Leaching characteristics of bottom ash from coal fired electric generating plants, and waste tire; individually and mixtures when used as construction site fill materials

Column leaching tests were conducted on bottom ash from coal fired electric generating plants, waste tires (WT), and bottom ash mixtures (ash–WT) to evaluate the environmental feasibility of using these materials as fill materials to raise the ground level at construction sites. The initial concentrations of As, Cd, Cr, Cu, Hg, F−, NO2-, NO3-, and PO42- from ash, WT, and ash–WT samples were lower than the drinking water standards (DWSs). The initial concentrations of Pb and Zn were slightly above the standards but within the DWS approximately one pore volume of effluent (PVE). However, the initial concentrations of SO42- from ash and ash–WT were 8–10 times greater than the standards and a maximum 8.21 PVE was required to meet the DWS. In general, the ash–WT combinations resulted in lower initial concentrations but greater partition coefficients for Pb and Zn than those for ash alone. These results suggest precautions are needed before using bottom ash as a fill material at construction sites because of the high SO42- levels.