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E CONCLUSIONS 1. During the November 1986 field investigation, floating product was found on standing water in two soil borings (B-1 and B-2) drilled within 5 feet of the underground gasoline tank then located at the Tracy service center. Benzene, toluene, ethylbenzene, xylenes (BTEX) and lead were detected in some of the soil and water samples collected from these Cborings. 2. The soil vapor survey performed at the Tracy service center in June 1987 indicated that elevated levels of volatile hydrocarbons existed to the northeast and, to a lesser extent, the southwest of the former underground gasoline tank location. Results suggest that, with the possible exception of the hydrocarbons found to the south of the tank site, the underground gasoline tank was the source of these hydrocarbons. 3. Hydraulic gradient analysis of the water level data collected at the facility from January to March 1988 indicates that groundwater flow beneath the site is in a north-northeasterly direction (toward the substation) . This information substantiates conclusions formed from the soil vapor survey and implies that, unless reversals in hydraulic gradient have occurred in the past, the elevated levels of gasoline hydrocarbons found in soil at OW-3 (south of the tank site) are not related to the former underground gasoline tank. Hydrocarbons detected in this area are probably the result of a small isolated spill. 4. Total petroleum hydrocarbons as gasoline (TPH) were detected at levels under 1000 ppm (to a maximum concentration of 840 ppm) in soil samples collected during this investigation. The highest concentrations were found in soil located within a few feet to the north-northeast of the former tank site at depths near the encountered water table (approximately 7 feet below ground surface) , and dropped off rapidly � above and below this level. Low levels of TPH were detected in soils 3286a/BAV100 29