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,Y %woe V COMPLETION OF PHASE 2 WORK PLAN FOR SOIL AND GROUNDWATER INVESTIGATION AT QUIK STOP MARKET NO. 132 3555 W. HAMMER LANE STOCKTON, CALIFORNIA Exceltech, Inc. proposes that excavation be terminated at Quik Stop No. 132, located at 3555 W. Hammer Lane, Stockton, CA (Figure 1). Exceltech also proposes that the excavation be refilled and the gasoline tank be reinstalled, the groundwater contamination plume be defined as covered under in work in Phase 3, and the groundwater contamination be remediated to levels set by Public Health Services. Quik Stop Markets has expressed to Exceltech its desire to begin work as soon as possible. SITE HISTORY Quik Stop Market No. 132 formerly utilized three underground fuel-storage tanks on-site two 10,000-gallon tank. contained regular unleaded and leaded gasoline and on 8,000- gallon tank contained super unleaded gasoline. In 1987, Exceltech installed a vadose monitoring system around the tanks the site. This system detected hydrocarbon contamination in July 1990. Gasoline contaminated fill was found in the lined trenches containing the product lines. The contaminated backfill has been removed from the trenches. Soil samples were collected and analyzed for gasoline components. The results of the analysis revealed that hydrocarbons have penetrated the soil adjacent to the product line trench which serves the north pump island. Exceltech drilled four exploratory borings and converted one of them to a groundwater monitoring well on August 23, 1990. The results of soil analysis of the soil samples from three boring showed little or no petroleum hydrocarbon contamination. One boring near the northwest portion of the north pump island contained 460 parts per million (ppm) total petroleum hydrocarbons as gasoline (TPHG). The groundwater from monitoring well MW-1 contained 470 parts per billion (ppb) TPHG and 21 ppb benzene as well as detectable levels of toluene, ethyl benzene, and total xylenes. On September 11, 12, and 13, 1990, Exceltech drilled five exploratory borings and converted three of them to groundwater monitoring well, monitoring groundwater located in a "lower" sandy unit. The results of soil analysis of the soil samples from these borings showed little or no petroleum hydrocarbon contamination. Analysis of groundwater samples collected from monitoring wells MW-3 and MW-4 detected no petroleum hydrocarbon related contaminates. Analysis of groundwater samples form MW-2 detected 1 ppb benzene and detectable levels of ethyl benzene and total xylenes. A leak was discovered in the subsurface piping and excavations to remove the contaminated soils indicated that the contamination had affected the tank backfill and possibly the soil beneath the tank backfill. T 'd 3E/H331733X3 CS:TT 06, 0T 33C