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' C'eafoguafTechnzcs Inc 46 Page 2 Project No 662 2 Cardoza(Super Stop) ' Soil& Groundwater Investigation . September 3, 1998 ' Upon completion of the boreholes they were backfilled to the surface with a neat cement grout containing less then 4%bentonite 3.0 Site Geology ' The field borehole logs have been included in Appendix B Listed below is a summary of the subsurface geology ' 1 The upper 20 feet of soils beneath the site consisted primarily of medium to coarse grained, loose silty sands 2 Below 20 feet to the total sampled depth of 33 feet, the soils were generally clayey with thin intervals of silts and sands ' 4.0 Soil Test Results The soil test results are summarized below 1 A chemical odor was noted in the samples from 15 to 25 feet in GP-1 2 Lab tests show that the soil samples from both boreholes were non-detect for BTEX and TPH-G 3 The soil samples from GP-1 showed the presence of MTBE, TBA and Methanol 4 The soil samples from GP-2 showed the presence of MTBE and TBA 5 The groundwater sample from GP-1 contained Toluene, Xylene and TPH-G at concentrations dust above detection limits MTBE was also detected ' 6 The groundwater sample from GP-2 contained Xylene at a concentration dust above detection limits The fuel oxygenates, MTBE, ETBE, TAME, TBA, Methanol and Ethanol were also detected ' The data is summarized in Table 1 and the lab data reports are attached in Appendix A ' 5.0 Conclusions and Recommendations Conclusions ' 1 There appears to have been two releases of gasoline fuel at this site The first is old and the gasoline appears to have degraded The second appears to be a more recent event and included several of the oxygenated fuel compounds ' 2 Since the soil test results showed such minor concentrations of chemicals in these boreholes, it is concluded that the release may not have occurred at the fill pipe end of the tanks 3 It is possible that the pipe fittings or connections are the cause of the leak ' Recommendations 1 Determine if a leak is currently taking place ' 2 Request an application from the Water Board for an application to the USTCFP 3 Determine the extent of the contamination to evaluate the risk these chemicals pose to human health and the environment 1 - 1