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SECOND QUARTER 2003 REPORT KWIKEE FOODS 2081 Country Club Boulevard Stockton, California .lane I2,2003 EXECUTIVE SUMMARY Groundwater monitoring took place on May 22. The depth to groundwater was measured with a water level meter and water samples were collected from four of seven monitor wells. A battery- operated purge pump was used to purge the wells of standing water, which was stored in DOT- approved drums on site. The samples were analyzed for Total Petroleum Hydrocarbons as gasoline, volatile aromatic hydrocarbons (BTEX), and five gasoline oxygenates. The depth to groundwater was essentially unchanged between February and May. However, the cone of depression that had resulted from the remediation system at the former Chevron site at 2103 Country Club Boulevard essentially disappeared, and the piezometric surface was irregular and variable in May. Slight north-trending ridges in the central part of the Kwikee site and eastern part of the Chevron site subdivide the area into three small, linear groundwater "troughs". • The hydraulic gradient from the ridges toward the troughs is steeper than the gradient within the troughs, creating a variety of local groundwater flow directions. This may account for slight increases in hydrocarbon concentrations along the northern and eastern margins of the ridge at the Chevron site, causing hydrocarbons to disperse downgradient from the ridge crest. Data supplied by Gettler-Ryan, Inc. indicate that north of the ridge crest, the concentration of Total Petroleum Hydrocarbons in the gasoline range increased to 370 parts per billion (ppb) in MW-2 and 280 ppb in MW-7. East of the crest, the concentration increased to 4600 ppb in Chevron well MW-6 and to 470 ppb in Kwikee well KF-3. In contrast, east of the crest of the ridge at the Kwikee site, the concentration remained below the detection limit in both KF-1 and KF-2. On the crest of this ridge, the concentration was constant at 190 ppb in KF-5. Benzene increased slightly in both -KF-3 and KF-5. Methyl-tertiary butyl ether (MTBE) decreased slightly in KF-3, increased slightly in KF-5-, and was unchanged in KF-2. Similar changes occurred in the nearby Chevron wells. One other oxygenate, tertiary amyl methyl ether, was detected in KF-3. TAME has been constant at about 1 ppb since February 2002. Although Chevron has occasionally analyzed samples from the contaminated wells at that site for TAME since 1997, the reporting limit has ranged from 20 to 100 ppb, so it is unknown whether this oxygenate is present in any of the Chevron wells. 1