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f No odor was detected during groundwater purging or sampling 4.3 Laboratory Results Six soil samples were selected for laboratory analysis, based on the field evidence of contamination and l the measured depth to groundwater The samples were analyzed for Total Petroleum Hydrocarbons in the gasoline and diesel ranges (TPH-g and TPH-d) and for benzene, toluene, ethylbenzene, and xylene I (BTEX) The results are shown in Table 1, and the laboratory report is included in Appendix B Both groundwater samples were also analyzed for TPH-g, TPH-d, and BTEX, and at the recommendation of Mr Mschael Infurna of PHS/EHD,the second (October) sample was also analyzed for volatile halocarbons using EPA method 8010 The results are shown in Table 2, and the laboratory report is included in Appendix B Of the soil samples, only VM-1-25 contained detectable concentrations of hydrocarbons Both gasoline and diesel were detected, but the more volatile compounds (benzene, toluene, and ethylbenzene) were not, suggesting that contan ination may have occurred many years ago and the volatile components have been lost All analytes, including all of the volatile compounds, were detected in the groundwater sample collected in September For this reason, Valley Motors elected to collect a second water sample approximately 30 days later As before, TPH-g, TPH-d, and BTEX were detected, and all analytes except xylene were detected at higher concentrations than in September (Table 2) In addition, five halocarbons (dichloroethene and related compounds) were detected above method reporting limits 4 4 Depth to Groundwater Appendix C shows the depth to groundwater on September 11 and October 12 On both days, the I depth was approximately 49 25 feet . 5.0 CONCLUSIONS AND RECOMMENDATIONS This investigation has achieved its objective of determining whether groundwater beneath the site has been'unpacted by hydrocarbons, and has also identified the maximum depth to which soil beneath the site has been contaminated by gasoline and/or diesel hydrocarbons Gasoline and benzene are dissolved I at moderate concentrations in the groundwater, and other aromatic hydrocarbons are also present Total petroleum hydrocarbon compositions extend into the range of intermediate-weight hydrocarbons, suggesting that diesel may also be present' Chlonnated hydrocarbons are also present at concentrations that exceed by several orders of magnitude the Maximum Contaminant Levels for drinking water in California (Table 3), and pose a serious health risk to domestic, water use The source of the halocarbons is unknown, but since most of these compounds are components of degreasing solvents 4 _