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2.05.3-1. All ditch and culvert designs for the entire site have been reviewed for the Mid Term <br />Review of 2006. This review resulted in the redesign of some culverts and ditches, all of which <br />are presented in Attachment 2.05.3(3)-1. However, the ditch designs for ditches C-1, C-7, C-8, <br />C-9, C-15, C-23, and C-29 in Attachments 2.05.3(3)-30, 2.05.3(3)-31, 2.05.3(3)-32, and <br />2.05.3(3)-33 supersede and replace those found in Attachment 2.05.3(3)-1. As of the Mid Term <br />Review of 2006, there are no surface water control structures of any kind at the New Horizon #1 <br />site. <br />All ditches were designed and constructed in accordance with the applicable regulations in <br />4.05.3. Diversions will be designed, constructed, and maintained in a manner which prevents <br />additional contributions of suspended solids to stream flow and to runoff outside the permit area, <br />to the extent possible, using the best technology currently available. Appropriate sediment <br />control measures for these diversions may include, but not be limited to, maintenance of <br />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 <br />needed, 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 <br />which has a velocity above 5.5 feet per second will be lined. Channel linings, <br />including channel riprap, will be designed using standard engineering practices to <br />pass safely the design velocities. These velocities assume the typical silty loam <br />soil conditions on site. If better conditions exist, the velocities will be allowed to <br />increase without lining. If worse conditions exist, lining may be needed for lower <br />velocities. <br />b. Freeboard will be a minimum of 0.3 feet. Protection will be provided for <br />transition of flows and for critical areas such as swales and curves when excessive <br />velocities are anticipated. <br />c. Energy dissipaters will be installed when necessary, such as at discharge points, <br />where diversions intersect with natural streams and exit velocity of the diversion <br />flow 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 />Page 2.05.3(3)-3 January 2016 (TR -70) <br />