A-01 Constructed Treatment Wetland Design and Monitoring Savannah River Site, South Carolina
Client: U.S. Department of Energy/Westinghouse Savannah River Co./Bechtel, Inc.
Location: Savannah River Site, South Carolina
Summary: Cardno ENTRIX scientists and engineers were principal members of the design and assessment team for a constructed wetland system located at the U.S. Department of Energy?s Savannah River Site in South Carolina. The constructed wetland treatment system was designed to treat a 1-mgd waste stream comprised of stormwater from a 200-acre watershed (42% of total flow) and effluent from research laboratories (58% of total flow) on the site.
The A-01 outfall is an NPDES permitted discharge at the Savannah River Site, and, prior to construction of the wetlands, contained copper at levels toxic to aquatic organisms. The conceptual design of the wetland treatment system was prepared using pilot studies to identify key aspects of wetland function and performance. The pilot studies led to specific design parameters such as physical/chemical characteristics of hydrosoil, appropriate hydraulic retention time, and selection of wetland vegetation appropriate for copper attenuation.
Our scientists and engineers were responsible for:
- Designing wetland facilities
- Preparing all permitting documents
- Assisting in the development of the vegetation planting strategy and the installation of plants within the 8-acre wetland system
- Working with Bechtel construction crews to provide construction oversight during the implementation of the wetland
- Monitoring performance and verifying internal wetland functions for the first year of start-up.
This constructed wetland treatment system, which included a detention basin and eight 1-acre wetland cells, was constructed for $5 million ($8 million less than the ion exchange system alternative) and has required less than $50,000 annually to operate and monitor.
The waste stream has consistently achieved compliance with NPDES permit standards since the wetlands came on line in October 2000. In addition, these wetlands received recognition from the U.S. Department of Energy and U.S. Environmental Protection Agency Region 4 as a model application of self- sustaining technology.