Laserfiche WebLink
Substation 3 Channels <br />SS-1, SS-2, SS-3, & SS-4 <br />Temporary Post Mine Channels <br />T-1, T-2, T-3 (temporary) <br />Permanent Post Mine Channel <br />Lower and Upper Refuse <br />Elk Creek Postmine Channel <br />Bear Creek Main Postmine Channel <br />Bear Creek Side Postmine Channel <br />All diversion ditches are designed to safely pass the peak flow from the 10-year, 24-hour storm event. Calculations <br />for the Bear Creek Steep Channel (BCCD-2) were evaluated using a conservative design flow of 2.0 cfs. The Elk <br />Creek postmine channel, Bear Creek Main postmine channel, and Bear Creek Side postmine channel are designed <br />to safely pass the peak flow from the 100-year, 24-hour storm event. All hydrologic and hydraulic inputs and <br />results are shown on the SEDCAD computer printouts in Sections 9 and 10. The locations of the ditches are <br />shown on Maps 2.05-M4, Drainage and Sediment Control Plan, and 2.05-M5 Postmining Topography. <br />The 100-year, 24-hour peak flow for Elk Creek is 107.Ocfs (using a conservative CN of GO). The 100-yr, 24-hr peak <br />flow for Bear Creek is 155.0 cfs (using a CN of 57). The methodology and assumptions used to determine the peak <br />flow are included in previously approved submittals (refer to Section 2). The existing, proposed, and postmine <br />channel profiles for Elk Creek are shown on the Elk Creek Profiles (Map 2.05-M7). Furthermore, the postmine <br />channel profiles for Bear Creek are shown on the Bear Creek Profiles (Map 2.05-M6) <br />A berm will be constructed to separate Ditches D3 and D4 and to separate Ditches DS and D1. The height of the <br />berm will be at least 1 foot higher than the high flow mark of the ditches. A summary of channel inputs and results <br />are 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 typical locations are shown on Map <br />2.05-M4. Small area exclusions for the Bear Creek fan site are identified on Map 2.05-E1-BCA2. <br />Designs for HCD-1, 1-iCD-2, and I-ICD-4 are shown on Map 2.05-MSJ. <br />Designs for BCCD-1 and BCCD-2 are shown on Map 2.05-E1-BCA2. <br />Designs for BCPCD-M andBCPCD-S are shown on Map 2.05-IvI6. <br />