2009-09-21_PERMIT FILE - C1981010A (46)

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• Flintlock Pit Mining Area The Baby Doe and Queen Anne draglines have been the primary stripping machines for this area. Located in the East Pyeatt drainage, mining in these F-pit dip line cuts will advance to the east for the 2008-2012 permit term. Refer to the M10 series maps for a yearly detail of the mining and reclamation sequences for the 2008-2012 permit term. Kimber Pit Mining Area The October 2006 landslide in the East Panel of Trapper Mine has resulted in a dramatic change in planned mining methods at Trapper Mine. The K Pit and L Pit (f.k.a. G Pit) were originally planned as dragline pits, consistent with Trapper's historic mining method. This pit layout is depicted on the M4 LOM Map submitted and approved in PR-5. After extensive geotechnical study and mine planning efforts, it has been determined that dragline mining is not a viable mining method for the K Pit due to the steeply dipping structure. i After the East Panel landslide, Trapper retained Agapito Associates, Inc. (AAI) to perform geotechnical investigation of the area to determine the causes and ramifications of the event. Numerous studies and evaluations were performed by AAI personnel. A detailed analysis of AAI's findings is available in AAI's January 2008 report, "Trapper G-Pit Landslide Mining Assessment" found in Appendix T. The K Pit mining is now planned as a truck/loader operation. This method was selected as the safest mining method and allows Trapper to recover coal resources in the affected area that would otherwise be lost. Reserve estimates show approximately 8.6 million tons of recoverable coal in K Pit. Blocks B and C of K Pit must be excavated to allow access to an additional 4.0 million tons in L Pd. Though this method is a more expensive mining method, and requires a large capital purchase, it is the preferred mining method for K Pit. This will result in a reclaimed landform that meets the requirements of Approximate Original • Contours, and provides for long-term stability. The general mine plan for the K Pit is to open the upper elevation of the mine area (designated as K Ridge Pit) with a dragline. The slide plane has been determined to be a mudstone layer in the L seam roof. The dragline bench for this pit will be below the subcrop of this seam, allowing the dragline to work from a stable surface that is outside of the area affected by the slide. Dragline spoil will be cast into the area of the Horse Gulch Fill. The truck/loader fleet will then open the B Blocks of the K Pit Due to the steeply dipping pit floors, overburden removed by this fleet will be placed in permanent fills, either the K Pit Buttress, or the Horse Gulch Fill. The B Block is, for all intents and purposes, a boxcut to open the pit for mining. To minim0 th e chance of a spoil er me slide origeinating updip of the active mining operation, a slide th at could have the potential to n and quipment the K Pit Buttress and endang Hors e Gulch Fill are necessary . Upon completion of th e B Bkx3c, the fleet will move to the C Bkx*. Some of this material will be placed in th e Horse Guch Fill; th e majority will be used to backfill B Bkxic. This backfill will be placed to grade, as depicted on Sheet 3 of the M12 map. L Pit (f.k.a. G Pit) Mining Area L pit has been developed as a strikeline and dipline dragline pit over the years. L pit currently occupies the eastern portion of the east panel landslide mass. Development of this pit will occur after the completion of K pit stripping and will utilize a combination of truck and loader stripping and dragline stripping. Development of L pit will occur early in the next permit term. It is necessary to develop blocks B and C of K pit before reserves in L pit can be recovered. Mining in Hawken pit (H-pit) was completed in April 1997. After performing reclamation activities, the • Queen Anne dragline walked to Ashmore pit in May 1997. Revision: Pp,-I° 1) -Al 3-15a '7(2( 0 Approved: