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Table 3.5-6 - Calculation for Typical Roadside Ditch Design <br />This roadside ditch was designed for a maximum peak flow of 11.6 cfs. <br />The ditch was sized from "Hydrology and Sedimentology of Surface Mined Lands" <br />by C.T. Hann and B.J. Barfield, pages 130-132, for a non-vegetated channel <br />with an earth bottom and rubble sides. A trial and error solution was used to <br />find depth of flow and the velocity in the channel. <br />Manning's Equation: Q = 1.99 Rz~J S1~z A <br />n <br />A = Cross Sectional Area of Flow in square feet. <br />S = Slope in ft/ft. <br />R Hydraulic Radius in Feet <br />n = Coefficient of Roughness for a triangular channel <br />T <br />i <br />ll t <br />- _ _ J <br />e <br />e <br />For Inflow Ditch: 2:1 Side Slopes <br />S = 0.033 ft/ft. <br />n = 0.032 (Earth Channel Rubble Sides) <br />d = Depth of Flow <br />z = g (Side Slopes) <br />d <br />T Top Width <br />Eor Design: A = zdz = 2dz <br />zd 2d 2d <br />2 ~I z+l \ I2r 2+i 2 y 3 <br />Q = ` 01032 / C~ 2~3 ) zi3~ (0.033112) 2dz <br />3.5-Si May 14,1993 <br />