During the removal of overburden, toxic or acid-forming materials are often encountered and must be segregated and isolated during mining so as not to be a detriment to successful revegetation, spoil disposal areas, affect the stability of backfill or contribute to acid mine drainage (AMD). It is not always apparent from an on-the-ground inspection that AMD is present or it may be in a location that is not easily accessed. (VIP 4) High resolution multispectral satellite imagery can help identify the location and extent of AMD on a mine site.
Slope Direction maps can provide the inspector with information to determine the most suitable vegetation for a site, depending on what has been identified for the post-mining land use. Slope Direction Maps were identified by the inspectors as an added benefit. Slope aspect maps can be readily created from the DSM derived from stereo high resolution orthorectified imagery. Aspect was computed on the same small regraded area as the Slope Angle map at the McKinley mine site (See Slope Angle Map of McKinley several figures above). The legend for the map below shows ten
Reclamation is required while coal removal continues nearby. Backfilling and grading operations are usually the first activities to occur in the reclamation process. These operations reestablish a stable land surface and configuration consistent with the needs of the post-mining land use identified in the permit. The inspector must evaluate the progress of backfilling and grading operations during inspections.
Regulations require that no surface coal mining operations be conducted within 100 feet of a public road right-of-way. (VIP 13) Compliance with the 100 foot regulation can be checked by using orthorectified satellite imagery and GIS technology. The figure below shows WorldView-1 imagery, and the public road along with a buffer of 100 feet outside of the right-of way. A 100 foot buffer can be generated beyond the road right-of-way. Visual inspection can determine if the mine operation is in compliance.
Geomorphic reclamation approximates the slopes, drainage divides, and stream geometries of the pre-mining topography and is encouraged to ensure slope stability and reduce stream sediment. . Channel length is measured along the thalweg - the deepest point of the channel which is also the line of fastest water flow (steepest descent). Channel length is the single most important measure of geomorphic reconstruction but the watershed area, shape, and placement are also vital for reclamation success.
One of the principal requirements regarding backfilling and grading is to return disturbed lands back to their approximate original contour. (VIP 6) The final land surface must be stable, not prone to landslides or erosion and blend into the surrounding natural topography. Finally, the land surface must be compatible with the intended postmining land use.
Impoundment structures hold water, sediments, or other liquid or semi-liquids and are designed to reduce the amount of Total Suspended Solids leaving the mine site. The inspector must determinine if impoundment structures are structurally stable and conform to the design approved in the permit. (VIP 12) They also need to know the water depth, the capacity and sediment load, and if discharges from the impoundment meet applicable effluent limitations. Using the spectral signatures of water or other impounded liquids, image classification techniques can identify c
A mining permit describes the lands that will be affected by coal mining activities. The SMCRA inspector ensures that the mining and associated operations are within these approved boundaries.
As part of the surface coal mining reclamation process, the operator is required to establish vegetative cover on all disturbed areas.
Slope angle is an important factor related to the stability and erosion susceptibility of the reclaimed land surface. (VIP 7) Once a DSM is generated from the satellite imagery, a slope angle or steepness map can be readily created. The figure below shows slope angles of an active mining area in the McKinley site. The legend depicts slope categories in units of degrees with green indicating flat slopes and progressing to steep slopes in red.