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5.3.2 AS SVE <br /> 5.3.2.1 DESCRIPTION <br /> SVE is a common remediation technology applied for addressing gasoline fuel impacts <br /> to soil. SVE is most effective in moderate- to high-permeability soils. <br /> SVE involves applying a vacuum to wells to extract hydrocarbon-bearing vapors from <br /> the vadose zone and capillary fringe area. Extracted hydrocarbons are typically treated <br /> by granular activated carbon, catalytic or thermal oxidizers, or internal combustion <br /> engines. Additionally, SVE can improve or protect groundwater quality by removing <br /> source area hydrocarbons, by facilitating hydrocarbon diffusion from groundwater, and <br /> by delivering oxygen to the subsurface. Increased oxygen concentrations can stimulate <br /> naturally occurring hydrocarbon biodegradation in soil and groundwater. <br /> SVE system components would include appropriately constructed SVE wells, <br /> vapor conveyance piping, a vapor/liquid separator, a vapor extraction device, and a <br /> vapor treatment device. The vapor extraction device (blower) would be sized based the <br /> radius of influence and applied vacuum of the vapor extraction wells observed during <br /> pilot testing. The treatment device is determined by the anticipated influent flow rate, <br /> hydrocarbon concentration, air quality requirements,and operating duration. <br /> SVE would not directly treat groundwater and saturated soils. SVE with AS may be <br /> significantly more effective than SVE alone. AS is a remedial technology whereby air is <br /> injected into the saturated zone to remove volatile contaminants. The technology is <br /> designed to operate at relatively high air flow rates (greater than 5 cubic feet per minute <br /> per injection point) in order to affect volatilization. AS is not specifically aimed at <br /> stimulating biodegradation, although enhanced biodegradation may be realized as a <br /> secondary effect. AS must operate in tandem with an SVE system that captures the <br /> volatile contaminants stripped from the saturated zone. <br /> Additional equipment required to implement AS would include a compressed air source <br /> (air compressor),compressed air conveyance piping, specifically designed AS wells, and <br /> a down-well delivery system (piping and/or stingers). The air compressor would be <br /> sized based on the number of injection points, pressure losses through the delivery <br /> system,and minimum pressure and flow delivery at the injection depth. <br /> 447729(33) 17 CONESTOGA-ROVERS&ASSOCIATES <br />