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• 70 bed slope is close to the natural channel slope in this area. In addition, this alternative has a lower velocity, and therefore, a smaller required riprap size is needed. This channel should be constructed at the design slope and have ' a riprao lined transition into the nine-foot culvert under the haul road. When the haul road and culvert are removed, the transition section to the culvert will be widened to the channel width. Maintaining the same channel slope, the lined channel will have to be extended downstream until it can make a smooth transition into the existing channel (PM-CH-10). This alignment is shown on Hydrology Nap 3, Appendix A. The results of the MULTSED model using alternative 17-D for post-mining conditions show that sediment concentrations entering and leaving PM-CH-17 to be nearly equal. L 6.4.3 Channel Restoration The channels designated for restoration include PM-CH-13, PM-CH-11, PM-CN-15, PM-CH-17, PM{f(-6, SW-11 drainage channel, and CH-8 on Newlin Creek "Prospecting Pit". Locations of all channels to be restored are shown on • Hydrology Map 3, Appendix A. The Colorado regulations require permanent 91- versions and restored stream channels to be constructed to approximate the pre- mining (i.e., before mining by G.E.C.) channel and floodplain configuration, approximate original channel pattern, maintain dynamic equilibrium, and restore natural riparian vegetation on the banks of the stream. The procedure to main- tain natural conditions on the G.E.C. permit area will be to restore disturbed drainage channels to their original shape and slope, design for the 10-year, ' 24-hour storm, design a stable channel in terms of erosion and sedimentation, 10:1 side slopes for the tloodplain, and channel protection to replace the natural brush and trees where required. All of the drainage channels can be restored back to natural conditions except PM-CH-15 and PM-CH-17. These two channels are controlled by the location and slope of the Dorchester diversion of Magpie Creek and were discussed in the previous section. The natural or premining condition (i.e., before mining by G.E.C.) of some of the drainages was greatly disturbed due to previous mining operations chat left large slag and spoils piles. Therefore, by reclaiming these areas back to natural conditions or as close to natural as is practical, G.E.C. will be leaving the area in better condition than when they started mining. • The first channel to be restored is Newlin Creek at the "Prospecting Pit". Restoration of the Newlin Creek channel is required for comp?etc reclamation of