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-IW,DA'MS &- lrlOORE, A PROFESSIONAL LIMITED PARTNERSHIP 1 <br /> i. Pacific Gas&ElecM'i"c Co. <br /> Page 3 <br /> C <br /> i PURPOSE AND SCOPE OF WORK <br /> The.purpose of our work was to evaluate.subsurface hydrocarbons in"subsoil at the-subject property. <br /> This was proposed to have been accomplished in-two ways.Initially,-it was proposed to obtain soil samples from the { <br /> } <br /> bottom of the over-excavated tank pit for.chemical analyses.In the eventsampled soils analyses.report persistent. <br /> s levels of:detectable petroleum hydrocarbons-above regulatory action levels,a more detailed investigation of. <br /> 1 <br /> subsurface hydrocarbons by commencing a pro-active Problem.Assessment Report study would be conducted. <br /> The initial phase of our site work was limited toobtained soil samples,chemical analyses of soil samples.obtained, <br /> and preparation.of this written' report.. . <br /> TECHNICAL APPROACH <br /> Based upon review of previous soil.sampling and chemical anilyses at the subject property and published data <br /> 1 regarding local geologic and hydrologic conditions,Dames&Moore proposed additional soil be excavated from the <br /> { previous tank removal pit.Soil samples obtained from the-limits of the excavation were chemically analyzed to <br /> detect the presence and concentrations of petroleum hydrocarbons as referenced to gasoline,and for the presence of <br /> lead.Our preliminary data regarding depth to groundwater in the vicinity of the subject property suggests <br /> groundwater currently occurs at an approximate depth of 60 feet below the surface grade. Since the results of <br /> chemical analyses from-samples obtained in native soils beneath the tanks were reported at significantly lower <br /> f <br /> concentrations than the stockpiled overburden-soils sampled,we surmised the concentrations of hydrocarbons reported <br /> suggest overfill spillage,rather than a tank-leak situation. <br /> FIELD.OBSERVATION AND SAMPLING <br /> On November i4, 1991,a Dames&Moore geologist visited the subject property'to observe the excavation in the tank <br /> removal pit,and obtain soil samples at thedepths,.locations and frequency specified by the San Joaquin County <br /> Environmental Health Department(SJCEHD) representative present at the site.Mr.Harlan Knoll of the SJCEHD directed <br /> j - <br /> PG&E Stockton Service Center <br /> 00160-290-042 <br /> I <br /> I <br /> . I <br />