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Y- <br />Mr. Kent Gorham <br />April 29, 2011 <br />Page 2 <br />NECC Response: Subsidence is no longer planned. The term edge offset does not appear in the <br />revised Exhibit 24. <br />5. DRMS: No indication of panel width was provided in the subsidence analysis in Exhibit 24. <br />Please provide panel width and indicate the vertical projection of the mined area used in the <br />analysis in Figures 1 and 2. <br />NECC Response: No subsidence is planned, therefore, the panel width is not included in the <br />analysis. <br />DRMS: No estimate of angle of draw was noted in Exhibit 24. If the complement angle to the <br />angle of influence can be assumed to be the angle of draw, (23.8 degrees) at 450 feet in depth, the <br />projection of measureable subsidence would project outward 198 feet from the vertical projection <br />of the edge of the workings at the surface. If a 300 foot square pillar is used to protect gas wells, <br />and the well is centered in the 300 foot square, 198 feet would intercept the gas well casing in the <br />subsurface from all sides assuming mining and subsidence on all sides of the protective square <br />pillar. In fact, if mining was to occur on all sides, no portion of the surface would be spared from <br />subsidence for the gas wells. This protective pillar area does not appear to be large enough to <br />protect gas wells from possible casing rupture or other damage. Please review Exhibit 24 with <br />regard to subsidence control for the gas wells. <br />NECC Response: No subsidence is planned. The wells will be protected by the MSHA pillar <br />protection of 300 ft and the remaining pillars following development-only works. <br />DRMS: In permit text narrative, define the term "pillar retreat line" and show in a figure or <br />cross-section how this "line" relates to surface features when used in the context of a subsidence <br />control plan. <br />NECC Response: The pillar retreat line is not relevant to development-only mining. <br />Please do not hesitate to contact me if you have any questions or require further clarification. <br />Sincerely, <br />,5twm 6 Fadak') <br />Susan Patton, PE. <br />Senior Associate <br />SP/hlw <br />cc: Ron Thompson, NECC <br />Attachments: <br />Permit pages 2.05-2, -3, -3a and -90f, -90g, -91, -92, -93, -94 (revised 4/29/11) <br />Exhibit 24 (revised 4/29/11) <br />Map 3 2011 Mine Plan (revised 4/26/11) <br />Agapito Associates, Inc.