Date of Award
Master of Science
The Saline Valley Conservancy District (SVCD) formed in 1980 to provide a stable source of water to many communities in Southern Illinois. The SVCD well field located in the thickest, most productive region of the Saline Valley Aquifer lies directly adjacent to a reclaimed coal mine. Subsurface movement and surface discharge from the mine has been shown to be responsible for deterioration of water quality in the surrounding area, including the aquifer. Previous studies conducted in the region have addressed water supply issues and simulated contaminant transport from the reclaimed mine. The limited scope of these models did not extend to natural hydrogeological boundaries. This study extended the model boundaries to natural boundaries including the Saline River to the south, the Wabash and Ohio Rivers to the east, and the bedrock high pinch-out and fining valley textures to the west. The flow model uses parameters from each study as a base then calibrated to 18 discrete head measurements. Initial contaminant transport runs using values from previous studies show successful mine reclamation except for surface discharge to a nearby ditch from well pumping. An analysis was performed that varied parameters to determine if any likely scenarios may cause the plume to travel farther than anticipated. These scenarios include things such as cessation of surface discharge, increasing contaminant source load, and altering recharge and hydraulic conductivity. In all cases sulfate concentrations in the SVCD production wells modeled up to 155mg/L which is under the EPA drinking water guideline for sulfate. Three wells in particular, SVCD-1, SVCD-4, and SVCD-7 never model higher than 7mg/L indicating that several wells lie outside the influence of the sulfate plume. Based on the results of the scenario analysis, the mine can shut off remediation pumping without overly contaminating the SVCD water supply.
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