2012-07-10_GENERAL DOCUMENTS - C1981041

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discharge site that would be used in the event of malfunction of Outfall 016. Outfall 001, a supplemental/back -up discharge via 4" diameter pipe through the South Portal conveyor entry concrete seal, has been permanently plugged in association with South Portal area final reclamation in 2007/2008. The Division has granted an exemption from the use of sediment ponds for NPDES discharge points 002 and 016 from underground mine workings because sediments are settled out in abandoned underground workings before being discharged into the Colorado River. Additional ponds and treatment facilities are not necessary for these discharge points to meet the effluent limitations of Rule 4.05.2 and applicable State and Federal water quality standards for receiving streams. B. Diversions and Conveyance of Overland Flow 1. All conveyance structures within the permit area are designed and constructed in accordance with Rule 4.05.3. Permanent diversions above coal mine waste banks are designed and constructed in accordance with Rule 4.09.2(7). Table 13-4 of the application lists all diversion and conveyance ditches along with references to the appropriate exhibits for designs and cross sections. Calculations used to design these structures are given in appendix 13 -2 of the permit application. A number of permanent channels or channel segments have been constructed or will be constructed following reclamation of temporary sediment and drainage control facilities at various locations. As described in greater detail below the Division has approved four permanent channel diversions located in Coal Canyon, Coal Gulch, at the ephemeral drainage above the Roadside South Mine Portal Bench Area, and at an ephemeral channel in the vicinity of the Two West Portals reclaimed area. A permanent reconstructed channel segment has been completed at the North Decline Reclaimed area, in accordance with the approved plan channel berm breaks have been installed. Several permanent ephemeral channels are to be constructed across the North Portal reclaimed area. The final channel designs were completed with this PR -5. The channels are shown on Exhibit 8C Roadside North Portal Post Mining Topography. As part of the redesign the West Diversion Ditch and the East Diversion Ditch will remain as permanent postmine features. Pond 13 will be reclaimed when the fmal ephemeral drainages are constructed later this year. Finally, several permanent drainage channels were constructed in association with the South Portal area reclamation grading. C. Stream Channel Diversions Construction of the Cameo Refuse Disposal Areas involved the installation of a permanent ephemeral stream channel diversion along a segment of Coal Canyon in the vicinity of the refuse areas. A total of approximately 600 feet of the Coal Canyon drainage was diverted. As part of the design for CRDA -2, the Coal Canyon drainage channel was realigned to provide a more uniform, controlled flow between CRDA 1 and 2. The four rock check dams constructed in the channel have caused significant deposition and necessitated frequent maintenance. In order to assure the channel is in equilibrium with the flow regime, the rock check dams were removed and the excess sediment was harvested and used as refuse cover soil during the 2002 reclamation project. The drainage channel was graded to an approximate uniform grade to the cross sections presented on Exhibits 53 and 55 of the permit document. Berms located along the middle and lower sections were leveled so the channel blends naturally into the adjacent terrain. Berms are Permit Revision No. 5 22 July 10, 2012