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Section 2 <br />Drainage ControtDesign <br />100-vear Peak Discharges for the Van 4 <br />Area rCalculated Increased by SE <br />29 <br />49 <br />2 4.i6 u.UUfO? 1.61 <br />s 030 0.00109 0.90 <br />2.4 Surface Water Control Structure Design <br />CDM designed one diversion channel to route offsite surface water runoff from Basin <br />1 around the surface mine facilities to the existing drainage located on the north side <br />of the Van 4 Mine. Storm water runoff from Basin 2 will be captured and retained by <br />an earthen berm along the crest of the DRA. Storm water runoff from Basin 3 will also <br />be captured and retained by an earthen berm along the toe of the DRA. <br />2.4.1 Channel Design <br />A. diversion channel was designed to convey the 100-year peak discharge from Basin 1 <br />to the existing drainage (refer to Exhibits A and B). CDM used the following <br />equations to calculate the flow velocity and depth in the diversion channel. Input <br />values (listed in Table 2-2) into the equations include 100-year peak discharge, cross <br />section geometry (triangular), slope, and Manning's n value. <br />Q=VA <br />A = (b + zh)h <br />2/3 <br />V= 1.49 (b+zh)h St/2 <br />n b+2h 1+z2 <br />where: <br />Q = discharge in cfs <br />V = velocity in ft/sec <br />z: 1 = side slope <br />A = flow area in ft2 <br />b = bottom width of the cross section in ft <br />h = flow depth in ft <br />S = channel slope in ft/ ft <br />n = Manning's roughness coefficient <br />2-2 In ut Values for Diversion t,nannai ,.a b <br />100-yr Q S z <br />rfIM n ft/ft fi <br />0146 <br />2-2 <br />cm <br />T:W4986Denison Mines%Task Order 1 - Sunday Mines Drainage SWdyWan 4 Mine Drainage SiudykReportWan4 Mine Drainage Report_final.d-