2019-05-29_REVISION - C1981018 (11)

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37 monitoring, repairs, and hazard signage will be conducted during “B” seam extraction beneath the road. The stock pond reservoirs referenced above could potentially be impacted by tension cracks due to longwall subsidence (Raven Park and Halandras Reservoir No. 1). Lincoln Reservoir is located over a room and pillar mining area. Pillar dimensions and extraction ratio consistent with main entries will be employed beneath the reservoir to prevent subsidence. The stock ponds will be visually monitored during undermining, and repaired as necessary (see discussion in the Probable Hydrologic Consequences narrative of this document). The powerline is owned by BME, and the mine is the only customer served by the powerline. Power structures within areas of active subsidence will be monitored periodically by the operator, and repaired if necessary. The operator has calculated the maximum predicted surface subsidence, based on previous mining conducted within the permit area, site specific geologic conditions, seam thickness, and overburden depths, utilizing British National Coal Board (NCB) and U.S. Bureau of Mines modeling. The operator has predicted up to 7.7 feet of surface subsidence for longwall mining areas and up to 0.5 feet of subsidence for room and pillar mining area. Based on predicted horizontal tensile strains, surface cracks up to several inches wide are anticipated near zones of maximal subsidence, with the extent of cracking dependent on the nature of near surface geologic strata and surface soil cover. Measures employed to prevent subsidence material damage are addressed in Section III.A.7.g, of the application, and include a network of permanently supported mains and submains, barrier pillars, chain pillars, and unmined coal blocks in specific areas. The operator has committed to a program of visual monitoring to identify subsidence caused damage to surface structures, stock ponds, and major drainages, and has committed to repair hazardous tension cracks, subsidence features interrupting flow in Red Wash or Scullion Gulch, or damage to surface structures. Subsequent monitoring and observation have largely verified initial subsidence impact projections. Current and future monitoring includes twice a year visual inspection of mining area RP-1, and monitoring of Scullion Gulch, County Road 65, and stock pond reservoirs during periods of undermining. XVI. Concurrent Surface and Underground Mining No specific approvals are granted to the applicant under this section. XVII. Operations on Alluvial Valley Floors The permit area and adjacent lands contain three stream channels - the White River, Red Wash, and Scullion Gulch - with enough associated alluvium to be considered as potential alluvial valley floors. All three channels cross the permit area as well as the adjacent area. The permittee's alluvial valley floor analysis is contained in Section II.D of the permit application.