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10. No indication of panel width was provided in the subsidence analysis in <br />Exhibit 24. Please provide panel width and indicate the vertical projection of <br />the mined area used in the analysis in Figures 1 and 2. <br />NECC Response: With no subsidence, panel width is not germane. <br />DRMS Response: Response accepted. <br />11. No estimate of angle of draw was noted in Exhibit 24. If the complement <br />angle to the angle of influence can be assumed to be the angle of draw, <br />(23.8 degrees) at 450 feet in depth, the projection of measureable <br />subsidence would project outward 198 feet from the vertical projection of the <br />edge of the workings at the surface. if a 300 foot square pillar is used to <br />protect gas we!/s, and the we!! is centered in the 300 foot square, 198 feet <br />would intercept the gas well casing in the subsurface from all sides <br />assuming mining and subsidence on all sided of the protective square pillar. <br />In fact, if mining was to occur on all sides, no portion of the surface would be <br />spared from subsidence for the gas wells. This protective pillar area does <br />not appear to be large enough to protect gas wells from possible casing <br />rupture or other damage. Please review Exhibit 24 with regard to <br />subsidence control for the gas wells. <br />NECC Response: The 300 foot MSHA protection pillar remains and <br />development only mining surrounds this area. <br />DRMS Response: Response accepted. <br />12. In permit text narrative, define the term `pillar retreat line" and show in a <br />figure or cross-section how this "line" relates to surface features when used <br />in the context of a subsidence control plan. <br />NECC Response: Pillar retreat line is no longer relevant due to no planned <br />subsidence. <br />DRMS Response: Response accepted. <br />13. The paved road mitigation plan states ""visual monitoring should be <br />performed on the roads weekly beginning when retreat operations are within <br />a 40 degree vertical offset angle." The Division understands that no retreat <br />mining will occur from mining in the Allen seam in Section 13, 14, 23, and 24 <br />of T33S R68W. This would preclude subsidence of Highway 12, the <br />Purgato!re River, and any structures or residences in the described area. <br />Please explain and/or correct the subsidence control plan as necessary. <br />NECC Response: No retreat mining is planned and Exhibit 24 has been <br />revised.