10.2190/22D2-HW73-J7JK-NL5C 22D2HW73J7JKNL5C 5 Leaching Behavior of Fly-Ash Piles: The Phenomenon of Delayed Rise in Toxic Concentrations 87 93 20020509 20020509 20020509 20020509 22D2HW73J7JKNL5C.pdf http://baywood.metapress.com/link.asp?target=contribution&id=22D2HW73J7JKNL5C 1 Bo Shi Arup K. Sengupta University of Delaware, Newark Lehigh University, Bethlehem, Pennsylvania Large fly-ash piles from coal-burning power plant utilities are generally viewed as innocuous solid wastes, because leachate generated by contact of rain water with fresh fly-ash particles is often very low in dissolved toxic concentrations. This view may be erroneous. With increased percolation of rain water, the concentrations of Cu, Zn, As, Cr, and other toxics in the run-off leachate may increase significantly, often over an order of magnitude. Fly-ash management practices must take this effect into consideration to avoid long-term groundwater contamination. The study reported here also shows that concentrations of dissolved non-toxic species-namely calcium, sodium, or potassium may be used as surrogate indicators to forewarn the impending rise in concentrations of various toxic species. Mass balance analysis on zinc shows that heavy metals distributed in various matrices of the fly-ash particles (glass, magnetic spinel and quartz) are quite accessible for complete dissolution in rain water. S. D. Strauss, Managing Powerplant Combustion Wastes, <i>Power, 131</i>:1, pp. 17-24, 1987. CFR 40, <i>Code of Federal Regulations 40, Protection of Environment</i>, published by the Office of Federal Register, U. S. Government, Washington, D. C., pp. 365-367, 1984. Batelle Pacific Northwest Laboratories, <i>Leachate Chemistry at the Montour Fly-Ash Test Cell</i>, Research Project 2485-8, EPRI, 1988. W. F. Koch, <i>Standard Reference Materials: Methods and Procedures Used at the National Bureau of Standards to Prepare, Analyze, and Certify SRM 2694, Simulated Rainwater and Recommendation for Use</i>, NBS-SP 260-106, PB 86-247483, National Bureau of Standards, Gaithersburg, Maryland, 1986. R. I. Malek, P. Licastro, and D. M. Roy, in <i>Fly Ash and Coal Conversion By-Products: Characterization, Utilization, and Disposal II</i>, Materials Research Society Symposia Proceedings Vol. 65, G. J. McCarthy, F. P. Glasser, and D. M. Roy (eds.), Materials Research Society, Pittsburgh, Pennsylvania, 1986. O. Hjelmar, Leachate from Land Disposal of Coal Fly Ash, <i>Waste Management Research, 8</i>:6, pp. 429-449, 1990. S. A. Wasay, Leaching Study of Toxic Trace Elements from Flyash in Batch and Column Experiment, <i>Journal of Environmental Science and Health, Part A, 27</i>:3, pp. 697-712, 1992. U. S. Environmental Protection Agency, <i>Methods for the Determination of Metals in Environmental Samples</i>, EPA 600/4-91/010, Washington, D. C., 1991. L. D. Hulett, A. J. Weinberger, K. J. Northcutt, and M. Ferguson, Chemical Species in Fly Ash from Coal-burning Power Plants, <i>Science, 210</i>:19, pp. 1356-1360, 1980.