Booth, Colin J.
M.S. (Master of Science)
Department of Geology
Groundwater--Illinois--Muddy; Coal mines and mining--Illinois--Muddy; Geology--Illinois--Muddy
The long-term hydrogeologic effects of underground mining and mine-induced fracturing and subsidence were studied at the town of Muddy, in Saline County, Illinois. Muddy is underlain by two mines, operated by the Sahara Coal Company, which from 1904 to 1940 mined the Harrisburg #5 Coal of the Pennsylvanian Carbondale Formation, at depths of 300 and 400 feet. The Pennsylvanian rocks include several minor sandstone aquifers and are overlain by glacial lake deposits (sand, silt, clay), some water-bearing. The Cottage Grove Fault (throw: 110 feet) separates the mines. It is generally thought that the strata fracturing associated with roof collapse, bed sagging and land subsidence can increase permeability and create interaquifer connections. In this study, subsidence features were located and water levels in wells were measured in 1985-1986. Although the water table, like the topography, is almost flat, the bedrock piezometric surface shows anomalies due to the mine (e.g., lows coincident with subsidence features). Possibly, mine-induced fractures connected aquifers and allowed ground- water to enter the mine conduit. However, transmissivities estimated from pumping tests (65-165 ft²/day for glacial wells and 110-548 ft day for bedrock wells) showed no relation to subsidence features. It is suggested that the mine is absorbing the regional upward discharge of groundwater, creating a depression in the piezometric surface. Mixing zones between glacial and bedrock aquifers were seen to occur as leakage occurred through mine-induced fractures and through leaky well casings. Water samples were analyzed for major ions. They show the glacial wells to have no dominant ion, but the Pennsylvanian bedrock wells to be dominated by Na+ and HC0g~. This is thought to be indirect evidence for the upwelling of mineralized water. Mixing is shown to occur between glacial and bedrock wells in relation to mine-induced fracturing and subsidence. Though little studied, the hydrogeological impacts of the abandoned underground mines in the Illinois Basin have considerable significance for the movement of naturally poor quality and contaminated groundwaters and for resources in the rural communities.
Saric, James A., "The hydrogeological effects of abandoned underground coal mines, Muddy, Illinois" (1987). Graduate Research Theses & Dissertations. 5834.
viii, 106 pages
Northern Illinois University
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