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`• SUMMARY OF ENVIRONMENTAL ACTIVITIES JACKPOT FOOD MART, 14000 E. HIGHWAY 88, LOCKEFORD, CALIFORNIA PROPERTY 04-049 Current as of October 29, 9996. Underground Storage Tank Removal - September 1991 On September 17, 1991, three underground storage tanks with volumes of 12,000 gallons, 8,000 gallons, and 6,000 gallons were removed from the subject site. The tank removal was performed by Scott Co. Contractors and consultant services were provided by Canonie Environmental. Upon removal, mild surface corrosion was present on each of the tanks; however, it did not appear that any of them had leaked. In the vicinity of the tank bed, native soil consisted of fine sand and a small amount of clay was encountered at a depth of 16 feet in the southeast corner of the excavation. Groundwater was not encountered within the excavation to a depth of 20 feet. At the direction of a representative of the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD), soil samples were collected from the tank excavation and from beneath each of the former pump islands. All samples were submitted to a laboratory and analyzed for total petroleum hydrocarbons (TPH) as gasoline by EPA Method 8015 and benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Method 8020. Samples collected from beneath the 12,000 gallon tank, 8,000 gallon tank and pump islands were also analyzed for ethylene dibromide and total lead. TPH was indicated in the samples collected from the tank excavation at concentrations ranging from "non-detect" to 8,900 ppm, with the highest concentrations being present beneath the west (fill) end of the 8,000 gallon tank and the east end of the 6,000 gallon tank. TPH and BTEX were not detected in the samples collected beneath the former pump islands. During the removal of the tanks, approximately 150 cubic yards of fill material were removed from the excavation and placed on plastic sheeting on the east edge of the property. Analysis of 6 soil samples collected from the stockpile indicated TPH levels ranging from "non-detect" to 2700 ppm. After collection of the samples, the fill sand was used to backfill the excavation with the intention of remediating it concurrently with cleanup of the rest of the site. A copy of Canonie Environmental's "Preliminary Investigation Report" was forwarded to the PHS/EHD and California Regional Water Quality Control Board (CRWQCB) on January 2, 1992. Workplan for Additional Site Activities-July 1992 Based on the results of samples collected during the tank removal, a workplan for the completion of a site assessment was forwarded to the PHS/EHD and CRWQCB on July 27, 1992. The workplan outlined the tasks to be completed during site assessment. 1. A soil vapor survey would be conducted to help define the vertical and lateral extent of contamination in the area of the former gasoline tanks. 2. Based on the results of the soil vapor survey, soil borings would be advanced at the estimated limits of the contamination plume. 3. Additional borings would be placed within the area of contamination and completed as vapor extraction wells for use in a future remediation system. The wells would be installed to a minimum depth of 40 feet or to 10 feet below the last observable contamination. Authorization to proceed with the proposed work was received from the PHS/EHD on August 4, 1992.