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ivision feels that the first ephemeral drainage above <br />subsidence will cause inriows into the mine Burin s rin <br />• and that the dischar ed water wil be of oor ua i1 <br />app scant nee s to iscuss mitigation o this prob em, e <br />non-sUbsldence Zone. <br />Response: As shown on the Mine Plan Map (Map 11) presented in <br />the Peerless permit application, the main underground mine entry <br />will proceed in a direction generally parallel to Coal Gulch. A <br />series of panels will be driven from the entry system. Barrier <br />pillars will be established in the area between the mining blocks <br />for years 3 anc'. 5, and 4 and 6 directly below the ephemeral <br />drainage. <br />In order to address Division concerns, Peerless does not plan to <br />extract pillars adjacent to main entries of the mine. As a <br />result, the barrier pillar between the mine main entry and the <br />panels will remain in place following mining. In addition, in <br />those areas where cover is less than feet, Peerless will not <br />~~ull~ill~ars. By leaving pillars in an area beneath the <br />ep an~-~eral~ainage and providing barrier pillars along the main <br />entry and between mining blocks, Peerless does not anticipate any <br />subsidence problems which could effect the ephemeral drainage. <br />If water is encountered in the mine, whether due to subsidence or <br />• natural infiltration, Peerless will route all such water to an <br />underground sump for use wring mining ac ivi ies as exp acne in <br />the permit application and su sequen responses to Division <br />concerns. Any water discharged from the mine workings will be <br />routed to the sedimentation pond and will be subject to NPDES <br />discharge effluent limitations. <br />If treatment of this water is required, treatment procedures will <br />be as described in the response to comment number 2, set forth <br />above. <br />5. <br />Response: At this time, Peerless will commit to no pillar <br />extraction in areas with less than 300 feet of overburden. This <br />should effectively prevent subsidence in the ephemeral drainages <br />found within the permit area. Peerless will also establish a <br />subsidence monitoring program in order to monitor subsidence in <br />the area. <br />In the future, after Peerless gains experience with underground <br />• mining in this area, a technical revision may be submitted to the <br />Division requesting extraction of pillars in areas with less than <br />300 feet of cover. <br />MpR 0 4 1986 <br />2. ~s - r z,g <br />