was identified within the EEL RFI site, other than the potential releases identified in Table A 2 or the CUAs identified in EEL RFI site media specific Tables A 3 through A 6 b Review of all available historical RCRA Facility Investigation related reports and documents that might contain information relevant to the RFI. RFA ) historical and current operational chemical use information was reviewed, a site inspection was performed, and previous sampling data were evaluated to determine the likelihood of a potential release to environmental media. One hundred and twenty five areas of SSFL that used, stored, or handled hazardous waste were identified for designation as SWMUs or AOCs by the USEPA. During the RFA, one SWMU was identified at the EEL RFI site: Building 3268 and Building 3271 SWMU 6.9). RFI Program Report Subsequent to the RFA, 10 additional AOCs were identified during the SSFL RFI Program Report preparation, for a total of 135 SWMUs and AOCs at the entire SSFL. These 135 SWMUs and AOCs were grouped into 51 RFI sites. Boeing, DOE, NASA, and DTSC subdivided the SSFL into 11 RFI groups for the purposes of RFI reporting work activities, each containing zero to 17 RFI sites. EEL was grouped with other RFI sites in the RFI Program Report to form Group 5. No additional SWMUs or AOCs were identified in the EEL RFI site during this process EEL RFI Report DTSC and Stakeholder Comments on this Report The 2008 EEL RFI Report considered all historical reporting and documentation available at the time of report preparation. Seventy nine soil samples and 23 soil vapor samples were collected from the EEL RFI site between February 1993 and May The analytical results for all these samples were included in the 2008 EEL RFI Report and were used to prepare CMS and CNFA recommendations for the EEL RFI site. Eight CUAs were identified in the 2008 EEL RFI Report, and these serve as the baseline compilation of CUAs for the EEL RFI site that are evaluated and expanded upon during implementation of the DQO evaluation process. DTSC and stakeholder comments on the 2008 EEL RFI Report are considered under the context of the comprehensive DQO process. No new release or potential release was identified as a result of DTSC's review of the EEL RFI Report. RFI relevant information derived from DTSC comments on the EEL RFI Report are included within the applicable DQO Report Figure 2 activities identified below. Activity completed and all relevant information and data reviewed? Yes Yes Yes CNFA Weight of Evidence Documentation, Question 1: Was a release or potential release c newly identified? No No No Sitewide Groundwater Remedial Investigation Report The Sitewide Groundwater Remedial Investigation Report 2009) presents an assessment of the nature and extent of SSFL site related chemicals in groundwater and the vadose zone bedrock. The Groundwater RI Report was reviewed to identify information relevant to the EEL SMOU. The report indicates that impacted groundwater has been found in samples collected from wells within the footprint of the EEL RFI site. The chemicals detected in groundwater samples collected from these wells are consistent with chemicals detected in surficial media samples or is attributed to sources at other RFI sites. Based on the above, no new releases or potential releases were identified at the EEL RFI site based on the review of this report. Yes No Review of Historic Documentation Review of historical documentation was performed, including but not limited to, reports, maps, inventories, spill records, notes, and correspondence to identify areas of chemical use not already identified during the prior RFA or RFI activities. Approximately 70,000 historic documents related to Group 5 were reviewed for identification of information potentially relevant to the Boeing SSFL RFI, and findings were included in the 2008 Group 5 RFI Report. Electronic copies of these historical documents were previously provided to DTSC on external hard drives. Subsequently, additional historical documents that became available were reviewed using the same process to identify RFI relevant information. Electronic versions of these documents were provided to DTSC in January If new documents containing RFI relevant information become available in the future, these documents will also be provided to DTSC. The review of the additional historical documentation resulted in the identification of new releases or potential releases beyond those presented in the 2008 EEL RFI Report. These releases or potential releases are listed in Table A 2. Some of the chemicals used of contained at the site that were identified during the recent review of historical documentation performed after 2008) were boron nitride, pyro putty 667 an adhesive), silicon nitride, compressed gases that is, hydrogen, nitrogen, helium, oxygen, methane, propane) Boeing, 1999). Consistent with the Field Sampling Methodology for CUA or CNFA Determination for the SMOU Table 2 of the Comprehensive DQO Report), no investigation is recommended for these features and chemicals. Consequently, these features and chemicals are not included in Table A 2. Yes Yes, see Table A 2 Review of historical documents is ongoing. Additional releases or potential releases that may be identified during the review of additional historical documents will be addressed during future evaluations of data gaps for the EEL RFI site, in accordance with the comprehensive DQO process. Page 1 of 5

39 TABLE A 1 Conditional NFA Area Weight of Evidence Documentation for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a Method 2: SSFL Sitewide Inventories Building Inventory and Feature Survey Assessment and documentation supporting recommendation that no release or potential release of any chemical previously used, stored, handled or disposed was identified within the EEL RFI site, other than the potential releases identified in Table A 2 or the CUAs identified in EEL RFI site media specific Tables A 3 through A 6 b Compilation and evaluation of sitewide inventories of infrastructure or features with potential chemical storage, distribution, use, or disposal history The building feature inventory and survey was performed at the EEL RFI site in 2008 to systematically identify the location and condition of all existing building features that potentially could have been a source of a chemical release to environmental media. All tasks identified in the Building Feature Survey SOP CH2M HILL, 2008) have been reviewed, and all available and relevant information was documented in the EEL building feature documentation logs. These logs were originally provided as an attachment to the 2008 EEL RFI Report and also provided with the Central Key Document Repository deliverable to DTSC in April 2011 and subsequently in May 2012). Five building features where a chemical release to environmental media may have occurred were identified during the building feature inventory and survey for the EEL RFI site. However, only one of the five building features Building Feature ) did not have nearby samples that may be used to characterize soil near the feature. This feature is listed in Table A 2. The other building features , , , and ) had nearby samples to characterize soil near the features. Sample location ELBS1024 is located near Building Feature , a discharge point located east of Buildings 3268 and Sample location ELBS1013 is located near Building Feature , a storm drain located west of Building Sample locations ELBS1005 and ELBS1405 are located near Building Features and , a concrete pad and storm drain located south of Building Soil sample results from these locations are below soil characterization levels. Aside from the building feature identified in Table A 2, no new releases or potential releases were identified during the building inventory and feature survey for the EEL RFI site. Activity completed and all relevant information and data reviewed? CNFA Weight of Evidence Documentation, Question 1: Was a release or potential release c newly identified? Yes Yes, see Table A 2 Tank Inventory A SSFL sitewide Tank Inventory was prepared by Boeing, DOE, and NASA. This inventory identifies all known information regarding the location, size, composition, contents, use period, and regulatory status of all underground storage tanks UST), aboveground storage tanks AST), and undetermined tanks. A total of 7 new undetermined tanks with unknown contents was identified at the EEL RFI Site during the historical document review and have been added to the tank inventory. These tanks are included in the review of historic documentation section in Table A 1 and addressed in the review of historic documentation section in Table A 2. The documentation for the entire Boeing SSFL tank inventory was provided with the Central Key Document Repository deliverable to DTSC in April 2011 and subsequently in May 2012). Aside from these 7 tanks, no other tanks were identified at the EEL RFI Site during the sitewide tank inventory compilation. Yes No Sewer System Survey The SSFL sitewide sewer system survey was performed in 2008 and 2009 to visually inspect sewer manholes and pipeline inlets and outlets and to identify manholes that are in poor condition and may have resulted in impacts to environmental media. CH2M HILL inspected the 33 sanitary sewer system manholes located in Group 5 in August A small section of the sewer pipeline runs through EEL. The manholes located in the EEL RFI site were inspected. These manholes were observed to be active and intact. No sediment was observed inside these manholes at the time of the inspection. No fractures or deterioration of the concrete manhole structure, including the inlet and outlet pipelines, was observed. All nearby soil and soil vapor data collected from within 100 feet of the manholes and sewer pipeline located within the reporting area were reviewed. There is no evidence of a release or potential release from the sewer system located within the EEL RFI site based on this information. No, currently under review TBD Further evaluation of potential impacts to environmental media resulting from potential releases from the sewer system in the Boeing RFI subareas is being performed. Recommendations for additional investigation of the sewer system in the Boeing RFI subareas, if needed, will be presented in a future report. Reclaimed Water System Inventory A comprehensive sitewide evaluation was performed by Boeing, DOE, and NASA to identify and document the locations and operational history of all features associated with the reclaimed water system. The documentation for the Boeing SSFL reclaimed water system was provided with the Central Key Document Repository deliverable to DTSC in May Spray fields and pipelines associated with the reclaimed water system were identified in the western and eastern portions of the EEL RFI site during the 2010/2011 reclaimed water conveyance system inventory activities. These spray fields are included in Table A 2. A second spray field was identified during this inventory compilation, but is located at the STL IV RFI site; this spray field is evaluated in the work plan addendum for that site. Further evaluation of potential impacts to environmental media resulting from potential releases from the reclaimed water system in the Boeing RFI subareas is being performed. Recommendations for additional investigation of the reclaimed water system in the Boeing RFI Subareas, if needed, will be presented in a future report. No, currently under review Yes, see Table A 2 Pipelines Wrapped with Mastic Tape Documentation A comprehensive sitewide evaluation was performed by Boeing, DOE, and NASA to identify and document the locations of natural gas pipelines wrapped with mastic tape that potentially contain PCBs and/or SVOCs). A summary of the natural gas pipeline system at SSFL was provided with the Central Key Document Repository deliverable to DTSC in May In addition, other pipelines wrapped with mastic tape have been identified elsewhere at SSFL. No natural gas pipelines wrapped with mastic tape have been identified within the EEL RFI site, as documented in the Natural Gas Pipeline GIS Feature Class Technical Memorandum MWH, 2012a). In addition, no other types of pipelines wrapped with mastic tape have been identified at the EEL RFI site. Yes No Primary Fuel oil and Chemical Pipeline Inventory A review of available documentation has been performed. No fuel oil or chemical pipelines extending within, to, or from the EEL RFI site were identified. Yes No Page 2 of 5

40 TABLE A 1 Conditional NFA Area Weight of Evidence Documentation for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a GIS Gold Copy Data Management Tool Assessment and documentation supporting recommendation that no release or potential release of any chemical previously used, stored, handled or disposed was identified within the EEL RFI site, other than the potential releases identified in Table A 2 or the CUAs identified in EEL RFI site media specific Tables A 3 through A 6 b The GIS Gold Copy Data Management Tool is a comprehensive GIS and analytical database that was compiled for SSFL and contains current and complete Boeing, NASA, and DOE chemical and radiological data for surficial media and groundwater. The GIS Gold Copy Data Management Tool was submitted to DTSC initially in April 2011 and an updated version of the tool was subsequently submitted to DTSC in May This tool was reviewed to identify any new features potentially associated with a release to environmental media that are not included in the 2008 EEL RFI Report and not identified elsewhere in this table. No other new features potentially associated with a release in the EEL RFI site were identified through this process. Activity completed and all relevant information and data reviewed? Yes CNFA Weight of Evidence Documentation, Question 1: Was a release or potential release c newly identified? No Method 3: SSFL Sitewide Inspections Debris Survey and Sampling SSFL sitewide comprehensive inspections and documentation Boeing, DOE, and NASA performed a sitewide debris survey in 2008 and 2009 to systematically identify surficial evidence of solid waste disposal through visual inspections of the SSFL. The debris survey was conducted on 50 foot transects across all of SSFL to document the types and locations of debris. The survey was performed in accordance with the Onsite Debris Survey and Sampling Methodology SOP CH2M HILL and MWH, 2008). No debris areas were identified at the EEL RFI site. Yes No Biological Survey and Mapping A sitewide survey of biological and ecological site conditions was performed in The results of the survey were mapped and included in the Boeing Group 5 RFI Report. No new releases or potential releases conditions were identified at the EEL RFI site during the biological survey. Yes No Aerial Photograph Review Review of historical aerial photographs was performed, commencing in 1997 USEPA) and continuing through 2011 Boeing, DOE, and NASA) to identify areas of chemical use not previously identified. Boeing, DOE, and NASA reviewed historic aerial photographs representing 17 photo coverage years that span the lifecycle of SSFL facility operations, from 1953 to Features identified in the aerial photograph review were documented in GIS. The documentation for the entire Boeing SSFL aerial photograph review was provided with the GIS Gold Copy Data Management Tool to DTSC in May New features in the EEL RFI site were identified during the aerial photograph review. These newly identified features are listed Table A 2. The soil disturbance area near the border with STP 3 is a demolition area of the EEL parking lot. It is not a newly identified feature and was not investigated because impacted soil was not discovered by the field geologist during demolition activities. Aside from the newly identified features listed in Table A 2, no other features were identified during the aerial photograph review at the EEL RFI site. Yes Yes, see Table A 2 Method 4: EEL RFI Site Inspections Topography and Physical Accessibility Proximity to Roadways and Operations EEL RFI site specific inspections and documentation The topography at the EEL RFI site was evaluated to identify areas of the site for which historic chemical use, storage, handling, or disposal activities would have been prohibitively difficult. No areas of the EEL RFI site were identified as being prohibitively difficult to access. Therefore, all portions of the EEL RFI site were subject to evaluations regarding the historic use, storage, handling, or disposal of chemicals. The roadways located within the EEL RFI site were evaluated in the context of the Field Sampling Methodologies for CUA or CNFA Determination for the SMOU Table 2 of the Comprehensive DQO Report). No releases or potential releases were identified based on an evaluation of operations in proximity to roadways at the EEL RFI site. Yes Yes No No Geophysical Survey A geophysical survey was performed at the EEL RFI site in Anomalies of interest mostly include buried conduits with occasional unknown features. The biased grid sampling that is proposed to address tanks with unknown locations will also serve to address the unknown features identified during the geophysical survey. Yes No Demolition Documentation and Sampling Field oversight was conducted during demolition of existing buildings and structures at the EEL RFI Site in 2012 to identify locations of potential impacts to environmental media beneath the buildings and structures through observation, field monitoring, and sample collection and chemical analysis). No impacted soil was observed during the building demolition activities and therefore no samples were collected. Portions of an underground sewer pipeline remain in place following demolition activities. The remaining portions of the pipeline are approximately 95 feet of 8 inch diameter vitreous clay pipe and 25 feet of 4 inch diameter steel pipe located southwest of the EEL RFI site under the road near the southwest manhole, MH D2 which remains), and approximately 90 feet of 10 inch diameter vitreous clay pipe along the eastern boundary of the EEL RFI site, north of the manhole along the eastern boundary, MH A1,D1 which remains). These portions of the pipeline will be removed during future building demolition activities, and sampling will be performed if warranted, based on observations during removal. An 80 foot portion of a surface water treatment pipeline also remains in place in the northeast corner of the EEL RFI site. This pipeline has been installed recently and there is no evidence of leaks and will not be investigated. Aside from these pipelines and the features listed in Table A 2, no new releases or potential releases were identified at the EEL RFI site during demolition oversight. No, currently under review TBD Interim Removal Actions Method 5: Chemical Migration Assessment Vapor Intrusion Pathway Evaluation An interim removal action for TPH was performed in 1993 at CUA 8 consisting of excavation of approximately 2 3 cubic yards of soil near the concrete pad where drums were stored. Aside from this interim removal action, no other interim removal actions have been performed at the EEL RFI site. Evaluation of potential chemical migration from any CUA to EEL RFI site areas thought to be unimpacted EEL RFI site CNFA areas) The vapor intrusion pathway will be evaluated in accordance with Appendix A of the Comprehensive DQO Report: Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RCRA Facility Investigation Project CH2M HILL, 2013a). Additional soil gas data will be collected where required to complete characterization of the nature and extent and fate and transport of impacts from source areas to impacted and unimpacted areas and to support remedial planning. The areas of the EEL RFI site where the vapor intrusion pathway might be complete will be spatially delineated by considering the known or suspected vapor sources, the nature and extent of impacts, the fate and transport of volatile organic compound constituents, and recommended CMS areas. Yes No, currently under review No TBD Page 3 of 5

41 TABLE A 1 Conditional NFA Area Weight of Evidence Documentation for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a Vadose Zone Mass Flux to Groundwater Modeling Assessment and documentation supporting recommendation that no release or potential release of any chemical previously used, stored, handled or disposed was identified within the EEL RFI site, other than the potential releases identified in Table A 2 or the CUAs identified in EEL RFI site media specific Tables A 3 through A 6 b Vadose zone mass flux to groundwater modeling will be performed to identify potential sources of groundwater impacts. The evaluation will be performed in accordance with Appendix D of the Comprehensive DQO Report: Recommended Approach for Evaluating Vadose Zone Mass Flux of Contaminants to Groundwater MWH, 2012b). The vadose zone mass flux to groundwater approach includes evaluating the need for additional field data; evaluating the need to model vadose zone mass flux to groundwater; modeling; and determining if the vadose zone should be recommended for the CMS or CNFA. Activity completed and all relevant information and data reviewed? No, currently under review CNFA Weight of Evidence Documentation, Question 1: Was a release or potential release c newly identified? TBD Air Deposition Modeling Air dispersion modeling is currently being performed for sources identified in Appendix B of the DQO Report: Recommended Approach for Air Dispersion Modeling, Boeing RCRA Facility Investigation Project CH2M HILL, 2013b). The need to model potential sources and to collect soil samples in impacted and unimpacted areas will be determined after the completion of modeling identified in Recommended Approach for Air Dispersion Modeling, Boeing RCRA Facility Investigation Project CH2M HILL, 2013b). No, currently under review TBD Surface Water Drainage Documentation A comprehensive sitewide evaluation was performed by Boeing, DOE, and NASA to identify and document the locations of all surface water drainage features and the direction of surface water flow at RFI sites and SSFL. The results of this comprehensive evaluation were included in the GIS Gold Copy Data Management Tool submitted to DTSC in May No newly identified surface water drainages were observed at the EEL RFI site through this process. Surface water drainage channels at the EEL RFI site have been investigated, the results of which were included in the 2008 EEL RFI Report. Portions of the drainage channels that were found to be impacted are included in an EEL CUA cluster and evaluated in Table A 4. Table A 4 identifies the additional characterization that is recommended for the drainage channels at the EEL RFI site. Yes No NPDES Surface Water Data Historical surface water data collected under the NPDES program were evaluated. Surface water runoff at the SSFL is regularly monitored as part of the NPDES monitoring program under the oversight of the California Regional Water Quality Control Board, Los Angeles Region. Two monitoring locations are monitored downgradient of the EEL RFI site: Outfall 002 at the south end of the Boeing RFI Subarea 10 and Outfall 018 at the discharge of the R 2 ponds. These discharge points are the ultimate discharge points for a large portion of the western half of SSFL. Ongoing monitoring and evaluation is being conducted under the NPDES program. NPDES data will be considered during preparation of future Boeing RFI documentation. No, currently under review TBD Seeps and Springs Data Ongoing seeps and springs investigation and evaluation is being conducted under the ongoing CFOU remedial investigation program and will be incorporated into groundwater DQO evaluations for the EEL RFI site. No, currently under review TBD Analytical Data Collected for Purposes Other than the RFI Analytical data, field notes, and field logs from all prior field investigations were reviewed. All locations with chemical constituent concentrations above the required characterization levels are included in the EEL CUA clusters Figure A 1). These locations are evaluated further in Tables A 3 through A 6. Based on a review of field notes and records, no observations have been made during field activities that suggest a chemical release may have occurred other than those documented in the 2008 EEL RFI Report or in this Master RFI Data Gap Work Plan Addendum for the EEL RFI site. Yes No Notes: a Activities presented in this table are consistent with the activities presented in Figure 2 of the Comprehensive DQO Report Chemical Use Area Confirmation and Conditional No Further Action Area Weight of Evidence Documentation for the Surficial Media Operable Unit; CH2M HILL, 2013c). b This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site located within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site that are located within Administrative Area IV are being characterized by the United States Department of Energy. c A "Yes" response to this question indicates a release or potential release that has not already been identified, investigated, and documented in the CH2M HILL 2008 Group 5 RFI Report was identified. A release or potential release can result in identification of a new CUA if constituent concentrations in the screening level sample exceed characterization levels) or can represent a new source and/or new chemicals) associated with an existing CUA. The status of each activity is designated by a color. The colors represent the following: DQO activity complete, no additional work required, no new CUA or existing CUA relevant new information identified. Additional investigation is required to determine if a new release or potential release is identified. See Table A 2. After evaluation of data collected during the proposed investigation, recommendations of CNFA or a new CUA will be made. DQO CNFA weight of evidence documentation completed, new CUA identified or new source and/or chemicals identified for existing CUA. See Table A 2. All CUAs addressed in media specific Tables A 3 through A 6. Page 4 of 5

42 TABLE A 1 Conditional NFA Area Weight of Evidence Documentation for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for Assessment and documentation supporting recommendation that no release or potential release of any chemical previously used, stored, handled or disposed was identified the SMOU a within the EEL RFI site, other than the potential releases identified in Table A 2 or the CUAs identified in EEL RFI site media specific Tables A 3 through A 6 b Acronyms: AOC = area of concern CFOU = Chatsworth Formation Operable Unit CMS = corrective measures study CNFA = conditional no further action CUA = chemical use area DOE = United States Department of Energy DQO = data quality objectives DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory GIS = geographic information system NASA = National Aeronautics and Space Administration NPDES = National Pollutant Discharge Elimination System PCB = polychlorinated biphenyl RFA = RCRA facility assessment RFI = RCRA facility investigation SMOU = Surficial Media Operable Unit SOP = standard operating procedure SSFL = Santa Susana Field Laboratory STL IV = Systems Test Laboratory IV SWMU = Solid Waste Management Units TPH = total petroleum hydrocarbons USEPA = United States Environmental Protection Agency Activity completed and all relevant information and data reviewed? CNFA Weight of Evidence Documentation, Question 1: Was a release or potential release c newly identified? Sources: Boeing Letter. Hazardous Matrials Inventory Update. BNA January 7. CH2M HILL. 2013a. Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RCRA Facility Investigation Project, Santa Susana Field Laboratory. Appendix A to DQO Report). March. CH2M HILL. 2013b. Recommended Approach for Air Dispersion Modeling, Boeing RCRA Facility Investigation Project, Santa Susana Field Laboratory. Appendix B to DQO Report). March. CH2M HILL. 2013c. Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California. March. CH2M HILL and Montgomery Watson Harza International MWH) Standard Operating Procedure, Onsite Debris Survey and Sampling Methodology, Santa Susana Field Laboratory, Ventura County, California. Prepared for The Boeing Company, United States Department of Energy, National Aeronautics and Space Administration. November. CH2M HILL and MWH Standard Operating Procedure, Building Feature Evaluation and Sampling, Santa Susana Field Laboratory, Ventura County, California. Prepared for The Boeing Company, The National Aeronautics and Space Administration, and The United States Department of Energy. July. MWH. 2012a. Technical Memorandum. Natural Gas Pipeline GIS Feature Class, Santa Susana Field Laboratory, Ventura County, California. April 6. MWH. 2012b. Recommended Approach for Evaluating Vadose Zone Mass Flux of Contaminants to Groundwater, Santa Susana Field Laboratory. November Page 5 of 5

43 TABLE A 2 CUA Confirmation and Supplemental Conditional NFA Area Weight of Evidence Documentation for the SMOU, EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a Review of Historic Documentation Description of the newly identified suspect feature or area of interest associated with the release or potential release b Chemicals: Halocarbon 275 lube oil, black paint, Glyptal insulating paint, clear spray coating, DTE24, DTE25, DTE26, Kinseal vacuum sealant, isopropyl alcohol, Molykote SSM, Molykote G n p, and liquid wrench were newly identified as used at Building 3271 CUA 1) during the 2012 review of historical documents BNA ). One ton and 20 ton metal cooling towers where KP 1 was used were newly identified at Building 3271 CUA 1) during the 2012 review of historical documents RAD ). Chemicals: Halocarbon 275 lube oil, black paint, Glyptal insulating paint, clear spray coating, Combat Boron Nitride Aerosol, DTE24, DTE25, DTE26, Kinseal vacuum sealant, isopropyl alcohol, Molykote SSM, Molykote G n p, and liquid wrench were newly identified as used at Building 3908 CUA 2) during the 2012 review of historical documents BNA ). Chemicals: Halocarbon 275 lube oil, black paint, Glyptal insulating paint, clear spray coating, DTE24, DTE25, DTE26, Kinseal vacuum sealant, isopropyl alcohol, Molykote SSM, Molykote G n p, and liquid wrench were newly identified as used at Buildings 3264 and 3227 CUA 3), during the 2012 review of historical documents BNA ). Chemicals: Acetone, Halocarbon 275 lube oil, Citigo hydraulic fluid SUS 2, black paint, Glyptal insulating paint, clear spray coating, DTE24, DTE25, DTE26, Kinseal vacuum sealant, Zirconia insulating products, Konica royal toner 200, isopropyl alcohol, Molykote SSM, Molykote G n p, and liquid wrench were newly identified as used at Building 3268 CUA 14) during the 2012 review of historical documents BNA , BNA , and BNA ). CNFA Weight of Evidence Documentation, Question 2: Is the feature or area of interest located within a CUA that has previously been identified? CNFA Weight of Evidence Documentation, Question 3: Was a release of any chemical previously used, stored, handled, or disposed documented at the feature or area of interest? CUA Reference ID or, if not located within previously identified CUA and does not meet criteria for new CUA, identify new potential CUA ID Yes No 1 Yes No 2 Yes No 3 Yes No 14 Data Gap Screening Samples to be collected in accordance with Comprehensive DQO Report Table 2 Field Sampling Methodologies for CUA or CNFA Determination for the SMOU)? c No. This information will be evaluated with the CUAs the samples are located in; see Tables A 3 through A 6. CNFA Weight of Evidence Documentation, Question 4: Were chemicals detected at concentrations that exceed characterization levels in screening level samples? N/A A 30 ton metal cooling tower where KP 1 was used was newly identified at Building 3268 CUA 14) during the 2012 review of historical documents RAD ). An office trailer Building 3272) was newly identified at the EEL RFI site during the 2012 review of historical documents BNA ). The location of the office trailer and its chemical use history are unknown. Seven new undetermined d tank features Tank features 44, 499, 649, 666, 667, 670, and 671) were identified during the 2012 review of historic documents BNA ). The locations and contents of these tanks are unknown. The size of the tanks ranged from 264 to 28,000 gallons. N/A e N/A N/A N/A e N/A N/A Yes. Samples will be collected and analyzed consistent with Comprehensive DQO Report Table 2. See Table C 1 in Appendix C for details on the proposed samples. TBD after EEL RFI Site Data Gap Work Plan is implemented. Building Inventory and Feature Survey f Building Feature Drain to the west of Building 3268). This feature is a 2 inch metal pipeline cut at the ground surface. It was determined to have a potential threat of a release to environmental media during the 2008 building feature survey and was noted that it may be sampled post demolition. Yes No 14 No. This information will be evaluated with the CUAs the samples are located in; see Tables A 3 through A 6. N/A Reclaimed water system inventory f One spray field STL IV sprayfield) and an associated pipeline was identified on the western side of the EEL RFI site during the 2010/2011 water conveyance system inventory activities see Figure A 1). No No A Yes. Samples will be collected and analyzed consistent with Comprehensive DQO Report Table 2. See Table C 1 in Appendix C for details on the proposed samples. TBD after EEL RFI Site Data Gap Work Plan is implemented. One spray field STL IV sprayfield) and an associated pipeline was identified on the eastern side of the EEL RFI site during the 2010/2011 water conveyance system inventory activities see Figure A 1). No No B Aerial Photograph Review One structure feature was newly identified near Building 3908, southeast of Building 3109, during the 2010/2011 review of aerial photographs see Figure A 1). One undefined feature was newly identified south of Building 3264 during the 2010/2011 review of aerial photographs see Figure A 1). Yes No 2 Yes No 3 No. This information will be evaluated with the CUAs the samples are located in; see Tables A 3 through A 6. N/A Page 1 of 2

44 TABLE A 2 CUA Confirmation and Supplemental Conditional NFA Area Weight of Evidence Documentation for the SMOU, EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Activities to Support CNFA Area Recommendations for the SMOU a Description of the newly identified suspect feature or area of interest associated with the release or potential release b One structure feature was newly identified northwest of Building 3905 during the 2010/2011 review of aerial photographs see Figure A 1). Two soil disturbance features were newly identified in the central portion of the EEL RFI Site during the 2010/2011 review of aerial photographs see Figure A 1). One of the soil disturbance features and the majority of the second disturbance feature are within the EEL RFI Site boundary, where biased grid samples are proposed to address undetermined tanks with unknown locations. For the portion of the soil disturbance feature that falls outside of the EEL RFI site boundary, potential CUA C has been identified and samples will be collected consistent with Comprehensive DQO Report Table 2. CNFA Weight of Evidence Documentation, Question 2: Is the feature or area of interest located within a CUA that has previously been identified? CNFA Weight of Evidence Documentation, Question 3: Was a release of any chemical previously used, stored, handled, or disposed documented at the feature or area of interest? CUA Reference ID or, if not located within previously identified CUA and does not meet criteria for new CUA, identify new potential CUA ID Yes No A Partially No C Data Gap Screening Samples to be collected in accordance with Comprehensive DQO Report Table 2 Field Sampling Methodologies for CUA or CNFA Determination for the SMOU)? c Yes. Samples will be collected and analyzed consistent with Comprehensive DQO Report Table 2. See Table C 1 in Appendix C for details on the proposed samples. CNFA Weight of Evidence Documentation, Question 4: Were chemicals detected at concentrations that exceed characterization levels in screening level samples? TBD after EEL RFI Site Data Gap Work Plan is implemented. Notes: a All tasks and activities in Figure 2 of the Comprehensive DQO Report Chemical Use Area Confirmation and Conditional No Further Action Area Weight of Evidence Documentation for the Surficial Media Operable Unit; CH2M HILL, 2013) have been reviewed and all available and relevant information was confirmed to either be presented in the 2008 Group 5 RFI Report or is included in the table above. b This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site located within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site that are located within Administrative Area IV are being characterized by the United States Department of Energy. c Analytical methods and sample depths for proposed data gap samples are presented in Tables C 1 and C 2 in Appendix C. d Based on historical documentation, the shallow depth to bedrock at the EEL RFI site, 2010 geophysical survey results, observations made during building and structure demolition activities at the EEL RFI site, these "undetermined" tanks are expected to likely be aboveground storage tanks, and will be investigated as such in accordance with Comprehensive DQO Report Table 3 Field Sampling Methodologies for CUA or CNFA Determination for the SMOU). However, in areas where these "undetermined" tanks could be underground storage tanks based on unknown features identified during the 2010 geophysical survey, they will be investigated accordingly as having potential underground storage tanks. e The specific locations of these features within the EEL RFI site are unknown; therefore, it cannot be associated with a CUA. Samples are proposed for collection based on an approximate 50 foot biased grid to address multiple newly identified features for which the specific location within the EEL RFI site is unknown. f The Building Inventory and Feature Survey Documentation Logs and Sitewide Summary of the Water Conveyance System are included in the SSFL Sitewide DTSC Hard Drive Deliverable CH2M HILL, 2012). N/A = not applicable TBD = to be determined Color designations represent: Additional investigation is required to determine if a new release or potential release is identified. After evaluation of data collected during the proposed investigation, recommendations of CNFA or a new CUA will be made. DQO CNFA weight of evidence documentation completed, new CUA identified or new source and/or chemicals identified for existing CUA. All CUAs addressed in media specific Tables A 3 through A 6. Acronyms: CNFA = conditional no further action CUA = chemical use area DQO = data quality objective EEL = Environmental Effects Laboratory N/A = not applicable PCB = polychlorinated biphenyl RFI = RCRA facility investigation SMOU = Surficial Media Operable Unit SSFL = Santa Susana Field Laboratory STL IV = Systems Test Laboratory IV TBD = to be determined Sources: Atkinson Baker, Inc. Court Reporters United States District Court, Central District of California, Lawrence O'Connor, et al. vs. Boeing North American, Inc., et al., Deposition of William McIlvaine, Woodland Hills California. RAD July 9. CH2M HILL SSFL Sitewide Gold Copy GIS Mapping and Analytical Geodatabase System hard drive deliverable). May. CH2M HILL Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California. March. Rockwell International "List of Buildings Ownership." BNA December 3. Unknown. Unknown date. "Material Safety Data Sheet MSDS) Index, Santa Susana Field Lab." BNA Unknown. Unknown date. "Business Plan HazMat Inventory, Environmental Effects Laboratory EEL)." BNA Unknown. Unknown Date. Chart/list. "SSFL Engineering and Test Pressure Vessel Inventory." BNA Page 2 of 2

45 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 UNDEVELOPED LAND # # * * EEL-CMS-S1 A EEL-CMS-S EEL-CMS-SV1 EEL CC EEL-CMS-S3 B EEL-CMS-SV LEGEND Newly Identified Features For a complete list of newly identified features, see Tables A-1 and A-2) Proposed Soil Vapor Sample Location # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Soil Vapor CMS Area Features ' Debris Point Transformer Pole Pipeline Leach Field Line Debris Line Drainage Channel Structure Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Debris Area Disturbed Soil Vegetation Clearing Excavation Area U U U U U U U U U U Undefined Feature U U U U U Spray Field Leach Field Area Septic Tank Sump 3251 Former Ranch House Operational Channel Notes: 1) Newly identified features with unknown locations are not shown. 2) CMS areas are interim and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 3) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE. # $ Feet in = 60 ft 3916 Western Eastern Forming Pit FIGURE A-1 Newly Identified Features and Potential CUAs at EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-1_NEWFEATURES.MXD RANHORN 5/16/2013 5:03:27 PM

46 TABLE A 3 Data Quality Objectives for Surface Water Bodies a at the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California EEL RFI Site d Notes: Sources and Chemicals Nature and Extent Fate and Transport CNFA or Cleanup Assessment Remedial Planning Information Study Question #1: Are all potential sources of contamination to, and chemicals within, surface water bodies identified within CUAs? Not applicable there are no surface water bodies within the EEL RFI site). Study Question #2: Are the nature and extent of chemical distributions characterized to required characterization levels b in surface water bodies within CUA clusters, or are data adequate to recommend the CUA cluster for CMS? Not applicable there are no surface water bodies within the EEL RFI site). Study Question #3: Are data adequate to understand the fate and transport of chemicals in surface water bodies, or are data adequate to recommend the CUA cluster for CMS? Not applicable there are no surface water bodies within the EEL RFI site). Study Question #4: Do concentrations of chemicals in surface water bodies within CUA clusters exceed action levels? c Not applicable there are no surface water bodies within the EEL RFI site). Study Question #5: Are existing data sufficient to perform remedial planning for surface water and source areas that exceed action levels? c Not applicable there are no surface water bodies within EEL RFI site). Comprehensive DQO Conclusions Additional data collection efforts are recommended at the EEL RFI site to address soil as presented in Table A 4), vadose zone as presented in Table A 5), and groundwater as presented in Table A 6). Yellow cells represent areas where additional work is required under the DQO process. a This table addresses current perennial surface water bodies only. Surface water runoff is managed under the NPDES program. Surface water migration of surface soil is addressed in Table A 4. Tables A 4, A 5, and A 6 provide the DQO evaluation for soil and sediment, vadose zone, and groundwater and seeps, respectively. b Boeing complies with the DTSC SSFL 2007 Consent Order for Corrective Action. Boeing currently conducts the RFI program under the 2007 Order. RFI required characterization levels depend on location and will be subject to final regulatory agreements. The RFI required characterization levels could be background chemical concentrations, MRLs, or other agreed upon risk based concentrations. c It is expected that action levels will be developed in the future based on the 2007 Consent Order for Corrective Action. For the Boeing land areas, human health and ecological risk assessments will be performed under Study Question #4 in accordance with the Standard Risk Assessment Methodology Work Plan, Revision 2 Addendum SRAM, MWH, pending). The Boeing SMOU RFI risk assessments will also be performed in accordance with the Integration of the Surficial Media Operable Unit Risk Assessment Methodology with the Data Quality Objectives Process, Boeing RCRA Facility Investigation, SSFL CH2M HILL, 2013). d This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site within Administrative Area IV are being characterized by the United States Department of Energy. Acronyms: CMS = corrective measures study CNFA = conditional no further action CUA = chemical use area DQO = data quality objective DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory MRL = method reporting limit NPDES = National Pollutant Discharge Elimination System RFI = RCRA facility investigation SMOU = Surficial Media Operable Unit SRAM = Standard Risk Assessment Methodology SSFL = Santa Susana Field Laboratory Sources: CH2M HILL Integration of the Surficial Media Operable Unit Risk Assessment Methodology with the Data Quality Objectives Process, Boeing RCRA Facility Investigation, Santa Susana Field Laboratory. Appendix C of the DQO Report). March. Montgomery Watson Harza International MWH). Pending. Standardized Risk Assessment Methodology Work Plan, Revision 2 Addendum, Santa Susana Field Laboratory, Ventura County, California. PAGE 1 OF 1

47 TABLE A-4 Data Quality Objectives for Soil and Sediment a at the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Sources and Chemicals Nature and Extent Fate and Transport CNFA or Cleanup Assessment Remedial Planning Information EEL CUA Cluster b Study Question #1: Are all potential sources and chemicals identified in soil and sediment within CUAs? Study Question #2: Are the nature and extent of chemical distributions characterized to required characterization levels c in soil and sediment within CUA clusters, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? d Study Question #3: Are data adequate to evaluate the fate and transport of chemicals in soil and sediment or are data adequate to recommend the CUA Cluster or a portion of the CUA cluster for CMS? e Study Question #4: Do concentrations of chemicals in soil or sediment within CUA clusters exceed action levels? f Study Question #5: Are existing data sufficient to perform remedial planning of soil or sediment that exceeds action levels? f Comprehensive DQO Conclusions EEL CC 1 CUAs 2, 3, 8 through 14, and portions of CUAs 1 and 7 g ) Yes. As presented in Table A 2, in addition to the sources and chemicals previously identified in the 2008 EEL RFI Report, 10 features two cooling towers, two soil disturbance areas, a drain west of Building 3268, two structures near Building 3908 and north of Building 3905, and an unidentified feature south of Building 3264) and newly identified chemicals were identified for CUAs 1, 2, 3, and 14 in EEL CC1 during the recent review of historical aerial photographs and historical documents and during the building inventory and feature survey. These newly identified features are evaluated as part of EEL CC1 in the DQO process. If new information regarding other potential sources or chemicals within CUAs 1, 2, 3, 8 through 14, and portions of CUAs 1 and 7 is identified in the future, the steps associated with this study question will be followed to identify the additional sources and/or chemicals that need to be evaluated as part of these CUAs. Specific information pertaining to all sources and chemicals in EEL CC 1 is documented in Table 2a. No. Nature and extent data gaps identified for EEL CC 1 are listed below. See Table 2a for a summary of the characterization that has been performed to date in EEL CC 1. See the SAP in Appendix C for specific details on the samples that are proposed to address the following data gaps; proposed sample locations are presented on Figures A 1 through A 6. Metals: It is recommended that the lateral and vertical extents of arsenic, selenium, and silver, and the lateral extents of barium and lithium be defined to SCLs. Energetics, Dioxins, and Perchlorate: It is recommended that soil samples be collected and analyzed for energetics, dioxins, and perchlorate to characterize soil at two dark areas identified in the 1959 and 1965 aerial photos, which were suspected of historical burn activities. Features/Chemicals Identified in Table A 2: It is recommended that soil samples be collected at the following newly identified features: two soil disturbance areas, one drain, two structures, and one unidentified feature. In addition, soil samples are recommended to characterize soil for newly identified chemicals. These features and chemicals were recently identified during a review of historical aerial photographs, review of historical documents, and building inventory and feature survey. It is recommended that soil samples be collected on a biased grid to address features with unknown locations within the EEL RFI site. MRL Exceedances: Nondetect results for three constituents Aroclor 1242, Aroclor 1254, and Aroclor 1260) have elevated MRLs and were never detected at the RFI site. To better address the uncertainty of the presence of Aroclor 1242, Aroclor 1254, and Aroclor 1260 in soil, one location will be analyzed for Aroclor 1242, Aroclor 1254, and Aroclor 1260 by methods that can achieve MRLs below SCLs. h In addition, silver has elevated MRLs at one sample location, which was used to define extent of known contamination. Silver will be analyzed again at this sample location by methods that can achieve MRLs below SCLs. f No. Fate and transport data gaps identified for EEL CC 1 are listed below. See Table 2a for a summary of the characterization that has been performed to date in EEL CC 1. See the SAP in Appendix C for specific details on the samples that are proposed to address the following data gaps; sample locations are presented on Figures A 1 through A 6. Surface Water Migration: It is recommended that soil samples be collected to characterize metals in soil in the drainage pathway downgradient of CUA 8. Yes. CMS areas were identified for arsenic in soil in the 2008 RFI Report. The extent of the CMS areas will be further defined based on results from proposed sampling presented in this work plan. No. Remedial planning will be required for EEL CC 1. However, additional data collection efforts are recommended to support estimation of impacted soil volume within a tolerance of +50%/ 30%. In addition, the volume of soil requiring corrective measures will be refined following re assessment of human health and ecological risks. Additional data collection efforts are recommended at EEL CC 1 to address soil as presented in this table), vadose zone as presented in Table A 5), and groundwater as presented in Table A 6). Notes: Bold font represents confirmed or potential data gaps. Yellow cells represent areas where additional work is required under the DQO process. a This table pertains to the sediment, unconsolidated soil, and weathered bedrock that may be accessed with a hand auger or a direct push rig in the SSFL areas for which Boeing is the responsible party. Deeper soil and bedrock are evaluated in Table A 5. For the purposes of this work lan, sediment is defined as material at the bottom of perennial surface water bodies and does not include soil in ephemeral streambeds. Soil and sediment data collected from the upper 10 feet will be used in future human health and ecological risk assessments, if performed. Tables A 3, A 5, and A 6 provide the DQOs for surface water bodies, vadose zone, and groundwater and seeps, respectively. The vapor intrusion pathway for all soil, rock, and groundwater is discussed in Tables A 5 and A 6. b This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site within Administrative Area IV are being characterized by the United States Department of Energy. c Boeing currently conducts the RFI program in compliance with the DTSC SSFL 2007 Consent Order for Corrective Action. RFI required characterization levels depend on location and will be subject to final regulatory agreements. The RFI required characterization levels could be background chemical concentrations, MRLs, or other agreed upon risk based concentrations. For this work plan, the assumed soil characterization levels are the 2005 background concentrations, the suburban residential RBSLs included in the May 2012 Gold Copy hard drive deliverable and the low toxicity reference value based ecological RBSLs for soil included in the May 2012 Gold Copy hard drive deliverable. d All analytical data are of sufficient quality for use by the project. Field procedures were performed in accordance with standard operating procedures applicable at the time of the investigations. e See Table A 5 Data Quality Objectives for the Vadose Zone) for fate and transport DQOs related to the mass flux of contaminants from the vadose zone to indoor air and the mass flux of contaminants from the vadose zone to groundwater. f It is expected that action levels will be developed in the future based on the 2007 Consent Order for Corrective Action. For the Boeing SMOU RFI, human health and ecological risk assessments will be performed under Study Question #4 in accordance with the Standard Risk Assessment Methodology Work Plan, Revision 2 Addendum SRAM, MWH, pending) and in accordance with the TM, Integration of the Surficial Media Operable Unit Risk Assessment Methodology with the Data Quality Objectives Process, Boeing RCRA Facility Investigation, SSFL CH2M HILL, 2013) see Appendix C of the DQO Report). DECEMBER 2012 PAGE 1 OF 2

48 g Potential CUAs A and B will be evaluated under Table A 2. Criteria from Figure 2 of the DQO Report and data collected during proposed investigations will be used to determine if Potential CUAs A and B should be identified as new CUAs or grouped with existing CUA, or if they should be recommended for CNFA. h A sensitivity analysis of MRLs was performed based on consideration of the following: 1) locations within CUAs but outside CMS areas where constituents have nondetect analytical results with MRLs that exceed characterization levels and those same constituents were never detected above MRLs at the RFI site this is to better address the uncertainty of the presence of specific constituents that were never detected at the RFI site; this evaluation focuses on constituents for which the number of MRL exceedances for a constituent relative to the total number of samples analyzed for that constituent is greater than 25 percent); and 2) locations where the existing nondetect/elevated MRL data are being used to define the extent of contamination outside of areas proposed for corrective measure studies. Potential matrix interference and technical limitations in obtaining lower reporting limits were also considered in identifying the need to re sample at previous locations with nondetect/elevated MRL data. Acronyms: CC = chemical use area clusters CMS = corrective measures study CNFA = conditional no further action CUA = chemical use area DQO = data quality objective DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory MRL = method reporting limit RFI = RCRA facility investigation SAP= sampling and analysis plan SCL = soil characterization level SMOU = Surficial Media Operable Unit SSFL = Santa Susana Field Laboratory Sources: CH2M HILL Integration of the Surficial Media Operable Unit Risk Assessment Methodology with the Data Quality Objectives Process, Boeing RCRA Facility Investigation, Santa Susana Field Laboratory. Appendix C of the DQO Report). March. Montgomery Watson Harza International MWH). Pending. Standardized Risk Assessment Methodology Work Plan, Revision 2 Addendum, Santa Susana Field Laboratory, Ventura County, California. PAGE 2 OF 2

49 TABLE A 5 Data Quality Objectives for the Vadose Zone a at the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California EEL CUA Cluster b EEL CC 1 CUAs 2, 3, 8 through 14, and portions of CUAs 1 and 7 c ) Sources and Chemicals Nature and Extent Fate and Transport CNFA or Cleanup Assessment Remedial Planning Information Study Question #1: Are all potential sources and chemicals identified in the vadose zone soil, rock, and soil vapor within CUAs? Yes. As presented in Table A 2, in addition to the sources and chemicals previously identified in the 2008 EEL RFI Report, 10 features two cooling towers, two soil disturbance areas, a drain west of Building 3268, two structures near Building 3908 and north of Building 3905, and an unidentified feature south of Building 3264) and newly identified chemicals were identified for CUAs 1, 2, 3, and 14 in EEL CC1 during the recent review of historical aerial photographs and historical documents, and during the building inventory and feature survey. These newly identified features are evaluated as part of EEL CC1 in the DQO process. If new information regarding other potential sources or chemicals within CUAs 1, 2, 3, 8 through 14, and portions of CUAs 1 and 7 is identified in the future, the steps associated with this study question will be followed to identify the additional sources and/or chemicals that need to be evaluated as part of these CUAs. Specific information pertaining to all sources and chemicals in EEL CC 1 is documented in Table 2a. Study Question #2: Are the nature and extent of chemical distributions in vadose zone soil, rock, and soil vapor adequately characterized to the required characterization levels, or are data adequate to recommend the CUA cluster or a portion of the CUA cluster for CMS? No. Nature and extent data gaps identified for EEL CC 1 and recommended additional samples are listed below. See Table 2a for a summary of the characterization that has been performed to date at EEL CC 1. See the SAP in Appendix C for specific details on the samples that are proposed to address the following data gaps; proposed sample locations are presented on Figures A 1, A 5, and A 6. Vadose Zone Soil Vapor: d It is recommended that both the lateral and vertical extents of benzene and toluene and the lateral extent of TCE be defined to SVCLs. Vadose Zone Mass Flux to Groundwater: It is recommended that groundwater samples be collected from monitoring wells RS 15, RS 17, and PZ 50 and analyzed for SVOCs, TPH, and metals to evaluate potential impacts in groundwater resulting from migration of these chemicals from the vadose zone. These wells will be sampled during an upcoming SSFL semiannual groundwater sampling event proposed groundwater samples are not included in the SAP in Appendix C). Features and Chemicals Identified in Table A 2: It is recommended that soil vapor samples be collected at the following newly identified features: two soil disturbance areas, one drain, two structures, and one unidentified feature. These features were recently identified during a review of historical aerial photographs, review of historical documents and building inventory and feature survey. It is recommended that soil vapor samples be collected on a biased grid to address features with unknown locations within the EEL RFI site. MRL Exceedance: e Nondetect results for VOCs 1,1,1,2 tetrachloroethane, 1,1,2 trichloroethane, 1,2 dichloroethane, chloroform, and methylene chloride) had elevated MRLs, and these VOCs were never detected at the RFI site. To better address the uncertainty of the presence of these constituents, one soil vapor sample, which was also used to define extent of known contamination for VOCs in the area, is proposed at a location with previous elevated MRLs and will be analyzed for VOCs by methods that can achieve MRLs below SVCLs. Study Question #3: Are data adequate to evaluate the fate and transport of chemicals in the vadose zone, or are data adequate to recommend the CUA Cluster or a portion of the CUA cluster for CMS? No. Fate and transport data gaps identified for EEL CC 1 are listed below. See Table 2a for a summary of the characterization that has been performed to date in EEL CC 1. Vadose Zone Mass Flux to Groundwater: It is recommended that vadose zone fate and transport modeling be performed for the following constituents to evaluate future potential impacts to groundwater: 1,1 DCE and trans 1,2 DCE. Fate and transport modeling for other VOCs, SVOCs, TPH, and metals will be determined following the collection of additional data under Study Question #2. Study Question #4: Do concentrations of chemicals in the vadose zone within CUA Clusters and/or above downgradient groundwater plumes exceed action levels? Yes. CMS areas were identified for TCE in soil vapor in the 2008 RFI Report. The extent of the CMS areas will be further defined based on results from proposed sampling presented in this work plan. Additional chemicals might be identified for remedial planning following additional data collection efforts and following fate andtransport modeling. Study Question #5: Are existing data sufficient to perform remedial planning in vadose zone soils and/or soil vapor that exceed action levels? No. Remedial planning will likely be required for EEL CC 1. However, additional data collection efforts are recommended to support estimation of impacted soil vapor volume within a tolerance of +50% / 30%. In addition, the volume of soil vapor requiring corrective measures will be refined following reassessment of human health and ecological risks and following vadose zone fate andtransport modeling. Concentrations in the vadose zone are not expected to pose an imminent threat to receptors. Comprehensive DQO Conclusions Additional data collection efforts are recommended at EEL CC 1 to address soil as presented in Table A 4), vadose zone as presented in this table), and groundwater as presented in Table A 6). Notes: Bold font represents confirmed or potential data gaps. Yellow cells represent areas where additional work is required under the DQO process. a For the purposes of the RFI Data Gap Work Plan, the vadose zone is defined as soil, rock, and soil vapor between the ground surface and the groundwater table. Tables A 3, A 4, and A 6 provide the DQOs for surface water bodies, soil and sediment, and groundwater and seeps, respectively. b This Master RFI Data Gap Work Plan Addendum only pertains to the portions of the EEL RFI site within Administrative Area III and Boeing RFI Subarea 5/9 South); the portions of the EEL RFI site within Administrative Area IV are being characterized by the United States Department of Energy. c Potential CUAs A and B will be evaluated under Table A 2. Criteria from Figure 2 of the DQO Report, and data collected during proposed investigations will be used to determine whether potential CUAs A and B should be identified as new CUAs or grouped with existing CUA, or if they should be recommended for CNFA. d The residential SVCLs published in Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RCRA Facility Investigation Project CH2M HILL, 2013; Appendix A of the DQO Report) are proposed for use as soil vapor to indoor air characterization levels. The soil vapor to indoor air characterization levels could change based on future land use decisions and future discussions with DTSC. The low toxicity reference values are included in the May 2012 Gold Copy hard drive deliverable and are the proposed characterization levels for evaluating the burrowing ecological receptor. e A sensitivity analysis of MRLs was performed based on consideration of the following: 1) locations within CUAs but outside CMS areas where constituents have nondetect analytical results with MRLs that exceed characterization levels and those same constituents were never detected above MRLs at the RFI site this is to better address the uncertainty of the presence of specific constituents that were never detected at the RFI site; this evaluation focuses on constituents for which the number of MRL exceedances for a constituent relative to the total number of samples analyzed for that constituent is greater than 25 percent); and 2) locations where the existing nondetect/elevated MRL data are being used to define the extent of contamination outside of areas proposed for corrective measure studies. Potential matrix interference and technical limitations in obtaining lower reporting limits were also considered in identifying the need to re sample at previous locations with nondetect/elevated MRL data. MARCH 2013 PAGE 1 OF 2

50 Acronyms: CC = chemical use area clusters CMS = corrective measures study CNFA = conditional no further action CUA = chemical use area DQO = data quality objective DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory MRL = method reporting limit RFI = RCRA facility investigation SAP= sampling and analysis plan SOP = standard operating procedure SVCL = soil vapor characterization level TCE = trichloroethene VOC = volatile organic compound Source: CH2M HILL Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RCRA Facility Investigation Project, Santa Susana Field Laboratory. March. PAGE 2 OF 2

51 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 UNDEVELOPED LAND *# RS-17 *# *# *# EEL-CMS-S1 A *# *# 11 *# *# 10 2 *# 3908 EEL-CMS-SV *# *# 3271 EEL-CMS-S2 *# 3268 *# *# *# 1 EEL CC *# 7 ## ** 8 *# EEL-CMS-S3 # * 9 B *# PZ-050 EEL-CMS-SV # *# 3251 Former Ranch House *# # RS LEGEND Soil Detect, <= Soil Characterization Levels Detect, > Soil Characterization Levels but <= 2x Soil Characterization Levels Detect, > 2x Soil Characterization Levels but <= 10x Soil Characterization Levels # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Soil Vapor CMS Area Disturbed Soil Features Vegetation Clearing Monitoring Well Proposed Excavation Area for Groundwater SamplingU U U U U U U U U UUndefined Feature U U U U U ' Debris Point Spray Field Transformer Pole Leach Field Area Pipeline Septic Tank Leach Field Line Sump Debris Line Detect, > 10x Soil Characterization Levels but <= 100x Soil Characterization Levels Detect, > 100x Soil Characterization Levels Non-detect Drainage Channel Operational Channel $ 1 Structure Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Debris Area Feet in = 60 ft *# Western Notes: 1) For the purpose of this figure, Soil Characterization Levels are the lowest of applicable Suburban Residential RBSLs and Ecological RBSLs, or are the background level if the background Eastern level is greater than one or more RBSLs 2) All chemicals for which a screening level exists are presented on this figure. 3) CMS areas Forming are interim Pit and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 4) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE FIGURE A-2 Comparison of Analytical Results to Characterization Levels for Soil from 0 to 2 Feet Below Ground Surface, EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-2_0_2.MXD RANHORN 5/21/ :29:15 AM

52 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 RS-15 UNDEVELOPED LAND RS-17 EEL-CMS-S1 A EEL-CMS-SV EEL-CMS-S EEL CC EEL-CMS-S3 PZ-050 B EEL-CMS-SV Former Ranch House LEGEND Soil Detect, <= Soil Characterization Levels Detect, > Soil Characterization Levels but <= 2x Soil Characterization Levels Detect, > 2x Soil Characterization Levels but <= 10x Soil Characterization Levels # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) Structure 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Debris Area Soil Vapor CMS Area Disturbed Soil Features Vegetation Clearing Monitoring Well Proposed Excavation Area for Groundwater SamplingU U U U U U U U U UUndefined Feature U U U U U ' Debris Point Spray Field Transformer Pole Leach Field Area Pipeline Septic Tank Leach Field Line Sump Debris Line Detect, > 10x Soil Characterization Levels but <= 100x Soil Characterization Levels Detect, > 100x Soil Characterization Levels Non-detect Drainage Channel Operational Channel $ 1 Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Feet in = 60 ft Western Notes: 1) For the purpose of this figure, Soil Characterization Levels are the lowest of applicable Suburban Residential RBSLs and Ecological RBSLs, or are the background level if the background Eastern level is greater than one or more RBSLs 2) All chemicals for which a screening level exists are presented on this figure. 3) CMS areas Forming are interim Pit and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 4) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE FIGURE A-3 Comparison of Analytical Results to Characterization Levels for Soil from 2 to 10 Feet Below Ground Surface, EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-3_2_10.MXD RANHORN 5/21/ :15:15 AM

53 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 RS-15 UNDEVELOPED LAND RS-17 EEL-CMS-S1 A EEL-CMS-SV1 EEL CC 1 EEL-CMS-S EEL-CMS-S3 PZ-050 B EEL-CMS-SV Former Ranch House LEGEND Soil Detect, <= Soil Characterization Levels Detect, > Soil Characterization Levels but <= 2x Soil Characterization Levels Detect, > 2x Soil Characterization Levels but <= 10x Soil Characterization Levels # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Debris Area Soil Vapor CMS Area Disturbed Soil Features Vegetation Clearing Monitoring Well Proposed Excavation Area for Groundwater SamplingU U U U U U U U U UUndefined Feature U U U U U ' Debris Point Spray Field Transformer Pole Leach Field Area Pipeline Septic Tank Leach Field Line Sump Debris Line Detect, > 10x Soil Characterization Levels but <= 100x Soil Characterization Levels Detect, > 100x Soil Characterization Levels Non-detect Structure Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Drainage Channel Operational Channel $ Feet in = 60 ft Western Notes: 1) For the purpose of this figure, Soil Characterization Levels are the lowest of applicable Suburban Residential RBSLs and Ecological RBSLs, or are the background level if the background Eastern level is greater than one or more RBSLs 2) All chemicals for which a screening level exists are presented on this figure. 3) CMS areas Forming are interim Pit and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 4) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE FIGURE A-4 Comparison of Analytical Results to Characterization Levels for Soil from Greater Than 10 Feet Below Ground Surface, EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-4_GT_10.MXD RANHORN 5/21/ :27:09 AM

54 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 RS-15 UNDEVELOPED LAND RS B 1 # * EEL-CMS-S3 13 EEL-CMS-S # * PZ # * EEL-CMS-S1 A EEL-CMS-SV1 EEL CC 1 6 Western EEL-CMS-SV Former Ranch House 3600 Notes: 1) For the purpose of this figure, Soil Characterization Levels are the lowest of applicable Suburban Residential RBSLs and Ecological RBSLs; Soil Vapor Characterization Levels are the lowest of applicable Vapor Intrusion Characterization Levels and Ecological Eastern Low Toxicity Reference Values. 2) All chemicals for which a screening level exists are presented on this figure. 3) CMS areas are interim Forming and will Pit be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 4) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE LEGEND ") Detect, <= Soil or Soil Vapor Characterization Levels Detect, > Soil or Soil Vapor Characterization Levels ") but <= 2x Soil or Soil Vapor Characterization Levels Detect, > 2x Soil or Soil Vapor Characterization Levels but <= 10x Soil or Soil Vapor Characterization Levels Detect, > 10x Soil or Soil Vapor Characterization Levels but <= 100x Soil or Soil Vapor Characterization Levels ") ") ") Detect, > 100x Soil or Soil Vapor Characterization Levels ") Non-detect * Soil Soil Vapor Proposed Soil Vapor Sample Location # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) Structure 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Soil Vapor CMS Area Disturbed Soil Features Vegetation Clearing Monitoring Well Proposed Excavation Area for Groundwater SamplingU U U U U U U U U U Undefined Feature ' Debris Point U U U U U Spray Field Transformer Pole Septic Tank Pipeline Leach Field Area Leach Field Line Sump Debris Line Drainage Channel Operational Channel Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Debris Area Feet in = 60 ft FIGURE A-5 Comparison of Analytical Results to Characterization Levels for VOCs Soil and Soil Vapor) from 0 to 10 Feet Below Ground Surface, EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California $ 1 SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-5_0_10.MXD RANHORN 5/21/ :29:49 AM

55 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV 5 RS-15 UNDEVELOPED LAND RS-17 *# EEL-CMS-S1 EEL-CMS-SV A EEL CC EEL-CMS-S2 9 EEL-CMS-S3 PZ-050 Western B EEL-CMS-SV # 3251 Former Ranch House # 3600 Notes: 1) For the purpose of this figure, Soil Characterization Levels are the lowest of applicable Suburban Residential RBSLs and Ecological RBSLs; Soil Vapor Characterization Levels are the lowest of applicable Vapor Intrusion Characterization Levels and Ecological Eastern Low Toxicity Reference Values. 2) All chemicals for which a screening level exists are presented on this figure. 3) CMS areas are interim Forming and will Pit be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 4) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE LEGEND ") Detect, <= Soil or Soil Vapor Characterization Levels Detect, > Soil or Soil Vapor Characterization Levels ") but <= 2x Soil or Soil Vapor Characterization Levels Detect, > 2x Soil or Soil Vapor Characterization Levels but <= 10x Soil or Soil Vapor Characterization Levels Detect, > 10x Soil or Soil Vapor Characterization Levels but <= 100x Soil or Soil Vapor Characterization Levels ") ") ") Detect, > 100x Soil or Soil Vapor Characterization Levels ") Non-detect * Soil Soil Vapor Proposed Soil Vapor Sample Location # Proposed Soil Sample Location BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) Structure 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Soil Vapor CMS Area Disturbed Soil Features Vegetation Clearing Monitoring Well Proposed Excavation Area for Groundwater SamplingU U U U U U U U U U Undefined Feature ' Debris Point U U U U U Spray Field Transformer Pole Septic Tank Pipeline Leach Field Area Leach Field Line Sump Debris Line Drainage Channel Operational Channel Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Debris Area Feet in = 60 ft FIGURE A-6 Comparison of Analytical Results to Characterization Levels for VOCs Soil and Soil Vapor) from Greater Than 10 Feet Below Ground Surface, EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California $ 1 SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREA-6_GT_10.MXD RANHORN 5/21/ :24:06 AM

56 TABLE A-6 Data Quality Objectives for Groundwater and Seeps at the EEL RFI Site Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Sources and Chemicals Nature and Extent Fate and Transport NFA or Cleanup Assessment Remedial Planning Information Comprehensive DQO Conclusions Study Question #1: Are all potential sources and chemicals identified in groundwater? Study Question #2: Are the nature and extent of chemicals characterized to required characterization levels a in groundwater, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? Study Question #3: Are data adequate to evaluate the fate and transport of chemicals in groundwater, including volatilization of chemicals from groundwater to the vadose zone and migration of chemicals to seeps and off-site wells, or are data adequate to recommend the CUA cluster or portions of the CUA cluster for CMS? Study Question #4: Do concentrations of chemicals in groundwater exceed action levels, b and/or do concentrations of chemicals present significant risk to current or future receptors indoor air, seeps, or offsite wells)? Study Question #5: Are existing data sufficient to perform remedial planning of groundwater with chemical concentrations above action levels? b EEL RFI Site TBD. The response to this study question will be confirmed after all potential sources of groundwater contamination have been identified and after soil and soil vapor sampling results and vadose zone fate and transport modeling results are evaluated. As presented in Tables A-4, A-5, and Table 4, additional sampling is recommended for the EEL RFI Site. As presented in Table A-5, vadose zone fate and transport modeling is recommended to evaluate future potential impacts to groundwater and additional modeling may also be required, pending receipt and evaluation of the recommended sampling results. TBD. The response to this study question will be confirmed after the response to Study Question #1 is complete. As presented in Table 4, additional sampling of VOCs, SVOCs, metals, and petroleum hydrocarbons is recommended at PZ-50, PZ-51, RS-15, and RS-17. For seeps, VOCs and SVOCs are not present in offsite seeps or wells above characterization levels. TBD. The response to this study question will be confirmed after the responses to Study Questions #1 and #2 are complete. TCE was detected above the soil vapor characterization level in soil vapor above the groundwater plume also containing TCE. As part of the fate-and-transport evaluation, groundwater will be evaluated as a potential source of TCE to indoor air through the vapor intrusion pathway in accordance with Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RFI Project, Santa Susana Field Laboratory, Ventura County, California CH2M HILL, 2013). The fate and transport of VOCs, SVOCs, metals and petroleum hydrocarbons will be verified and evaluated when additional sampling results are available. TBD. The response to this study question will be confirmed after the responses to Study Questions #1 through #3 are complete and after groundwater action levels are confirmed. All VOCs were detected below their respective GCLs except for cis-1,2-dce and TCE. As presented in Table A-5, TCE was recommended to be evaluated in the CMS for groundwater protection. The response to this question for other VOCs, SVOCs, metals, and petroleum hydrocarbons will be verified and evaluated when additional sampling results are available. TBD. The response to this study question will be confirmed after the responses to Study Questions #1 through #4 are complete. Additional data collection efforts are recommended at the EEL Site to address soil as presented in Table A-4), vadose zone as presented in Table A-5), and groundwater as presented in this table). Notes: Bold font if present) represents any confirmed or potential data gaps. Yellow cells if present) represent areas where additional work is required under the DQO process. a The required characterization levels for groundwater will be subject to final regulatory agreements. Currently, groundwater characterization levels are based on a combination of maximum contaminant levels, notification levels, taste/odor thresholds, riskbased screening levels, and SSFL comparison criteria. To evaluate indoor air quality risks via volatilization from a groundwater plume, the current groundwater characterization levels are expected to be adequate; this will be confirmed through soil vapor sampling to be performed above known groundwater plumes see Study Question #3). b It is expected that action levels will be developed in the future based on the 2007 Consent Order for Corrective Action. Acronyms: CMS = corrective measures study CUA = chemical use area DCE = dichloroethene DQO = data quality objective EEL = Environmental Effects Laboratory GCL = groundwater comparison level RFI = RCRA facility investigation SSFL = Santa Susana Field Laboratory SVOC = semivolatile organic compound TBD = to be determined TCE = trichloroethene VOC = volatile organic compound Source: CH2M HILL Recommended Approach for Assessing the Vapor Intrusion Pathway, Boeing RCRA Facility Investigation Project, Santa Susana Field Laboratory, Ventura County, California. March. ES BAO 1 OF 1

57 TCE Trend Decreasing Indeterminate Not evaluated Aerial Photo circa 1967 HAR-18 g HAR-17 g ES-32 PZ-053 E STL-IV E Compound A ES-15 RS-14 ES-17 PZ-015A-G RD-58A ES-26 E E E RS-17 RS-33 PZ-037 RD-58C PZ-034 HAR-32 HAR-33 HAR-34 RS-09 RD-55A ES-16 g PZ-036 ES-24 PZ-038 g PZ-50 RS-12 PZ-050 RD-55B ES-28 ES-14 ES-25 WS-11 RS-17 EEL PZ-031 = == PZ-030 ES-30 ES-28 PZ-51 RS-15 ES-23 ES-30 PZ-028 PZ-029 PZ-018A-E RS-15 ES-23 E EEL E E E E E E Compound A E E E E E E E E E E E E E E E E PZ-051 PZ-054 PZ-149 STL-IV HAR-28 HAR-27 HAR-29 E PZ-040 HAR-07 RD-58B WS-09A g E E RS-13 g E RD-67 Basemap TCE Exceedance = E Wells impacted from sources other than EEL Deformation Bands g g Structures Exceedance likely associated with EEL Finer Grained Unit shale/siltstone)g Exceedance likely associated with EEL and/or adjacent site No exceedance g Area in Which Finer Grained Unit May Be Discontinuous Transport-truncated Flow Paths SSFL Area Boundary Groundwater Pumping Condition Faults SP-882A-D,G Non-pumping Condition E RD-06 Site Boundary CUA Cluster Panel 1 Assessment of Contaminant Distribution To evaluate the distribution and extent of contaminants at EEL to groundwater, existing site data were evaluated in combinati on with results from groundwater flow and contaminant transport simulations as presented in the Draft SSFL Site-Wide Groundwater RI Report, MWH 2009). This information assists in confirming the effectiveness of the monitoring network and the extent of contaminant impacts. Blue lines show forward flow paths from the EEL site to a de pth of 200 meters below the water table under a non-pumping condition. Black lines show the same, except it represents a historical period of groundwater extraction at SSFL between 1995 and The length to the flow paths are truncated to 135 and 130 meters for the non-pumping and pumping conditions, respectively. These estimated transport distances represent an upper bound estimate of the extent of contaminant distribution to site characterization levels. Wells colored red contain concentrations of s ite-related contaminants above site characterization levels, while those colored green do not. There are other source areas beyond EEL that result in comminglin g of contaminant plumes i.e., Compound A). These results show that the extent of groundwater impacts from EEL are defined by the collective monitoring system, including ultimately the seeps well clusters installed along the southwest drainage in Path: U:\BoeingSantaSusana\MXD\Vadose Zone Mass Flux\EEL.mxd Panel 2 Assessment of Plume Stability To evaluate if the lateral or vertical extent of contaminated groundwater is increasing, a statistical trend evaluation 99% confidence level) was conducted over the full period of record for TCE and cdce and groundwater elevation at 5 monitoring locations. This panel shows the results of the statistical evaluation for TCE. Statistically significant decreasing TCE concentration trends wells shown in green) were found in 2 of the 5 wells and no trend stable) was measured in the remaining 3 wells. Concentration trend graphs for a well RS-15) near the source and a clean well beyond the plume RS-17) are provided on the right. No well showed a statistically significant increasing TCE trend. This assessment shows that the lateral and vertical boundaries of the plume as defined by the monitoring network are stable. Note: non-detect values are shown on these graphs as detects because 1/2 of the detection limit was used for the trend analysis. ± ,160 Feet 1 inch = 580 feet DRAFT February, 2013 SANTA SUSANA FIELD LABORATORY VENTURA COUNTY, CALIFORNIA SUMMARY EVALUATION OF GROUNDWATER ASSESSMENT AT EEL Figure A-5 A-7 Figure

58 Appendix B Responses to DTSC Comments Relevant to the EEL RFI Site

59 Appendix B Contents Table B 1: Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report Table B 2: Reponses to DTSC GSU Groundwater Comments on the 2008 EEL RFI Site Report B-1 COPYRIGHT 2013 BY CH2M HILL, INC.

60 Table B 1 Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report, dated December 4, 2009 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California DTSC Comment Response to Comment Proposed Sample IDs a Collection Activities Other Proposed Data Engineering Effects Laboratory Volume V, Appendix G) General Comments 1a. Historical features App G EEL) Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI This RFI Site Report is lacking information that is readily available from historical aerial photos. Additional site Data Gap Work Plan. features that potentially could be release areas are seen on several photos, and should be described in this report. Additional characterization will be required for these features. DQO that will be Satisfied by Proposed Samples 1b. Historical features App G EEL) Also, this RFI Site is located down slope from Area IV which had historical radiological related operations. This RFI Site Report does not adequately address the potential for surface runoff from historical operations at Area IV. 1c. Historical features App G EEL) Also, public comments have indicated that documentation for this site is inadequate, and waste disposal was reportedly handled at this facility throughout the active life span of this facility. The potential for contaminant migration from Area IV to Area III via surface water runoff is being evaluated by the DOE as part of the characterization of Area IV. Soil samples will be collected by DOE as needed to support this evaluation. Comment noted. Small quantities of solvents were used to clean materials that were tested at the laboratory. The spent solvent/rags were stored in drums on the hazardous materials storage pad until they were disposed of offsite. Engineering Effects Laboratory Volume V, Appendix G) Specific Comments 1. Section G Other EEL Site Features Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI Several historic features, disturbed areas, and discolored areas were identified during a cursory review of historical Data Gap Work Plan. Based on the 1957 and 1959 aerial photographs, two soil disturbance areas were identified at the aerial photos. Some of these historical features are not described in this section, and may potentially be associated center of the EEL RFI site. In accordance with the DQO Report CH2M HILL, 2013), soil samples will be collected from 10 with historical contamination. Revise this section to describe all relevant historical features associated with this RFI locations, and soil vapor samples will be collected from six locations from the two soil disturbance areas. Two soil samples Site. will be collected from the drainage pathway downstream of these areas. These additional samples and analytical methods have been incorporated into the EEL SAP. 2. Section G.2.2 EEL Site History No information is provided in this section regarding historical features that are readily identifiable in historical aerial photos dated prior to The following observations were identified during GSU s cursory review. Revise this section to include a thorough description of all identifiable relevant historical features : The site appears undeveloped through 1953, with only the Ranch House appearing to the southeast. 1957: The next available aerial photo 1957) shows a rectangular shaped cleared area at the Site location. Building 4011 does not yet exist. 1959: The 1959 photo shows the northern portion of the rectangular cleared area is covered with a dark material not a stain ). Building 4011 is now present, and this dark feature appears to be directly downslope from nearby Building 4011 s leach field. A white rectangular feature AST?) is south of and adjacent to the dark feature. A welldefined unpaved road extends from this site in a NE direction to the lot parking lot?) located due south of Building The 17th St drainage appears to have possibly been graded and is linear no pond yet). 1960: The EEL area is now a vacant pad can't tell if paved) with what appears to be a large white feature AST?) present. Linear features may correlate with location of recently placed sewer lines north and east of EEL lot. 1963: A larger area of this site is now cleared. The17th St drainage now has a pond, and the STP pond is now present. An unpaved road extends from Building 4011 to the EEL lot : In the 1964 photo, a structure B3268) is now present in the center of the EEL cleared lot with a dark spot located west of the building. The dark spot is surrounded by a darkened halo. This feature may be a pit, possibly used for burning or handling of dark materials. The pits) can still be seen in the 1965 photo, but are not clear in the 1967 poor resolution photo. 1972: A small structure is now near B3268, and may be B3108. This newer structure is located roughly where the dark pits) was located. 1975: More structures now present. An unpaved road from B4011 leads to a dark feature located adjacent and to the east of the EEL lot. The location of this feature corresponds to the location of some tanks tank not yet determined and piping shown on Figure G.1 1 Site Location Map). This feature is not as obvious in the 1977 photo. Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Five newly identified features were identified during the 2010/2011 review of aerial photographs in the portion of the EEL RFI Site located in Area III see Figure A 1). Features identified in Area IV will be addressed by DOE during characterization of Area IV. Two soil disturbance areas were newly identified from review of the 1957 and 1959 aerial photos. In accordance with the DQO Report CH2M HILL, 2013), soil samples will be collected from 10 locations and soil vapor samples will be collected from 6 locations from the two soil disturbance areas. Two soil samples will be collected from the drainage pathway downstream of these areas. One of the soil disturbance areas identified in the 1959 aerial photo appears to be darker than other features. Perchlorate, dioxins, and energetics will be analyzed at samples collected from one location at this soil disturbance area to evaluate whether there were potential burning activities at this area. In addition, two structure features and one undefined feature were newly identified from review of the 1959, 1977, and 1999 aerial photos. In accordance with the DQO Report CH2M HILL, 2013), soil and soil vapor samples will be collected from each of these newly identified features. The additional samples identified above are incorporated into the EEL SAP. The findings from the recent aerial photograph review were incorporated into the Comprehensive Electronic SSFL Sitewide GIS Mapping and Analytical Geodatabase System and will be incorporated into future EEL RFI documentation. ELBS2003, ELBS2004, ELBS2005, ELBS2006, ELBS2016, ELBS2022, ELBS2024, ELBS2025, ELBS2026, ELSV2000, ELSV2001, ELSV2006, ELSV2011, ELSV2012, ELSV2016 ELBS2003, ELBS2004, ELBS2005, ELBS2006, ELBS2016, ELBS2020, ELBS2022, ELBS2024, ELBS2025, ELBS2026, ELSV2000, ELSV2001, ELSV2006, ELSV2009, ELSV2011, ELSV2012, ELSV2015, ELSV2016 Figure 2 and Table 2 Figure 2 and Table 2 3. Section G The TPH excavation area CUA 8) is located adjacent to, and south of, the hazardous material storage area CUA 7) where This section describes an excavation conducted near a concrete drum storage pad. Clarify was this excavated area drums were typically stored. Soil disturbance areas are included in the comprehensive SSFL Sitewide Gold Copy GIS Mapping located near the eastern feature observed in the 1975 aerial photograph? Also, the required soil disturbance map and Analytical Geodatabase System, which has been submitted to DTSC. was not provided for this RFI Site. Include a soil disturbance map for this and all other RFI Sites. Page 1 of 5

61 Table B 1 Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report, dated December 4, 2009 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California DTSC Comment Response to Comment Proposed Sample IDs a Collection Activities Other Proposed Data There were two areas identified with dark discoloration during the 2010/2011 review of aerial photographs. One of the soil disturbance areas identified in the 1959 aerial photograph appears to be darker than other features. In the 1965 aerial photograph, the area west of Building 3108 appears to be darkened. Perchlorate, dioxins, and energetics will be analyzed at two soil sample locations at these locations to evaluate whether there were potential burning activities at these areas. 4. Section G.2.3 EEL Site Chemical Use Areas Include dioxins into the suite of chemicals potentially associated with this site, since it is unclear if historical features having dark discoloration may have been associated with burn activities. Public comments requested that all COPCs including perchlorate, dioxins, and energetics be sampled at the EEL. DQO that will be Satisfied by Proposed Samples ELBS2020, ELBS2025, Figure 2, Tables 2, 5, and 6 5. Section G Surface Water Figure 2.7b in Volume I of RFI 5) is lacking sufficient detail to evaluate the surface flow at and near the EEL Site. More detail is needed at a better scale. Based on a cursory review of historical aerial photographs, south trending well defined drainages appear to be located to the west and east of the EEL Site. These drainages likely received runoff from upslope Area IV operations. Some of the nearby upstream Area IV facilities had rad related operations. Note that the EEL area is down slope and due south of Building 4011 and the B4011 leach field. The potential for surface flow from previous rad related operations to the EEL area cannot be ruled out. More investigation is needed regarding this potential contaminant pathway. Another potential contaminant migration pathway of concern is possible migration of historic leach water from the uphill Building 4011 leach field down to the EEL lot. Leach fields were used at throughout the site prior to establishment of a sewer system in the early 1960s. In a 1959 photo, a black feature can be observed along the northern portion of the EEL lot. This feature has an appearance similar to other former leach field features. Please refer to the Gold Copy GIS Mapping and Analytical Geodatabase System to view the EEL drainage pathways at any scale. The potential for contaminant migration from Area IV to Area III via surface water runoff is being evaluated by the DOE as part of the characterization of Area IV. Soil samples will be collected by DOE as needed to support this evaluation. In the western side of EEL RFI site, two soil samples have been proposed to address potential runoffs from newly identified spray field. ELBS2008 Figure 2 and Table 2 6a. Section G.3.4 Soil Matrix and Soil Vapor Findings Solvents are documented to have been used at this RFI Site HDMSp ), and elevated VOCs have been Please refer to the response to recapitulated DTSC Comment Category 4a presented in Appendix A to the Boeing Master RFI ELBS2002, ELBS2003, ELBS2004, Data Gap Work Plan. In accordance with the DQO Report, soil and soil vapor sampling on a 50 foot biased grid is proposed at ELBS2005, ELBS2006, ELBS2011, sporadically detected in soil and nearby groundwater. Insufficient soil vapor data is available to evaluate the source, the EEL RFI site to evaluate potential releases from undetermined tanks with unknown contents and locations. Soil and soil ELBS2016, ELBS2020, ELBS2021, nature and extent of VOC impacts at this site. A soil vapor survey is thus required for this entire RFI Site. vapor samples are also proposed for other specific locations to define the nature and extent of VOCs in soil and soil vapor. ELBS2022, ELBS2024, ELBS2025, ELSV2000, ELSV2001, ELSV2002, ELSV2003, ELSV2004,STSV2006, STSV2009, ELSV2005, ELSV2006, ELSV2007, ELSV2009, ELSV2010, ELSV2011, ELSV2012, ELSV2015, ELSV2016, ELSV2017 Figure 2, Tables 2, 5, 6, 7, and 8 6b. Section G.3.4 Soil Matrix and Soil Vapor Findings In accordance with the DQO Report CH2M HILL, 2013), soil samples will be collected from this area and are incorporated Additional characterization may be required to investigate the potential release from EEL to the sampled location at into the EEL SAP. the sewer manhole located southwest of EEL. ELBS2023, ELBS2034, ELBS2035, ELBS2036 Tables 5 and 6 6c. Section G.3.4 Soil Matrix and Soil Vapor Findings Additional characterization must be conducted of the discolored area located west of Building 3271 observed in 1964 and 1965 aerial photos). Other features observed in the historical aerial photographs must also be addressed. Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. In accordance with the DQO Report CH2M HILL, 2013), soil and soil vapor samples will be collected from this area and are incorporated into the EEL SAP. ELBS2003, ELBS2020, ELSV2009, ELSV2015 Figure 2 and Tables 2, 7, and 8 6d. Section G.3.4 Soil Matrix and Soil Vapor Findings This comment pertains to the portion of the EEL RFI site located in Area IV, which is being characterized by DOE. Please refer A feature was observed in the northern portion of the EEL Site in the 1959 aerial photo, and elevated metals and to documentation being prepared by DOE regarding characterization of Area IV. VOCs have been detected in this area at depth. Note that the suite of chemicals detected in the northern portion of this RFI Site appear similar to that detected nearby in Area IV. This feature must be adequately investigated, as should the feature located east of the site which can be seen in the 1975 aerial photo. 6e. Section G.3.4 Soil Matrix and Soil Vapor Findings The extent of detected SVOCs, TPH and PCBs at this RFI Site should be delineated to nondetect using the lowest reasonably attainable methods reporting limit. Please refer to the response to recapitulated DTSC Comment Category 14b and 8b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. SVOCs and TPH were not detected at concentrations exceeding their SCLs. PCB exceedances of its SCLs are located in the portion of the EEL RFI site in Area IV, which is being characterized by DOE. Please refer to documentation being prepared by DOE regarding characterization of Area IV. Page 2 of 5

62 Table B 1 Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report, dated December 4, 2009 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California 6f. Section G.3.4 Soil Matrix and Soil Vapor Findings More characterization is also needed of the drainages located to the west and east of EEL. DQO that will be DTSC Comment Response to Comment Proposed Sample IDs a Collection Activities Samples Other Proposed Data Satisfied by Proposed ELBS2008 Figure 2 and Table 2 Please refer to the response to recapitulated DTSC Comment Category 6b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. In the western side of EEL RFI site, two soil samples have been proposed to address potential surface water runoff from the newly identified spray field. The drainage pathway on the eastern side of EEL RFI site will be addressed in the Compound A RFI site work plan and will also be addressed by DOE for upgradient sources in Area IV. 6g. Section G.3.4 Soil Matrix and Soil Vapor Findings Aluminum was detected at a concentration of 15,300 mg/kg in the primary sample and at a concentration of 31,900 mg/kg Section G indicates that aluminum was detected up to 25,000 mg/kg, yet aluminum is reported in samples in the split sample collected at ELBS1408. Reported concentrations were calculated average concentrations for those up to 31,900 mg/kg. Clarify this discrepancy. All areas of elevated aluminum need to be reported in this section, and samples with more than one result. An average concentration of 23,600 mg/kg was reported at ELBS1408 and an average elevated aluminum must be delineated at all locations. GSU does not accept the argument that elevated aluminum concentration of 17,067 mg/kg was reported at ELBS1028. Therefore, the maximum reported concentration for aluminum at is attributed to naturally occurring background, as this has not been demonstrated. All metals must be delineated the EEL RFI Site was previously reported as 25,000 mg/kg, detected in ELBS1027. However, going forward, the maximum to background. concentration between original, duplicate, and/or split sample results will be used in performing nature and extent characterization and/or risk assessment evaluations related to the Boeing RFI work. In addition, all analytical data for original, duplicate, and split samples are included in the comprehensive SSFL Sitewide Gold Copy GIS Mapping and Analytical Geodatabase System, which has been submitted to DTSC. The maximum aluminum concentration detected at the EEL RFI site 31,900 mg/kg) is less than the 95/95 upper threshold limit combined background threshold value proposed for use by Boeing for aluminum 37,900 mg/kg). 7. Section G Groundwater Data Summary This section indicates that it may be more likely that VOC impacts to soil and NSGW are related to upgradient or adjacent sources. However, this section does not describe what these sources are. Solvents are documented to have been used at this RFI Site HDMSp ). Impacts to the soil and nearby groundwater could potentially have originated from this Site location. Note that some features observed in historical aerial photos could potentially have resulted in impacts to the site prior to construction of current existing buildings and structures, and must be investigated. Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Additional samples are recommended to better characterize the presence of VOCs in soil and soil vapor at the EEL RFI Site. Five new features 2 soil disturbance areas, 2 structures, and 1 undefined feature) have been identified during the aerial photograph review. In accordance with the DQO Report CH2M HILL, 2013), soil and soil vapor samples will be collected from each of these newly identified features. The additional samples identified above are incorporated into the EEL SAP. ELBS2002, ELBS2003, ELBS2004, ELBS2005, ELBS2006, ELBS2016, ELBS2020, ELBS2021, ELBS2022, ELBS2024, ELBS2025, ELSV2000, ELSV2001, ELSV2003, ELSV2004,STSV2006, STSV2009, ELSV2005, ELSV2006, ELSV2007, ELSV2009, ELSV2010, ELSV2011, ELSV2012, ELSV2015, ELSV2016, ELSV2017 Figure 2 and Table 2 8. Section G.3.6 Surface Water Findings GSU does not concur with the statement that soil within the EEL Site is not likely impacted by upgradient sites via surface water transport, as this has not been adequately demonstrated. The potential contaminant pathway of leach water flow from the former upslope Building 4011 Leach Field has not been addressed. 9. Section G.5.2 CMS Site Recommendations At a minimum, GSU concurs with the three sites recommended for CMS. However, more characterization is needed, and based on the results, more areas may potentially be recommended for CMS. Until characterization is completed for this RFI Site, no NFA recommendations will be considered. The potential for contaminant migration from Area IV to Area III via surface water runoff is being evaluated by the DOE as part of the characterization of Area IV. Soil samples will be collected by DOE as needed to support this evaluation. Please refer to the response to recapitulated DTSC Comment Category 13a presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. The need for additional CMS areas and the extent of existing CMS areas will be further defined after all data gaps identified through the comprehensive DQO process have been filled and after additional human health and ecological risk assessments are performed. 10. Section G Historical Uses This section is deficient and must be revised, as it does not describe various features, areas of soil disturbance, and discolored areas observed in historical aerial photos. Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Historical aerial photographs reviewed during 2010/2011 are integrated into the comprehensive SSFL Sitewide Gold Copy GIS Mapping and Analytical Geodatabase System, which includes aerial photograph overlays that identify the locations of site features relevant to potential chemical use. 11. Inventory Tables App G EEL) Revise these tables to incorporate information obtained from a thorough review of historical aerial photographs e.g., use periods and existence of buildings, tanks, transformers, and other site features). Please refer to the response to recapitulated DTSC Comment Category 3a presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Page 3 of 5

63 Table B 1 Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report, dated December 4, 2009 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California 12. Table G.2 1 Building Inventory This table indicates that Building 3108 has unknown use for an unknown duration and it does not recommend a chemical use for the building. As a result, this location was not intended for sampling. Note that this building footprint overlies a dark pit like feature with a darkened halo observed in aerial photos). This discolored SVOCs, TPH, and metals. All results were either nondetect or less than soil characterization levels. No additional sampling is feature could potentially be a burn area or a potential release area, and must be investigated. All potential source recommended at Building Soil samples will be collected at a location in the darkened area west of Building 3108 and historical features preceding buildings must be identified and addressed in the RFI. analyzed for perchlorate, dioxins, and energetics to evaluate whether there were potential burning activities at this area. DQO that will be Satisfied by Proposed Other Proposed Data DTSC Comment Response to Comment Proposed Sample IDs a Collection Activities Samples Please refer to the response to recapitulated DTSC Comment Category 3b presented in Appendix A to the Boeing Master RFI ELBS2020 Tables 5 and 6 Data Gap Work Plan. Building 3108 was used as an EEL Cryogenic Test Cell and has been classified as CUA 10. Soil samples were collected at ELBS1004, ELBS1007, ELBS1013, and ELBS1015 in the vicinity of Building 3108 and were analyzed for VOCs, 13. Table G.2 2 Tank Inventory This table is missing information regarding the tank not yet determined shown in Figure G.2 2 and depicted as Chemical Use Area 6 in Figure G.2 1. Include information regarding chemical use at this location in the table. Not that this location corresponds to a location of a feature identified in the 1975 aerial photo. In this photo, an unpaved road from B4011 leads to a dark feature at this location, located adjacent and to the east of the EEL lot. The CUA descriptions have been updated in Table 1. All available information regarding these tanks is documented in the sitewide tank inventory, which was provided with the comprehensive SSFL sitewide gold copy hard drive submittal in May These tanks are located in the portion of the EEL RFI Site located in Area IV, which is being characterized by DOE. Please refer to documentation being prepared by DOE regarding characterization of Area IV. 14. Table G.2 8 Chemical Use Summary Include Chemical Use Area 8 in this table, as it is mentioned in other figures and tables as the TPH excavation area. What was the likely source of this release? 15. Table G.4 1 Chemicals of Potential Concern COPC) for Human Health This table erroneously lists various metals as not exceeding background, when they actually have. Review and revise the entire table and all other COPC tables in the RFI 5 Report) to accurately depict the data. A description of CUA 8 has been added to Table 1. The source of TPH contamination in this area is unknown; however, the TPH excavation area is adjacent to the former hazardous materials storage area CUA 7). Please refer to the response to recapitulated DTSC Comment Category 10c presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. 16. Missing Figure App G EEL) The soil disturbance map is missing and must be included. It must depict all features noted from historical documents and aerial photos that indicate past soil disturbance, excavation and/or fill. Details on the locations and types of soil disturbance at the EEL RFI site can be found in the comprehensive SSFL sitewide ELBS2004, ELBS2005, ELBS2006, gold copy GIS mapping and analytical geodatabase system, which was provided to DTSC in April 2011 and May This ELBS2016, ELBS2022, ELBS2024, system depicts soil disturbance areas based on aerial photographs. Based on the 2010/2011 review of 1957 and 1959 aerial ELBS2025, ELBS2026, ELSV2000, photographs, two soil disturbance areas were identified at the center of the EEL RFI site. In accordance with the DQO Report ELSV2001, ELSV2006, ELSV2011, CH2M HILL, 2013), soil samples will be collected from 10 locations,and soil vapor samples will be collected from six locations ELSV2012, ELSV2016 from the two soil disturbance areas. Two soil samples will be collected from the drainage pathway downstream of these areas. These additional samples and analytical methods have been incorporated into the EEL SAP. Figure 2 and Table Figure G.2 3A EEL Cross Section Location Include a NW SE trending cross section line through the operational area through buildings 3271 and 3268) of the EEL Site. The current section line is located outside of the building area, along the eastern edge of the site. This line should also depict the nearby sewer line that is located along the eastern edge of the Site. 18. Figure G.3 7 VOCs Data Results It is difficult to differentiate soil matrix sample locations from soil vapor sample locations. Previous RFI Reports Groups 6 and 8) used different symbols to differentiate between sampled media and it is not clear why this was not continued with the Group 5 RFI Report. Revise the VOC Results figures to use different symbols to differentiate samples by media. Please refer to the response to recapitulated DTSC Comment Category 1c presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Please refer to the response to recapitulated DTSC Comment Category 10a presented in Appendix A to the Boeing Master RFI Data Gap Work Plan. Figures A 5 and A 6 in Appendix A differentiates sample matrix types by using different symbols for soil and soil vapor. 19a. Figure G.3.8 SVOCs, TPH and PCBs Data Results On April 30, 2008, GSU conducted a site walk to view and discuss sample locations at EEL. GSU observed that one boring location ELBS1009) was marked at approximately five feet away from the northern wall of Building This same boring location is plotted on this figure as being approximately 15 feet from the wall of the building. Provide an explanation regarding this discrepancy, and describe the accuracy of all plotted sample locations. ELBS1009 was originally located approximately 5 feet from Building However, ELBS1009 could not be completed at its original location due to underground utilities in the area. The closest location to the original location that the boring could be safely advanced was approximately 15 feet away from Building b. Figure G.3.8 SVOCs, TPH and PCBs Data Results This wall is located in the portion of the EEL RFI site located in Area IV, which is being characterized by DOE. Please refer to Note that a significant amount of staining was observed on the concrete in the vicinity of the pumps along this wall. documentation being prepared by DOE regarding characterization of Area IV. The locations of these stains should be clearly noted in the Building Feature Survey map for EEL, and should be sampled for the appropriate constituents. Notes: a See Table C 1 in Appendix C for further detail regarding sample media, sample depths, and analyses for each proposed sample location. Page 4 of 5

64 Table B 1 Responses to DTSC GSU Specific Comments on the 2008 EEL RFI Site Report, dated December 4, 2009 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California DQO that will be DTSC Comment Response to Comment Proposed Sample IDs a Collection Activities Samples Other Proposed Data Satisfied by Proposed b Each proposed sample is intended to satisfy a data DQO set forth in Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California CH2M HILL, 2013). See EEL RFI Site Tables A 3 through A 6 for further details regarding the data gaps identified through the DQO process. Acronyms: CMS = corrective measures study DOE = United States Department of Energy DQO = data quality objectives DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory GIS = geographic information system mg/kg = milligrams per kilogram PCB = polychlorinated biphenyl RFI = RCRA facility investigation SAP = sampling and analysis plan SCL = soil characterization level SSFL = Santa Susana Field Laboratory SVOC = semivolatile organic compound TPH = total petroleum hydrocarbons VOC = volatile organic compound Source: CH2M HILL Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California. March. Page 5 of 5

65 TABLE B 2 Responses to DTSC Groundwater Comments on the 2008 Draft Group 5 RFI Report, dated January 25, 2010 Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California DTSC Comment Group 5 GW Report Vol III, App B) General Comments 56m. B Summary of Metals in Groundwater within the Group 5 Reporting Area Environmental Effects Laboratory EEL) There is only one well PZ 050) that was identified within the EEL RFI area. This well is not located directly downgradient of the EEL RFI and therefore is not located well to assess any impacts to the groundwater from the activities at EEL. There are no wells in the area that are located to adequately assess any potential impacts to groundwater by the activities of this RFI group. The GSU, therefore, recommends that the facility install both near surface and Chatsworth formation wells upgradient and downgradient to assess the nature and extent of any releases from this RFI group. Response to Comment Groundwater flow path analysis from the three dimensional groundwater flow model as presented in the Site wide Groundwater Remedial Investigation Report, Santa Susana Field Laboratory, Ventura County, California MWH, 2009) shows that both RS 15 pumping) and RS 17 and PZ 51 non pumping) intercept groundwater from EEL, and both are located within the projected extent of impacted groundwater based on the calculated Darcy flux and considering expected retardation. As such, Boeing believes that these three wells along with PZ 50 are sufficient for evaluating groundwater impacts from EEL. 56n. B Summary of Metals in Groundwater within the Group 5 Reporting Area Aluminum was detected at a concentration of 217 µg/l in a sample collected on Environmental Effects Laboratory EEL) May 7, 2009 from PZ 050. However, aluminum was not detected above the Aluminum, arsenic, barium, beryllium, cadmium, chromium, lithium, silver, sodium, reporting limit in a subsequent sample collected on February 10, Updated and zinc were detected in the soil above their respective background groundwater data are included in in the SSFL Sitewide Gold Copy GIS Mapping concentrations. Aluminum, copper, and selenium were detected above the GWCC. It and Analytical Geodatabase System, which has been submitted to the DTSC. should be noted that the report does not acknowledge the elevated aluminum Future updates to the electronic database will include new groundwater data concentration 217 µg/l with a GWCC of 200 µg/l) reported in PZ 050 page G3 9). following future semiannual groundwater sampling events. 56o. B Summary of Metals in Groundwater within the Group 5 Reporting Area Environmental Effects Laboratory EEL) Sodium and lithium have not been analyzed in the groundwater samples collected from PZ 050. There are no indications in historical documentation of use of sodium or lithium at this site, and no soil samples analyzed for metals had sodium or lithium concentrations above the 2012 background levels. Therefore, there appears to be no basis for evaluation of sodium or lithium at PZ 050, and the well will not be sampled for these constituents. Notes: µg/l = micrograms per liter DTSC = California Environmental Protection Agency, Department of Toxic Substances Control EEL = Environmental Effects Laboratory GSU = Geological Services Unit DTSC) MWH = MWH International, Inc. RFI = RCRA facility investigation SSFL = Santa Susana Field Laboratory MWH International, Inc. MWH) Site wide Groundwater Remedial Investigation Report, Santa Susana Field Laboratory, Ventura County, California. December. ES BAO Page 1 of 1

66 Appendix C EEL RFI Site Data Gap Sampling and Analysis Plan

67 Appendix C Contents EEL RFI Site Data Gap Sampling and Analysis Plan Table C 1: EEL RFI Site Proposed Data Gap Sampling and Analysis Table C 2: EEL RFI Site Soil and Soil Vapor Analyses Figure C 1: Proposed Sample Locations for the EEL RFI Site

68 EEL RFI Site Data Gap Sampling and Analysis Plan, Santa Susana Field Laboratory, Ventura County, California Prepared for The Boeing Company May 2013 Prepared by COPYRIGHT 2013 BY CH2M HILL, INC.

69 Contents Section Page Acronyms and Abbreviations... v 1.0 Introduction Summary of Proposed Samples for EEL RFI Site Field Sampling Procedures Sampling Guidelines Soil Soil Vapor Analytical Guidelines Criteria for Contingent Analyses Criteria for Contingent Samples Quality Assurance/Quality Control Sampling Requirements Step out and Step down Samples References... 4 Tables C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis C 2 EEL RFI Site Soil and Soil Vapor Analyses Figure C 1 Proposed Sample Locations for the EEL RFI Site COPYRIGHT 2013 BY CH2M HILL, INC. III

70 Acronyms and Abbreviations bgs DQO EEL mg/kg MRL QAPP RCRA RFI SAP SOP SSFL VOC below ground surface data quality objective Environmental Effects Laboratory milligram/kilogram method reporting limit quality assurance project plan Resource Conservation and Recovery Act RCRA facility investigation sampling and analysis plan standard operating procedure Santa Susana Field Laboratory volatile organic compound COPYRIGHT 2013 BY CH2M HILL, INC. V

71 EEL RFI Site Data Gap Sampling and Analysis Plan, Santa Susana Field Laboratory, Ventura County, California 1.0 Introduction This document presents the data gap sampling and analysis plan SAP) for the Environmental Effects Laboratory EEL) Resource Conservation and Recovery Act RCRA) facility investigation RFI) site in Boeing RFI Subarea 5/9 South at the Santa Susana Field Laboratory SSFL) in Ventura County, California. The purpose of this SAP is to present the plan for addressing data gaps identified for the EEL RFI site through the comprehensive data quality objectives DQOs) evaluation. The data gaps identified for the EEL RFI site are presented in the Addendum to Master Resource Conservation and Recovery Act Facility Investigation Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California CH2M HILL, 2013a). The SAP presented herein describes how and where data will be collected to address the data gaps identified for the EEL RFI site. 2.0 Summary of Proposed Samples for EEL RFI Site Table C 1 presents the sample media, sample depth, and analytes for each sample proposed for collection at the EEL RFI site. In addition, Table C 1 presents the rationale, the specific DQOs that each proposed sample are intended to satisfy, and the California Environmental Protection Agency, Department of Toxic Substances Control DTSC) comments) that each proposed sample is intended to address where applicable). Table C 2 presents the laboratory analytical methods proposed for the analytes listed in Table C 1. Figure C 1 presents the locations of the proposed samples. The proposed samples presented in Table C 1 and Figure C 1 were identified based on the characterization sampling and analysis strategy presented in the draft Comprehensive Data Quality Objectives, RCRA Facility Investigation, Santa Susana Field Laboratory, Ventura County, California DQO Report) CH2M HILL, 2013b) for surface water bodies, soil and sediment, and the vadose zone. Samples will be collected from the locations presented in Table C 1 and Figure C 1. However, field staff will field check proposed sample locations relative to site drainage patterns, surface slope, and topography and will use professional judgment to modify sample locations accordingly. In addition, field staff will field check proposed sample locations relative to existing structures, rock outcrops, above and below ground utilities, or other obstacles and will adjust the sample locations accordingly. The final locations of each sample will be recorded using handheld global positioning system equipment. Soil sample depths may also be adjusted from the depths shown in Table C 1 based on observed staining, discoloration, or elevated volatile organic compound VOC) levels recorded with a photo ionization detector during drilling. Sample location identifications were developed using the two digit code that indicates the RFI site associated with the sample EL was used for EEL), followed by the two digit code that indicates the sample/matrix type for example, BS was used for soil boring samples and SV was used for soil vapor samples), followed by four numerical digits starting with 2000 at each site). For example, a sample numbered ELBS2002 would be a soil boring sample BS) and is the third consecutively numbered sample 2002) for the EEL RFI site. Several existing monitoring wells are proposed for sampling as presented in Section of the STP 3 Master Data Gap Work Plan Addendum. The groundwater sampling will not be conducted as part of this SAP and therefore the sampling details are not presented herein. Instead, the proposed groundwater sampling will be conducted in accordance with the Site Wide Water Quality Sampling and Analysis Plan, Revision 1, for the Santa Susana Field Laboratory, Ventura County, California Haley & Aldrich, December 2010). COPYRIGHT 2011 BY CH2M HILL, INC. 1

72 EEL RFI SITE DATA GAP SAMPLING AND ANALYSIS PLAN, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA 3.0 Field Sampling Procedures Samples will be collected in accordance with the SSFL standard operating procedures SOPs) Boeing, 2013), which were submitted to and approved by DTSC in March Prior to sample collection, sample locations will be cleared of vegetation, SSFL utility diagrams will be reviewed, sample locations will be staked, third party utility surveys will be performed, and DigAlert will be contacted. The sample locations may be adjusted based on information regarding subsurface utilities or other subsurface structures provided by the third party utility survey company and DigAlert. The final locations of each sample will be recorded using handheld global positioning system equipment. 3.1 Sampling Guidelines Samples will be collected in accordance with the DQO Report and field SOPs. However, additional guidelines for soil and soil vapor sample collection are outlined in Sections and Soil In cases where all the planned soil samples at a specific location cannot be collected due to the presence of bedrock, a soil sample will be collected just above the depth where the rig encountered refusal. However, the soil sample will not be collected from the refusal depth if the following two criteria are satisfied: A more shallow samples) was collected at the same location. The bottom depth of the shallower samples) would be less than 2 feet above the top of the refusal depth sample. In accordance with DQO Report Table 2, step out samples typically are collected at the same depth as the original sample with concentrations that exceed characterization levels. However, VOC step out soil samples will not be collected from a more shallow depth than 1.5 feet bottom sample depth). For example, if the original sample that contained VOCs at concentrations that exceed the corresponding characterization levels was collected from 0.5 foot below ground surface bgs), the step out sample for that location would be collected from 1.5 feet bgs Soil Vapor Soil vapor samples will be collected from a minimum depth of 5 feet bgs. In cases where a soil vapor sample cannot be collected from at least 5 feet bgs due to refusal on bedrock or inadequate air flow, a soil sample will be collected in lieu of the soil vapor sample and analyzed for VOCs. This soil sample will be collected to support an evaluation of the vapor intrusion pathway. The soil sample will be collected from the maximum depth possible at that location but no shallower than 3 feet bgs. The soil sample will not be collected if refusal on bedrock is encountered shallower than 3 feet bgs. In addition, the soil sample will not be collected if previous soil samples collected from greater than 3 feet bgs at that location were analyzed for VOCs. At locations where a soil vapor sample may be collected from a minimum depth of 5 feet bgs but deeper samples cannot be collected from the proposed sample depths due to the presence of bedrock, a soil vapor sample will be collected just above the depth where the rig encountered refusal. However, the soil vapor sample will not be collected from the refusal depth if the bottom depth of the shallower soil vapor samples) would be less than 3 feet above the top of the refusal depth soil vapor sample. 4.0 Analytical Guidelines Table C 1 presents the chemicals that are proposed for analysis in each sample. Table C 2 presents the analytical methods that are proposed for use during implementation of this SAP refer to the Quality Assurance Project Plan, Santa Susana Field Laboratory SSFL) RCRA Field Investigation, Surficial Media Operable Unit, Revision 5 QAPP) MECx, 2013) for the specific chemicals that will be analyzed and reported under each method). Soil samples will be homogenized by the analytical laboratories in accordance with Boeing SSFL SOP 21, Laboratory Homogenization of Soil Samples. 2 COPYRIGHT 2013 BY CH2M HILL, INC.

73 Analytical guidelines that were followed during preparation of this SAP include: EEL RFI SITE DATA GAP SAMPLING AND ANALYSIS PLAN, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA For features where the historical uses are not known and therefore, the chemical uses are also unknown), a screening for total petroleum hydrocarbons, VOCs, semivolatile organic compounds, and metals will be performed. Soil at these features also might be analyzed for other chemical groups based on the chemical uses of adjacent features/rfi sites. In areas where burnt materials are observed or combustion products are suspected, dioxins and polynuclear aromatic hydrocarbons will be analyzed. Because hydrazine degrades rapidly in the environment, features that have known hydrazine uses will be analyzed for the breakdown products of hydrazine nitrosodimethylamine and formaldehyde). 4.1 Criteria for Contingent Analyses In some cases, the need for performing select analytical methods is contingent on the results of performing other analytical methods on a particular sample. In these cases, the laboratory will be notified to hold the sample for analysis of select constituents until CH2M HILL has the opportunity to review the results of other analyses performed on the sample. CH2M HILL will notify the laboratory if analysis for the held constituents is necessary based on these results based on a comparison of the analytical results to characterization levels). Table C 1 identifies the constituents that will be held for analysis by the laboratory pending the results of other analytical methods. Examples of contingent analyses include: In accordance with DQO Report Table 2, for newly identified features for which VOCs are listed for analysis in soil and soil vapor, the VOCs in soil samples will only be collected if the VOCs in soil vapor sample cannot be collected either due to refusal on bedrock at a depth more shallow than 5 feet bgs or due to poor air flow in the soil vapor probe). In accordance with DQO Report Table 2, three to four discrete samples will be mixed into a single composite sample at pole mounted transformers and electrical substations. The composite sample will be analyzed for polychlorinated biphenyls. CH2M HILL will provide the analytical laboratory with direction to analyze the discrete samples only if the polychlorinated biphenyls are detected in the composite sample. 4.2 Criteria for Contingent Samples In some cases, the need for collecting a sample is contingent on the analytical results of other samples. Table C 1 identifies the samples that will be held for collection or analysis pending the analytical results of other samples. Examples of contingent samples include: In cases where the 10 foot bgs sample is collected in the field, lab analysis of that sample will sometimes be held by the lab until CH2M HILL provides direction to analyze the sample. CH2M HILL will evaluate the need for lab analysis based on the results of samples above the proposed sample generally based on analytical data for the 6 foot bgs sample). The 10 foot bgs sample will generally be analyzed by the lab following direction from CH2M HILL) if constituents are detected above characterization levels in the 6 foot bgs sample. The need to analyze the 10 foot bgs sample is also dependent on the site conceptual model. In some cases, samples will be re collected to address previous method reporting limits MRLs) that exceed characterization levels. One instance in which samples may be re collected to address elevated MRLs is for analytes with previous elevated MRLs that have never been detected in the reporting area. If an analyte was never detected in the reporting area, data for that analyte would generally not be included in the risk assessment for that reporting area. Therefore, greater assurance that the analyte is not present above characterization levels is desired. Soil and soil vapor samples are proposed for collection in Table C 1 to address this uncertainty. However, if the specific analytes that have not been detected previously are detected in one or more of the other samples planned for collection, the samples proposed to address this issue will not be collected. COPYRIGHT 2013 BY CH2M HILL, INC. 3

74 EEL RFI SITE DATA GAP SAMPLING AND ANALYSIS PLAN, SANTA SUSANA FIELD LABORATORY, VENTURA COUNTY, CALIFORNIA 5.0 Quality Assurance/Quality Control Sampling Requirements Laboratory analysis will be performed in accordance with the QAPP MECx, 2013). The QAPP describes the quality assurance/quality control requirements for SSFL and identifies the analytical methods, method detection limits, and analyte lists for the constituents used at SSFL. In accordance with the QAPP, quality assurance/quality control samples will be collected and analyzed at the following frequency: Field Duplicate: Collected on a 5 percent frequency for each matrix and for each type of analysis. Laboratory Split: Collected on a 5 percent frequency for each matrix for each type of analysis. Split samples are analyzed by a laboratory other than the primary laboratory. Matrix Spike/Matrix Spike Duplicate: Collected on a 5 percent frequency for each matrix and for each type of analysis. Equipment Blanks: One sample collected per day for each equipment type that is decontaminated. Trip Blank: One sample per cooler containing samples for analysis of VOCs. 6.0 Step-out and Step-down Samples Following the collection of the proposed samples identified herein, the need to collect step out to define lateral extent to required characterization levels) and step down to define vertical extent to required characterization levels) samples will be assessed. If the samples proposed herein are found to contain constituents at concentrations that exceed the required characterization levels and the extents of the elevated concentrations are not defined by concentrations in existing samples, step out and step down samples will be collected using the characterization sampling and analysis strategy presented in the DQO Report CH2M HILL, 2013b). For the upper 10 feet of soil and sediment, step down samples will be collected to the maximum depth possible using a hand auger or direct push rig. Step down samples will not be re attempted at locations that have previously been drilled to and characterized at) the maximum depth that may be accessed with a hand auger or direct push rig. Soil and bedrock deeper than 10 feet bgs are addressed by DQO Report Table 8. The results of all data gap sampling at the EEL RFI site will be presented in a future data summary and findings report for Boeing RFI Subarea 5/9 South. 7.0 References CH2M HILL. 2013a. Addendum to Master RCRA Facility Investigation Data Gap Work Plan, Boeing RFI Sub Area 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California. March. CH2M HILL. 2013b. Comprehensive Data Quality Objectives, Santa Susana Field Laboratory, Ventura County, California. March. Haley & Aldrich Site Wide Water Quality Sampling and Analysis Plan, Revision 1, for the Santa Susana Field Laboratory, Ventura County, California. December. MECx Quality Assurance Project Plan, Santa Susana Field Laboratory SSFL) RCRA Field Investigation, Surficial Media Operable Unit, Revision 5. March. The Boeing Company Boeing) Standard Operating Procedures for Areas I and III of the Santa Susana Field Laboratory, Ventura County, California. March. 4 COPYRIGHT 2013 BY CH2M HILL, INC.

75 Tables

76 TABLE C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite EEL CC Chemical Use Area No. Location ID NA A ELBS2000 Location Western Sprayfield Potential CUA A) Matrix Sample Depth feet bgs) TPH ext.) VOCs Full) VOCs Soil Vapor) SVOCs Metals Metal Mercury Metal Arsenic soil 0.5 X X X X X X X X X NA A ELBS2000 ELSV2008 soil 1.5 b X VH X X X X NA A ELBS2000 ELSV2008 soil 6 b X VH X X X X X X X X X X X X Metal Selenium Metal Silver ph PCBs Energetics Formaldehyde Perchlorate Dioxins Inorganics Chromium VI Pesticides Herbicides Cyanide Alcohols DQO Cross Reference Table 2 and Figure 2 DTSC Comment No. Cross Reference NA Rationale/Objectives Potential CUA A newly identified spray field identified during the 2010/2011 water conveyance system inventory activities). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. NA A ELBS2000 Western Sprayfield Potential CUA A) soil 10 H H H H H H H H H H H H H H 1 A, 2 ELBS2001 soil 0.5 X X X X X X X 1 A, 2 ELBS2001 soil 1.5 X X X X X X 30' E of ELBS A, 2 ELBS2001 soil 6 X X X X X X X X X X X X X 1 A, 2 ELBS2001 soil 10 H H X H H H H H H H H H H H Tables 2, 5, 6 and Figure 2 NA Potential CUA A newly identified spray field identified during the 2010/2011 water conveyance system inventory activities) and newly identified structure feature identified during the 2010/2011 review of aerial photographs in CUA 2. Define E extent of arsenic and lithium exceeded SCL) at ELBS1014 5' bgs) and NE extent of barium and lithium exceeded SCL) at ELBS1016 5' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. 1 B ELBS2002 ELBS1028 soil 0.5 X X X X X X X 1 B ELBS2002 ELSV2003 soil 1.5 b X VH X X X X 1 B ELBS2002 ELSV2003 soil 6 b X VH X X X X X X X X X X X X 1 B ELBS2002 ELSB1028 soil 10 H H H H H H H H H H H H H H Tables 2, 5, 6, 7, 8 and Figure 2 6a, 7 Define vertical extent of silver exceeded SCL) at ELBS1028 1' bgs). Potential CUA B newly identified spray field identified during the 2010/2011 water conveyance system inventory activities). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. 1 A ELBS ' NW of ELBS1014 soil 0.5 X 1 A ELBS2003 ELSV2015 soil 1.5 b X VH X 1 A ELBS2003 ELSV2015 soil 6 b X VH X X 1 A ELBS ' NW of ELBS1014 soil 10 H H H X Structure Feature NW of 1 A ELBS2004 soil 0.5 X X Building 3905) 1 A ELBS2004 ELSV2001 soil 1.5 b X VH X 1 A ELBS2004 ELSV2001 soil 6 b X VH X X X 1 A ELBS2004 Structure Feature NW of Building 3905) soil 10 H H H H H Tables 2, 5, 6, and Figure 2 Tables 2, 7, 8 and Figure 2 1, 2, 6a, 6c, 7 1, 2, 6a, 7, 16 Define NW extent of arsenic and lithium exceeded SCL) at ELBS1014 5' bgs) and barium and lithium exceeded SCL) at ELBS1016 5'bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Newly identified former structure feature identified during the 2010/2011 review of aerial photographs. Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected ELBS2005 Building Feature soil 0.5 X X X 1 14 ELBS2005 ELSV2011 soil 1.5 b X VH X X X 1 14 ELBS2005 ELSV2011 soil 6 b X VH X X X X X X 1 14 ELBS2005 Building Feature soil 10 H H H H H H H H Structure Feature S of Building 1 3 ELBS2006 soil 0.5 X 3264) 1 3 ELBS2006 ELSV2006 soil 1.5 b VH X X X 1 3 ELBS2006 ELSV2006 soil 6 b X VH X X X X X 1 3 ELBS2006 Structure Feature S of Building 3264) soil 10 H H H H H H H Table 2 and Figure 2 Tables 2, 7, 8 and Figure 2 1, 2, 6a, 7, 16 1, 2, 6a, 7, 16 Building feature , a newly identified former building feature identified during the 2008 building feature survey placed near former 2 inch metal pipeline. Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Newly identified undefined feature identified during the 2010/2011 review of aerial photographs. Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Page 1 of 5

77 TABLE C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite EEL CC Chemical Use Area No. Location ID NA A ELBS2007 Location Western Sprayfield Potential CUA A) Matrix Sample Depth feet bgs) TPH ext.) VOCs Full) VOCs Soil Vapor) SVOCs Metals Metal Mercury Metal Arsenic soil 0.5 X X X X X X X X X NA A ELBS2007 ELSV2013 soil 1.5 b X VH X X X X NA A ELBS2007 ELSV2013 soil 6 b X VH X X X X X X X X X X X X X NA A ELBS2007 Western Sprayfield Potential soil 10 H H H H H H H H H H H H H H H CUA A) NA A ELBS2008 soil 0.5 X X X X X X Drainage Pathway Sample for NA A ELBS2008 soil 1.5 X X X X Western Sprayfield CUA A) NA A ELBS2008 soil base of alluvium a X X X X X X X X X Eastern Sprayfield Pipeline 1 B ELBS2009 soil 0.5 X X X X X X X X X Potential CUA B) 1 B ELBS2009 ELSV2014 soil 1.5 b X VH X X X X 1 B ELBS2009 ELSV2014 soil 6 b X VH X X X X X X X X X X X X X Eastern Sprayfield Pipeline 1 B ELBS2009 soil 10 H H H H H H H H H H H H H H H Potential CUA B) 1 8, B ELBS2010 Drainage Pathway Sample for soil 0.5 X X X X X X X X X 1 8, B ELBS2010 Eastern Sprayfield CUA B) soil 1.5 X X X X X X As deep as possible past NA NA ELBS2011 ELSV2002 soil 3' bgs b,c VH Tables 2, 7, 8 and Figure 2 6a Eastern Sprayfield Pipeline NA 8, B ELBS2012 soil 0.5 X X X X X X X X X X Potential CUA A) NA 8, B ELBS2012 ELSV2018 soil 1.5 b X VH X X X X Table 2 and Figure 2 NA NA 8, B ELBS2012 ELSV2018 soil 6 b X VH X X X X X X X X X X X X X NA 8, B ELBS2012 Eastern Sprayfield Pipeline Potential CUA A) soil 10 H H H H H H H H H H H H H H H 1 A ELBS2015 soil 1.5 X X 1 A ELBS ' S of ELBS1014 soil 5 X X X 1 A ELBS2015 soil 10 H H X Metal Selenium Metal Silver ph PCBs Energetics Formaldehyde Perchlorate Dioxins Inorganics Chromium VI Pesticides Herbicides Cyanide Alcohols DQO Cross Reference Table 2 and Figure 2 Table 2 and Figure 2 Table 2 and Figure 2 Tables 2, 5, 6 and Figure 2 Tables 2, 5, 6 and Figure 2 DTSC Comment No. Cross Reference NA 5, 6f NA NA NA Rationale/Objectives Potential CUA A newly identified spray field and pipeline identified during the 2010/2011 water conveyance system inventory activities). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Drainage pathway sample for western sprayfield potential CUA A). Potential CUA B newly identified spray field pipeline identified during the 2010/2011 water conveyance system inventory activities). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Drainage pathway sample for eastern sprayfield potential CUA B) and CUA 8. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Drainage pathway sample for newly identified spray field identified during the 2010/2011 water conveyance system inventory activities potential CUA B) and CUA 8. Potential CUA B newly identified spray field pipeline identified during the 2010/2011 water conveyance system inventory activities). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Define S extent of arsenic and lithium exceeded SCL) at ELBS1014 5' bgs) and SW extent of barium and lithium exceeded SCL) at ELBS1016 5' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. 1 B, 8 ELBS2016 ELSV2012 soil 6 b VH X 1 B, 8 ELBS2016 ELBS02 soil 9 H NA A ELBS2017 ELBS10 soil 0.5 X Tables 5 and 6 NA 1 NA ELBS2018 ELBS1018 soil 6 X Tables 5 and 6 NA 1 B ELBS2019 ELBS13 soil 0.5 PS Tables 5 and 6 NA 1 11, A ELBS ' NE of ELBS1007 soil 0.5 X X X 1 11, A ELBS2020 ELSV2004 soil 1.5 b X VH X X 1 11, A ELBS2020 ELSV2004 soil 6 b X VH X X X X X 1 11, A ELBS ' NE of ELBS1007 soil 10 H H H H H H H Tables 2, 5, 6 and Figure 2 Table 2 and Figure 2 1, 2, 6a, 7, 16 2, 4, 6a, 6c, 7, 12 Define vertical extent of arsenic exceeded the SCL) at ELBS02. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Resample at ELBS10 where a ND result for silver has an elevated RL and is used to define its extent in soil. Define vertical extent of arsenic exceeded the SCL) at ELBS1018 1' bgs). Resample at ELBS13 where Aroclor 1242, Aroclor 1254, and Aroclor 1260 PCBs) were nondetect, have elevated RLs, and were not detected at any other location at EEL. Biased grid sampling for newly identified undetermined tank features with unknown location and contents. To address DTSC comment regarding dark area identified in 1965 aerial photo suspected of historical burn activities energetics, perchlorate, and dioxin analyses). 1 A ELBS ' S of ELBS1017 soil 0.5 X 1 A ELBS2021 ELSV2010 soil 1.5 b X VH X 1 A ELBS2021 ELSV2010 soil 6 b X VH X X 1 A ELBS ' S of ELBS1017 soil 10 H H H X Tables 2, 7, 8 and Figure 2 6a, 7 Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. Page 2 of 5

78 TABLE C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite EEL CC Chemical Use Area No. Location ID Location Matrix Sample Depth feet bgs) TPH ext.) VOCs Full) VOCs Soil Vapor) SVOCs Metals Metal Mercury Metal Arsenic Metal Selenium Metal Silver ph PCBs Energetics Formaldehyde Perchlorate Dioxins Inorganics Chromium VI Pesticides Herbicides Cyanide Alcohols DQO Cross Reference DTSC Comment No. Cross Reference Rationale/Objectives 1 A ELBS ' E of ELBS1017 soil 0.5 X X X X X X X X 1 A ELBS2022 ELSV2000 soil 1.5 b X VH X X X X 1 A ELBS2022 ELSV2000 soil 6 b X VH X X 1 A ELBS ' E of ELBS1017 soil 10 H H H H Tables 2, 5, 6, 7, 8 and Figure 2 1, 2, 6a, 7, 16 Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Drainage pathway sample for western sprayfield potential CUA A). Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. NA NA ELBS2023 Soil 0.5 X NA NA ELBS ' S of SWBS1006 Soil 6.5 X NA NA ELBS2023 Soil 10.5 X Tables 5 and 6 6b NA NA ELBS2023 Soil 15.5 H 1 NA ELBS ' SW of ELBS1005 soil 0.5 X X 1 NA ELBS2024 ELSV2016 soil 1.5 b VH X 1 NA ELBS2024 ELSV2016 soil 6 b X VH X X 1 NA ELBS ' SW of ELBS1005 soil 10 H H H H Table 2 and Figure 2 1, 2, 6a, 7, 16 Define S extent of selenium exceeded SCL) at SWBS ' and 10.5' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected ELBS ' NE of ELBS1005 soil 0.5 X X 1 13 ELBS ' NE of ELBS1005 soil 1.5 X X 1 13 ELBS2025 ELSV2007 soil 6 b VH X X X X 1 13 ELBS ' NE of ELBS1005 soil 10 H H H H Tables 2, 7, 8 and Figure 2 1, 2, 4, 6a, 7, 16 Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Added energetics, perchlorate, and dioxin analyses because or dark discoloration at this soil disturbance area. Evaluate VOCs using a soil sample at this location if a soil vapor sample cannot be collected. 1 B ELBS2026 soil 0.5 X Define SE extent of barium and silver exceeded SCL) at ELBS B ELBS2026 soil 1.5 X 1' bgs). Biased grid sampling for newly identified undetermined 30' SE of ELBS1026 Tables 2, 5, 6 and Figure 2 1, 2, 16 tank features with unknown location and contents. Newly 1 B ELBS2026 soil 6 X X identified disturbed soil feature identified during the 2010/ B ELBS2026 soil 10 H H review of aerial photographs. NA B ELBS2028 soil 0.5 X NA B ELBS ' NE of ELBS1028 soil 6 X Tables 5 and 6 NA Define NE extent of silver exceeded the SCL) at ELBS1028 1' bgs). NA B ELBS2028 soil 10 H 1 NA ELBS2034 Soil 15.5 X Define vertical extent of selenium exceeded SCL) at SWBS1006 SWBS1006 Tables 5 and 6 6b 1 NA ELBS2034 Soil 20.5 H 6.5' and 10.5' bgs). NA NA ELBS2035 Soil 0.5 X NA NA ELBS2035 Soil 6.5 X X X X X X X Define NW extent of selenium exceeded SCL) at SWBS ' 25' NW of SWBS1006 Tables 5 and 6 6b NA NA ELBS2035 Soil 10.5 X X X X X X X and 10.5' bgs). Evaluate potential release from sewer manhole. NA NA ELBS2035 Soil 15.5 H H H H H H H NA NA ELBS2036 Soil 0.5 X NA NA ELBS2036 Soil 6.5 X Define NE extent of selenium exceeded SCL) at SWBS ' 25' NE of SWBS1006 Tables 5 and 6 6b NA NA ELBS2036 Soil 10.5 X and 10.5' bgs). NA NA ELBS2036 Soil 15.5 H 1 NA ELSV2000 soil vapor 5.5 X 1 NA ELSV ' SE of ELSV03 and 50' NE of ELSV1003 soil vapor 10 X 1 NA ELSV2000 soil vapor 15 e H Tables 2, 7, 8 and Figure 2 1, 2, 6a, 7, 16 Define SE extent of TCE exceeded the SVCL) at ELSV03 4' and 8' bgs). Define NE extent of benzene and toluene exceeded the SVCLs) at ELSV1003 5' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Page 3 of 5

79 TABLE C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite EEL CC Chemical Use Area No. Location ID Location Matrix Sample Depth feet bgs) TPH ext.) VOCs Full) VOCs Soil Vapor) SVOCs Metals Metal Mercury Metal Arsenic Metal Selenium Metal Silver ph PCBs Energetics Formaldehyde Perchlorate Dioxins Inorganics Chromium VI Pesticides Herbicides Cyanide Alcohols DQO Cross Reference DTSC Comment No. Cross Reference Rationale/Objectives 1 A ELSV2001 soil vapor 5.5 X 1 A ELSV ' NE of ELSV03 soil vapor 10 X 1 A ELSV2001 soil vapor 15 e H Tables 2, 7, 8 and Figure 2 1, 2, 6a, 7, 16 Define NE extent of TCE exceeded the SVCL) at ELSV03 4' and 8' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. 1 NA ELSV ' SW of ELSV01, 60' SW of soil vapor 5.5 X 1 NA ELSV2002 ELSV1004, and 60' NW of soil vapor 10 X 1 NA ELSV2002 ELSV1402 soil vapor 15 e H Tables 7 and 8 6a Define SW extent of TCE exceeded the SVCL) at ELSV01 5' bgs). Define SW extent of toluene exceeded the SVCL) at ELSV ' bgs). Define NW extent of toluene exceeded SVCL) at ELSV ' bgs). 1 B ELSV2003 soil vapor 5.5 X ELSV08 Tables 2, 7, 8 and Figure 2 6a, 7 1 B ELSV2003 soil vapor 10 e H Resample at ELSV08 5' bgs) where ND results for toluene and TCE have elevated RLs and are used to define the extent of VOCs in soil vapor. Also where some constituents were not detected 1,1,1,2 tetrachloroethane, 1,1,2 trichloroethane, 1,2 dichloroethane, chloroform, and methylene chloride) at any other locations at EEL and have elevated RLs above SLs. A larger sample size low level method) may be needed and lab will need to report nondetects to the MDL. Define NE extent of TCE exceeded the SVCL) at ELSV02 6' bgs). Define N extent of TCE exceeded SVCL) at ELSV01 5' bgs). Potential CUA B newly identified spray field identified during the 2010/2011 water conveyance system inventory activities). 1 A, 10 ELSV2004 soil vapor 5.5 X Biased grid sampling for newly identified undetermined tank 20' NE of ELBS1007 Table 2 and Figure 2 6a, 7 1 A, 10 ELSV2004 soil vapor 10 e H features with unknown location. NA NA STSV2006 soil vapor 5.5 X NA NA STSV ' S of ELSV1402 soil vapor 10 X Tables 7 and 8 6a, 7 Define S extent of toluene exceeded SVCL) at ELSV ' bgs). NA NA STSV2006 soil vapor 15 e H NA NA STSV2009 soil vapor 5.5 X Define SE extent of toluene exceeded the SVCL) at ELSV ' 60' SE of ELSV1004 and 50' NE NA NA STSV2009 soil vapor 10 X Tables 7 and 8 6a, 7 bgs). Define NE extent of toluene exceeded SVCL) at ELSV1402 of ELSV1402 NA NA STSV2009 soil vapor 15 e H 10' bgs). 1 NA ELSV2005 ELSV1402 soil vapor 15 e X Tables 7 and 8 6a, 7 Define vertical extent of toluene exceeded the SVCL) at ELSV ' bgs). 1 3 ELSV2006 soil vapor 5.5 X 60' S of ELSV02 and 60' W of ELSV ELSV2006 soil vapor 10 e H Tables 2, 7, 8 and Figure 2 1, 2, 6a, 7, 16 Define S extent of TCE exceeded the SVCL) at ELSV02 6' bgs). Define W extent of TCE exceeded SVCL) at ELSV01 5' bgs). Newly identified undefined feature identified during the 2010/2011 review of aerial photographs. Biased grid sampling for newly identified undetermined tank features with unknown location. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. 1 NA ELSV2007 soil vapor 5.5 X 40' SW of ELSV02 1 NA ELSV2007 soil vapor 10 e H Tables 2, 7, 8 and Figure 2 6a, 7 Define SW extent of TCE exceeded the SVCL) at ELSV02 6' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. NA A ELSV2008 Western Sprayfield Potential soil vapor 5.5 X NA A ELSV2008 CUA A) soil vapor 10 H Table 2 and Figure 2 NA Potential CUA A newly identified spray field identified during the 2010/2011 water conveyance system inventory activities). 1 A ELSV2009 soil vapor 5.5 X 1 A ELSV ' W of ELSV03 soil vapor 10 X 1 A ELSV2009 soil vapor 15 e H Tables 2, 7, 8 and Figure 2 2, 6a, 6c, 7 Potential CUA A newly identified spray field identified during the 2010/2011 water conveyance system inventory activities). Define W extent of TCE exceeded the SVCL) at ELSV03 4' and 8' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. To address DTSC comment regarding dark area identified in 1965 aerial photo suspected of historical burn activities. Page 4 of 5

80 TABLE C 1 EEL RFI Site Proposed Data Gap Sampling and Analysis Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite EEL CC Chemical Use Area No. Location ID Location Matrix Sample Depth feet bgs) 1 A ELSV2010 soil vapor 10 X ELSV A ELSV2010 soil vapor 15 e H 1 14 ELSV2011 soil vapor 5.5 X 1 14 ELSV2011 soil vapor 10 H TPH ext.) VOCs Full) VOCs Soil Vapor) SVOCs Metals 1 B ELSV ' E of ELSV02 soil vapor 5.5 X Tables 2, 7, 8 and Figure 2 NA A ELSV2013 Western Sprayfield Potential soil vapor 5.5 X NA A ELSV2013 CUA A) soil vapor 10 H 1 B ELSV2014 Eastern Sprayfield Pipeline soil vapor 5.5 X 1 B ELSV2014 Potential CUA B) soil vapor 10 H 1 NA ELSV ' SW of ELBS1005 soil vapor 5.5 X Table 2 and Figure 2 1 NA ELSV2017 ELSV1004 soil vapor 15 e X Tables 7 and 8 6a, 7 NA B ELSV2018 Eastern Sprayfield Pipeline soil vapor 5.5 X NA B ELSV2018 Potential CUA B) soil vapor 10 H Metal Mercury Metal Arsenic Metal Selenium Metal Silver ph PCBs Energetics Formaldehyde Perchlorate Dioxins Inorganics Chromium VI Pesticides Herbicides Cyanide Alcohols DQO Cross Reference Table 2 and Figure 2 DTSC Comment No. Cross Reference Tables 2, 7, 8 and Figure 2 6a, 7 Building Feature Table 2 and Figure 2 Table 2 and Figure 2 Table 2 and Figure 2 1, 2, 6a, 7, 16 1, 2, 6a, 7, 16 NA Rationale/Objectives Define vertical extent of benzene and toluene exceeded the SVCLs) at ELSV1003 5' bgs). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. To address potential mass flux to clean fill in CUA 8. Biased grid sampling for newly identified undetermined tank ELSV2015 soil vapor 5.5 X features with unknown location and contents. To address DTSC NA A 30' SW of ELSV1002 Table 2 and Figure 2 2, 6a, 6c, 7 comment regarding dark area identified in 1965 aerial photo ELSV2015 soil vapor 10 H suspected of historical burn activities. 1, 2, 6a, 7, 16 NA NA Building feature newly identified former building feature identified during the 2008 building feature survey). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Potential CUA A newly identified spray field and pipeline identified during the 2010/2011 water conveyance system inventory activities). Potential CUA B newly identified spray field pipeline identified during the 2010/2011 water conveyance system inventory activities). Biased grid sampling for newly identified undetermined tank features with unknown location and contents. Newly identified disturbed soil feature identified during the 2010/2011 review of aerial photographs. Define vertical extent of toluene exceeded the SVCL) at ELSV ' bgs). Potential CUA B newly identified spray field pipeline identified during the 2010/2011 water conveyance system inventory activities). Total Soil Samples for Analysis Total Soil Samples on Hold Total Soil Vapor Samples for Analysis Total Soil Samples to be Collected 95 Total Number of Locations Proposed for Sampling 50 Note: X = Analyze sample H = Hold sample analysis until instructed by PM VH = Vapor intrusion hold sample. Vapor intrusion will be evaluated using a soil sample at this location if a soil vapor sample cannot be collected. PS = Provisional sample. Sample will be put on hold pending results from other site wide samples for specific trigger analytes. SCL = soil characterization level SVCL = soil vapor characterization level CC = CUA clusters TCE = trichloroethene Sample bottom depths are listed above. If burnt materials are observed during sampling activities, add dioxins and PAHs to the analytical suite. For features for which VOCs are listed for analysis in soil and soil vapor, the VOCs in soil samples will only be collected if the VOCs in soil vapor sample cannot be collected either due to refusal on bedrock at a depth more shallow than 5 feet bgs or due to poor air flow in the soil vapor probe). a In drainage channels, samples should also be collected at the base of the alluvium, but not at a depth greater than 10 feet bgs. Samples should be targeted to areas with sediment accumulation. b A soil sample would only be collected for analysis of VOCs if the soil vapor sample at the same location could not be collected. The soil sample should be collected at a depth as deep as possible greater than 3 feet bgs. c In debris areas, soil and soil vapor samples will be collected in native soil beneath the debris piles. d If channel banks are not observed, this sample does not need to be collected. e Field teams will continue to collect soil vapor samples at 5 feet intervals until bedrock is reached. Samples should not be collected within 3 feet from bottom of more shallow sample to top of refusal sample. Page 5 of 5

81 TABLE C 2 EEL RFI Site Water, Soil, and Soil Vapor Analyses Addendum to Master RFI Data Gap Work Plan, Boeing RFI Subarea 5/9 South, EEL RFI Site, Santa Susana Field Laboratory, Ventura County, California Analytical Suite Analytical Method Volatile Organics VOCs) 8260B Semivolatile Organics SVOCs) including Polynuclear Aromatic Hydrocarbons and phthalates) 8270C SIM* Dioxin/Furans 1613B Metals 6010B/ 6020 Hexavalent Chromium 7196A Formaldehyde 8315A Perchlorate 6850 Pesticides 8081A Polychlorinated Biphenyls PCBs) 8082 Herbicides 8151A n Nitrosodiphenylamine NDMA) 8270C SIM* Energetics 8330A Inorganics 9056A ph 9045 Total Petroleum Hydrocarbons TPH) 8015B Cyanide 9012B Alcohols 8015B Soil Vapor VOCs a 8260B Note: a Soil vapor samples will be analyzed on site by a mobile laboratory using Method SW8260B. In addition, at least one confirmation sample will be collected each day, or one per every 10 samples collected, and sent to a fixed laboratory to be analyzed by Method TO 15. See Quality Assurance Project Plan for details on analytical suite and methods Page 1 of 1

82 Figure

83 VICINITY MAP UNDEVELOPED LAND NASA UNDEVELOPED LAND AREA III AREA II AREA I AREA IV ELBS2000 ELSV ELSV ELBS ELSV2016 ELBS2018 ELBS EEL CC 1 12 EEL-CMS-S ELSV2006 ELBS ELBS ELSV2004 # # * * ELBS2005 ELSV ELSV2011 ELSV2001 ELBS2017 ELBS ELBS2004# * ELBS2011 ELSV2009 ELSV2002 EEL-CMS-S1 ELBS2001 ELBS ELSV2013 EEL-CMS-SV1 ELSV2000 ELBS2022 ELBS2015 A ELBS2008 ELBS2021 ELSV ELBS ELSV2012 ELBS2016 ELBS2002 ELBS2019 ELSV2003 ELBS2009 ELSV2014 ELBS2028 B EEL-CMS-SV2 ELSV2017 ELSV2018 ELBS STSV2006 EEL-CMS-S3 ELSV Former Ranch House STSV2009 ELBS BASEMAP LEGEND Boeing RFI Site Dirt Road RFI Group Boundary Paved Road Administrative Boundary Rock Outcrop EEL RFI Site Pond Reporting Area Transformer Pad Chemical Use Area CUA) Structure 1 CUA Reference Number CUA Cluster CC) Potential CUA A Potential CUA ID Soil CMS Area Soil Vapor CMS Area Features ' Debris Point Transformer Pole Pipeline Leach Field Line Debris Line Drainage Channel Operational Channel UNDEVELOPED LAND LEGEND Proposed Soil Vapor Sample Location # Proposed Soil Sample Location Proposed Soil Vapor Sample Location on hold until further evaluation of sample results Proposed Soil Sample Location on hold until further evaluation of sample results Aboveground Storage Tank Underground Storage Tank Not Yet Determined Storage Yard Debris Area Disturbed Soil Vegetation Clearing Excavation Area U U U U U U U U U UUndefined Feature U U U U U Spray Field Septic Tank Leach Field Area Sump Notes: 1) CMS areas are interim and will be finalized following collection of additional data and additional risk assessment. Refer to Table 3 for a list of risk-driving chemicals associated with each CMS area. 2) Portions of EEL RFI Site located within Administrative Area 4 are being characterized by US DOE ELBS2035 ELBS2034 ELBS2023 ELBS2036 Western Eastern Forming Pit $ Feet in = 60 ft FIGURE C-1 Proposed Sample Locations for the EEL RFI Site Addendum to Master RFI Data Gap Work Plan Boeing RFI Subarea 5/9 South, EEL RFI Site Santa Susana Field Laboratory, Ventura County, California SCO K:\BOEING\362070\MAPFILES\2013\DQO\EEL\REPORTFIGURES\EEL_FIGUREC-1_PROPSAMPLES.MXD RANHORN 5/17/ :15:53 AM