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West Elk Mine <br />Room and Pillar Panels <br />In general, the F Seam room and pillar panels consisted of 6 to 8 entries driven parallel to each <br />other on 60- to 100 -foot centers. Crosscuts were on 60 to 120 foot centers. Room and pillar <br />panel entries consisted of intake and return ventilation, conveyor belt, haulage, and escape -ways, <br />separated as necessary by stoppings. During secondary mining of the room and pillar panels, <br />additional rooms may have been developed on one or both sides of the initial development. <br />Sufficient barrier pillars were left to protect the main entries and bleeder entries (if separate <br />bleeders were utilized). During secondary mining, partial or full pillar extraction was used, <br />depending on conditions in the panel. <br />Longwall Gate -Roads <br />Room and pillar methods are used to develop gate -road entries for the longwall mining <br />equipment. Generally, two to five parallel entries are driven on from 55 to 120 foot centers. <br />Currently, a three -entry yield abutment design is typically used. The size and configuration of <br />longwall gate pillars is based on the regional geology, and depth of cover. Different <br />configurations are now used in the eastern portion of the B Seam reserve. Longwall panel <br />barrier pillars will be left to protect main entries and bleeder entries. <br />Bleeder Entries <br />Bleeder entries are typically developed to ventilate active and previously mined longwall areas <br />until those areas can be permanently sealed. Bleeder entries are connected to the main return air <br />ventilation system. Continued use of bleeder entries is currently being evaluated. Preliminary <br />plans for the E Seam include a "bleederless" ventilation system resulting in each panel being <br />progressively and/or completely sealed upon completion of mining a particular panel. This <br />alternative may be implemented in the B Seam as well. <br />Barrier Pillars <br />A barrier pillar is a large block of solid coal left in place to protect active mine workings. Barrier <br />pillars are left, as necessary, between longwall panels and main entries, between submains and <br />longwall panels, or in other areas, as needed. Barrier pillars vary in size, and designs are based <br />primarily on life -expectancy and degree of protection required for the barrier. Design criteria <br />include depth of overburden, horizontal stresses, etc. In all cases, the dimensions of barrier <br />pillars will be adjusted for prevailing conditions, to provide the protection for which they are <br />intended. <br />Longwall Mining Methods <br />MCC is using longwall mining technology in the B Seam and has plans to continue this method <br />of mining in the E Seam. Longwall panel layouts consist of gate -roads driven by continuous <br />miners, a 600 to 1,100 foot wide longwall face, necessary ventilation entries, and barrier pillars. <br />205-8 Rev 11/04- PRII, 03/06- PRIO <br />