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C A M B R f A Mr Ron Rowe <br /> April 16, 1999 <br /> fSoil Physical Parameter Analyses One soil sample from each distinct lithologic unit that was <br /> not encountered in previous investigations was submitted for physical <br /> parameter analysis Two soil samples were submitted from CPT-11 for <br /> physical parameter properties The first was from a fine-grained material <br /> at 49 ft-bgs and the second was from a gravel layer at the base of the <br /> boring at 58 ft-bgs The soil samples were analyzed for permeability, <br /> porosity, density, and organic carbon content The analytical reports for <br /> these samples are not complete on the date this report was issued A <br /> separate letter reporting the results of these analyses will be issued when <br /> the reports are complete <br /> Backfill Method Boring locations were backfilled with cement grout and capped with <br /> asphalt patch for the top six inches to match the existing grade <br /> Ground Water Depth• Ground water in the monitoring and extraction wells was initially <br /> encountered between 27 4 and 30 ft-bgs (Attachment B) Based on the <br /> pore pressure dissipation tests in the CPT borings, the calculated static <br /> ground water depth ranged from 19 0 ft bgs to 24 2 ft bgs The results of <br /> the pore pressure dissipation calculations are presented in Table 4 <br /> (Attachment D) <br /> Well Elevation Survey• Virgil Chavez Land Surveying of Vallejo, California performed a well <br /> elevation survey at the site on March 25, 1999 The rim and top of <br /> casing elevations for monitoring wells MW-1, MW-2, and MW-3, and <br /> extraction well EW-1 and EW-2 are included in Attachment E <br /> Soil Disposal Soil cuttings produced from the well installation were stockpiled and <br /> sampled for disposal Upon review of the analytical results, Equilon will <br /> arrange for transportation of the stockpile to an approved <br /> disposal/recycling facility <br /> INVESTIGATION RESULTS <br /> Soil Analytical Results No TPPH, BTEX, TAME, DIPE, ETBE, tert-Butanol, or ethanol were <br /> detected in the twelve soil samples analyzed MTBE was detected in one sample, EW-1, at a <br /> concentration of 149 milligrams per kilogram (mg/kg) at a depth of 29 5 ft-bgs, and methanol <br /> was detected in the same sample at a concentration of 6 2 mg/kg Analytical results are <br /> 5 <br />