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• Room and pillar panels will be developed off of the mains using five to <br />seven entries. A typical mining sequence for mains and panels is shown on <br />Drawing 4.3 of the Resource Recovery and Protection Plan and is incorporated <br />by reference. A typical mining sequence for panels is given in Drawing 4.4 of <br />the Resource Recovery and Protection Plan and is incorporated by reference. <br />Rooms will be driven in sets of two to four for a distance up to 240 feet. <br />The return side rooms will be mined on advance and the intake side will be <br />mined on retreat. If the roof is competent, pillar extraction may be done with <br />pillar slabbing procedures that are similar to wing and pocket recovery. The <br />first panel off the mains will be used as a bleeder for the successive panels and <br />will not be pillared. <br />Conventional room and pillar panels without pillar slabbing are proposed <br />under the Jerry Creek and Coal Creek drainages. To minimize the effect of <br />subsidence on the drainages, there will be a maximum of 50 percent extraction <br />in protective zones under the drainages. Previous studies have indicated that a <br />120 angle of draw should be utilized. The protective zone shown on Figure 5-3 <br />is 200 feet wide and will be sufficient for overburden of up to 450 feet. The <br />maximum overburden is 400 feet in the area where the creek channels will be <br />undermined. These panels will be developed in a manner similar to those <br />panels in which pillar slabbing will occur. <br />The reserves were estimated for the Cameo C seam based on seam <br />thickness isopachs and calculated mine recoveries for various entry and <br />crosscut centers. Mining recoveries (not including barrier pillars) ranged from <br />43 percent in main entries to 73 percent in panels with pillar recovery. The <br />overall mining recovery is estimated to be 34 percent of the entire reserve. <br />An area of Cameo C seam coal exists over the proposed southwest mains <br />in the Cameo B seam. If the in -mine exploration drilling shows that the high <br />ash area encountered in the Cameo B seam at the end of the 2 n West Panel is <br />of limited extent, then mining of the Cameo B seam may be feasible. If mining <br />in the Cameo B seam is projected to resume, this area should not be mined to <br />PHCC R2P2 Page 7 2-28-99 <br />