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Pacific Gas&Electric Co. Page 5 hydrocarbons in subsoils and to evaluate the subsurface conditions. Soil samples would be maintained and r _ transported under:proper chain of custody protocol to a State-approved1aboiatory for chemical analysis.Soil samples would be analyzed to detect the presence and concentration of benzene,toluene,xylenes,ethylbenzene and J total petroleum hydrocarbons as referenced to gasoline_ 5.0 METHODOLOGY Soil Sampling,and Drilline: In the event soil sampling at the limits of over-ezcacation occurs,soil samples will be obtained by the drive-tube- f method from soils obtained in the excavator's bucket.`A stainless steettube will be pushed into the sampled:soils, and contained in the sample tube with plastic,caps over teflon seals at each end:` l.J Drilling will be performed utilizing a truck mounted drill rig equipped.with flight hollow-stem auger.A Dames& Moore eolo t or en eer will be resent durin to assist in_obtainin relativel undisturbed.sam les of g i P. g drilling g Y,: P the subsurface materials,to maintain a'log of borings,to field screen samples with a device capable of detecting volatile organic hydrocarbons as a trace gas,and to make observations of the site conditions. Field screening of F - the subsoils samples will help to descnbe hydrocarbons persistence in a vertical relationship to the previous } :tanks. Subsoils will be.sampled at approximate 546ot vertical intervals,commencing at an approximate depth of five feet below the existing grade. Samples will be obtained by means of a California Modified sampler which will be lined with stainless steel sleeves or rings. The sampler will be:advanced by blows from a 140.pound hammer.falling 30 inches. Soils mill be classified according.to.the Unified Soil Classification System. La Proposal Stockton Service iCenter DAMES &MOORE