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Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation
Citation:
Wilkin, Rick AND R. Puls. Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation. U.S. EPA Office of Research and Development, Washington, DC, EPA/600/F-13/324, 2014.
Impact/Purpose:
For public distribution relating to journal article published in Science of the Total Environment.
Description:
The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminanttreatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium source zone, reactive andhydraulic longevity of the PRB has outlived the mobile chromate plume. Chromium concentrations exceeding 3 μg/L have not been detected in regionslocated hydraulically down-gradient of the PRB. Trichloroethylene treatment has also been effective, although non-constant influent concentrations oftrichloroethylene have at times resulted in incomplete dechlorination. Daughter products: cis-1,2-dichloroethylene, vinyl chloride, ethene, and ethane havebeen observed within and down-gradient of the PRB at levels <10% of the influent trichloroethylene. Analysis of potentiometric surfaces up-gradient andacross the PRB suggests that the PRB may currently represent a zone of reduced hydraulic conductivity; however, measurements of the in-situ hydraulicconductivity provide values in excess of 200 m/d in some intervals and indicate no discernible loss of bulk hydraulic conductivity within the PRB. Theresults presented here are particularly significant because they provide the longest available record of performance of a PRB. The longevity of theElizabeth City PRB is principally the result of favorable groundwater geochemistry and hydrologic properties of the site.