2013-01-29_PERMIT FILE - C1981022A (3)

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Section - 2.05.3 erosion or instability. Pond maintenance includes timely repair of any erosion or damage, cleanout of discharge structures and removal of excess sediment accumulations. Pond construction practices and ongoing maintenance have limited any need for supplemental embankment protection. Generally, sediment levels are monitored by visual inspection and pond cleanout is scheduled before sediment levels reach the invert of the primary spillway inlet. Sedimentation ponds will remain in place during the initial portion of the reclamation liability period and will be removed, unless previously approved as permanent structures. Removal and reclamation of associated disturbance areas will occur following DMG approval of Phase II Bond Release or the drainage restoration demonstration under Rule 4.05.2 (2). Pond reclamation will involve draining any accumulated water, removal of outlet structures, backfilling the ponds, grading the associated disturbance areas, replacement of soil material, and revegetation. Stream Channel Diversions -The stream channel diversions required in conjunction with mining and related activities has been temporary culverting of the lower and middle portions of Elk Creek through part of the Elk Creek Mine surface facilities area and the Elk Creek support facilities area and the Bear Creek shaft and fan facility. In conjunction with the historic Somerset Mine mining activities, U.S. Steel placed approximately 800 feet of 9-foot diameter culvert in the Elk Creek drainage channel and backfilled over the culvert to create a level facilities area near the mouth of Elk Creek Canyon. OMLLC subsequently extended this culvert another 650 feet to accommodate progressive mine expansion activities. The culvert has been sized, bedded, placed, and backfilled to assure it's long-term stability. The Elk Creek culvert is designed to safely pass the peak flows resulting from a 100-year, 24-hour storm event and is permitted under applicable provisions of Nationwide Permit 26 by the U.S. Army Corps of Engineers (Permit No. 199675449). OMLLC placed two additional segments totaling an additional 1,600 feet under COE Permit No. 199975232 in the middle portion of Elk Creek in order to establish the portal area, haul road, and facilities pads for the Elk Creek Mine. Additional culvert installation will be scheduled, if reasonably feasible, during a low flow period to minimize potential water quality impacts. Stream flows will be diverted around the construction disturbance by either a temporary ditch or pipeline and silt fence, straw bales, or other appropriate temporary control measures will be used to minimize additional sediment contributions to the stream. On completion of active operations for the associated disturbance areas, most of the Elk Creek culvert will be removed (except for that associated with the Elk Creek road crossings) and the associated stream channel reestablished. Two sections of the Elk Creek culvert will remain in place as permanent road crossings in conjunction with the postmining land use as shown on the Facilities Postmining Topography Map, (Map 2.05-M6). The Elk Creek culvert sections are designed to safely pass the peak flows from a 100-year, 24-hour storm event with significant excess culvert capacity (approximately 320 percent). Design information for the Elk Creek culvert is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan, and the culvert location and design configuration is illustrated by the Drainage and Sediment Control Plan Map, (Map 2.05-M4). A 450 foot section of ephemeral Bear Creek is to be routed (2009) through a 6-foot diameter culvert for the Bear Creek shaft and fan facility under ACOE Nationwide Permit 50: SPK-2008-1035-CW. The Bear Creek culvert section is designed to safely pass the peak flows from a 100-year, 24-hour storm event. Design information for the Bear Creek culvert is provided in Exhibit 2.05-E3, Drainage and Sediment Control Plan. The culvert location and design configuration is illustrated by the Exhibit 2.05-E1-BCA2, Facility Layout -Drainage and Sediment Control. The temporary culvert will be removed, the shaft backfilled and sealed, the Bear Creek drainage reestablished and the area reclaimed in accordance with the design provided on Exhibit 2.05-M6, Sheet 7 of 7, Bear Creek Fansite -Facility Post Mining Topography. The location of the facility is also shown on Map 2.05- Ml, Sheet 6 of 6. ` TR-60 2.05-36a Revised Jan 2009