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Copyright© Geo/Environmental Associates, Inc. 1995 through 2008

Flat land suitable for industrial development is at a premium in many regions of the eastern coal fields. Local officials in Coeburn, Virginia are working with Coastal Coal Company to convert an active 368-acre surface mine site to an eventual industrial site which will provide jobs to a region with double digit unemployment. D. R. Allen and Associates developed a plan to only partially backfill 1.8 miles of highwall to create flat land for the development. In reviewing the plan, state and federal regulatory agencies expressed concerns over the stability of the highwalls and related safety issues. Of particular concern was the impact that existing abandoned deep mine workings would have on the stability of the exposed highwalls.

GA performed in-mine reconnaissance of the abandoned deep mine workings using a robot video camera. Subsurface conditions were assessed using cored holes, and instrumentation devices were installed within the bedrock comprising highwalls that had already been surface mined. Kinematic analyses showed that the potential exists for shallow instability (rockfalls) along primary and secondary joint sets. As a result, a fall zone (safety berm) was designed to collect shallow rockfalls based on computerized methods developed by the Colorado School of Mines.

Mass stability of the highwalls was analyzed using finite element methods. Specifically, stress conditions within the exposed highwalls, as a result of potential deformations of the underlying deep mines, were predicted using computerized methods. Results of the stress analyses were then imported into finite element stability analyses to verify mass stability of the exposed highwalls. Implementation of the plan will create approximately 165 acres of flat land suitable for future industrial development.

Copyright© Geo/Environmental Associates, Inc. 2000