MODELING GROUNDWATER FLOW IN ABANDONED UNDERGROUND COALMINES OF THE CORNING MINE COMPLEX, PERRY COUNTY, OHIO

Mine drainage, particularly acid mine drainage (AMD), is the most pervasive water pollution problem in the Appalachian region. Watersheds that contained the coal that fostered this nation’s industrial growth often now are impacted by AMD, which contaminates both surface and subsurface water with acidity, sulfate, iron and other metals dissolved in the acid mine discharges. The Corning mine, an abandoned room-and-pillar coalmine complex in Perry County, Ohio has been identified as a major source of metals and acidity loading to adjacent streams, resulting in the degradation of the water quality in the Sunday Creek Watershed. The mine discharge is a high priority for remediation, which requires an understanding of the mine’s water budget, specifically the recharge sources, flow paths, underground pool interconnections, and residence time of water in various parts of the mine. The Corning discharge, which has high flow (0.04 to 0.15 cu. m/s), high acidity loads (340 to 1,300 kg/day) and high metal loads (90 to 480 kg/day), is not well suited for conventional treatment by wetland systems, for example. However, remediation methods such as closing stream capture holes, or introducing alkalinity via leach beds at stream capture points, or sealing the mine discharge and decanting the mine pool at a higher elevation to flood the mine workings and quench acid-producing reactions, are alternatives that can be tested with a hydrologic model. A numerical model of the mine, calibrated with field measurements of hydraulic head, hydraulic gradients, and water chemistry measured in six monitoring wells drilled into mine tunnels, and isotopic (16O/18O) signatures and discharges of inflow waters, mine water and outflow waters, provides a tool for testing hypotheses about the mine hydrology. The first phase of modeling, the topic of this presentation, assumes laminar flow (equivalent porous medium assumption) and is done using Visual MODFLOW. A later phase of modeling, if necessary, will explicitly model mine tunnel hydraulics. Understanding the flow system dynamics of this mine complex, made possible with the numerical model, is essential to developing remediation plans for Corning as well as other large acid mine drainage discharges.