ARCHIVED REPORTS_REMEDIAL ACTION PLAN

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Attachment A:Previous Environmental Activities down gradient of the site. The Central Valley Regional Water Quality Control Board (RWQCB)reviewed the work plan, and in a November 2003 letter to Chevron Environmental Management Company requested further lateral and vertical delineation of soil and groundwater beyond what was proposed in the work plan. Therefore, SAIC also collected seven shallow soil samples (HR-1 through HR-7) in the vicinity of the former pipeline, the former blow-off pond, the former above-ground storage tanks ' (ASTs), the former boiler house, and near previous boring TS-07 near the southern site boundary. Detectable concentrations of TPHc ranged from 71 mg/kg in soil sample HR-1 to 930 mg/kg in soil sample HR-4. The highest TPHc concentration was from a sample collected in the proximity of the former pipeline near previous boring TS-15, down ' gradient of the former pump station. BTEX compounds were not reported in the seven soil samples submitted for analyses. PAHs were detected in each of the seven shallow soil samples; the highest reported concentrations were detected in HR-4. Detectable ' concentrations of benzo(a)pyrene were reported in four of the seven soil samples and ranged from 0.001 mg/kg in HR-1 to 0.016 mg/kg in HR-4. Dibenzo(a,h)anthracene was not reported at or above the laboratory detection limits. To confirm whether the affected soil in boring SB-3 was a result of residual petroleum , observed on site, SAIC collected one soil sample at 11 feet bgs for fuel-fingerprint analysis. The soil sample was submitted to Chevron Energy Technology Company under , SAIC chain-of-custody protocol. The results of the analysis indicated the sample contained a hydrocarbon most likely to be weathered crude oil typical of San Joaquin Valley crude oil and bunker fuels refined from San Joaquin Valley crude oil. ' SAIC collected grab groundwater samples from 12 of the 13 soil borings, and collected one depth-discrete groundwater sample from SB-13 to evaluate the vertical extent of dissolved-petroleum constituents beneath the site. TPHg were not detected at or above ' the reporting limit in 12 of the 13 grab groundwater samples. TPHg were detected at a concentration of 420 µg/L in the grab groundwater sample from boring SB-3, down gradient of the former pump station. TPHd were detected above the reporting limit in , seven of the 13 grab groundwater samples. The TPHd ranged from 86 µg/L in a grab groundwater sample from SB-7 to 260,000 Itg/L in a grab groundwater sample from SB-3. BTEX compounds were not detected at or above the laboratory reporting limits in ' any of the grab groundwater samples. PAHs were detected at or above the laboratory reporting limits in 10 of the 12 groundwater samples analyzed. The highest concentration of PAHs was reported in a , grab groundwater sample from SB-3, down gradient of the former pump station. Two grab groundwater samples from SB-8 and SB-12 were analyzed for total dissolved solids (TDS), which ranged from 2,800 milligrams per liter(mg/L)to 2,200 mg/L,respectively. ' As part of the investigation, SAIC located and sampled an on-site water supply well (DW-1) to determine if dissolved-petroleum constituents were affecting groundwater ' pumped from DW-1. BTEX, TPHg, TPHd, and PAHs were not detected at or above the reporting limits. TDS and nitrate were reported at 1,300 mg/L and 2.81 mg/L, respectively.