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, Site Investigation Report <br /> BP Oil Site No 11191 <br /> Stockton, California <br /> C A M B R I A March 29, 2002 <br /> Soil Handling Soil cuttings produced during drilling activities were stored onsite and <br /> subsequently transported to Forward Landfill in Manteca, California <br /> Investigation Results <br /> Water Supply Well Survey City of Stockton and DWR data indicate 4 four water supply wells <br /> within '/i-mile of the site and 6 water supply wells beyond i/z-mile of the site City of Stockton <br /> well 3-2, approximately 2,000 feet south of the site, is the closest identified water supply well <br /> Site Hydrogeology In general, the soil types observed during drilling activities were consistent <br /> with previous investigations at the site Soil types encountered consisted of silty clays and clayey <br /> and sandy silts to approximately 25-35 feet bgs, underlain by sandy gravels, silty and gravelly <br /> sands, and sands to the total depth explored of 60 feet bgs Groundwater was first observed at <br /> depths ranging from 40 to 45 feet bgs Based on first quarter 2002 monitoring data, groundwater <br /> beneath the site flows to the west at a horizontal hydraulic gradient of 0 001 (see Figure 3) <br /> Soil Analytical Data TPHg and MTBE were reported in the analyzed soil samples at maximum <br /> concentrations of 12 and 0 97 mg/kg, respectively, in well MW-3 TBA was reported in the <br /> analyzed soil samples from wells MW-3 and MW-4 at concentrations of 2 66 and 0 496 mg/kg, <br /> respectively No BTEX, EDB or 1,2-DCA were reported in the analyzed soil samples from the <br /> four wells No TPHg or MTBE were reported in the analyzed soil samples from well MW-2 The <br /> analytical results are summarized in Table 3 and presented in Appendix E Soil samples analyzed <br /> during this investigation did not report BTEX or MTBE at the depths where these constituents <br /> were previously reported or suspected in adjacent borings (see Table 5 and Appendix A) <br /> Groundwater Analytical Data More than 20,000 micrograms per liter (µg/L) TPHg and MTBE <br /> and more than 10,000 µglL TBA were reported in well MW-3 (see Table 4 and Appendix F) No <br /> BTEX, EDB, or 1,2-DCA were reported in the analyzed groundwater samples except for <br /> 0 615 ltg/L benzene and 1 04 µg/L xylenes in well MW-1 <br /> 6 <br />