--> Impacts of Underground Coal Mining on Surface and Ground Water Resources, by L. L. M. Kadnuck; #90986 (1994).

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Abstract: Impacts of Underground Coal Mining on Surface and Ground Water Resources

Liane L. M. Kadnuck

In the western United States, coal is mined in both surface and underground mines. Currently, the most widely used method of extracting coal involves the longwall mining method. Longwalling is a total extraction method where coal is removed in large blocks, and the immediate mine roof is allowed to cave into the mine void. As the roof caves, the movement is transferred through the overburden stratigraphy creating zones where the rock mass is fractured or bent. The induced caving and fracturing can alter the intrinsic hydraulic properties of the stratigraphic units by increasing permeability, redirecting flow and changing flow gradients. The U.S. Bureau of Mines is currently evaluating the effects of underground coal mining on the local hydrologic regime in western coalfields. Studies o date have focused on the response of springs to undermining, alterations in surface-water flow and channel morphology, and effects on near-surface aquifers. Observations include: (1) minor variations in flow from springs occurred after mining, but flow returned to normal within a year after undermining, (2) water levels in wells dropped as the mine face approached, and (3) stream-channel morphology altered in response to surface subsidence. The magnitude of hydrologic response is dependent on site-specific conditions, including the thickness and composition of overburden, climatic variation, and location of the water resource above the mine level.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994