Remediation of Abandoned Mine Lands

Thursday, October 2, 2008 : 3:40 p.m.

Water Quality Evolution in Flooded Underground Coal Mines

Bruce R. Leavitt, PE, PG, Consulting Hydrogeologist, Paul F. Ziemkiewicz, Ph.D., West Virginia University, James M. Stiles, Ph.D., Limestone Engineering and Raymond J. Lovett, Ph.D., ShipShaper LLC

After below drainage underground coal mines are abandoned, the mines flood to form an aquifer. The size of the voids in these mine aquifers depends upon the mining techniques and the mechanical properties of the coal and roof. In Longwall and full extraction room and pillar mining the roof collapse is immediate. However, where pillars are left in place, and where the roof is well supported large openings can remain for decades. During the flooding process, acid mine drainage (AMD) is liberated from the rock and coal surfaces after years of formation in the mine. New AMD may continue to form as water and oxygen in the mine atmosphere are exposed to pyritic minerals in the coal and overburden. When the mine aquifer is completely flooded, less oxygen can come into contact with the pyritic minerals in the mine and the discharge from the mine aquifer can become net alkaline with decreasing metal loads. In addition, inflow to the mine from recharge can bring alkalinity into the system altering the mine water chemistry. Understanding these processes requires a regional appreciation of mine geometry, interconnectivity and hydrogeology.

This paper summarizes ten years of study at West Virginia University that began with regional mine structural mapping, flooding dynamics and is now investigating the evolution of mine water chemistry. Observations were processed through the TOUGHREACT model by incorporating the results of the coal and overburden geology, mine water, and mine atmosphere analyses.

Bruce R. Leavitt, PE, PG, Consulting Hydrogeologist Mr. Leavitt has 35 years experience in coal mining and mine hydrogeology. He has worked as a mine engineer, a staff Hydrogeologist for a major coal company, and for the last eight years as a consulting Hydrogeologist in private practice. Recent work has included: a study of the effects of longwall mining on domestic water supplies in Pennsylvania; mapping the extent of mining and mine flooding in the Pittsburgh Coal; The potential use of mine water for power plant cooling; and the potential for in situ treatment of net alkaline mine water.


Remediation of Abandoned Mine Lands