Effect of ash disposal ponds on groundwater quality at a coal-fired power plant

Abstract

The impact of fly and bottom ash disposal ponds on groundwater quality was investigated at the coal-fired Columbia Power Plant at Portage, Wis. Groundwater sampling was conducted utilizing a network of piezometers and multilevel wells located at various cross-sections of the ash disposal facility. Analyses were performed for 16 major and minor elements, pH and conductivity. Data for a 3-yr monitoring program established the existence of large B, Na and SO 4 plumes in the groundwater system surrounding the ash disposal area. Substantial amounts of B, Na and SO 4 were present in the plume and portions were discharged into an adjacent wetland as the plumes moved with groundwater flow. The secondary fly ash settling pond was the major source of B and SO 4, while the main source of Na was from previous releases to the aquifer from the use of Na 2CO 3 to condition fly ash to enhance removal of SO 2 from flue gas by electrostatic precipitation. Movement into the groundwater of heavy metals such as Cu and Zn was not observed and their concentrations are likely attenuated in the pond.