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JD -6 Mine - Drainage Design Plan 38 <br />Results indicate that the existing MDS, LDS -E, and LDS -N diversion structures are capable of conveying <br />the 100 -year 24 -hour storm with an average velocity of less than the design criteria of 7 ft/sec. The average <br />calculated velocity for the MDS, LDS -E, and LDS -N profiles was 3.20 ft/sec and the maximum calculated <br />velocity was 5.79 ft /sec (Table 20). <br />As currently constructed, the UDS is incapable of conveying the 100 -year 24 -hour storm with an average <br />velocity of less than 7 ft/sec. The calculated flow velocities, based on local bed slopes and an assumed D84 <br />grain size of 25 mm, range from 7.4 to 16.3 ft/sec (Table 21). A stability analysis was conducted to <br />determine the D84 grain size necessary to impede flow velocities and prevent scour, based on the existing <br />channel geometries (side slope ratio and bed slope). The required rock size would range from 127 to 330 <br />mm (5 to 13 inches) for the surveyed segments, based on the existing channel slopes (Table 21). <br />The UDS channel has been redesigned with shallower side slopes (3:1), a shallower local bed slope, and six <br />check/drop structures to dissipate grade and energy. The allowable bed slope for the D84 grain size of 25 <br />mm is 0.035 ft/ft. This slope will be graded into native material between the drop structures, as shown in <br />Plate 3. The drop structures will be constructed with 4:1 bed slopes and will be constructed with a 2 -ft <br />vertical drop (DS -1, DS -2) or a 3.5 -ft vertical drop (DS -3, DS -4, DS -5, and DS -6) over a span of 8 to 14 <br />feet. Channel scour analysis, based on the Thorne and Zevenbergen (1985) resistance equations, indicates <br />that a D84 grain size of 406 mm (16 inches) would be required to keep flow velocities below 7 ft/sec during <br />peak flows of the 100 -yr 24 -hr storm. The planned channel design is shown in Plate 3 and the calculated <br />flow velocities, channel stage, and shear stress are summarized in Table 21. <br />Table 21. Stage, Velocity, and Shear Stress for 100 -year Peak Flow for the Existing and <br />Planned UDS <br />4148A.131028 Whetstone Associates <br />Q100 <br />D84 <br />Stage <br />Area <br />Perimeter <br />Width <br />R <br />Hydraulic <br />Slope <br />n <br />Vavg <br />Q <br />Shear <br />Froude <br />Structuren <br />Radius <br />(cfs) <br />(mm) <br />(ft) <br />(sq ft) <br />(ft) <br />(ft) <br />(ft) <br />(ft) <br />(fvft) <br />(ft/s) <br />(cfs) <br />(psf) <br />UDS -Pl <br />62.40 <br />25 <br />0.7 <br />538 <br />11.54 <br />11 32 <br />047 <br />0.47 <br />0.1008 <br />0 031 <br />9.06 <br />48.69 <br />2.93 <br />2.3157 <br />08 <br />6.54 <br />12.16 <br />119 <br />0.54 <br />055 <br />01008 <br />0.031 <br />10.18 <br />6657 <br />3.38 <br />2.4210 <br />UDS -P2 <br />6240 <br />25 <br />1 1 <br />7.08 <br />11.9 <br />1143 <br />0.6 <br />062 <br />00434 <br />0.03 <br />741 <br />5243 <br />1.61 <br />1.6586 <br />1.2 <br />825 <br />12.5 <br />12 <br />066 <br />0.69 <br />00434 <br />0.029 <br />8.03 <br />66.25 <br />179 <br />1 7063 <br />UDS -P3 <br />6240 <br />25 <br />1.4 <br />6.4 <br />7.99 <br />7.31 <br />08 <br />088 <br />00375 <br />0 029 <br />866 <br />55.46 <br />1.88 <br />16302 <br />1.5 <br />7.16 <br />859 <br />7.86 <br />083 <br />0.91 <br />0.0375 <br />0 029 <br />895 <br />64.13 <br />1.95 <br />1 6530 <br />UDS -P4 <br />6240 <br />25 <br />1.3 <br />5.18 <br />6.66 <br />576 <br />0.78 <br />0.90 <br />00666 <br />0.029 <br />11.22 <br />58.12 <br />3.23 <br />20853 <br />14 <br />5.76 <br />6.92 <br />59 <br />0.83 <br />0.98 <br />00666 <br />0.029 <br />11.85 <br />6825 <br />3.46 <br />2.1129 <br />UDS -P5 <br />62.40 <br />25 <br />1.1 <br />4.43 <br />627 <br />5.55 <br />0.71 <br />080 <br />0.1027 <br />0 029 <br />12.85 <br />5692 <br />4.53 <br />2.5341 <br />12 <br />5.00 <br />6.58 <br />5.78 <br />076 <br />086 <br />0.1027 <br />0 029 <br />1362 <br />68.07 <br />4.87 <br />2.5817 <br />UDS -P6 <br />62.40 <br />25 <br />1.9 <br />5 12 <br />6.11 <br />4.67 <br />084 <br />1 10 <br />00633 <br />0.028 <br />11.91 <br />61 <br />3.31 <br />20053 <br />20 <br />5.60 <br />638 <br />4.86 <br />0.88 <br />1 15 <br />00633 <br />0 028 <br />12.34 <br />6907 <br />346 <br />2.0253 <br />UDS -P7 <br />62.40 <br />25 <br />1 5 <br />4.30 <br />571 <br />4.71 <br />0.75 <br />0.91 <br />0.1003 <br />0.029 <br />1365 <br />5868 <br />471 <br />15155 <br />1.6 <br />4.78 <br />602 <br />4.94 <br />0.79 <br />097 <br />0.1003 <br />0 028 <br />1424 <br />68 11 <br />4.97 <br />2.5505 <br />UDS -P8 <br />62.40 <br />25 <br />14 <br />352 <br />502 <br />3.88 <br />07 <br />0.91 <br />0.1458 <br />0 029 <br />15.57 <br />54.78 <br />6.38 <br />2.8807 <br />1 5 <br />3.91 <br />5.28 <br />4.06 <br />0.74 <br />097 <br />0.1458 <br />0.029 <br />16.27 <br />6371 <br />674 <br />2.9186 <br />UDS -Pl <br />6240 <br />127 <br />1.0 <br />9.03 <br />1339 <br />1306 <br />067 <br />069 <br />0.1008 <br />0.057 <br />635 <br />5739 <br />4.24 <br />1.1 <br />1037 <br />13.99 <br />13.62 <br />0.74 <br />0.76 <br />0.1008 <br />0 055 <br />702 <br />72.75 <br />466 <br />UDS -P2 <br />62.40 <br />127 <br />1.4 <br />1076 <br />13.72 <br />13.13 <br />0.78 <br />0.82 <br />00434 <br />0 052 <br />503 <br />54.15 <br />2 13 <br />1 5 <br />12.11 <br />1462 <br />14 <br />083 <br />087 <br />0.0434 <br />0 051 <br />532 <br />64.47 <br />224 <br />UDS -P3 <br />62.40 <br />127 <br />1 8 <br />977 <br />10.38 <br />9.52 <br />094 <br />103 <br />0.0375 <br />0.049 <br />565 <br />55.18 <br />2.2 <br />1.9 <br />10.75 <br />1098 <br />1008 <br />0.98 <br />1.07 <br />00375 <br />0.048 <br />5.88 <br />63 19 <br />2.29 <br />UDS -P4 <br />62.40 <br />203 <br />1.9 <br />8.89 <br />821 <br />6.63 <br />108 <br />1.34 <br />0.0666 <br />006 <br />676 <br />60.1 <br />45 <br />2.0 <br />956 <br />8.46 <br />677 <br />1.13 <br />1.41 <br />0.0666 <br />0 059 <br />7.07 <br />6762 <br />47 <br />UDS -P5 <br />6240 <br />279 <br />1.8 <br />879 <br />8 17 <br />6.81 <br />1.08 <br />1.29 <br />0.1027 <br />0 074 <br />6.8 <br />59.72 <br />689 <br />1.9 <br />948 <br />8.45 <br />7 <br />1 12 <br />1.35 <br />0.1027 <br />0 072 <br />7.15 <br />67.77 <br />7 18 <br />UDS -P6 <br />62.40 <br />254 <br />2.7 <br />9.45 <br />8.3 <br />6.14 <br />1.14 <br />1.54 <br />0.0633 <br />0 063 <br />6.46 <br />61.02 <br />4.5 <br />28 <br />10.07 <br />8.57 <br />633 <br />1.18 <br />1.59 <br />00633 <br />0.062 <br />6.69 <br />6733 <br />4.64 <br />UDS -P7 <br />62.40 <br />330 <br />2 3 <br />8.77 <br />79 <br />606 <br />1.11 <br />1.45 <br />0 105 <br />0.078 <br />666 <br />5843 <br />7.28 <br />2.4 <br />939 <br />8.14 <br />619 <br />1.15 <br />1.52 <br />0 105 <br />0.076 <br />6.97 <br />6542 <br />7.55 <br />4148A.131028 Whetstone Associates <br />