2007-07-30_GENERAL DOCUMENTS - C1981041

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The Division has approved permanent diversion of a segment ofCoal Creek, a segment of Coal Gulch, and permanent diversion of unnamed ephemeral drainages above the South Mine facilities and Roadside Refuse Disturbance area. These diversions are consistent with applicable state law, will not diminish downstream vJater rights, and will meet the requirements of Rules 4.05.4 and 4.05.18 (4.05.4(4)). ~, 2. The permanent diversions shall make use of artificial structural controls in order to allow them'to remain in dynamic equilibrium with the drainage basin system. The Division approves the use of rip-rap channel lining along various sel;tttents of these channels. 3. Channel lining structures and artificial channel reughness structures are proposed for use to control erosion. Artificial structures include arip-rap transition zone stmcture in the Coal Creek channel at the location of the former Haul Road 2 crossing, and riprap lining along the South Portal facilities permanent diversion and the Cos~tl Gulch permanent diversion segment. These means were approved by the Division sing^~ they aze necessary to control erosion, they are stable and will require infrequent maintenance (4.05.4(2)(a)). 4. In addition to the permanent diversions mentioned above,',a permanent diversion of an ephemeral stream draining less than one squaze mile has been approved for an unnamed ephemeral tributary to the Colorado River located within the 2 West Portal Disturbance Area., The outside bank closest to the North Portal was built up to prevent the diverted stream from entering the portal. Bedrock lies close to the bottom of the diverted channel and the channel does not require armoring. This decision is based on a finding that the proposed diversion meets the requirements of 4.05.18 and 4`.05.4, applicable local, State, and Federal statutes and regulations and that the diversion is'designed to safeguard public safety, and to minimize adverse impacts to the hydrologic balance (4.05.4(1) and (4)). D. Sedimentation Ponds Information on the surface water sediment control system can be; found in Volume 3, Tab 13, page 13-5 of the permit application. A list ofsediment control stnctures, along with references to appropriate exhibits for designs and cross sections, are found in: Table 13-4 ofthe application. Calculations used to design these structures are given in appendix 13-2 of the permit applications Sediment Pond 8 in the South Portals area will be;'reduced in size and storage capacity in association with the PR-3 amended reclamation plan. Designs for Sediment Pond 8, as revised, by PR-3, are provided in Appendix 13-2, pages RSS-1 through RSS-7. Documentation included in the appendix demonstrates that the''down-sized pond will have adequate capacity to contain the 10-year, 24-hour storm event. Loiation and configuration ofthe revised Pond 8 is depicted on Exhibit 6C-A, and design elevations and capacities are listed on page RSS-4, of Appendix 13-2. Eight sediment ponds are in place, as previously approved by the Division and have been treating disturbed-area surface water runoff under the existing permit for the Roadside Mines. All ponds have performed well over this period. These ponds aie described in the Summary, "Description of Operations Plan" section of this document. References to designs for these ponds and their locations are found in Tables 13-5 and 13-6 of th'e permit application. All but two sediment ponds are designed to contain the runoffand,sediment from a l0-year, 24- hourprecipitation event. Sediment Ponds #1 and #2 were combined to contain [he 25-year, 24- hour storm event. Sediment ponds #l, #2, #7, #8 and #I l recjuire pumps as the principal I Permit Revision No. 3 July 30, 2007 Permit No. C-1981-041 Page 24