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Z1 INC <br /> subsurface from surface spillage; and 3) exploratory excavation of three shallow trenches <br /> to a depth of 7 feet to investigate shallow hydrocarbon compounds in soil from surface <br /> spillage at Area "A". All borings were backfilled with grout as per specifications of San <br /> Joaquin County Local Health District on-site supervision. Cuttings from the borings were <br /> stockpiled on 10 mil visqueen and covered to prevent unauthorized aeration until <br /> analytical sampling for characterization can be conducted. <br /> Results from the Site Characterization Study indicate the following: <br /> Area A. Three exploratory trenches allowed direct subsurface investigation to determine <br /> the presence and extent of subsurface hydrocarbon compounds in the soil. inspection <br /> of the exploratory excavations did not reveal any obvious visual evidence of hydrocarbon <br /> contamination. Analytical sampling from soil samples obtained from the bottomy _ <br /> ff <br /> of.�the exploratory-trenches indicatedthpresence ofiTotaPeroleumHydrocarbons i <br /> sil,samples at concentrationf1.3, 65, and!29 parts per million (ppm) at-depths upto <br /> VA e'_Eifbelowground surf ca e. Additional analytical work conducted indicated that all <br /> hydrocarbons detected were apparently related to heavy fraction asphaltine-type similar <br /> to that of asphalt pavement. This portion of the Lustre-Cal facility is covered by an older <br /> asphalt surface and it is possible cross-contamination during excavation may have <br /> occurred. No significant hydrocarbon compounds are present at concentrations that <br /> threaten ground water or public health in the subsurface and no further site assessment <br /> is warranted at this site. <br /> Area D: Three shallow soil borings to 16.5 feet below ground surface investigated <br /> previously reported soil impacted by hydrocarbon compounds. No hydrocarbon or <br /> chlorinated hydrocarbon soil compounds were found to be present. No additional <br /> assessment is deemed warranted at this site. <br /> Concrete Tank Area: Three soil borings (two vertical and one angle) were drilled to <br /> supplement subsurface data obtained by the TMG (1992) investigation. The integrated <br /> data suggest that soil impacted by hydrocarbon compounds are present to a maximum <br /> 12274010.013 Page 2 <br />