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No Further Action Required Request Report US Can—Welty Road September 24,2013 2. PREVIOUS INVESTIGATIONS In the process of investigating a former bum pit and a release from a condensate outlet, petroleum hydrocarbons were encountered in soil and groundwater on the Hunter Container Company(Hunter Container)property in the vicinity of the former HPP-BTR pipelines. As a result, in 1997 Chevron Pipeline Company(CPL)initiated investigation of the former HPP-BTR pipelines in the area near the Hunter Container property. SAIC and others have performed investigations at the Site between 1995 and 2010 to assess the extent of soil and groundwater affected by crude oil. For investigations performed by SAIC at the Site, soil analytical results were compared to the lowest,most conservative United States Environmental Protection Agency(EPA)Preliminary Remediation Goals (PRGs,which have been replaced by Regional Screening Levels [RSLs; EPA,2008])and San Francisco Bay RWQCB Environmental Screening Levels(ESLs; San Francisco Bay RWQCB,2008). Similarly, groundwater analytical results were compared to WQOs and ESLs. Note that the RSLs and ESLs have changed over time,but they have always been conservative for delineation purposes, as used at CEMC's HPP-BTR sites. A summary of previous investigations is provided as Appendix A. Copies of reports describing these activities are provided as Appendix B. Historical tables and figures are included as Appendix C. Central Valley RWQCB correspondence is included as Appendix D. In a letter dated April 20, 2011, the Central Valley RWQCB concurred that affected soil and groundwater had been adequately delineated and that an HHSE could be submitted(Central Valley RWQCB, 2011; Appendix D). The results of the HHSE are included in section 2.1. 2.1 HUMAN HEALTH SCREENING EVALUATION/ECOLOGICAL SCREENING EVALUATION,2012 SAIC evaluated cancer risks and non-cancer hazards from exposure to COPCs in soil and groundwater in a residential land-use scenario. SAIC also evaluated the potential for exposure of sensitive ecological receptors to COPCs at the Site. SAIC developed the HHSE using approaches and methodology consistent with those presented in the Preliminary Endangerment Assessment(PEA)Guidance Manual (California Environmental Protection Agency[Cal/EPA] Department of Toxic Substances Control [DTSC], 1999). SAIC quantitatively evaluated the exposure routes of incidental ingestion of soil and dermal contact with soil; inhalation of wind-blown dust for non-volatile constituents; inhalation of chemical vapors from soils for volatile constituents; and inhalation of chemical vapors from subsurface vapor intrusion to indoor air for volatile constituents detected in groundwater. Shallow groundwater is unlikely to be used as a drinking-water source at the Site; therefore, exposure to groundwater was not evaluated quantitatively in the HHSE. All analytes detected in soil in at least one sample between 0 and 10 feet below ground surface (bgs)were considered COPCs. Metals are not typically considered critical constituents of crude oil at former OVP and TAOC sites; therefore, soil samples from the Site were not analyzed for metals. Benzene, toluene, ethylbenzene, and total xylenes(BTEX) and polynuclear aromatic hydrocarbons (PAHs)were detected in soil, are therefore considered to be COPCs for the Site, and were evaluated quantitatively in the HHSE. 2 SAIC