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Abstract

The discovery of chlorinated volatile organic compounds (CVOCs) in the aquifer underlying a manufacturing facility prompted the initiation of an aggressive voluntary site wide soil and groundwater cleanup. Given a large number of potential source areas within the plant, delineation of CVOC impacts to the unsaturated zone was performed by the installation of an innovative soil vapor extraction system, rather than performing extensive soil sampling within the operating manufacturing facility. The system was designed with a pneumatically actuated valve manifold system to cycle the 120 extraction points which allowed for delineation of impacts, targeting hot spot source area removal, and overall contaminant reduction while remaining below regulatory discharge requirements, thereby eliminating the need for more costly air treatment. The innovative system design reduced equipment size by 80% while improving system recovery by operating in the most productive range of the removal curve. The groundwater remediation system, consisting of 6 extraction wells and 7 injection wells, is capable of extracting up to 600 gallons per minute (gpm) of groundwater. Up to 200 gpm of the extracted groundwater is treated by shallow tray air strippers with subsequent discharge via NPDES permitted outfall and re-injection of up to 400 gpm of substrate augmented groundwater into the upgradient portion of the plume. The net loss from the NPDES discharge provides capture and treatment of offsite groundwater downgradient of the site. The groundwater remediation system operates as a closed loop bioreactor allowing downgradient microbial seed to be recycled into the up gradient heart of the plume to increase the rate and effectiveness of CVOC removal via reductive dechlorination. Operations have so far have removed over 900 pounds of CVOCs from the unsaturated zone and over 1500 pounds CVOCs from the groundwater within the treatment zone. Groundwater treatment is ongoing.

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