2012-06-21_PERMIT FILE - C1981022A (3)

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Starctrs - 2.05.3 Pmduction Methods and Eauivment Somerset Mine -The Somerset Mute, which produced coal from the B and C Coal Seams, ceased production at the end of 1985. The portal to the mine has been sealed, associated facilities in the Bear and Hubbard Creek drainages have been partially or fully reclaimed, and no further rrtinirtg is currently proposed for the Somerset Mine. Areaz rained in the Somerset NLne are delineated on both the Coal Seam Isopach Maps, (Maps 2.04-M4A through 2.04-M4D), and the Mtne Plan Map, (Map 2.05-M2) Sanbom Creek Mine -Underground mining is ongoing at the Sanbom Creek Mute in the B Seam, with mining up through the first part of 1998 using room and pillar mining techniques, shifting to longwall mining in August 1998. For those portions of the Sanbom Creek Mme where room and pillar methods were used, development mining was generally limited to the upper 8 to 10 feet of the seam Rooms and pillars were developed doting mining advance. Using room and pillar methods, coal was cut and loaded from [he working face by continuous miners into shuttle cars that transported the coal to the conveyor belt loading point. Mme conveyor bela then transported the coal to the surface and the Sanbom Creek Mute overland conveyor transferred the coal from the mine porcals to either the East Yard or Elk Creek coal stockpiles. Once thine sections reached the operational or economic mining limit, retreat miming was conducted to attain the maximum recovery possible consistent with the safety and protection of mine personnel and equipment and effective caving of the mined-out areas. In the B Seam, 4 to 6 feet of bottom coal was mined during mining retreat, with the objective of extracting the upper 12 to 14 feet of the seam, and support pillars were partially extracted by taking multiple cuts from the sides of the pillars. The Sanbom Creek Mtne reserve area was entered at the outcrop of the C Seam Three entries were used to access the reserve. The mine was expanded to five entries az soon az mining and physical conditions allowed. The mine was initially developed with twent}xfoot wide by 7.5 to 8-feet high • entries driven on 70-foot centers each way As mining and ground conditions changed this spacmg waz adjusted. Crosscut spacing ranged from a rt,~.,~rt„~rt, of 50-feet to a m~~mum of 150-feet. Entry spacing ranged from a minimum of 50-feet to a maximum of 100-feet. Initial entry to the reserve area was complicated by old workings to the northwest of the new entries. The new entries were developed at least 100-feet from the old works. Probe drilling was conducted to assure that the old works were not accidentally intercepted during mine development. The initial development on the C Seam consisted of five entries extending about 1,000-feet to the northeast, where the mains were tamed to the southeazt. About 250-feet after the tttm to the southeast, 6 to 9-feet high by 16 to 18-feet wide rock declines were developed to access the B Seam The intake entry was developed on a 15 to 18 percent slope and the belt-line and return entries were developed on a 25 percent slope. The rock tunnels were developed ruing conventional drilling and blasting cechniques. Development material excavated from the rock tunnels a classified az mine development waste and was placed underground. Coaly materials excavated during mine development were transported to the surface and placed in the existing Eazt Yana coal refuse disposal area. During 1995, a rock incline was developed from the C Seam to the surface to provide an additional air intake. The 10-foot high by 20-foot wide opening was excavated from the mine to the surface. All construction work was performed from the mine workings, therefore, no surface disturbance occurred. The rock from the development work was disposed of undergrotmd. The new mine opening is located above and west of the existing Sanbom Creek Mute portak. During development of the rock tunnek, mining continued in the C Seam After the rock tunnels • were complete, mining proceeded concurrently in both seams until January 1993 when the C Seam workings were idled due to market conditions and ground control concerns. Muting conditions in the C Seam are considered average although marginal roof conditions pose some unique problerru. As rrtining advanced in the C Seam, the roof conditions deteriorated. The weak roof caused; 1) Safety concerns; 2) Production to decrease; and 3) Coal quality to deteriorate. Market conditions would PR04 2.05-4 Revised August 2000