THE MINE WATER LEACHING PROCEDURE: EVALUATING THE ENVIRONMENTAL RISK OF BACKFILLING MINES WITH COAL ASH
Paul F. Ziemkiewicz1, Jennifer S. Simmons1 and Anna
S. Knox 2
1West
Virginia Water Research Institute, National Mine Land Reclamation Center,
West Virginia University,
Morgantown, WV 26506-6064 U.S.A.
2Savannah River Ecology Laboratory, University of Georgia,
Drawer E, Aiken, SC 29802 U,S.A.
ABSTRACT
Federal
and State regulations encourage reduction of industrial waste streams
to decrease the acreage consumed by landfills. In particular, applications
that resolve environmental problems are recognized by state policy as
"beneficial uses." These large-scale projects may involve filling
surface and underground coal mines with ash to address hydraulic problems,
acid mine drainage, pit backfilling and subsidence. In some states, those
mine filling projects classified as beneficial are not subject to industrial
waste disposal conditions such as liners, leachate collection and monitoring.
Coal Combustion Byproducts (CCBs) are attractive for such applications
because they constitute a source of low cost alkalinity and favorable
economics resulting from transport back to the mine in otherwise empty
coal haulage trucks. The environmental risk of land filling CCBs is generally
evaluated by the Toxic Characteristics Leaching Procedure (TCLP) or the
Synthetic Precipitation Leaching Procedure (SPLP). However, there is doubt
regarding the applicability of these tests to long-term CCBs leaching
behavior in groundwater associated with coal mines. The Mine Water Leaching
Procedure (MWLP) was developed to provide a site specific risk assessment
tool. The MWLP procedure is presented in this chapter as a study case
and comparisons with TCLP results were made.
SREL Reprint #2754
Ziemkiewicz, P. F., J. S. Simmons and A. S. Knox. 2003. The mine water leaching procedure: evaluating the environmental risk of backfilling mines with coal ash. p. 75-90. In Chemistry of Trace Elements in Fly Ash, edited by K. S. Sajwan, A. K. Alva and R. F. Keefer. Kluwer Academic/Plenum Publishers.
