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permit area, to the extent possible, using the best technology currently available. Appropriate <br />sediment control measures for these diversions may include, but not be limited to, maintenance <br />of appropriate gradients, channel lining, revegetation, roughness structures, and detention basins. <br />No diversion will be located so as to increase the potential for landslides. When no longer needed, <br />each temporary diversion will be removed and the affected land regraded, topsoiled, and <br />revegetated in accordance with 4.06, 4.14, and 4.15. If the temporary diversion was for an <br />ephemeral stream, the channel will be reestablished to functionally blend with the undisturbed <br />drainage above and below the area to be reclaimed. Diversion design will incorporate the <br />following: <br />(a) Most ditches will not need to be lined, however, any stretch of collection ditch which <br />has a velocity above 5.5 feet per second will be lined. Channel linings, including <br />channel riprap, will be designed using standard engineering practices to pass safely <br />the design velocities. These velocities assume the typical silty loam soil conditions <br />on site. If better conditions exist, the velocities will be allowed to increase without <br />lining. If worse conditions exist, lining may be needed for lower velocities. <br />(b) Freeboard will be a minimum of 1.0 feet. Protection will be provided for transition of <br />flows and for critical areas such as swales and curves when excessive velocities <br />are anticipated. <br />(c) Energy dissipators will be installed when necessary, such as at discharge points, <br />where diversions intersect with natural streams and exit velocity of the diversion flow <br />is greater than that of the receiving stream. <br />(d) Excess excavated material not necessary for diversion channel geometry or <br />regrading of the channel will be disposed of in accordance with 4.09. <br />(e) Topsoil will be handled in compliance with 4.06. <br />(f) All ditches, culverts and diversions will be temporary; therefore peak flows will be <br />designed for the 10 year 24 hour event of 2.0 inches. <br />Section 2.05.3(4) Page 3 September 2014 (TR -06) <br />