| The objective of this research was to determine the changes in acidity, sulfate, iron, aluminum, and calcium concentrations over time in above-drainage, underground mines. Water analyses were compiled from four sampling dates for two coal seams. Results for all sites showed declines in all parameters. Acidity decreases from the 40 sites were compared to three acidity decay curves. The data most closely matched the 5 percent decay curve. Acidity values from a different mine most closely matched the 10 percent decay curve during its first 12 years after closure. None of the five parameters showed significant relationships with either decade of mine closure or coal seam.;Five sites were more intensively sampled during March, May, and July 2007 to determine how flow and acidity changed over differing time periods. Flows were found to vary significantly between months. However, flow differences were not significant within the same month. Acidity followed a similar trend. |
