SITE INFORMATION AND CORRESPONDENCE

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Sent By.: BASELINE; 510 420 1707; Nov-9-99 le:29; Page 19129 Sail borings were located based on a review of past land uses and collected to assess possible migration of c;ontaminants from off-site sources upgradi mt of the site. Soil samples were,analyzed for semi-volatile organic compounds,including diberizofuran and pentachlorophenol(EPA Method 5270),pesticides and polychlorinated biphenyls(EPA Method 8080),and were selectively analyzed for total metals(EPA Method 60417004),volatile organic compounds(VOCs),including methyl tent butyl ether(MTBE)(EPA Method 8260),total petroleum hydrocarbons as gasoline(TPA-gasoline) (LUFT Method),and total organic carbon and percent moisture.Groundwater samples were analyzed for total metals, VOCs and MTBE, SVOCs, including dibenzofuran and pentachlorophenol,TPH- gasoline,and pesticides and PCBs. Sediment samples were analyzed for total metals,and SVOCs. Wood piling samples were analyzed for SVOCs only;sampling of the wood pilings was performed to determine disposal options for the treated piles,once rem oved z e w tr 1 No samples s ere collected at the P P PP site and analyzed for dioxins, and there is no known historic or current land uses at the site that would suggest the presence of dioxins. I� All samples were stored in cooled containers until submitted to the laboratory for anal P ry yS1s under. chain.-of-custody procedures. Analysis of samples was coordinated through U.S. EPA's Quality Assurance Management Section(QAMS). Analytical data were also validated by EPA QAMS using standard EPA protocols.3 Minor field variations from the SAP and HSP occurred in response to conditions encountered in the field(e.g.,not enough sample because ofpoor re'tri oval,modifications to decontamination procedures). Summary tables of soil, groundwater, and sediment data are presented in Tables 1, 2, and 3 and Appendix B. See Figure 6 for sampling locations. Former Shell Station/Bridgestone Tire and Auto Repair Facilii P rY Soil and groundwater samples were also collected for the investigation of the underground storage tanks and operation of a groundwater extraction systern and soil vapor,extraction system(SVE) at the former Shell Service Station. The purpose of these investigations was to determine the type and extent of subsurface contamination awociated with operation of the former tanks. It is assumed that the tanks removed from the site were disposed of or recycled at an off-site location following removal and excavated soils were properly disposed of in accordance with local, State, and Federal req uirements. Disposition of the tank and excavated soils were not identified in the records reviewed. I The SVE remediation system removed 37 pounds ofliquid phase and 3,277 pounds of vapor phase total purgeable petroleum hydrocarbons from the site (Enviros, 1997; Cambria, 1999). Eight soil borings (5-1 through B-8) were drilled following shutdown of the SVE system to evaluate its r effectiveness(Figure 7,Table 4). BTEX and MTBE were reported below laboratory reporting limits in samples collected from these borings,with one detection of benzene at 0.10 ppm. Total purgeable petruleurn hydrocarbons (TPPH) .ranged from below laboratory reporting limits to 970 Mg/kg. In contrast,prior to operation of the treatment system,the maximum detected concentration of benzene 'Since collection of samples from She wood pilings was made for tentative clamification of the pile,once removed,and not for estimating human healths risks,they are not discussed further in this PEA.DTSC staff indicated that they would not provide oversight for the removal of the wood piles at the site(Cambridge and Lile, 1999). ' All data evaluated as collected during this investigation were determined by the EPA validators as usable-, however.some data were"flagged"as having miner qualifications. 97369V1c.pcs.wpd-11 l9M9 13 f t