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<br />Reach Slope Flow <br />Depth <br />(ftl Channel <br />Depth <br />(ft) Vel. <br />(fps) Flow <br />(cfs) Dso <br />(in) SF~ SFb~k <br />1 0.014 0.8 2.0 3.2 10.3 4 3.5 1.6 <br />2 0.230 0.4 2.0 8.9 10.7 30 1.6 1.5 <br />3 0.120 0.5 2.0 7.3 11.8 18 2.0 1.5 <br />East Channel <br />The permanent East Channel consists of three sections. The upper section <br />which runs along the toe of the coal waste pile will not be changed (reach 1 in <br />hydrology study). The second section (reach 2 in the hydrology study) will be <br />converted from a buried pipe to an open channel. The third section (reach 5 in the <br />hydrology study) is the existing channel runs behind the office. This channel will <br />remain unchanged and will carry the combined East and West Channel flow to the <br />basin outlet. The design of the upper and lower sections (reach 1 and 5 of <br />hydrology study) are adequate to transport the 100yr-24hr event. See the report <br />• entitled Hydrologic and Hydraulic Design of Sedimentation Ponds and other <br />Drainage Features of National King Coal Mine, May 1995, for specific information. <br />The buried pipe in the middle section is to be replaced with a trapezoidal <br />channel with the same dimensions as specified above for the West Channel. This <br />section is divided into two reaches. Reach 1 is the lower, flatter reach and reach 2 <br />extends up the steep bench. As with the West Channel this section exhibits high <br />velocities and thus requires bed and bank protection to prevent severe scouring. As <br />with the West Channel, a Gabion rock structure, may be easier to construct and <br />would require much smaller stones and thus may be a better choice for reach 2. <br />East Channel (middle section): <br />shape -trapezoidal <br />side slopes = 2.5 horz : 1 vert <br />bottom width = 2 feet <br />freeboard depth = 1 foot <br />total depth = 2 feet <br />required discharge = 5.9 cfs <br />• <br />June 1995 <br />