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! • . samples were collected from this boring Groundwater was found at a depth of approximately 12 5 feet below ground surface (bgs) One soil sample was collected form each boring at a depth of 12 feet bgs One grab water sample was collected from each boring A total of 9 soil samples and 9 groundwater samples were collected and analyzed Each sample was packaged and submitted to McCampbell Analytical Laboratory in Pacheco, California under chain of custody requirements for analysis Except as noted below, all soil and groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG) using EPA Modified Method 8015 and for benzene, toluene, ethylbenzene and total xylenes (BTEX) using EPA Method 8020 and for methyl t-butyl ether (MTBE) using EPA method 8020 Samples from boring B-9 were analyzed for total petroleum hydrocarbons as diesel (TPHD) using EPA Modified Method 8015 in addition to TPHG, BTEX and MTBE Samples from boring B-10 were analyzed for TPHD only 3.4 SAMPLE RESULTS 3.1 Soil Sampling Analytical Results Several soil samples were found to contain petroleum compounds The highest levels were found • in borings B-2 and B-3, east of the dispenser islands The soil sample from boring B-3 was reported to contain 880 ppm (mg/kg) TPHG, with 9 2 ppm MTBE, 0 89 ppm benzene, 15 ppm toluene, 10 ppm ethylbenzene and 63 ppm xylenes GeoAudit reported 18,000 ppm TPHD, 1400 pprn TPHG, 1 2 ppm ethylbenzene and 8 3 ppm xylenes at a depth of three feet in boring IW This was a hand augered boring adjacent to the diesel dispenser, east of the UST location They also reported 590 ppm TPHG, 9 1 ppm TPHD, 2 5 ppm benzene, 4 4 ppm toluene, 2 4 ppm ethylbenzene and 1 2 ppm xylenes at a level of 15 feet bgs in boring GBS This boring was approximately 50 feet northwest of the dispenser islands, near Yosemite Avenue Several other soil samples from both investigations contained less significant levels of petroleum compounds Complete soil sample results are presented in Table 1 for this investigation and in Table 3 for the GeoAudit investigation Soil sample results for TPHG are shown on Figure 3 3.2 Groundwater Sampling Analytical Results The majority of the groundwater samples from both investigations were found to contain petroleum compounds The highest levels were found in samples from borings B-2, B-3 and B-5 with 13-3 showing the highest levels These were all near the dispenser islands The sample from boring B-3 contained the 130,000 ppb (gg/L) TPHG with 21,000 ppb MTBE, 3800 ppb benzene, 18,000 ppb toluene, 3100 ppb ethylbenzene and 17,000 ppb xylenes Initial Site Characterization Report April 1997 2072 IV Yosemite,Ave,Manteca, CA 2 015 OOINP