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• action alternatives, so the evaluation of these alternatives focuses on the type of treatment <br /> technology that would be used to remove VOCs from the extracted groundwater. <br /> Groundwater Extraction Systems: Viable — The advantage of a groundwater extraction and <br /> treatment system is that it is a well-accepted treatment and containment alternative that <br /> can be enhanced or modified periodically based on field observation of the system <br /> effectiveness. Existing monitoring wells could be used to monitor the effectiveness of the <br /> system. <br /> The disadvantages of a groundwater extraction and treatment system include: <br /> • Cost to install, <br /> • Cost to operate, including a permanent energy source to operate the extraction <br /> pumps, <br /> • Requires extensive above-ground facilities (well heads, control panels, power lines, <br /> storage tanks, conveyance pipes, and treatment systems) that are prone to <br /> vandalism, <br /> • Requires routine, long-term maintenance, significant energy for operation, and <br /> • • Uncertain effectiveness if hydrogeologic properties are not conducive to sustainable <br /> groundwater extraction <br /> • May require large-volume removal rates in order to reduce contaminant mass <br /> effectively. <br /> A groundwater extraction and treatment system is considered a viable alternative for <br /> groundwater remediation at the CHLF. A number of treatment alternatives for the extracted <br /> groundwater should be considered, and are outlined below. <br /> Air Stripping Treatment of Collected Groundwater: Viable—Air stripper systems use a cross- <br /> flow pattern of air to strip volatile contaminants from the extracted water into the cross- <br /> flow air, which is removes the VOCs from the extracted groundwater. Air stripping generally <br /> involves simple operation and requires only limited maintenance and is often used in <br /> association with pump-and-treat applications for clean-up of chlorinated VOCs. For an air <br /> stripping system at the CHSL, the low VOC concentrations and small volumes of water that <br /> would be treated would require are small-scale off-gas collection and filtration system. <br /> Air stripping is a proven ex-situ treatment process. It is the most often used technology to <br /> • mitigate VOC-contaminated groundwater (United States Environmental Protection Agency <br /> Engineering Feasibility Study Geo-Logic Page ■ 18 <br /> Corral Hollow Sanitary Landfill ASS OC I A T E S <br /> January 25,2013 <br />