A Multi-Objective Water Quality Wetland to Complement Phytoremediation of Contaminated Groundwater

This paper describes the planning and design of a constructed wetland that is part of a groundwater remediation project in Murdock, Nebraska. The wetland design attempts to optimize the carbon tetrachloride remediation process while protecting adjacent properties from flooding and channel instability, enhancing wildlife habitat, and creating recreational and educational opportunities for the citizens of Murdock. Features were incorporated into the wetland design that would encourage volatilization of carbon tetrachloride during the non-growing season, as well as phytovolatilization and rhizodegradation during the growing season. As with any constructed wetland, control of the hydrologic regime was an important consideration for water quality improvement, habitat development, and maintenance. The water level is controlled by adjustable stop-logs mounted in a concrete outlet structure. Although typical wetland restoration sites are designed to safely pass 25-year storm events, this outlet structure was sized to safely pass a 100-year storm event. The interpretive trail that winds around the wetland offers opportunities for recreational and educational activities. The wetland is also accessible for water quality monitoring and further scientific investigations. Lessons learned in the design and construction of this polishing wetland should provide valuable insights for future efforts to complement phytoremediation with constructed wetlands.