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In the event the highwall proves to be unstable over the entries, steel arches, mats, and/or concrete will be installed to stabilize the area. The entries will be driven from the Main North workings, and approximately 13,000 tons of coal will be mined during the development of these entries. The entries will be approximately 900 feet in length. • The location of the entries is shown on Map 23. When the eritries are no longer needed, they will be sealed per the procedure outlined on page 2.05-119, with the approved typical seal is shown on Figure 15. After construction of the seals is completed, the site will be backfilled in accordance with the approved plan. No additional work, except for. seal construction, will bG required as a result of developing the eastern portals. Minine Method _The mining method planned for the Foidel Creek Mine is a combined system of room and ~tillaz and longwall mining. Both mining methods aze successfully used in western U.S. coal operations having similar mining conditions. Room and Pillar Mining Room and pillar mining refers to the extraction of rooms (mine openings) and pillars using a continuous mining machine. Rooms aze mined on development and the pillazs aze extracted during retreat. This mining method has been the backbone of the U.S. coal mining industry, and it owes its popularity to its relatively low cost and flexibility. This method easily adapts to changes in the geological and physical conditions of the mine. Continuous miners can negotiate tectonically disturbed areas of the mine and adapt to seam variations and uneven reserve blocks. The continuous miner sections equipment can easily be transported to different locations in the mine, and total production is only proportionately affected by stoppages of any one unit. The productivity of a continuous miner unit in room and pillar extraction is less than longwall mining, under most • conditions, and thus more expensive in operating cost per ton. The overall coal recovery seldom exceeds 55 to 60 percent, due to the necessity to leave barriers and pillaz stumps. Lonewall Minine Longwal] mining has gained great acceptance and is increasing in popularity in the U.S., primarily because of its inherent advantages for high productivity, low operating cost, high reserve recovery, and high safety record. Longwall mining derives its name from the several hundred-foot long faces from which coal is cut. Longwall panels aze huge, solid blocks of coal laid out several thousands of feet long by several hundreds of feet wide. Extraction is by a powerful cutting machine with rotary drums which cut slices of coal from the block. All work takes place under a canopy of hydraulic steel supports. The roof supports aze placed in a straight line with skin to skin contact separating the work azea from the cave. The cutting step is followed by advance of the steel supports in a continuous cycle of operation. Longwall mining achieves upwazd of 75 percent recovery, because the entire seam is extracted in major blocks. TCC stresses the importance of maximizing resource recovery. Geologic and mineability evaluations indicate that the Foidel Creek Mine reserve has coal seam and overburden conditions and configuration suitable for this superior mining technology. Longwall mining also has a superior record of safety. Production The annual amount of production will be dictated by market demand and as such, is subject to yearly adjustments. Table 46, Production Schedule, shows current estimated annual production for the life of the operation. Production began in 1983 with 21,500 tons mined. Production has increased over the years to current levels. Full production is projected to be reached in 2008 at a peak of approximately 12,000,000 tons per year. Between now and the end of the mine life, production will be maintained at a maximum actual annual production dictated by market . conditions. PR06-07 2.05-9 11/07/06