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r <br /> Chapter 4 - Best Management Practices for Erosion and Sediment Control <br /> ' When used in conjunction with diversion dikes , temporary slope drains can be used to <br /> convey stormwater from the entire drainage area above a slope to the base of the slope <br /> without erosion . It is very important that these temporary structures be installed properly <br /> ' since their failure will often result in severe gully erosion . The entrance section must be <br /> securely entrenched , all connections must be watertight, and the conduit must be staked <br /> _ securely. <br /> Desian Criteria <br /> Drainage Area <br /> The maximum allowable drainage area per drain is 5 acres (2 ha) . <br /> i <br /> Flexible Conduit <br /> 1 . The slope drain shall consist of heavy duty flexible material designed for this <br /> purpose. The diameter of the slope drain shall be equal over its entire length . <br /> Reinforced hold-down grommets shall be spaced at 10 foot (3 m) maximum <br /> intervals. <br /> 2 . Slope drains shall be sized according to the following table : <br /> Table 4.30a <br /> SIZE OF SLOPE DRAIN <br /> Maximum Drainage Area (Acres) Pipe Diameter (in .) <br /> 0 . 5 12 <br /> 1 . 5 18 <br /> 2 .5 21 <br /> 3 . 5 24 <br /> r 5 . 0 30 <br /> Overside drain <br /> For small flows and/or short slopes , an open top chute may be used in place of a pipe. <br /> (See Plate 4 . 30c) . <br /> r <br /> Entrance Sections <br /> r The entrance to the slope drain shall consist of a Standard FDOT " Flared End-Section for <br /> Metal Pipe Culverts . Extension collars shall consist of 12 inch (30 cm) long corrugated <br /> metal pipe. Watertight fittings shall be provided . (See Plates 4. 30d & 4 .30e) . <br /> r <br /> r <br /> r <br /> 4- 101 <br /> i <br />