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• Highwalls will be reduced and sloped towards the open pit. This would be accomplished by drilling and <br />shooting the highwall (see worksheets) and then dozing/ripping the blasted material into the open pit. See <br />appropriate worksheets in Attachment 25-1 for a complete listing of volumes to be dazed into the open pit. <br />A Caterpillar computer program called EMF was used to determine dozer production. This program utilizes <br />information given in the Caterpillar Handbook. All tables and charts have been computerized to simulate <br />production for track type equipment. See various worksheets for production and costs. <br />The premining and postmining topography maps were compared for material movement. Although a specific <br />postmine topography map is not available fora 2005 mine closure, drainage patterns will generally remain <br />the same as the planned final Topography. Due to the fact that the topographic highs and lows will generally <br />be located in the same area after mining as they were prior to mining, it is not anticipated that wheel type <br />earthmovers will be needed to backfill the final pit. <br />No box cut spoil grading is included in this estimate. The timing and location of the box pit spoil is such that <br />all box pit spoil will be reclaimed by the end of 2005, and therefore, was not included as a liability in the <br />"worst case" year. <br />Ramp grading estimates are included with spoil grading. It was assumed that ramps would be graded at the <br />• same time as two spoils are pushed into the pit and, therefore, additional cost is not estimated for this <br />project. <br />Currently, the Division determines the worst-case condition and uses the CIRCES Cost Estimating <br />Software to estimate liability costs. <br />Toosoil Replacement. Topsoil replacement volumes were based on the volume of material in stockpiles at <br />the end of year 2005. The estimated volume in each stockpile was based on topsoil salvage depth per soil <br />type over a particular area (acres). In an effort to arrive at realistic stockpile volumes, topsoil densities were <br />measured in the field. The material density, as measured in the stockpile, was 2518 LBS/CCY. According <br />to Caterpillar, the swell factor far this type of topsoil would be around 35 percent from BCY to LCY. <br />Assuming this material was compacted to 90 percent of its original density, the original density would have <br />been 2518 LBS/CCY divided by .90 = 2800 LBS/BCY. To arrive at the LCY density, take 2800 LBS/BCY <br />divided by 1.35 = 2075 LBS/LCY. Alf tables and calculations are based on these densities. <br />Revepetation <br />After the topsoil has been replaced from stockpiles, the seedbed must be prepared prior to seeding. This is <br />accomplished by ripping and disking the seedbed. Seeding is principally accomplished using a Rangeland <br />• drill. It was assumed that 10 percent of the area would have to be mulched. Shrub and trees are also <br />planted in designated areas in the reclamation and reflected in the costs as shown here. All costs, including <br />fencing, are shown on appropriate worksheets. Areas to be revegetated are shown on the worksheets. A <br />PR04 3 Revised 09/04 <br />