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Treatment of Gasoline Contaminated Soil <br /> The "Preliminary Soil Remediation Work Plan, Gasoline Contaminated Soil, <br /> Forward Landfill Unit WMU G, Stockton, California" (Harding Lawson Associates, <br /> July 1991) describes the treatment system for gasoline contaminated soils. The <br /> specifications and reporting requirements of the treatment system are specified in <br /> the WDRs, Order No. 97-141 and in an October 31, 1990, letter from SJCPHS to <br /> Forward. <br /> Although Forward is not currently treating gasoline contaminated soil;these soils <br /> have been treated inAhe,past.and may e.atreated in the future. Gasoline- <br /> contaminated soils will be treated in WMU G-North or G-South by a vapor <br /> extraction and thermal=acid -t .hnigq its accordance with San Joaquin <br /> County Unified Air Pollution Control District regulations on uncontrolled air <br /> emissions. The vacuum extraction (VE) treatment system will consist of treatment <br /> cells approximately 20.f+eet.wide at the base by..200.feet,long and 5 feet.high.. The <br /> volume of soil in each treatment cell will be approximately 550 cy. The base of <br /> each treatment cell will consist of compacted native soil covered by a 20-mit <br /> polyethylene liner. <br /> The stockpiled soil..wiU.be placed in 1-foot-thick lifts over..the..treatment..cell..liner,to <br /> a height of approximately 5 feet. An air delivery system consisting of perforated <br /> PVC pipe will be installed in each treatment cell to aid in removing residual volatile <br /> organic chemical concentrations present in the soil. A 4-inch pipe will be placed at <br /> the bottom of the treatment cell with a set of three pipesplaced at the top. The <br /> top pipes will be equipped with a one-way valve. When a vacuum is,apphed o <br /> the bottom pipe, air will-flow through the one-way valve in the top.pipesand <br /> through the soil to the bottom pipe. The vacuum extraction pipes from the various <br /> cells will be manifolded together such that the air will flow to an internal <br /> combustion engine. Each treatment cell is covered with 10-mil polyethylene <br /> sheeting to prevent uncontrolled air emissions of volatile organics during the <br /> remediation process. <br /> The treatment process takes approximately 12 weeks from the start of vacuum <br /> extraction. To verify that vacuum extraction has sufficiently reduced soil <br /> contaminant levels below the designated level for disposal, soil samples will be <br /> collected from the cell at the initiation of remediation and then monthly to monitor <br /> the remediation process. The samples will be analyzed for total petroleum <br /> Forward Landfill JTD 6-10 <br /> L:\Allied\2000.193\Reports\fi naljtd:Sec-6.0:08/20/01 <br /> BRYAN A.STIRRAT&.ASSOCIATES <br />