Groundwater Remediation Technologies Analysis Center

In-well Vapor Stripping - Technology Overview


Courtesy of Groundwater Remediation Technologies Analysis Center

In-well vapor stripping technology involves the creation of a ground-water circulation pattern and simultaneous aeration within the stripping well to volatilize VOCs from the circulating ground-water. Air-lift pumping is used to lift ground-water and strip it of contaminants. Contaminated vapors may be drawn off for aboveground treatment or released to the vadose zone for biodegradation. Partially treated ground-water is forced out of the well into the vadose zone where it reinfiltrates to the water table. Untreated ground-water enters the well at its base, replacing the water lifted through pumping. Eventually, the partially treated water is cycled back through the well through this process until contaminant concentration goals are met.

Modifications of the basic process involve combinations with soil vapor extraction and aboveground treatment of extracted vapors and/or injection of nutrients and other amendments to enhance natural biodegradation of contaminants. Applications of in-well stripping have generally involved chlorinated organic solvents (e.g., TCE) and petroleum product contamination (e.g., BTEX, TPH). Proposed application of this technology, based on system modifications, may address non-halogenated VOC, SVOC, pesticide, and inorganic contamination. In-well stripping has been used in a variety of soil types from silty clay to sandy gravel.

Reported advantages of in-well stripping include lower capital and operating costs due to use of a single well for extraction of vapors and remediation of ground-water and lack of need to pump, handle, and treat ground-water at the surface. Additional advantages cited involve its easy integration with other remediation techniques such as bioremediation and soil vapor extraction and its simple design with limited maintenance requirements. Limitations reported for this technology include limited effectiveness in shallow aquifers, possible clogging of the well due to precipitation, and the potential to spread the contaminant plume if the system is not properly designed or constructed.

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