2013-11-27_PERMIT FILE - C1981018A (2)

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mark. No problems are anticipated due to this cracking. Repairs will be made in the future if warranted. There will be no mining beneath any known aquifer that serves as a significant source of water supply to any public water systems and there will be no mining beneath any public buildings, urbanized areas or towns. III.A.7.11k Subsidence Effects on the Powerline. A need to re- orient the mine plan impacted the initially proposed non - subsidence corridor. Either considerable longwall tonnage would be eliminated or the concept of a non - subsidence corridor had to be abandoned. To ensure that maximum economic recovery of the coal is achieved, BME chose the latter alternative. As discussed elsewhere, the waterline could be protected from subsidence either by relocating underground or constructing an offset line to bypass any affected portion of the waterline. However, relocation of the 138 -Kv powerline was not economically feasible and portions of the powerline were allowed to subside with mitigative measures in place. In actuality no effect of subsidence was noted on the waterline during the mining of LW -1 to LW -5. An analysis of subsidence effects on the 138 -kV powerline indicated that some of the pole structures would be affected by the subsidence. The worst possible consequences of subsidence to the power line would be the interruption of power supply to the mine. The consequences of such a power failure would be the same as those experienced in past power failures; the mine would be evacuated of all personnel until the power supply is reestablished and all safety procedures determine that the mine is safe to reenter. There are a total of 28 structures within the permit boundary on the 138 -kV powerline. Of this total, 11 structures are in positions where they could have been affected by subsidence. The structures are bolted wooden two -pole structures with connecting crossbraces. BME owns the structures and lines and is the only customer served by the powerline. On the north -south leg of the powerline, two structures and possibly a third were expected to be affected by longwall subsidence. One structure overlies room - and - pillar area 2 (RP -2). Two structures are within the outline of longwall panels 1 and 2 (LW -1 and LW -2) and initial tilting toward the southwest was expected as the subsidence wave passed them. As subsidence is completed they were expected to return to a vertical or near vertical orientation. The third structure was on the edge of the subsidence. The three structures over the longwall panels, as discussed above, were to be affected in 1987, 1988 and 1989. No tilting of the structures due to longwall mining was observed during active subsidence. Permit Revision #8 (05/2013) III -21