2018-01-23_GENERAL DOCUMENTS - C1981041

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26 C1981-041 RN7 findings discharge associated with the Roadside North Portal Mine, NPDES discharge point 004. Discharge from the North Portal Mine required pumping, which ceased in December 1999 when operations ceased. Outfall 004 has been discontinued and Pond 12 has been eliminated by reclamation operations. Pond 12 has received Phase III bond release and has been removed from the permit with the approval of TR-70. Discharge Outfall 015 had been approved for minewater discharge from the South Mine 2 West Portals. The outfall was never activated and the 2 West Portals have been sealed and reclaimed. Only two approved minewater discharge sites remain, both at the South Mine. Outfall 016, located near the North Decline Area is the primary dewatering site. Outfall 002, the siphon discharge system at the reclaimed Northwest Intake Portal, has been retained as a back-up 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 No rth Decline Reclaimed area, in accordance with the approved plan channel berm breaks have been installed. Several permanent ephemeral channels were constructed across the North Portal reclaimed area. The final channel designs were completed with approval of 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 post-mine features. Pond 13 was reclaimed when the final ephemeral drainages were constructed in 2012. Finally, several permanent drainage channels were constructed in association with the South Portal area reclamation grading.