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Attachment A:Previous Environmental Activities Soil analytical results for naphthalene exceeded RSLs in borings SB-46 (44.5 feet bgs) and SB-47 (34.5 feet bgs)with concentrations of 0.00073 mg/kg and 0.00084 mg/kg, respectively. There were no other detections of TPHc, BTEX, or PAHs in excess of screening levels. TPHd concentrations were detected in excess of WQO and/or ESL screening levels in the groundwater samples from SB-46 and SB-47 at 3,100 µg/L and 100 ttg/L, respectively. Benzo(a)pyrene was detected in excess screening levels in all of the groundwater samples with concentrations ranging from 0.0032 µg/L (SB-44)to 0.021 ttg/L (SB-47). Dibenz(a,h)anthracene was detected in excess of screening levels in the groundwater sample from SB-47 at a concentration of 0.0068 µg/L. No other PAHs or BTEX were detected above screening levels. SAIC 2012 HUMAN HEALTH SCREENING EVALUATION (HHSE)19 SAIC completed an HHSE for the Site in 2010 to evaluate potential risks to human health and the environment following procedures described in the Preliminary Endangerment Assessment(PEA) Guidance Manual20 and the Vapor Intrusion Guidance document21. SAIC constructed a conceptual site model for the Site to identify the on-site contaminant sources, release mechanisms,transport media, exposure pathways, exposure routes, and potential human receptors. SAIC evaluated the on-site residential land-use scenario for the Site as required in the PEA Guidance Manual. SAIC concluded that potential on-site residential cancer risks and non-cancer health hazards are at the de minimus levels of 2E-06. The results of the HHSE indicate that exposure to chemicals present in soil and groundwater at the Site should not result in unacceptable health risks for an adult or child on-site resident. The ecological screening evaluation indicated that there do not appear to be any threatened species within 1 mile of the Site. Therefore, no remedial action is necessary at the Site to protect human or ecological health, and a risk management decision of no further action required (NFAR) can be made for on-site affected soils and groundwater. The Central Valley RWQCB concurred with the findings of the HHSE and supporting documentation that the Site is a candidate for closure, and recommended that a soil and groundwater management plan be developed and implemented for use if future construction activities require management of affected soil and groundwater at the Site. ADJACENT PROPERTIES • CPS (formerly Western Farm Service): CPS is located at the northwest corner of the intersection of Highway 33 and Welty Road. CPS has stored and distributed bulk liquid and dry fertilizers on its facility since 1969. Records indicate this site contained a 10,000-gallon diesel UST, and 5,000-gallon and 10,000-gallon gasoline USTs. The USTs were removed in 1987, and their approximate locations are shown on Figure 2 of the main report. Wells were 19.SAIC,2012. Human Health Screening Evaluation, US Can—Welty Road,35275 Welty Road, Vernalis,San Joaquin County, California.March 22. 20.California EPA, 1999. Preliminary Endangerment Assessment Guidance Manual,DTSC. June. 21.DTSC,2004. Interim Final Guidance For the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air. (Revised February 7,2005).