Savannah River H-02 Constructed Treatment Wetland Design, Monitoring, and Water Effects Ratio Study

Client: U.S. Department of Energy/Washington Savannah River Co./Bechtel, Inc.

Location: Savannah River Site, SC

Summary: Cardno ENTRIX scientists and engineers comprised the final design and implementation team for a constructed treatment wetland located at the U.S. Department of Energy?s Savannah River Site (SRS) in South Carolina. This is the second constructed treatment wetland (CTW) of its kind at SRS in which Cardno ENTRIX has been involved. We have a history of working closely with the Site and all the involved parties to develop innovative, scientifically sound, and cost effective means for solving unique water quality issues. The CTW system was designed to treat 175,000 gallons per day of a mixture of non-contact cooling wastewater and storm water runoff generated by a 25-year, 24-hour rainfall event occurring on a 33-acre drainage basin within the H-02 Tritium Extraction Area. Constituents of concern in the H-02 outfall included copper, lead, mercury, and zinc. The CTW was specifically designed to decrease concentrations of these constituents in the water, thereby mitigating their potential to caused adverse effects downstream and achieving stringent water quality standards. In addition, Water Effect Ratio (WER) studies were conducted in order to negotiate site-specific regulatory standards for copper and lead. Based on pre-compliance monitoring of the CTW and WER studies, a new National Pollution Discharge Elimination System (NPDES) was successfully negotiated for copper, lead, zinc, and effluent toxicity.

The constructed wetland treatment system, which included a 3.3 million gallon detention basin, two 0.5-acre wetland cells, and associated piping and appurtenances was constructed for $3.4 million dollars and will require less than $75,000 annually to operate and monitor.

The project was completed on schedule (three months for design, one month for permitting, and six months for wetland construction) and within budget.

The H-02 system is the second of two CTW projects in which Cardno ENTRIX scientists and engineers have involved in collaboration with SRS and researchers at Clemson University. Both projects were very successful, and offer excellent examples of sustainable, ?green? technology for treating problematic waters and achieving water quality requirements.