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West Elk Mine <br /> <br />2.05-123 Rev. 06/05- PR10, 03/06- PR10, 05/06- PR10, 11/060- TR107, 04/07- TR108, 09/07- PR12, 02/08- PR12; 11/10- MR372; 10/20- MR-452; <br /> 12/20- TR149; 12/21- TR150, 1/24-TR152 <br />MCC recognizes that proposed mitigation to surface waters, roads, vegetation, wetlands, etc. on <br />Forest System (USFS) lands will be accomplished in accordance with the USFS stipulations <br />specified in MCC’s coal leases. These lease documents contain the stipulations agreed to by MCC <br />with the Forest regarding, in part, the mitigation requirements for mining related impacts within the <br />Forest. <br />MCC will repair impacts of subsidence on surface drainages on private or USFS lands, including <br />revegetation as necessary to control erosion. For any impacts occurring on USFS lands, MCC will <br />consult the USFS immediately to determine; a) the level of mitigation needed, and b) the feasibility <br />of employing the proposed mitigations. Should these impacts occur on USFS lands, MCC, in <br />conjunction with the USFS, will evaluate the impacts on a case by case basis to assess the most <br />appropriate mitigation. MCC will seek Forest Service approval for any mitigation(s) on USFS <br />lands. <br />If stream channels are impacted by subsidence, efforts will be made to repair the channel to ensure <br />that flow continues in the channel. If cracking, headcutting or significant channel incising occurs, <br />MCC will evaluate the channel morphology and prepare a mitigation plan. Mitigation may require <br />the sealing of fractures, if they occur in the stream channel, with bentonite/soil mixes to stop <br />water loss, excavating ridges or high areas created by subsidence within the stream channel that <br />impede flow, and redirecting flow, if necessary, back into the original channel if diverted due to <br />subsidence. Temporary culverts in ditches and streams may also be used to bridge surface cracks <br />while the best method to seal the fractures is determined. A 0.6 acre area of subsidence on South <br />Prong Creek at the confluence with the North Fork of South Prong Creek (see Map 34) on MCC <br />property was repaired 2020 by backfilling with nearby native soils, injecting the backfill with <br />cementitious grout and sealing the area with a bentonite cap. <br />If stream courses are blocked by mining induced slide movement, MCC will use hand tools or <br />appropriate heavy equipment to reopen affected channels. The necessary permits to perform such <br />work will be obtained prior to performing mitigation. Other mitigation may include the <br />placement of straw bale dikes or silt fences below slide areas to reduce sediment loading. If <br />ponding occurs due to rockfalls or slides within the stream channels and is not determined to <br />create a hazard to the public, no additional mitigation is proposed. However, if the ponding <br />creates hazardous conditions, the structure creating the ponding may be breached or bypass <br />channel(s) built. The mitigation work will only be accomplished after the appropriate permits <br />are obtained. <br /> <br />If ponding occurs within the stream channels due to differential subsidence and is not determined <br />to create a hazard to the public, no additional mitigation is proposed. However, if the ponding <br />creates hazardous conditions, the structure creating the ponding may be breached or bypass <br />channel(s) built. The mitigation work will only be accomplished after the appropriate permits <br />are obtained. <br /> <br />If subsidence of existing wetlands raises the water table to a point where the wetlands are in <br />danger of destruction, the CDRMS and Forest will be notified and appropriate actions taken. <br />These actions may include excavating the portion of the channel that has created the damming <br />effect on the wetlands. No action may be appropriate where the ponding would result in an