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• Postmine slopes were then superimposed on the diagrams. For [he sake of continuity, it was estimated that all spoil would be graded towards the open pit at Sh:ly slopes. All highwall slopes would be reduced to Sh:ly. This produced a final topography that could not only be revegetated, but would also allow drainage to flow through the pit area without impounding water. IC was also assumed that in all cases Chere would be tour standing spoils behind the open pit. This is a very conservative estimate because, in most cases, reclamation grading is current to within two spoil piles . A digitizer was used to balance the cut and fill volumes of material needed to create the above-described topography. A swell factor of 1~ percent was utilized for the bonding estimate. The adjacent spoil would be dozed into the open pit and the three other spoils would be graded into Che adjacent v's created by the spoil (see appropriate worksheets in Attachment 25-11. H ighwal is will be reduced and eloped [owa rds the open pit. This would be accomplished by drilling and shooting the highwall and then dozing/ripping the blasted material into the open pit. See appropriate worksheet in Attachment 25-1 for a complete listing of volumes • to be doz ed into the open pit. A Caterpillar computer program called EMF was used to determine dozer production. This program utilizes information given in the Caterpillar Handbook. All tables and charts have been computerized to simulate production for track type equipment. See various worksheets for production and costs. The premising and poatmining topography maps were compared for material movement. Although a specific postmine topography map is not available for a 2009 mine closure, drainage patterns will generally remain the same as the planned final topography. Due to the fact that the topographic highs and lows will generally be located in the same area after mining as they were prior to mining, it is not anticipated that wheel type earthmovers will be needed to backf ill the final pi[. No box cut spoil grading is included in this estimate. 7'he timing and location of the box pit spoil is such that all box pit spoil will be reclaimed by the end of 1004, and therefore, was rot included as a liability in the "worst case" year. • Ramp grading estimates are included with spoil grading. It was assumed that ramps will be graded at the same time as two spoils are pushed into she pit and, [heref ore, additional cost is not estimated for this project. 3 Revised 1'1/00