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RULE 4 PERFORMANCE STANDARDS <br /> In those areas where topsoil is stripped and hauled directly back to contoured backfill, some of the <br /> established native species can be expected to occur in the revegetated area. <br /> Stockpiled topsoil will not be moved when required for redistribution on disturbed areas prior to <br /> seeding. An exception to this can occur to facilitate mining, construction of sediment control <br /> ditches, ponds, etc. Approval from the Division will occur prior to moving stockpiled topsoil for <br /> purposes other than seedbed preparation. <br /> All topsoil stockpiles should be protected with a ditch and berm around their perimeter to conserve <br /> the resource. <br /> 4.06.4 Redistribution <br /> After the final grading is completed, the topsoil will be reapplied as shown on the disturbed land <br /> areas shown on the Topsoil Handling Map(Map 28 and 28A). Please see section 2.05.4 for topsoil <br /> redistribution depth replacement. <br /> Where necessary, to prevent slippage surfaces and promote root penetration the spoil will be <br /> scarified by ripping and/or rough grading. This practice will assure a solid bond between the spoil <br /> and reapplied topsoil. To date, there is no evidence of topsoil slippage on reclaimed areas. A few <br /> small tension cracks resulting from settling of fill and topsoil have occurred in a few areas within <br /> a year or two after reclamation, but soon stabilize and begin to fill in. <br /> Since all available topsoil existing on areas to be disturbed will be removed and reapplied, it will <br /> be fully capable of supporting growth necessary for the proposed post-mining land use. <br /> Compaction will be alleviated through chisel plowing. The method of topsoil replacement most <br /> often used at Colowyo, which makes use of dozers, leaves the surface in a rough condition which <br /> minimizes wind and water erosion. The use of a chisel plow following topsoil replacement and the <br /> construction of contour furrows at the time of seeding or before will also aid in erosion control. <br /> 4.06.5 Reconditioning <br /> Topsoil quality at Colowyo is excellent in terms of providing a suitable plant growth medium <br /> capable of supporting the approved post-mining land use and the revegetation requirements of <br /> Section 4.15. Soil testing has not indicated any deficiencies. Refer to Volume 3, Exhibit 10, <br /> Establishment of Native Shrubs on Disturbed Lands in the Mountain Shrub Vegetation Type. This <br /> study was conducted on the Colowyo Mine July 1975 through December 1979. Colowyo has the <br /> option to apply 50-70 pounds of phosphorus per acre to all safely accessible reclaimed mine areas <br /> prior to chiseling and seeding. <br /> Rule 4 Performance Standards 4-23 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />