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1.0 INTRODUCTION SECOR International Incorporated (SECOR) has prepared this report to document recent environmental field activities conducted at the Jackpot Food Mart at 14000 East Highway 88 in Lockeford; California(Figure 1). This report was prepared at the request of Time Oil Company,the property owner. The objective of this investigation was to further delineate the extent of petroleum hydrocarbons in soil and groundwater in the vicinity of the site. The investigation involved the preparation of a site-specific health and safety plan, obtaining permits and utility clearance, drilling six soil borings and installing groundwater monitor wells, developing and sampling all the monitor wells, surveying all of the site monitor wells to a common datum, and the preparation of a technical report detailing the findings of the investigation. All work was conducted under the direction of a California registered geologist. 2.0 BACKGROUND =1 The site is located on East Highway 88 on the east side of the community of Lockeford in San Joaquin County,California at an elevation of approximately 100 feet above mean sea level. The site >I is currently an operating Jackpot Food Mart/Exxon gas station. The former and current site features are shown on the Site Plan (Figure 2). In September 1991, three tanks were removed from the site by Scott Company as part of a facility upgrade. In addition,the pump islands and dispensers were removed and replaced. After removal of the USTs and the pump islands, soil samples were collected from the tank and pump island _ = excavations. The highest levels of petroleum hydrocarbons were found beneath the 6,000 gallon and the 8,000 gallon USTs at 8,900 parts per million(ppm)and 6,700 ppm total petroleum hydrocarbons as gasoline (TPHg) respectively. Soil samples analyzed for total lead were below the laboratory detection limit. Approximately 150 cubic yards of soil was removed from the UST and pump island excavation. Soil samples collected from the excavated soil after it was stockpiled indicated it contained levels of petroleum hydrocarbons up to 3,700 ppm TPHg and 0.98 ppm benzene. This soil was returned to the excavation as backfill to be remediated concurrently with the rest of the site. In September 1992, a preliminary site assessment was conducted by Canonic Environmental to further evaluate the subsurface conditions at the site. This investigation involved drilling a total of nine soil borings. Three of the borings were completed as 4-inch diameter vapor extraction wells (W-1, W-2, and W-3) and three of the borings were completed as 2-inch diameter vapor-inlet wells (W-4, W-5, and W-6). Approximate locations of these borings and wells are shown on Figure 2. Results appeared to define the extent of soil contamination and indicated that petroleum hydrocarbons exist primarily in the area of the former tanks to a depth of 30 to 35 feet below ground surface (bgs). The data for this investigation is contained in the document, Site Assessment Work Plan dated July 24, 1992, prepared by Canome. In December 1993, an additional site assessment was conducted by SECOR to verify the extent of i petroleum hydrocarbons in soil at the site. This investigation involved the drilling of five soil !ob Na.]0710-061-61 SECOR O LOCKEFORD.INV 1 uober 9,1996 .I I L_d f .1 J