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RULE 4 PERFORMANCE STANDARDS <br /> <br />Rule 4 Performance Standards 4-36 Revision Date: 4/9/25 <br /> Revision No.: MR-261 <br />Colowyo will rough backfill and grade as shown on the Spoil Grading Map (Map 29) by <br />methodically and actively dumping and backfilling overburden in the West and East pits very close <br />to final contour so that minimal work will be needed to complete final re-grade of these areas in <br />the future. All disturbed areas will be returned to the approximate original contour by grading and <br />backfilling with the use of a dragline, trucks, dozers, scrapers and dozers assisting a dragline. <br />Additional detail of the backfilling and grading for the mining operation is set forth in the <br />discussion under Sections 2.05.3 and 2.05.4. <br /> <br />The area to be mined will be restored to a topography approximating premining grades. The <br />outslopes of the completed fill in Streeter Draw and areas backfilled, as necessary, will utilize <br />terraces and/or contour furrows for erosion control and stability. These terraces and contour <br />furrows will be constructed according to the requirements outlined in Section 2.06.2. Where <br />applicable, Colowyo will retain all overburden and spoil on the solid portion of existing benches. <br />The final graded slopes will not exceed the approximate original premining slope grade as shown <br />on the Postmining Topography Map (Map 19). Postmining surface drainage channels will be <br />located to minimize erosion and to minimize slippage. <br /> <br />The final pit highwalls will be eliminated in Section 16 by backfilling X seam overburden materials <br />from the West Pit mining area to achieve the final topography. Rehandle of the X seam overburden <br />will be occur concurrently with the advance of the multiple-seam advance during the 2003-2010 <br />period. Also, as mining advances into the final pit, the working area on the pit spoil side will <br />decrease to a point where insufficient spoil room below the proposed postmining contours is <br />available. When that point is reached, material will be temporarily placed above the proposed <br />postmining topography. When the final pass of the West Pit is mined out, this temporarily-placed <br />spoil will be rehandled concurrently with Section 16 virgin and rehandle material to fill and slope <br />the pit to the configuration shown on Map 19 (Postmining Topography). Because the area will be <br />redisturbed by the rehandle activities, that portion of the north end of Section 16 that is above final <br />grade will not be topsoiled or otherwise reclaimed until final reclamation. <br /> <br />Final reclamation of the East Pit will take place via the sequence shown on Map 29 (Spoil Grading <br />– South Area) with the reclamation blocks advancing from east to west or from the topographic <br />bottom to the topographic top of the mining areas. Just as in the West Pit, all disturbed areas will <br />be returned to approximate original contour by grading and backfilling with the use of draglines, <br />trucks, dozers, scrapers and dozers assisting a dragline. As reclamation of the East Pit progresses, <br />all non-reclaimed areas will be contained so that any residual runoff from these areas will be <br />isolated within the remainder of the East Pit. All methods of erosion control and stability such as <br />contour ditches, contour furrows, internal ditches and internal sumps will be established on an as- <br />needed basis to ensure the integrity of the Prospect Pond and the surrounding areas include the <br />final East Pit Ditch. Closure of the East Pit is dependent on the final reclamation and closure of <br />the West Pit as the western most portion of the East Pit will tie-in with the West Pit in this area. <br /> <br />A haul road corridor from the Administration/Shop area to the South Taylor Pit will remain in <br />place until final reclamation is completed in that area. The corridor is sufficient in width to provide <br />a material balance as the corridor is regraded to the post mine topography. The <br />administration/shop/facilities area will be the last area to be reclaimed. A light duty road intended <br />for post mining use may be left as a postmining feature in this corridor with land owner consent.