|Contour Surface Mining|
Contour mining is practiced in areas where it is uneconomical to remove all the overburden from a coal seam or series of coal seams. In contour mining, surface mining machinery follows the contours of a coal seam or seams around a ridge excavating the overburden and recovering the coal seam or seams as a “contour bench” around the mountain is created. Excavation proceeds inward towards the mountain to a pre-determined depth. Contour mining results in excavation areas or “contour cuts” that wrap around mountaintops or ridgelines parallel to the contour of a given mountain or ridge line. Contour cuts may be conducted on multiple seams on a ridge or mountain side, stepping upward in elevation much like a layer cake pattern. In multiple seam contour mining, the cuts for multiple seams extend deeper into the mountainside moving upwards towards the ridge top. Figure A-7 is a photograph of an active contour mine in West Virginia. The photograph in Figure A-8 shows active contour mining along with reclaimed areas.
Contour Surface Mine in West Virginia
Active Contour Surface Mine in West Virginia with Initial Reclamation Visible in Distance
As coal removal proceeds around the mountain side, the excavated material from new overburden cuts is used to backfill the previous mining area to restore the pre-mining contours of the land or Approximate Original Contour (AOC). Figure A-9 is a photograph of a former contour mine that is in the first stage of reclamation. Overburden has been returned to the mining area and it is ready for compaction. In Figure A-10 the reclamation area has been graded, seeded and initial vegetation has been established.
Initial Reclamation of a Contour Surface Mine
Regrading and Seeding of a Reclaimed Contour Surface Mine
In final reclamation, the initial vegetation has been succeeded by mature and successful tree growth. The existence of a now-reclaimed contour mine in Figure A-11 is discernible only because of a slight difference in tree height between the reclaimed mine bench and the undisturbed, existing topography and vegetation.
Reclaimed Contour Surface Mine