FGD Constructed Treatment Wetland Design Asheville Coal-Fired Power Generating Plant

Client: Progress Energy

Location: Asheville, North Carolina

Summary: Innovative designs for dealing with industrial wastewater and stormwater quality are an evolving science. Cardno ENTRIX has teamed with local universities in order to provide clients with innovative and progressive designs utilizing results from active research programs involving treatment wetlands for industrial and domestic wastewater and stormwater.

Cardno ENTRIX was part of the design team constructing a wetland to remove selenium and mercury from blowdown generated by the FGD scrubber being installed at the Asheville (NC) Coal-Fired Power Generating Plant. Cardno ENTRIX, in partnership with a local university, developed the conceptual design based on pilot scale wetland testing performed by graduate students. The results of two years of pilot work formed the basis of the design criteria of the wetland treatment system.

The treatment system was constructed in one corner of an abandoned ash basin adjacent to the plant. It consists of an equalization/cooling basin followed by two parallel trains of wetland cells and effluent monitoring prior to discharge to the French Broad River and will receive up to 0.54 mgd of wastewater. The treatment system occupies approximately ten acres with 6-acres of active wetlands.

This system does not require plant harvesting, constant chemical addition, or continuous sludge removal. The system uses gravity flow from the equalization basin through the discharge and does not have any electrical requirements. The Constructed Treatment Wetland has been operable since 2005.