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r <br /> N <br /> n <br /> f 404 WEST FREMONT STREET <br /> fi WgA No. 1628.09 <br /> August 31 , 2001 <br /> k Page 9 <br /> screened interval to approximately two feet above the top of the screened interval. A minimum <br /> ` two-foot thick bentonite seal will be placed in the well annulus above the filter pack. A grout seal <br /> consisting of Portland cement and bentonite slurry will be placed into the well annulus above the <br /> r bentonite seal. Each well will be completed with a locking well cap and aflush-mounted, traffic- <br /> rated well cover. All drilling equipment will be steam cleaned as described above. All soil cuttings <br /> generated during drilling will be placed on a stockpile stored on site, <br /> The air sparging points will be connected to underground piping and stubbed-up, manifolded and <br /> connected to the air sparging unit inside the treatment enclosure. The air sparging points will be <br /> strategically placed in the petroleum hydrocarbon groundwater plume. The points will be spaced <br /> such that the entire zone of contamination receives maximum airflow. <br /> I <br /> General Description of Soil Vapor Extraction System <br /> The soil vapor extraction system (SVES) will consist of a 280-cubic-foot-per minute (cfm) <br /> regenerative blower with a 5.5 horsepower explosion-proof motor. The SVES will be equipped <br /> with a 40-gallon moisture separator, fittings, magnehelic pressure gauges, wellhead connections, a <br /> dilution valve, a pressure relief valve, shut-off valve, an in-line filter and sample ports. <br /> The SVES will be complete with instrumentation for measuring the following: <br /> • airflow rate <br /> d � <br /> • temperature <br /> • vacuum pressure <br /> • volatile organic compound (VOCs) and petroleum hydrocarbon concentrations <br /> Approximately 140 lineal fedof Schedule 40 PVC pipin <br /> g will be installed underground in <br /> connected to the SVES unit via trenches. <br /> The SVES will be used to induce airflow and vacuum in the subsurface unsaturated and vadose <br /> f zones in order to capture displaced petroleum hydrocarbons as a result of air sparging. Airflow <br /> rate in the vapor extraction well will be determined by measuring the pressure differential across an <br /> average pitot tube with a magnehelic vacuum gauge. Two carbon air filters connected in series will <br /> Vi <br /> WALLACE • KLIHL <br /> llao ��l nw-'T Er ASSOCIATES INC. <br />