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RULE 2 PERMITS <br />The temporary overburden stockpile that is to be built will be placed in a stable location that will not <br />exceed a 33 percent slope to ensure stability. The spoil suitability and special handling procedures are <br />described in detail in section 2.05.3(1) of the Collom permit revision. The initial development of the <br />stockpile is anticipated to begin during the year 2012 with the excavation of the initial box cuts and <br />continue over the next five years of operation. Following this period mine pit advancement will allow for <br />placement of mined spoil into the original box cut area. <br />The temporary spoil pile will be used to fill and recontour the final pit sequence in the final two years of <br />mining activities (See Map 29C — Temporary Spoil Pile Design). Out of pit stored spoils will be used in <br />the construction of the post mine topography. Approximately 250 million cubic yards of storage capacity <br />for the temporary spoil stockpile will be needed. <br />The toe of the fill will be placed near the floor of the X4 coal seam and the stockpile will eventually <br />extend upward about 775 feet in thickness to an elevation of 7675. The stockpile will remain in place <br />until the last few years of mining and will have a life of about 15 -20 years depending on production rates. <br />Construction of the stockpile is expected to take about 7 to 10 years. As such, the lower portions of the <br />stockpile will be completed and stabilized before the top is completed. To ensure that a phreatic water <br />surface does not develop during the life of the stockpile, a rock drain will be installed at the base of the <br />fill along its entire length. The spoilpile will be confined by the valley slopes on both sides. Volume 20, <br />Exhibit 23, Item 1 provides the geotechnical report for the temporary spoil pile. <br />The temporary overburden stockpile will be constructed in 50 to 100 foot lifts by use of trucks, dozers <br />and loaders. Initially, each lift will be dumped at angle of repose and then subsequently dozed down to an <br />overall slope of less than 3H:1 V. The side slope of the active dump will not exceed a 33 percent overall <br />slope and will be maintained during active times of operation (See Map 29C — Temporary Spoil Pile <br />Design). Maintenance techniques will consist of blading of roads and ramps, along with the use of dust <br />control during active times of operation. During construction a dozer will be used develop and spread the <br />end -dumps created by the trucks, this will be the primary method used to build the temporary overburden <br />stockpile. Sediment control will be implemented to ensure adequate containment of potential runoff <br />throughout the life of the operation. Temporary seeding via the broadcast method may be employed <br />during inactive times of operations on the temporary stockpile to reduce the erosion potential utilizing the <br />following seed mix: <br />Western wheatgrass @ 4 lbs PLS /Acre <br />Mountain Brome @ 4 lbs PLS /Acre <br />Kentucky Bluegrass @ 2 lbs PLS /Acre <br />Sanfoin @ 2 lbs PLS /Acre <br />Total 12 lbs PLS /Acre <br />Following the completion of mining, this temporary overburden stockpile will be removed and placed <br />back into the open pit. The area that was disturbed in conjunction with this stockpile will be reclaimed in <br />accordance the procedures outlined in the reclamation plan. <br />2.05.3 (7) Coal Handling Structures <br />Please Refer to Volume 1, Section 2.05, Coal Handling Structures and Map 22B. <br />2.05.3 (8) Coal Mine Waste and Non -Coal Processing Waste <br />Not applicable. Colowyo uses dry crushing facility for coal preparation, no coal processing waste, as <br />defined in Rule 1.04 "Definitions ", is produced from any part of the mining operations. <br />Collom — Rule 2, Page 103 Revision Date: 9/28/11 <br />Revision No.: PR -03 <br />