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_ L"Y <br /> Chevron/Stockton 3 <br /> November 1989 <br /> i <br /> a BACKGROUND <br /> In October of 1989, Chevron retained GTI to prepare a work <br /> E . plan for soil excavation at former Chevron Station # 9-0342 (see <br /> Figura 2, site F'.-an) . The site had been an active service <br /> station from August, 1963 to June, 1987. The station had <br /> I ; <br /> utilized four fiberglass underground storage tanks since June, <br /> 1983. Three of the tanks were 10,000-gallon, gasoline-fuel tanks <br /> located in the southeast corner of the site. The fourth tank was <br /> a 1,000-gallon waste-oil tank located north and west of the fuel- <br /> tank pit. These underground storage tanks were removed on <br /> s + September 1 and 2, 1987, and twelve sail samples were collected <br /> # during the excavation. Samples were taken from the tank-pit <br /> excavations and From the soil adjacent to the three pump islands. <br /> F Analyses of these soil samples showed a range of hydrocarbon <br /> r concentrations. Samples taken adjacent to the former waste-oil <br /> tank pit showed concentrations of oil and grease as high as 3 ,800 <br /> parts per million (ppm) , as well as a number of other <br /> constituents. Samples from the area of the fuel-tank pit showed <br /> generally low levels of hydrocarbons. One sample, S-8, taken by <br /> the eastern end of the northern-most tank indicated 890 ppm total <br /> petroleum hydrocarbons (TPH)-as-gasoline and 144.93 ppm total <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX) . A sample <br /> _ collected by the northern pump island, S-9, showed 60 ppm TPH-as- <br /> gasoline and 4.5 ppm total BTEX. The three samples taken by the <br /> - southern two pump islands showed either very low total BTEX <br /> (less than 0.1 ppm) or no detectable hydrocarbons. The total <br /> depth to which these contaminants extend is unknown. <br /> ~w �� (JRI)l'1U151Tt:R <br /> J Tl:re��d.uw he <br /> y <br />