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Ic <br /> N%MOI <br /> T <br /> A S S O C I A T E S I N C <br /> b. 2_4 Soil and Groundwater Sample Analysis <br /> Selected soil and groundwater samples were analyzed by Sequoia Analytical for total petroleum <br /> �- hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, xylenes (BTEX), oxygenate <br /> fuel additives, and total lead. The analytical results for soil samples are summarized in Table 1 <br /> and the analytical results for groundwater samples are summarized in Table 2. Laboratory data <br /> %W sheets and chain-of-custody documentation are included in Appendix C. <br /> 3.0 SUBSURFACE CONDITIONS <br /> L <br /> Soils encountered beneath the site consist primarily of sand and silt to a depth of approximately <br /> 31 feet below grade, the maximum depth explored. From the surface to approximately 11 to 14 <br /> ` feet bgs, soil consists of poorly graded sand with silt. From 11 to 14 feet bgs to a depth of 20 to <br /> 24 feet bgs, soil consists of sand and silty sand. From 20 to 24 feet bgs to 31 feet bgs, the <br /> aw maximum depth explored, soil consists of silts and sands. <br /> Groundwater beneath the site was encountered at approximately 30 feet bgs in boring SB3 and at <br /> 24 feet bgs in borings SB4, SB5, and SB6. Based on the San Joaquin County Flood Control and <br /> Water District, Spring 1997 report, groundwater flows to the northeast. <br /> 4.0 RESULTS <br /> 4.1 Soil Contamination <br /> Results of laboratory analyses performed on selected soil samples indicate that petroleum <br /> hydrocarbons are present in the soil beneath the site. Soil samples SB3-30.0 and SB3-25.0 <br /> �- contained detectable concentrations of toluene, ethylbenzene, xylenes, and TPHg. The soil <br /> samples collected from borings SB5 and SB6 contained no detectable concentrations of TPHg, <br /> BTEX, or oxygenate fuel additives. None of the soil samples collected from soil borings SB3 <br /> through SB6 contained detectable concentrations of oxygenate fuel additives although the sample <br /> SB4-25.0 had elevated detection limits due to high concentrations of non-target compounds. <br /> Results of laboratory analyses performed on selected soil samples indicate that total lead, detected <br /> in all but one soil sample, is present beneath the site at concentrations ranging from nondetectable <br /> concentrations to 10 milligrams per kilogram (mg/kg). The analytical results for total lead were <br /> �. consistent with the typical U.S. Mean and typical Bay Area concentrations in soil as presented in <br /> Summary of Typical Metals Concentrations in Soils and Surficial Materials, from U.S.G.S. <br /> r. Professional Paper 1270 for the Conterminous United States. Analytical results of soil samples <br /> are summarized in Table 1. <br /> v <br /> w:\14981\14981\reporls\psii.doc 3 <br /> r <br />