Treating landfill-contaminated groundwater using surface-flow wetlands

A groundwater contamination plume from the Douglas Road Landfill Superfund Site extends approximately 3,800 feet southwest of the landfill. The contaminants of concern include volatile organic compounds and metals. A Remedial Action Plan has been implemented that involves capping the landfill, installation of five groundwater extraction wells to contain the contaminant plume, and treatment of extracted groundwater using surface flow wetlands. The treatment wetland system has been operating in start-up mode since May 2000. The average influent flow rate has been 360 gallons per minute, delivered primarily from the most downgradient extraction well. The most prevalent contaminant at the location of the most downgradient extraction well is trichloroethene (TCE). Preliminary results indicate that the treatment wetland system is successfully removing TCE from the extracted groundwater; average influent is 4.0 mug/L, average effluent is 1.0 mug/L.