Analysis of coal combustion by-product disposal practices in arid climates: Leachate water quality

Coal combustion by-products (CCBs)have been disposed of in a nearby coal mine since 1973. There is concern that disposal of these materials in an unlined surface mine may cause ground and surface water contamination. This research project focused on determining the leachate characteristics from fresh unburied and buried CCBs, and investigated the geochemical transformations that occur with time.;The analyses found that unburied and buried ash contained elevated concentrations of arsenic and barium relative to spoil material.;Concentrations of chemical constituents in ash samples varied with sample depth to which suggested geochemical evolution of CCBs as a function of time. Barium and arsenic demonstrated the largest change in concentration over depth. Barium showed the highest leach concentration. Mineralogical examination found older ash samples showed evidence of secondary mineralization leading to formation of calcite. Dissolution of aluminosilicate minerals was found in unsaturated column leach tests as increasing concentrations of aluminum.