There are four mining methods typically used in the state of Kentucky: area mining, contour mining, mountaintop removal and underground or deep mining.

The area mining method is commonly used to mine coal in the flat to moderately rolling terrain found in western Kentucky.  In this method, the overburden is excavated down to a coal seam, and then the mining area is enlarged horizontally to expose and remove the coal.  Large draglines are commonly used to scoop and move overburden onto an adjoining previously mined area in one motion.  In some mining operations overburden is removed with power shovels, bulldozers or scrapers instead of draglines. The ridges formed by the dragline as it dumps the overburden are regraded with bulldozers. Then topsoil is spread to provide a finished surface similar to the surface before mining.

Typical Area Mine in Western Kentucky

The contour mining method is typically used in the mountainous terrain of eastern Kentucky where coal seams are exposed on hillsides and mountains. First, a cut is made in the hillside above a coal seam, and the coal is further exposed as the overburden is removed. The mine site is then enlarged by successive cuts that follow the coal seam around the side of the hill. The mining extends into the hill until the overburden is too thick to make further exposure of the coal economically feasible.  Auger mining is often used at this stage to maximize recovery.

Contour Mine near Middlesboro, Kentucky

After coal removal has been completed on a section, the spoil is stacked as closely as possible to its original formation and graded with bulldozers. Topsoil is spread over the spoil and a seedbed is prepared. Grasses and legumes are planted to establish a vegetative cover. Later, tree seedlings and shrubs are planted to enhance the wildlife habitat, stabilize the site and provide a long-term economic return from the reclaimed land.

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The mountaintop removal method involves the removal of most of the overburden and several seams at the highest elevations of a mountain. Instead of mining along the contour, sections of overburden and coal are removed in progression along the mountaintop or ridge. As in area mining, draglines and large shovels may be used to remove the overburden.  In some areas as many as seven separate seams of coal may be removed by this method.

Reclaimed Mountaintop Mine in Eastern Kentucky

After coal removal is completed at a location, overburden is replaced and graded to closely resemble the terrain as it looked prior to mining. In some cases approval may be granted to replace only a portion of the overburden creating a level plateau or a gently rolling contour capable of supporting postmining land uses of industrial, commercial, agricultural, residential or public facilities.

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Underground mining methods are used where the coal seam is too deep or the land is too hilly for surface mining. Underground mines differ according to how the coal seam is situated with respect to the surface.

Aerial View of a Deep Mine Operation

A drift mine is driven horizontally into the coal seam and is the most common type of mine in Kentucky.  This type of mining is used when coal deposits appear at the surface of a hillside.

A slope mine is used when coal is relatively close to the surface but too deep to be recovered by surface mining. With this method, shafts slant down from the surface to intersect the coal seam.

In a shaft mine, vertical shafts are cut through the overburden to the coal bed.  Machines are typically used to excavate the coal. This type of deep mine is used at sites where coal is located at depths of 2,000 feet or more.

In most deep mines, the seam is mined in carefully engineered patterns that keep as much as half of the coal in place to help support the roof of the active mining area. This "room and pillar" method requires that large columns of coal remain between mined-out areas, or rooms, which are created when the coal is mined.

Coal may also be removed by the "longwall" method in which all the coal is removed in a given area.  In this case, subsidence (the collapse of the earth above the coal bed) is expected.  Plans for repair and compensation for damage to property are provided in the approved permit application.

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