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Former Discovery Chevrolet March 20, 1998 Tracy.California Problem Assessment Report (Kiff), a State-certified laboratory in Davis, California (Certificate No. 2236). Selected soil samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) by modified Environmental Protection Agency (EPA) Method 8015, and for the gasoline constituents benzene, toluene, ethylbenzene, and xylenes (BTEX), and the oxygenated fuel additive compounds tertiary butanol, methyl tertiary-butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), and tertiary amyl methyl ether (TAME) by EPA Method 8260. Additional soil samples, as required by SJC DHS/EHD, were also analyzed for TPHg, BTEX, MTBE, and the oxygenated fuel additive compounds. Analytical results for the soil samples are summarized in Table 1, and the laboratory analytical data sheets and COC reports for the soil samples are included in Appendix H. 5.2 Analytical Results - Groundwater Groundwater samples collected from borings GP-1 through GP-10 were submitted under COC to Kiff. Each groundwater sample was analyzed for TPHg by modified EPA Method 8015, and for BTEX and the oxygenated fuel additive compounds tertiary butanol, MTBE, 4 } DIPE, ETBE, and TAME by EPA Method 8260. Analytical results for the groundwater samples are summarized in Table 2, and the laboratory analytical data sheets and COC reports for the groundwater samples are included in Appendix I.. 6.0 PROBLEM ASSESSMENT The environmental investigations conducted at the site have produced a total of five monitoring well borings (MW-1 through MW-5), 10 Geoprobe® borings (GP-1 through GP- 10), and 11 hand-augered soil borings (SA through SK). A total of 42 soil samples collected from these borings have been submitted for laboratory analyses. A total of 62 groundwater samples have been collected from monitoring wells MW-1 through MW-5 and Geoprobe® borings GP-1 through GP-10. Intersecting cross-sections through the area of investigation indicate relatively flat-lying sediments of silty to sandy clays and silts overlying water- bearing silty to clayey sands (Figures 4 and 5). Laboratory analytical soil sample results above the minimum detection levels are indicated on the corresponding boring location, and 3001-12.par 7 HORIZON ENVIRONMENTAL INC.