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• Channel Flow, reprinted in 1979 by the U.S. Department of <br />Commerce, Bureau of Public Roads. The ditches were assumed to <br />be stabilized with grass iiniub and design velocities kept <br />under 5-feet per second, to prevent erosion and additional <br />contribution of sediment to runoff. <br />Plate 32 entitled Ditch Schedule, illustrates a typical <br />cross-section view of the interceptor ditches. Also <br />summarized, are all of the design and physical parameters for <br />each ditch. <br />CULVERTS <br />A single culvert crossing is required along the access road <br />to the mine site, at its intersection with Mann Draw. The <br />• publication entitled Hydraulic Charts for the _Selection of <br />Highway Culverts, Hydraulic Engineering Circular No. 5, <br />April, 1964, prepared by the U.S. Department of Commerce, <br />Bureau of Public Roads was utilized to design the required <br />culverts. Based on the 10-year storm event of 12]. cfs and <br />water ponding to the top of the pipe, it is recommended that <br />2, 60-inch diameter CMP be used at the subject crossing of <br />Mann Draw. <br />BAFFLES <br />In order to prevent short-circuiting in the sedimentation <br />ponds, baffles will be required in Ponds A and B to increase <br />the flow length from the inlet to the primnrv outlet. A <br />typical baffle design is shown on Plate 33 entitled Inlet <br />Baffle Details, and the dimensions of each baffle are <br />included. <br /> <br /> <br />