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t 12 7 0 CONCLUSIONS Laboratory analyses and the results of the SVE test indicate that petroleum hydrocarbon-based VOCs appear to be present within the Site soils During field activities, six of the 10 borings were converted to vapor extraction/inlet wells Ground water was not encountered Information provided by County EHD officals suggests that the ground water level near the Site generally exists at approximately 100 feet below ground surface The deepest borings drilled at the Site for this tinvestigation were S13-2 and W-2, at 46 5 feet, contaminants were not indicated at this depth Soils at the Site were predominantly sand or silty sand with some silt lenses Several soil samples collected from SB-1 , SB-2, S13-3, W-2, and W-3 were found to contain TPH-G above the recommended 100 ppm cleanup level listed in the California Leaking Underground Fuel Tank (LUFT) Manual Based on the results of the site assessment, it appears that contamination is limited horizontally to the area near the ' former tank bed Soil samples collected from borings taken the furthest away from 1 the former tank excavation contained low or nondetectable concentrations of VOCs The higher concentrations of VOCs detected appear to be located in the vicinity of the former tanks around a depth of 30 feet The soil boring logs show a silt tense at that depth below the Site, which may be slowing the vertical migration of the VOCs Laboratory results of vapor samples collected during the SVE pilot testing indicate high concentrations of TPH-G and BTEX vapors in the vadose zone of the Site The SVE system was able to readily extract the soil vapors from the generally sandy soils at the Site During the pilot testing, the wells that were not attached to the extraction system were checked for a vacuum When checked, all of the wells were drawing a W l97 634 REPOfiT5i5f7E ASSILOCK EFOftD1LO CREFOR❑RPT IAp111 26 1993E CanomeEnvi of i r ,et ita