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December a, 19$9 <br /> Work Plan Evaluation of Soil and Ground !Yater AGS 38032-3W <br /> Unocal Station No. 6981, Stockton, California <br /> Soil samples were collected from beneath the tanks on lune 14, 1988, at locations shown <br /> on Plate P-2. Because gasoline contamination was detected in the samples,the soil beneath <br /> the removed tanks was suspected to be contaminated with gasoline (Table 3). In response <br /> to the gasoline detected, and at the request of Unocal,excavation of soil from the bottom <br /> of the tank pit was conducted on .tune 15, 1988, to remove contaminated soil. Applied <br /> ¢q <br /> GeoSys#erns collected soil samples following excavation of soil from the lank pit: <br /> les collected from this excavation.indicated that <br /> Results of the analyses of soil samp <br /> li il in the center and the northeast corner of the <br /> hydrocarbon contamination remains in the so <br /> excavation (Table 3). <br /> d Unocal replaced the three underground gasoline storage tanks with t:vo new tanks during <br /> titer <br /> this soil excavation, and installed a conductor casing between the tanks to allow drilling at <br /> a later date without damaging the new tanks. <br /> At the request of Unocal,Applied GeoSystems cop 'ucted a soil-"'-'P survey at the site on <br /> December 4, 1988, to evaluate the extent of hydrocarbon vapor in the soil (Applied <br /> GeoSystems Report i�1o. 38032-2V, January 12, 1989). <br /> Field work included use of the <br /> Applied GeoSystems Nh.jbile Soil-Vapor laboratory to collect and analyze soil vapor at 13 <br /> sampling locations, Plate P-2. A Photovac IOS70 portable gas chromatograph was used to <br /> toluene. and total xylene <br /> analyze vapor samples of benzene, isomers (BTX), with a <br /> detection limit of 1 PPM- <br /> 7 <br /> , AVAOd GOOSYStOn7s <br />