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West Elk Mine <br />• Cracking of the earth along or across the trails or unimproved roads of the coal lease azea already <br />naturally occurs, but in the "worse case" could be accelerated by, or additional cracks created by, <br />subsidence. As the trails and roads aze unimproved, typically only all-terrain or four-wheel drive <br />vehicles are utilized and rough terrain is expected, so the hazards created by any additional <br />subsidence (rather than natural) cracking would be minimal. MCC will conduct visual inspections <br />of primary public access to the USFS lands on a monthly basis, weather and ground conditions <br />allowing, when these roads could be potentially impacted by undermining. MCC will mitigate all <br />roads that may have been impacted due to subsidence and provide signage, particulazly on public <br />roads, warning of potential hazards. <br />Subsidence Prediction - 2.05.6 (6)(e)(i) <br />Brief Description of Mining Method - 2.05.6 (6)(e)(i)(A) <br />Apache Rocks and Box Canyon Mining Areas -The longwall mining method will be utilized in the <br />Apache Rocks and the Box Canyon mining azeas. The panel design will be similar to the current <br />West Elk Mine longwall panels. An average of 12 feet of coal will be extracted from the B Seam in <br />both azeas and an average of 11 feet will be extracted from the E Seam in the western panels of the <br />Apache Rocks mining azea. The E Seam is not planned to be mined in the Box Canyon permit <br />revision azea. In the Apache Rocks mining area, E Seam mining is planned to occur in Sections 28, <br />29, and 30. Top coal and bottom coal may be left in place in these azeas to improve roof and floor <br />• stability. <br />In the Apache Rocks mining azea the three eastern panels aze designed to be 8,500 to 8,800 feet <br />long; the three western panels will trend east-west and range from 10,600 to 12,700 feet in length. <br />As currently planned, the four eastern panels aze projected to trend N80°W and be 950 feet wide. E <br />and B Seam mining gate road entries and longwall panels aze currently planned to be vertically <br />superimposed in the western panels. In the Box Canyon mining azea, the panels currently planned <br />trend about N80°W, are 1,100 feet wide, and range in length from 6,250 to 7,900 feet. The panel <br />layouts for the Apache Rocks and the Box Canyon mining azeas are shown on Map 51 (E Seam) <br />and Map 52 (B Seam). The NE longwall panels include two north-south oriented panels. Both <br />panels aze 950 feet in width. The eastern panel (LONE) is 3,325 feet in length while the western <br />panel (11NE) is 3,625 feet in length. <br />Gateroad development typically entails development of three entries leaving two rows of chain <br />pillars; one row a rigid pillar design and one row a yielding pillar design. Chain pillars (headgate <br />and tailgate entries) aze currently planned to include one row of rigid pillazs approximately 100 feet <br />wide by 130 feet long (120 x 150 foot centers and one row of yielding pillazs approximately 40 feet <br />wide by 130 feet long (50 x 150 foot centers). These planned mine and pillaz designs are subject to <br />change pending geotechnical analysis and mining experience from the new areas. Panel lengths and <br />widths will be maximized as possible. Additionally, the deeper cover in the Apache Rocks and the <br />Box Canyon mining azeas may require design alterations to gate roads, pillaz sizes and barrier pillars <br />as well. <br />• <br />2.05-I05 Revised November 2004 PRIO <br />