Case history of a large-scale air sparging soil vapor extraction system for remediation of chlorinated volatile organic compounds in ground water

A large-scale air sparging/soil vapor extraction (AS/SVE) project constructed within coastal plain sediments in New Jersey has demonstrated substantial progress toward remediating ground water through removal of volatile organic compounds (VOCs). Potential concerns identified prior to project implementation regarding hydraulic mounding, reduction in hydraulic conductivity, development of air channels, and the absence of hydraulic containment were assessed and addressed through testing and operational features incorporated into the project. At the project site, AS/SVE has successfully reduced the presence of many VOCs to undetectable levels, while reducing the concentrations of the remaining VOCs by factors of two to 500. The physical agitation caused by air sparging, and incomplete transformation from sorbed and nonaqueous phases to the vapor phase, appears to temporarily increase VOC concentrations and/or mobility of dense nonaqueous phase liquids (DNAPLs) within source areas at the project site, but this is addressed in terms of subsequent removal of VOCs by properly placed downgradient treatment lines and DNAPL recovery wells. This case study identifies and evaluates project-specific features and provides empirical data for potential comparison to other candidate AS/SVE sites.