2007-11-16_GENERAL DOCUMENTS - C1981041 (3)

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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, is no longer used and will be permanently plugged with pumped concrete 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 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 oftemporary sediment and drainage control facilities at various locations. A segment of the Coal Creek permanent diversion is to be re-constructed following reclamation of Pond 6 and Pond 10, and a final reclamation segment of the Coal Gulch permanent diversion is to be constructed following removal of Pond 11. A permanent reconstructed channel segment has been completed at the North Decline Reclaimed, with the exception that channel berm breaks will be installed prior to final bond release. Several permanent ephemeral channels are to be constructed across the North Portal reclaimed area following removal of the temporary upper diversion ditch and reclamation of Pond 13. Finally, several permanent drainage channels are to be constructed in association with South Portal area reclamation grading and subsequent removal of Sediment Ponds 8 and 9. 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. The channel segment was originally constructed with four rock drop structures to minimize erosion along the segment. The channel obstructions caused by the drop structure installations were determined by the Division to be inappropriate, due to the potential for high flow to escape the channel. As a result, modified interim and final designs have been approved. The interim channel was constructed by removing the rock structures and grading the channel segment to a uniform gradient in 2002. The final design provides for re-alignment of the upper segment of the channel section to allow installation of a meander in the vicinity of Sediment Pond 6, in conjunction with Pond 6 reclamation. Designs are located in Appendix 13-2 and channel locations and cross sections are shown on Exhibit 51, 52, 53 and 55. Pursuant to TR-42 Permit Renewal No. 5 23 November 16, 2007