Laserfiche WebLink
JD -6 Mine - Drainage Design Plan 18 <br />4.4 Reach Definition <br />Stormwater runoff from the sub -basins described above is routed through the site via natural channels, <br />diversion ditches, borrow ditches, and perimeter ditches. The major channels and ditches are entered as <br />reaches in the WinTR55 run -off model. The reaches are shown in Figure 4. The hydraulic parameters, <br />including length, width, slope, and Manning's n, are shown in Table 10. <br />Table 10. Reach Geometry and Hydraulic Parameters <br />Reach <br />Reach <br />Reach <br />Friction <br />Bottom <br />Side <br />Identifier <br />Length <br />Manning's <br />Slope <br />Width <br />Slope <br />20.78 <br />(ft) <br />n <br />(ft /ft) <br />(ft) <br />38.97 <br />------------------------------------------------------------------------------- <br />UDS (existing) 690 <br />0.047 <br />0.088 <br />2 <br />2.0 :1 <br />UDS (planned) <br />690 <br />0.047 <br />0.088 <br />2 <br />3.0 :1 <br />MDS <br />384 <br />0.047 <br />0.0933 <br />0.9 <br />4.8 :1 <br />LDS -E <br />255 <br />0.05 <br />0.0800 <br />1.8 <br />3.4 :1 <br />LDS -N <br />335 <br />0.05 <br />0.0794 <br />1.7 <br />3.1 :1 <br />SWRP -Inl <br />194 <br />0.047 <br />0.1907 <br />2 <br />3.0 :1 <br />SWRP -In2 <br />141 <br />0.047 <br />0.1773 <br />2 <br />3.0 :1 <br />NJR <br />240 <br />0.05 <br />0.0443 <br />1.5 <br />3.0 :1 <br />SWRP -Inlet <br />(This reach <br />is a structure: <br />SWRP) <br />2.6 <br />Side Slope Ratio, Right Bank: <br />4.4.1 Upper Diversion Structure (UDS) <br />The UDS intercepts stormwater runoff from upslope (sub- basins N -A, N -B, and N -C) and diverts it <br />eastward into the adjacent sub -basin, east of the mine site (Figure 1). The UDS channel is normally dry, <br />and flows only in response to precipitation events. <br />The UDS was initially constructed in the 1990s, is regularly maintained, and has achieved a relatively <br />stable channel configuration over time. The channel was inspected on May 28, 2013, and eight cross <br />sectional profiles were surveyed along the 690 -ft channel (Plate 2). The survey results are presented in <br />Attachment 3 and are summarized in Table 11. The channel is eccentric, with a shallower average side <br />slope on the left bank (2.6:1) and a steeper average side slope on the right bank (1.4:1). The overall <br />average side slope ratio for the UDS channel is 2.0:1. The average local bedslope is 0.0825 for the eight <br />profiles and 0.088 for the entire channel. <br />Table 11. Upper Diversion Structure Channel Geometry <br />Profile ID: <br />UDS -P1 <br />UDS -P2 <br />UDS -P3 <br />UDS -P4 <br />UDS -P5 <br />UDS -P6 <br />UDS -P7 <br />UDS -P8 <br />Avg. <br />Area, bank full (ft): <br />44.99 <br />20.78 <br />11.23 <br />49.74 <br />36.59 <br />39.74 <br />38.97 <br />30.74 <br />34.1 <br />Area,0.5 -ft freeboard (ft): <br />35.17 <br />12.05 <br />6.54 <br />41.61 <br />29.11 <br />32.22 <br />31.77 <br />22.68 <br />26.4 <br />Area,l -ft freeboard (fe): <br />25.68 <br />5.68 <br />3.18 <br />34.06 <br />21.89 <br />25.47 <br />26.43 <br />17.13 <br />19.9 <br />Top Width (ft): <br />20.0 <br />20.0 <br />10.3 <br />17.00 <br />15.68 <br />15.50 <br />14.40 <br />15.35 <br />16.0 <br />Bottom Width (ft): <br />5.6 <br />2.3 <br />0.0 <br />1.70 <br />3.60 <br />0.00 <br />1.80 <br />0.98 <br />2.0 <br />Side Slope Ratio, Left Bank: <br />3.1 <br />5.3 <br />2.9 <br />2.06 <br />2.08 <br />1.84 <br />1.87 <br />2.03 <br />2.6 <br />Side Slope Ratio, Right Bank: <br />1.5 <br />3.6 <br />2.4 <br />0.70 <br />0.89 <br />0.89 <br />0.48 <br />1.06 <br />1.4 <br />Average Side Slope Ratio: <br />2.3 <br />4.4 <br />2.7 <br />1.4 <br />1.5 <br />1.4 <br />1.2 <br />1.5 <br />2.0 <br />Local Channel Bed Slope (ft): <br />0.1008 <br />0.0434 <br />0.0375 <br />0.0666 <br />0.1027 <br />0.0633 <br />0.1003 <br />0.1458 <br />0.0825 <br />4148A.131028 Whetstone Associates <br />