ABSTRACT: In October 2000, a constructed wetland treatment system began receiving a combination of storm water and wastewater from the A-01 outfall located at the U.S. Department of Energy’s Savannah River Site (SRS) in South Carolina. The constructed wetland treatment system was designed to treat 1 million gallons per day of storm water from a 200-acre watershed (42% of total flow) and effluent from research laboratories (58% of total flow) at SRS. The A-01 outfall is an NPDES permitted discharge, and prior to construction of the wetlands, copper was at levels toxic to aquatic organisms.

The conceptual design of the wetland treatment system was developed from pilot mesocosm studies to identify key aspects of wetland function and performance. The pilot studies determined specific design parameters such as physical/chemical characteristics of hydrosoil, appropriate hydraulic retention time, and selection of wetland vegetation effective for copper attenuation. The full-scale constructed wetland system consisted of an upstream retention basin that provided consistent flow via gravity to eight one-acre wetland cells planted with giant bulrush (Schoenoplectus californicus). The A-01 outfall has consistently achieved compliance for copper, mercury, and toxicity since the wetlands came on line 16 years ago.

The constructed wetland system has provided numerous research opportunities from conceptual design through long-term operation. Much of the research will be highlighted here. The A-01 constructed wetland system received recognition from the U.S. Department of Energy and U.S. Environmental Protection Agency Region 4 as a model application of sustainable technology, having saved SRS more than $60 million over the life of the system.

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