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RULE 4 PERFORMANCE STANDARDS <br />effectiveness of sediment control structures to be constructed around several topsoil stockpiles planned <br />outside of primary sediment control may be found under Exhibit 7, Item 23, Part D. <br />4.05.4 Stream Channel Diversions (Relocation of Streams) <br />The drainage and sediment control measures described under Section 2.05.6 and presented in the Erosion <br />and Sedimentation Control Plan (Exhibit 7, Item 23) will provide for temporary diversion of surface <br />drainages within the permit area, as needed for mine operations. A system of temporary ditches will be <br />used to divert runoff from disturbed areas to sediment ponds. The natural drainage systems will be <br />restored to historic drainage patterns once diversion ditches are removed; therefore, there will be no <br />permanent diversions of these channels. <br />The only stream channel that will be impacted by the Collom Pit is the main stream of Little Collom <br />Gulch, an ephemeral stream draining less than one square mile at the upstream pit boundary. Clean water <br />diversions will be installed above the Collom Pit (Exhibit 7, Item 23, Part A) and will be removed as <br />mining progresses. It will also be channelized further downstream, alongside the haul road leading from <br />the Collom Pit to the spoil pile, where it drains greater than one square mile (Exhibit 7, Item 2, Part B). <br />4.05.5 Sediment Control Measures <br />Sediment control measures to be implemented are shown in Exhibit 7, Item 23 Erosion and Sedimentation <br />Control Plan, and postmining channels are shown on Map 41B. These facilities, consisting primarily of <br />diversion ditches and sedimentation ponds, will be located, constructed and maintained to avoid erosion <br />and increased contribution of sediment load to runoff. <br />Facilities to control sediment are typically installed in areas above and/or below the planned sites of <br />disturbance. "Upstream" facilities, such as clean water diversion ditches upslope from the mining <br />activities, serve to divert runoff away from the disturbed areas. Temporary diversion ditches below the <br />disturbed area of the pit will help collect runoff from disturbed areas and route it into the sedimentation <br />ponds. During active mining, the mining areas will aid in retaining sediment within the disturbed areas <br />by catching water in pits, small depressions and dozer basins, etc. Once reclaimed, the basins will drain <br />as they did prior to mining activities (i.e., historic drainage patterns will be re-established). <br />All temporary diversions will be removed and reclaimed when no longer needed for sediment control in <br />accordance with Rule 4.05.2(2) <br />Channel lining rock riprap and energy dissipaters will be used when necessary. As stated above, all <br />temporary diversion structures will be seeded and revegetated after removal. Colowyo does not anticipate <br />that there will be any significant excess material resulting from the construction of diversion ditches. <br />None of the proposed diversions will drain into underground mines. <br />4.05.6 Sedimentation Ponds <br />The location, design parameters, and detailed sedimentation calculations of all planned sedimentation <br />ponds are presented in Erosion and Sedimentation Control Plan (Exhibit 7, Item 23). The design plans <br />and specifications for the sedimentation ponds are described in this section (Part Q. All sedimentation <br />ponds will be located as close as practical to the areas to be disturbed. Steep terrain in the upper basins <br />precludes location of the ponds at the Collom Pit disturbance boundaries during the critical early phase of <br />operations, necessitating down -valley locations downstream of the Collom Pit and temporary spoi pile <br />Collom — Rule 4, Page 4 Revision Date: 4/18/16 <br />Revision No.: PR -04 <br />