A 46 meter long, 7.3 meter deep and 0.6 meter wide reactive barrier was installed at the U.S. Coast Guard Support Center (USCG) in Elizabeth City, North Carolina, in June 1996. The reactive barrier was designed to remediate a hexavalent chromium (Cr(VI)) groundwater plume, in addition to treating portions of a larger and not yet fully characterized trichloroethylene (TCE) groundwater plume at the site. The barrier is composed of Peerless Metal and Abrasives of Detroit, Michigan (Peeerless) granular iron and removes (Cr(VI)) and TCE from the groundwater via processes of reduction and precipitation, and reductive-dechlorination, respectively. In addition to nine large-screen compliance wells, a monitoring network of approximately 150 small-screen sampling points was installed in November 1996 to provide detailed information on changes in porewater geochemistry through the barrier. This network was sampled seven times between November 1996 and December 1998 at 3 to 6 month intervals: November 1996, February 1997, June 1997, September 1997, March 1998, June 1998 and December 1998.