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'Cemporar}~ Post Aline Channels <br />T- 1, T-2, "1'-3 (remporary) <br />Permanent Post \-Sint Channel <br />Lo~acr and Upper Refuse <br />Elk Creek postmine Channel <br />All diversion ditches are designed to safely pass the peak flow Erom the 10-year, 24hour storm event The Elk <br />Creek postmine channel is designed to safelc pass the peak flow from the 100 }'ear, 34-hour srorm event. All <br />h7dxologic and hydraulic inputs and results are shown on the SEDCAD computer printouts in Scc[ions 9 and 10. <br />The locations of the ditches axe shown on \-taps 2.05-M4, Drainage and Sediment Control Plan, and 2.05-MS <br />Postmining Topography. <br />The 100-year, 24-hour peak flow for Elk Creek is 107.Ocfs (using a conservative CN of 60). The methodology and <br />assumptions used to determine the peak flow are included in previously approved submittals (refer to Section 2). <br />The existing, proposed, and postmine channel pro6lcs for Elk Creek are shown on the Elk Creek Profiles (~fap <br />2.05-M7). <br />A berm will be constmcted to separate Ditches D i and D4 and to separate Ditches DS and Dl. The height of the <br />berm will be at ]cast 1 foot higher than the high flow mark of the ditches. A summax}~ of channel inputs and xesults <br />axe shown on the attached Figures. <br />Channel outlets have been designed for Ditches D4, D6, and D7. A conservative design flow of 4 cfs was used in <br />the designs. Channel downdrains to Elk Creek will be armored and the designs are shown in Section 11. <br />Downdrains will be incorporated into the slope stabilization area. The downdrains will be field fitted as the slope <br />area is graded. Atypical downdrain configuration is shown in Figure 7.1 and t}~pical locations arc shown on Mnp <br />2.05-M4. <br />Designs for l-iCD-1, 1 SCD-2, and HCD-4 are shown nn Jlap 2.05-MSJ. <br />