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Chevron Products Company 4
<br /> Chevron Service Station 9-0557, 139 South Center Street.Stockton,CA March 21,2001
<br /> • after the first boring (HP-4). Field and laboratory procedures are described in
<br /> Attachment B. Boring logs are presented in Attachment C. Certified analytical reports
<br /> are presented in Attachment D.
<br /> Applicable permits for soil borings were obtained from the PHS/EHD prior to drilling.
<br /> Additionally, prior to the drilling soil borings within the City of Stockton and CalTrans
<br /> right-of-ways, the appropriate encroachment permits were secured.
<br /> The findings of the assessment are discussed below:
<br /> Lithology. In all four of the borings, mostly clay, clayey silt, and silty clays
<br /> with a few small layers of sand to sandy silt were encountered to the total depth
<br /> of each boring (approximately 53 to 74 feet bgs). Geologic cross-sections are
<br /> presented in Figures 3 and 4.
<br /> Soil Results. Two soil samples were collected. The samples were analyzed
<br /> for TPHg, BTEX, and fuel oxygenates by EPA Method 8260. HP-4,69'
<br /> contained 5.8 mg/kg TPHg, 0.34 mg/kg benzene, 0.70 mg/kg toluene, 0.19
<br /> mg/kg ethylbenzene, and 0.54 mg/kg xylenes. HP-4,74' contained 350 mg/kg
<br /> TPHg, 0.88 mg/kg benzene, 11 mg/kg toluene, 5.0 mg/kg ethylbenzene, and 23
<br /> mg/kg xylenes. Soil analytical results are presented in Table 1.
<br /> Groundwater Results. Groundwater samples were submitted to a California
<br /> State-certified laboratory and analyzed for the presence of TPHg, BTEX, and
<br /> MtBE by EPA Method 8260B. Soil samples from borings HP-2 through HP-4
<br /> were also analyzed for the full EPA Method 8260 suite, including the fuel
<br /> oxygenates ethyl-tertiary-butyl-ether(EtBE), di-isopropyl ether (DIPE),
<br /> tertiary-amyl-methyl-ether (TAMC), tertiary-butyl-alcohol (TBA), 1,2
<br /> dichloroethane (1,2 DCA), and 1,2 dibromoethane (EDB). Results are
<br /> presented in Table 2.
<br /> Boring HP-I and HP-3 contained no detectable concentrations of any of the
<br /> analytes. HP-2,57' contained 210 µg/1 TPHg, 0.58 µg/1 xylenes, 1.0 ggll DIPE,
<br /> and 38 µg/] TBA. HP-4,58' contained 420,000 gg/I TPHg, 36,000 gg/1
<br /> benzene, 54,000 µg11 toluene, 5,000 µg11 ethylbenzene, 23,000 µg11 xylenes,
<br /> 120 µg11 MtBE, and 52 gg/I 1,2 DCA.
<br /> Soil Stockpile Sampling and Results. Less than a cubic yard of soil was produced
<br /> during assessment activities. Stockpile soil was temporarily stored in DOT approved
<br /> 55-gallon drums pending characterization. One four by one composite sample (SP IA-
<br /> D) was taken from the stockpile. SP 1A-D reported 29 mg/kg TPHg, 0.0087 mg/kg
<br /> benzene, 0.13 mg/kg toluene, 0.21 mg/kg ethylbenzene, 0.83 mg/kg xylenes, and 120
<br /> mglkg lead. Soil stockpile analytical data is summarized in Table 3.
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<br /> IAChevron1905571REP0RTS\MtBE Eva11MtBE eval.doc
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