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• RANGER. This range diagram was the basis for future volume calculations. A pic width of <br />110 feet was used for all pit areas. <br />Postmine slopes were then superimposed on the diagrams. For the sake of continuity, it <br />was estimated that all spoil would be graded towards the open pit at SH:lV slopes. All <br />highwall slopes would be reduced to SH:lV. This produced a final topography that could <br />not only be revegetated, but would also allow drainage to flow through [he pit area <br />without impounding water. It was also assumed that in all cases there would be tour <br />standing spoils behind the open pit. This is a very conservative estimate because, in <br />most cases, reclamation grading is current to within two spoil piles. <br />A digitizer was used to balance the cut and fill volumes of material needed to create the <br />above-described topography. A swell factor of 15.3 percent was utilized based on studies <br />discussed in Chapter 20 for the bonding estimate. The two adjacent spoils would be dozed <br />into the open pit and the two back (furthest from the pitl spoils would be graded into the <br />adjacent v's created by the spoil (see appropriate worksheets in Attachment 25-1). <br />• Highwalls will be reduced and sloped towards the open pit. This would be accomplished by <br />drilling and shooting the highwall (see worksheets) and then dozing/ripping the blasted <br />material into the open pi[. See appropriate worksheets in Attachment 25-1 for a complete <br />listing of volumes to be dozed into the open pit. <br />A Caterpillar computer prop [am called EMF was used to determine dozer production. This <br />program utilizes information given in the Caterpillar Handbook. All Cables and charts <br />have been computerized to simulate production for track type equipment. See various <br />worksheets for production and costs. <br />The premin ing and postmin ing topography maps were compared for material movement. <br />Although a specific postmine topography map is not available for a 2007 mine closure, <br />drainage patterns will generally remain the same as the planned final topography. Due to <br />the Eact that the topographic highs and lows will generally be located in the same area <br />after mining as they were prior to mining, it is not anticipated [hat wheel type <br />ear[hmovexs will be needed to backf ill the final pit. <br />• <br />3 Revised 3/01 <br />