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i 1 . 2 . 2 UST System Removal On August 13, 1996 , Fisch Environmental removed the two USTs . The USTs included an 8, 000- gallon tank (Tank 1 ) and a 1 , 000-gallon tank (Tank 2) . According to the PHS/EHD inspection notes, both tanks appeared corroded , and holes were observed in the 1 , 000-gallon UST. Gasoline odor was also noted in both UST excavations. The tanks and rinsate water were disposed at Erickson , Inc. in Richmond , California . Two soil samples were collected from beneath each former UST , and a single soil sample was collected from beneath the former dispenser. The results of these soil sample analyses are also summarized in Table 1 . In addition , two composite soil samples were collected for analysis from the waste soil stockpiles. The soil sample collected from beneath the former dispenser island contained the highest J concentrations of gasoline hydrocarbons. This sample contained 12 , 000 mg/kg of TPH-as- I! gasoline, 67 mg/kg of benzene, 710 mg/kg of toluene, 220 mg/kg of ethylbenzene, 1 , 200 mg/kg of xylenes , 215 mg/kg of total lead , and 2 , 100 mg/kg of TPH-as-kerosene . All four of the soil samples collected from beneath the former USTs contained detectable concentrations of TPH-as- gasoline (up to 2, 000 mg/kg) , toluene (up to 26 mg/kg) , ethylbenzene (up to 7 . 1 mg/kg) , and xylenes (up to 16 mg/kg) . The two soil stockpile samples did not contain detectable concentrations of TPH-as-gasoline, benzene, toluene , ethylbenzene , xylenes (BTEX) , or methyl tertiary butyl ether (MTBE) . MTBE was not detected in any of the samples analyzed . 1 , 2. 3 Preliminary Investigation and Evaluation The objectives of the preliminary investigation were to further define the extent of impacted soil and to determine if groundwater had been impacted beneath the site. To achieve these objectives, soil and groundwater-grab samples were collected for laboratory analysis from three soil borings . Soils observed in the three soil borings consisted mostly of clay and silt sequences uences to the total drilling depth of 35 feet bgs . This sequence appears to be massive and laterally continuous across the site. During drilling , groundwater was first encountered at depths ranging from 23 . 5 to 26. 0 feet bgs . Groundwater did not appear to be confined and recharge was moderately strong . 5 FI