Mountaintop Removal Mining
The mountaintop removal method is used predominantly in the East to remove coal in layers beneath the tops of mountains. Instead of mining along the contour around the perimeter of a mountain, the entire top of the mountain is area-mined, resulting in almost 100 percent recovery of the coal seam(s).
Removing the top of the mountain results in a unique opportunity to create relatively flat terrain that is suitable for residential, agricultural, and other development in areas where much of the natural terrain is too steep for any developed economic use. Except where there is advance approval to create a level plateau, however, the finished reclamation must approximately resemble the original contour of the land
The flat or very gently rolling area on the right side of the illustration is land reclaimed after a mountaintop removal operation was completed. Many new land uses can be established on reclaimed mountaintop removal mining sites. The illustration shows a mined area reclaimed for agricultural use in the foreground, and for the site of a new village in the background. In the far background to the left of this reclaimed operation, another mountaintop removal operation is underway on an adjacent hilltop.
To provide a flat surface for the operation of equipment, a first cut is made parallel to the top of the ridge after the vegetation and topsoil have been removed. The overburden is loosened by blasting, removed in a series of parallel cuts, and loaded into trucks in a fashion similar to that of contour mining. If the entire top of the mountain is to be removed, the spoil created by the mining is disposed of on an adjacent area. The spoil is usually placed in a valley or head-of-hollow fill. Special care is taken to stabilize large-scale fills, and to provide adequate drainage for safety and stability. Once the coal seam is uncovered, the coal is removed and trucked to a preparation plant in a fashion similar to the other types of operations.
In the illustration, the valley fill is located immediately to the left of the active operation. Here, the spoil was placed at the head of the narrow, steep-sided valley or hollow. In preparation for filling this area, the vegetation and soil have been removed and a rock drain constructed down the middle of the area to be filled, where a natural drainage course previously existed. When the fill is completed, this underdrain will form a continuous water runoff system from the upper end of the valley to the lower end of the fill. Typical head-of-hollow fills are graded and terraced to create permanently stable slopes.
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