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Ditches will be used to transport runoff into sedimentation ponds for treatment in accordance with the <br />requirements of applicable regulations and divert surface runoff away from topsoil stockpiles and active <br />mining areas. The location of each ditch is presented on Exhibit 13-2, Surface Hydrology. The design <br />information can be found in Attachment 13-2, Diversions. With the exception of a short (- 30 feet) <br />segment of Ditch No. 7, the diversion ditches have all been reclaimed. <br />Each ditch has been designed and constructed in accordance with the applicable regulations in Rule 4.05.3. <br />Diversions will be designed, constructed, and maintained in a manner which prevents additional <br />contributions of suspended solids to streamflow and to runoff outside the permit area, to the extent possible, <br />using the best technology currently available. Appropriate sediment control measures for these diversions <br />may include, but not be limited to, maintenance of appropriate gradients, channel lining, revegetation, <br />roughness structures, and detention basins. No diversion will be located so as to increase the potential for <br />landslides. When no longer needed, each temporary diversion will be removed and the affected land <br />regraded, topsoiled, and revegetated in acwrdance with Rules 4.06, 4.14, and 4.15. If the temporary <br />diversion was for an ephemeral stream, the channel will be reestablished to functionally blend with the <br />undisturbed drainage above and below the area to be reclaimed. Diversion design will incorporate the <br />following: <br />(a) Channel linings, including channel riprap, will be designed using standard engineering practices <br />to pass safely the design velocities. <br />(b) Freeboard will be no less than 0.5 feet. Protection will be provided for transition of flows and for <br />critical areas such as swales and curves when excessive velocities are anticipated. <br />(c) Energy dissipators will be installed when necessary at discharge points, where diversions <br />intersect with natural streams and exit velocity of the diversion flow is greater than that of the <br />receiving stream. <br />(d) Excess excavated material not necessary for diversion channel geometry or regrading of the <br />channel will be disposed of in accordance with Rule 4.09. <br />(e) Topsoil will be handled in compliance with Rule 4.06. <br />Sedimentation Ponds <br />In accordance with Rule 4.05.2 and the approved NPDES permit, SCC will use sedimentation ponds to <br />prevent, to the extent possible, additional contributions of sediment to streamflow or runoff outside the permit <br />area due to mining disturbance (see Exhibit 13-2). Please refer to Attachments 13-3 (Pond 005), 13-4 <br />(Pond 005), and 13-5 (Ponds 009, 015, 016, 016A and 017) for pond designs. <br />The sedimentation ponds and impoundments are designed, constructed, and maintained to achieve the <br />following: <br />a. Provide storage and treatment for the runoff or inflow entering the pond as a result of a 10-year, <br />24-hour precipitation event and to meet all applicable State and Federal regulations for all <br />PR-05 3 Revised 01/06 <br />