ABSTRACT
Ash storage pond seepage has concentrations of metallic ions similar to acid mine drainage (AMD), but the aggregate flow from many seeps along one ash pond dike may be orders of magnitude greater than individual mine drainage seeps. Since water chemistry is similar and constructed wetlands have successfully treated acid mine drainage at a number of Tennessee Valley Authority (TVA) sites, the authors explore constructed wetlands for treatment of ash pond seepage at three TVA coal-fired generating plants. Limited land availability for wetlands treatment systems directly resulted in construction of systems at Kingston 006 and Widows Creek 018 that lacked sufficient treatment area for the loading rate. Potential remedies under investigation include the possible lack of Fe-Mn coprecipitation at Colbert 013, alkalinity buffering and sulfate reduction mechanisms for Widows Creek 018 and Kingston 006, and flow reductions or increased treatment area at Widows Creek and Kingston.
