Chlorinated Solvent Treatment Wetland



A first-of-its-kind wetland restoration project was completed in October 2000 to treat trichloroethene-(TCE-)impacted groundwater from a former manufacturing facility prior to discharge into a highly valued recreational surface water body in the upper Midwest. This article summarizes the design, construction, operation, and effectiveness of the restored wetland. The groundwater-surface water discharge zone at the site was restored as a wetland to improve the natural degradation of TCE and subsequent degradation by-products. For the past 11 years, the treatment wetland performance was evaluated by monitoring the wetland vegetation, wetland hydraulics, and water chemistry. Water quality data have been used to assess the wetland geochemistry, TCE and TCE-degradation by-product concentrations within the wetland, and the surface water quality immediately downgradient of the wetland. The treatment wetland has been performing according to design, with TCE and TCE-degradation by-products not exceeding surface water criteria. The monitoring results show that TCE and TCE-degradation by-products are entering the treatment wetland via natural hydraulic gradients and that the geochemistry of the wetland supports both reductive dechlorination (anaerobic degradation) and cometabolic degradation (aerobic degradation) of TCE and TCE-degradation by-products: cis- and trans-1,2-dichloroethene and vinyl chloride. © 2013 Wiley Periodicals, Inc.