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Channels(Figure E-1a) • Channels(.Fi=4.2 and 4.3 )Upper Cache Creek Basin Trapezoidal Channel-100 year- 24 hour storm—Channel Trapezoidal Slope=106 will be constructed with an four foot bottom-16 feet wide-2.00 feet deep with 3(H):l(V)slopes will convey approximately 26S at a peak flow velocity of 13 fps. (Rip rap sizing(D-50)for the 10 year storm will range from 0.75-1.0 feet) • Lower Upper Cache Creek Basin Trapezoidal Channel -100 year-24 hour storm— Trapezoidal Channel Slope=3%will be constructed with an four foot bottom-21.5 feet wide-2.25 feet deep with 3(H):1(V)slopes will convey approximately 220 cfs. (See Table 5-2)at a peak flow velocity of 7.9 fps. (Rip rap sizing(D-50)for the 10 year storm will range from 0.75 -1.0 feet) • Middle Cache Creek Basin Trapezoidal Channel A 00 year-24 hour storm—Trapezoidal Channel Slope=10°lo will be constructed with an 6 foot bottom-19 feet wide-2 feet deep with 3(H):1(V)slopes will convey approximately 330 cfs. (Sere Table 5.3) 14 fps. (Rip rap sizing(D-50)for the 10 year storm will range from 0.5.•0.75 feet). In Middle Cache Creek stream segment(Figure 4-2)a diversion(Figure 4-4)is proposed to return the stream channel to approximate pre-mine alignment and at an estimated gradient of 12%. • Lower Cache Creek Basin Trapezoidal Channel-100 year-24 hour storm —Trapezoidal Channel Slope=90/o will be constructed with an six foot bottom-18 feet wide-2 feet deep with 3(H):1(V) slopes will convey approximately 316 cfs. (See Table 5-4) 13 fps. (Rip rap sizing(D-50)for the 10 year storm will range from 0.75 -1.0 foot). Culverts 5 ear-24 hour storm • Eighteen inch culverts will be used,as necessary, within the project area. The culverts will be installed with a maximum gradient 0.03 feet per foot gradient which are capable of carrying 9.9 cfs-with a 5.6 fps flow velocity Table E-2.5 Upper Basin-Five year-24 hour storm will generate a peak flow of approximately 6 cfs. (SCS, 1975)(Table E2-6); c. Channel Construction Channels will be constructed in areas identified on Figure F-2 using the design criteria summarized on Tables E2-2 through E2-5. Channels(including realignment-[diversion])will be constructed using BMPs presented in Exhibit E-Attachment B and supplemental design sheets. a. December 28,2014 Colorado Division of Reclamation Mining and Safety Gold Basin Mine,Inc. Gold Basin Mine Granite,Colorado