Assessment of contaminant load changes caused by remining abandoned coal mines.
Proceedings of the International Land Reclamation and Mine Drainage Conference and Third International Conference on the Abatement of Acidic Drainage, April 24-29, 1994. Washington, DC: U.S. Bureau of Mines, 1994 1:20-29
Determination of contaminant loading changes caused by remining of abandoned coal mines requires knowledge of the characteristics of the hydrologic data before and after remining. Under an approved remining program, a coal mine operator can remine abandoned coal mines without assuming treatment responsibilities of the previous 1 y degraded water, as long as these discharging waters are not further degraded. Normality tests performed on the hydrologic data from 57 mine discharges from 24 remining operations indicate generally nonnormal distributions and extreme right-skewness (toward the smaller values). Analysis of the differences among medians indicates that the water quality of underground mines was more highly degraded than that of surface mines. Analyses of pre- and post-remining mine discharge water quality and flow rates of the 57 discharges illustrate that most the sites exhibited either no change or a significant decrease in contaminant rate because of remining. The discharge flow rate was the dominant controlling factor when the post-remining pollution load was observed to be significantly better or worse than the pre-remining load, as was shown with the correlation and other analyses. Generally, when the mine discharges were degraded as a result of remining, this was caused by short-term changes in flow and/or concentration that occurred shortly after reclamation. Reduction of recharge from the surface and adjacent unmined strata should decrease the mine discharge flow rate and in turn the contaminant load.
alternate effluent standards; contaminant load; remining
Proceedings of the International Land Reclamation and Mine Drainage Conference and Third International Conference on the Abatement of Acidic Drainage, April 24-29, 1994