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September 13, .1995 Page 2 Site product facilities consist of two 10,000-gallon and one 5,000-gallon gasoline underground storage tanks (USTs), one 1,000-gallon waste oil UST, and two product islands (Figure 2). Site-specific hydrogeologic information regarding soil type and groundwater conditions is presented in the findings section of this report. Regional hydrogeologic information was obtained during a conversation with a representative of the San Joaquin County Department of Environmental Health. Regional groundwater depths range from 40 to 60 feet below ground surface (bgs). Regional groundwater flow direction in the site area is south to southwest. 'Off--site data indicate that 19 hazardous material sites are located within a I-mile radius of the site. These sites include two leaking UST sites and three other non-investigated UST sites., One fuel leak case is in close proximity to the site, Circle K located at 1225 West Lockford Street approximately 350 feet to the'northeast. These data were obtained from Environmental Risk Information and Imaging Services (ERIIS) in June I995. A field reconnaissance was performed by PACIFIC during site work to confirm the presence of these potential off-site sources in the immediate vicinity of the site. No other off-site sources were visually identified; however, this does not suggest that none exist. t.... SCOPE OF WORK To investigate if petroleum hydrocarbons are present in the soil and groundwater beneath the site, the following scope of work was performed: • Permits. PACIFIC obtained the appropriate groundwater monitoring well permits from San Joaquin County prior to initiating field work. • Well Installation. PACIFIC installed four groundwater monitoring wells (M'W-I through MW-4) on July 25 and 26, 1995. Three of 5 `these wells were installed downgradient of the site product facilities (USTs and product islands) and one well was installed upgradient of the site product facilities (Figure 2). • Well Elevation Survey, Well Development, and Well Sampling. The new wells were surveyed to MSL by a California State-certified surveyor. The wells were developed and sampled by Blaine on August 2, 1995. Blaine's procedure reports including field data sheets are presented in Attachment A. • Soil and Groundwater Analysis. Selected soil samples and groundwater samples were submitted to a California State-certified laboratory and analyzed for the presence of total petroleum hydrocar- bons as gasoline (TPH-g), benzene, toluene, ethylbenzene, and 320153 1 AIREPORT