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West Elk Mine <br />under or within the angle of draw or influence to sensitive renewable resource lands or existing <br />occupied residential dwellings. <br />Preventative Measures - 2.05.6(61(tl (iii 1 <br />State-of--the-art longwall minnrg technology will continue to be utilized for extraction of the B- <br />Seam and for the extraction of the E-Seam in the permit area. Although longwall mining may <br />initially induce more caving and fracturing of the roof rocks, as compazed to the room-and- <br />pillar method, it offers the advantages of maximizing resource recovery; more complete <br />subsidence; equilibrium conditions occurring in a shorter period of time; more uniform and <br />predictable pazameters necessary for the evaluation of probable hydrologic consequences; and in <br />general, fewer and less significant adverse hydrologic impacts than room-and-pillaz mining. <br />Anticipated Effects- 2.05.6 (6)(~(iii)(A) <br /> <br />Long-term impacts on the surface are predicted to be minimal above the longwall panels. The <br />few surface cracks over the mining panels that may occur aze expected to close once the longwall <br />face moves past the surface area of influence. Surface cracks present above the chain or barrier <br />pillars or mine boundaries tray remain open where permanent tensile strains remain after mining <br />is completed. However, at least several hundred feet of unfractured rock will typically exist <br />between any mine-induced surface fractures and the upper part of any mine-induced fractures <br />above the caved zone in the mining panels. Therefore, from a practical standpoint, no <br />interconnection between the surface fractures and the mine workings is anticipated. Again, under <br />a worst case scenario, if a surface fracture were to occur concurrently within an area controlled <br />by faults or bedrock lineaments, there could be interconnection between adjacent sandstones. <br />However, even under these conditions, the fractures would most likely not extend through the <br />ductile claystones. <br />Reduction Measures (Underground) - 2.05.6 (6) (fj (iii) (B) (I-III) <br />• <br />Underground measures that may be taken to reduce surface strains above the chain pillars <br />could include, but are not limited to; (1) designing the pillazs to yield and crush after mining <br />(thus minimi?ing humps in the subsidence profile), (2) planning a rapid and uniform mining <br />rate. Any plans to reduce chain pillar dimensions to reduce subsidence impacts must, of <br />course, be balanced with health and safety conditions in the mine. Plans for a rapid and <br />uniform mining rate are affected by market demands for constant, high volumes of coal as well <br />as unsafe mining conditions, such as accumulations of methane, but will be implemented if at <br />all possible, under areas that are particularly sensitive to surface cracking, such as perennial <br />stream channels. <br />2.05-136 Revisrll.Am 1995 PR06: IN6 RN03; RevisedJmi. l998PR08; RevisedMay7999TR89 <br />