2008-03-21_PERMIT FILE - C1980007A (5)

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West Elk Mine subsidence (rather than natural) cracking would be minimal. MCC will conduct visual inspections of primary public access to the USFS lands on a monthly basis, weather and ground conditions allowing, when these roads could be potentially impacted by undermining. MCC will mitigate all, roads that may have been impacted due to subsidence and provide signage, particularly on public' roads, warning of potential hazards. Subsidence Prediction - 2. 05.6 (6) (e) 0) Brief Description of Mining Method - 2.05.6 (6) (e) (i) (A) Apache Rocks and Box Canyon Minim Areas - The longwall mining method will be utilized in, the Apache Rocks and the Box Canyon mining areas. The panel design will be similar to the current West Elk Mine longwall panels. An average of 12 feet of coal will be extracted from the B Seam in both areas and an average of 11 feet will be extracted from the E Seam in the western panels of the Apache Rocks mining area. The E Seam is not planned to be mined in the Box Canyon permit revision area. In the Apache Rocks mining area, E Seam mining is planned to occur in Sections 28, 29, and 30. Top coal and bottom coal may be left in place in these areas to improve roof and floor stability. In the Apache Rocks mining area the three eastern panels are designed to be 8,500 to 8,800 feet long; the three western panels will trend east-west and range from 10,600 to 12,700 feet in length. As currently planned, the four eastern panels are projected to trend N80°W and be 950 feet wide. E and B Seam mining gate road entries and longwall panels are currently planned to be vertically superimposed in the western panels. In the Box Canyon mining area, the panels currently planned trend about N80°W, are 1,100 feet wide, and range in length from 6,250 to 7,900 feet. The panel layouts for the Apache Rocks and the Box Canyon mining areas are shown on Map 51 (E Seam) and Map 52 (B Seam). The NE longwall panels include two north-south oriented panels. Both panels are 950 feet in width. The eastern panel (LONE) is 3,325 feet in length while the western panel (I INE) is 3,625 feet in length: Gateroad development typically entails development of three entries leaving two rows of chain pillars; one row a rigid pillar design and one row a yielding pillar design. Chain pillars (headgate and tailgate entries) are currently planned to include one row of rigid pillars approximately 100 feet wide by 130 feet long (120 x 150 foot centers and one row of yielding pillars approximately 40 feet wide by 130 feet long (50 x 150 foot centers). These planned mine and pillar designs are subject to change pending geotechnical analysis and mining experience from the new areas. Panel lengths and widths will be maximized as possible. Additionally, the deeper cover in the Apache Rocks and the Box Canyon mining areas may require design alterations to gate roads, pillar sizes and barrier pillars as well. South of Divide and Dry Fork Mining Area - The long wall mining method will be utilized in the South of Divide mining area. The planned panel design is similar to the current West Ells Mine longwall panels where subsidence measurements were used to obtain the baseline data on which this discussion is based. A range of 8 to 14 feet of coal will be extracted from tlne E Seam depending on seam structure, coal quality, and other operating constraints. It is anticipated that extraction will be limited to 12 feet only on the easternmost edge of the panels. The extraction i thicknesses are projected based on exploration hole data; actual thicknesses may vary depending on mining conditions encountered. 2.05-119 Revised Jane 2005 PRIO, Rev. A4arch 2006; May 2006 PRIO, Nov. 2006TRIO7,April 2007TRIO Sep. 2007 PR12; Feb. 2008 PR-12