Impact of Coal Pile Leachate and Fly Ash on Soil and Groundwater

Abstract

Six samples of crude coal and fly ash were collected from the D-Area electric power plant of U.S. Department of Energy (DOE) at Savannah River Site to determine their chemical composition for the purpose of safe disposal. Groundwater samples were also collected from five monitoring wells near the coal pile to determine water characteristics as affected by the coal pile leachate. Concentrations of metals, phosphorus and boron were determined in the coal, fly ash samples. Groundwater samples were analyzed for pH, dissolved oxygen (DO), and concentrations of metals, total organic carbon (TOC), sulfate, chloride, nitrate and acetate. Fly ash samples had higher concentrations of major and trace elements including some toxic elements than crude coal. Weathered ash had much lower concentrations of most elements, B was completely removed, and was considered safe for field application. Groundwater leached from the coal pile contained high concentrations of sulfate, Fe and Al and had low DO and an acidic pH with high redox potential. Attenuation of coal pile leachate contaminants occurred in the surrounding subsoil both vertically and laterally. Most contaminants were removed in the vicinity of coal pile and lower contamination was observed in the distant wells.