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Sedimentation ponds or impoundments will be constructed before creating new disturbances, <br />unless approved drainage diversions or other surface water control structures are installed. <br />3. Collection Ditches. Culverts and Diversion Design Parameters <br />The main collection ditches in the original permit area are the 007 East and 007 West Ditch. <br />These have been renamed Ditches C18 and C17, respectively. These ditches are used to <br />transport runoff into Sedimentation Pond 007 for treatment in accordance with the requirements <br />of applicable regulations. The location and drainage area of these ditches can be found on Map <br />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 Attachment 2.05.3 (3) -1. As of the Mid Term Review of 2006, there are no <br />surface water control structures of any kind at the New Horizon #1 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, <br />and 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 <br />practices to pass safely the design velocities. These velocities assume the typical <br />silty loam soil conditions on site. If better conditions exist, the velocities will be <br />allowed to increase without lining. If worse conditions exist, lining may be needed <br />for lower velocities. <br />(Revised June 2010) 2.05.3(3) -3 <br />