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Geological Audit Services Inc. 1803 W. March Lane, Suite A•Stockton, CA 95207•(209) 956-0264•FAX (209)956-0700 PROPOSED MITIGATION OF HYDROCARBON CONTAMINATION AT ARTS AND ARTISTS 204 East Lodi Avenue Lodi, California EXECUTIVE SUMMARY An underground storage tank for leaded gasoline was excavated and removed from this business in 1987 . Subsequent soil testing revealed that soil beneath the tank was contaminated with gasoline. Three soil borings were then drilled around the tank cavity and soil samples were analyzed for evidence of contamination. The samples indicated that the soil in one boring was slightly contaminated. The groundwater table was reached at 50 feet, and the borings were converted to groundwater monitoring wells. A water sample was collected from each well. Dissolved gasoline was present in two of the wells, and other volatile hydrocarbons (benzene, toluene, ethylbenzene, and xylene) were present in all wells. The wells were sampled again in November, 1991. A layer of gasoline was found to be floating on top of the water table in one well, at a depth of 60 feet. This indicated that the water level has dropped about 10 feet since 1987 . As a result, the other two wells, which do not go below 60 feet, are now dry. San Joaquin County Environmental Health Department has ordered the property owner to submit a work plan to remove the gasoline from the third well. GEOLOGICAL AUDIT SERVICES, of Stockton, California, has submitted the required work plan to the County. This document summarizes the proposed method of removing the floating gasoline. A floating product recovery system will be installed. The system will consist of a down-hole pump and fuel skimmer in monitoring well MW-1, connected by fluid recovery hoses to a control box located near the alley behind the building. The control box will also be connected to a generator to operate the pump, and an above-ground storage tank for containment of removed fluids. This tank will be located in the vacant lot to the south of the building. The fuel skimmer repels water but accepts gasoline, thereby allowing the selective withdrawal of gasoline from the well. . The control box monitors the operation of the generator and pump system, and routes the fluid to the storage tank. Periodically, a vacuum truck will be used to empty the tank. The frequency of removal will be determined by the rate at which gasoline can be withdrawn. The recovered fluid will be transported to a recycling facility under proper manifest. The removal period is expected to last three to six months, depending on the total volume of gasoline in the well. Environmental Services•Hydrogeology•Geotechnical Services