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' on their treatment facility (personal communication, Mary Meays) There is also doubt whether <br /> . the aquifer would be able to sustain this amount of groundwater withdrawal (approximately 3.25 <br /> million gallons/month) No pumping test has been performed The remediation times for this <br /> ttechnology are generally long, with little contaminated mass removal per million gallons <br /> pumped, and therefore this technology is more costly than other alternatives For these reasons <br /> this technology option was not retained for further evaluation. <br /> Insitu Air Sparging/Soil Vapor Extraction <br /> Description- An air sparging/sod vapor extraction (AS/SVE) system consists of a network of <br /> AS wells installed into the saturated zone and SVE wells installed into the vadose zone The <br />' network of wells is designed so that all the area requiring treatment is effectively aerated Air <br /> compressors are used to deliver air under pressure, and vacuum pumps are used to create <br /> negative pressures for vapor removal. A process control system is used to monitor and adjust <br /> the air delivery and removal equipment Additional aboveground equipment may also include <br /> a gas-liquid separator connected to the SVE well network and a vapor treatment system. Once <br /> the extracted mass removal rate has reached an asymptotic level, the AS/SVE system can be run <br />' intermittently to be more cost effective <br />' Vapor extraction is implemented by applying a vacuum to remove the generated vapor phase <br /> contamination Volatile and some sernivolatile contaminants in the soil above the groundwater <br /> table will also be removed <br /> lie <br /> Four-inch diameter air sparging wells would be installed into the aquifer Air sparging (AS) is <br /> used in conjunction with soil vapor extraction (SVE) to infect air into the contaminated <br /> groundwater and extract vapor in the unsaturated (vadose) zone above the aquifer This <br /> technology also promotes biodegradation in saturated and unsaturated soils by increasing <br /> subsurface oxygen concentrations Air is bubbled into the aquifer and travels both horizontally <br />' and vertically, removing contaminants by volatilization Volatilized contaminants would be <br /> removed by SVE <br /> Evaluation In situ air stripping has been shown to be effective for treating VOCs in <br /> groundwater and has been implemented successfully at many sites This technology is relatively <br /> simple to implement and does not require significant operations and maintenance costs Since <br /> the groundwater is treated in place, there is no need for disposal of treated groundwater BTEX <br /> compounds are easily stripped from water using air The soil in the contaminated zone consists <br />' of silt and clay overlain by sand and gravel SVE applied in the upper more permeable zone <br /> will have much greater effectiveness Due to the potential effectiveness of this technology, air <br /> stripping has been retained for further evaluation <br /> Physical Containment <br />' Description This technology consists of installing an impermeable barrier around the impacted <br /> groundwater to minimize migrating of the contaminant plume. Steel sheet piles or a slurry wall <br /> LTROJECCSISANJOQUiSMAC ION PL 31 <br />