OSM

The mission of the Office of Surface Mining (OSM) is to carry out the requirements of the Surface Mining Control and Reclamation Act (SMCRA) in cooperation with States and Tribes. A primary objective of SMCRA is to ensure that coal mines are operated in a manner that protects citizens and the environment during mining, and to ensure the land is restored to beneficial use following mining activities.  To support this mission, active and inactive surface coal mining and reclamation operations are inspected on a routine basis to ensure compliance with approved permits.

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.

Water diversions are constructed to prevent and control water runoff and erosion problems associated with the disturbed area.  Water diversions constructed on mine sites must be the same in terms of placement and size as identified in the permit requirements. (VIP 3) Using orthorectified satellite imagery in a GIS, the inspector can determine if water diversions have the correct location, length, and in rare cases, width as specified in the permit. 

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.

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.

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.

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.

After reclamation, slopes should be a uniform, or smooth shape.  Concave slopes may retain too much water and not drain properly.  Convex slopes may cause water to run off the slope causing erosion issues.

Slope length of the reclaimed surface is another parameter that falls under regulatory permit. (VIP 9)   The inspector can use measurement tools in a GIS to compare the length of a regraded slope on the DSM and compare the results to the length of the proposed slope specified in the permit.  

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