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•k CHAPTER 4 F';ELD ANALYTICAL RESULTS Selected subsurface soil samples from boreholes drilled during April 23, 1990 through May 10, 1990 and one groundwater sample from each monitoring well were analyzed for benzene, ethylbenzene, toluene, xylene isomers (BETX), and total petroleum hydrocarbons (TPH) using U.S.Environmental Protection Agency (EPA) Method 8015, modified using extraction Method 5030. Water samples from monitoring wells located within 60 feet of a sewer line were analyzed for fecal coliform. Laboratory results for soil samples are summarized in Table 4-1. Complete results are shown in Appendix D. Laboratory results for water samples are summarized in Table 4-2. Complete results are shown in Appendix D. Fecal coliform results for the selected water samples are shown in Table 4-3. Complete results are shown in Appendix D. Analytical results shown in Table 4-1 show benzene concentrations in soil samples from borings V-4, V-6, V-7, and V-8 and ethylbenzene, toluene, and xylene concentrations in soil from boring V-4 are greater than California Regional Water Quality Control Board Designated Levels in a Solid to Protect Groundwater. In boring VA the contamination was located between 25 and 55.5 feet below ground surface. In all the other borings, the contamination was located between 50 and 55.5 feet below ground surface. In each of these borings,the C4-02 hydrocarbons ranged from 6 to 17,000 parts per million (ppm). Analytical results shown in Table 4-2 show that benzene concentrations in groundwater monitoring wells W-lA, W-2, W-2A, W-3, W-9, W-10, and W-11, and toluene and xylene concentrations in groundwater monitoring wells W-2, W-2A, W-3, and Wa9 are greater than Department of Health Services (DHS) Maximum Contaminant Levels (MCLs). DHS Drinking Water MCLs for benzene,ethylbenzene,toluene,and xylene are 0.001 ppm,.680 ppm,.100 ppm, and 1.75 ppm,respectively. No DHS levels have been established for TPH. Analytical results from groundwater monitoring wells W-2B,W-5,W-6,W-7,W-8,and W-12 indicate some BETX is present at concentrations far below the DHS MCLS. -Analytical results shown in Table 4-3 show that fecal coliform concentrations`in groundwater monitoring wells W-12 and W-10 are above the detection. Iimits used No DHS levels have been established for fecal coliform. The low concentrations of fecal coliform that were found in the water samples suggest that the-mount found was due to native coliform within the soil.