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FOURTH QUARTER 2001 REPORT AND SITE CLOSURE REPORT KWIKEE FOODS 2081 Country Club Boulevard Stockton, California December 10,2001 EXECUTIVE SUMMARY Groundwater monitoring took place on November 20. The depth to groundwater was measured with a water level meter and water samples were collected from all 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. Samples were analyzed for Total Petroleum Hydrocarbons as gasoline and BTEX, and two were also analyzed for MTBE. The groundwater flow direction is to the west, which is unusual. Flow in this direction has only been observed on two previous occasions; May 2001 and (possibly) January 1999, as reported in the July 2001 Problem Assessment Report. The hydraulic gradient appears to be steeper along the . eastern margin of the site and there is a flat spot in the central part of the property beneath the store. The west-sloping gradient appears to be caused by groundwater remediation at the neighboring Chevron site, where a closed depression in the gradient has formed around the remediation wells. This suggests that the water level there has been lowered by either groundwater extraction or in-situ air sparging. Only three wells yielded laboratory data that matched recent results. All analytes were below laboratory detection limits for gasoline and BTEX in KF-6 and KF-7, and all analytes were detected in KF-3 at typical concentrations (TPH-g = 740 µg/l, BTEX = 14-140 µg11, MTBE = 140 µg/1). In three other wells that had been free of all hydrocarbons for the previous four quarters (KF-1, 2, and 4), xylene and/or toluene was detected at <1 ppb: The sample from KF-5 followed the recent trend of decreasing concentrations in this well, but this is the first time that the well has been free of all hydrocarbons. Investigation at this site has included four phases of drilling (March 1990, December 1994, May 1998, and July-August 2000), collection and analysis of soil samples during underground storage tank removal (March 1998), and fourteen quarters of groundwater monitoring and sampling. Synthesis of the data from these studies indicates that petroleum leakage from the two former underground tanks was remarkably minor, resulting in very minimal soil contamination (only one of twenty-six soil samples collected from the twelve borings contained a detectable concentration of gasoline: 2.98 parts per million [mg/kg]). The data further indicate that a plume of gasoline- 1