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West Elk Mine <br /> <br />2.05-122 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 />As discussed in previously in section 2.05.6, Wright Water Engineers has completed detailed <br />subsidence modelling and evaluations from longwall mining in the SOD, Southern Panels, Apache <br />Rocks West, Dry Fork and Sunset Trail mining areas and provided recommendations for longwall <br />mining heights and cover depths. MCC will adhere those recommendations as detailed in Exhibit <br />60E, including not longwall mining where actual overburden depths are less than 250’. E seam <br />overburden depths are shown on Map 19 and were based on surface topographic surveys <br />compared to top of seam elevations derived from nearby drillhole data. MCC will continue to <br />survey actual roof elevations in the mine as each longwall panel is developed and adjust the <br />panel length as necessary to ensure that no longwall mining occurs where actual overburden <br />depths are less than 250’. <br />Preventive Measures (Surface) - 2.05.6 (6)(f)(iii)(C)(I-V) <br />Surface measures that may be taken to reduce or prevent damage to applicable structures or water <br />resources could include, but are not limited to; (1) Engineering, design, and construction of <br />structures to withstand varying ground stresses, (2) Re-locating structures or ponds to mid-panel or <br />outside the angle of mining influence, and/or (3) Enhancing or reinforcing water resource <br />production or delivery systems (e.g., pipeline), respectively. <br />A total of five reflector stations will be placed in the ditch at the transition of Deep Creek Ditch <br />to the Dry Fork Basin. They will be surveyed on the following schedule. <br /> <br />1) Pre-mining – At least one baseline survey will be conducted within the 30-day period <br />before the longwall mining under the ditch starts. If the ditch will be undermined during <br />winter conditions this survey may be done at the end of the period of seasonal access <br />prior to the expected start of mining in panel E5. <br />2) During Mining – Monthly surveying will be conducted while the longwall face is within <br />1000 feet of being underneath the ditch (if seasonal access permits). <br />3) Post-mining – Monthly surveys will be completed for the first two months after each <br />longwall face has proceeded to more than 1000 feet from being underneath the ditch (or <br />only one final survey will be done if seasonal access is unavailable during the 30-day <br />period immediately following undermining of the ditch). Data from the surveys will be <br />reported in the semi-annual subsidence report. <br /> <br />Detailed Description of Mitigating Measures – 2.05.6(6)(f)(iv)(A-D) <br />Impacts to structures (buildings) and ground and surface water resources will be monitored and <br />mitigated, if necessary, as presented later in this section, in Sections 2.04.7(3) and <br />2.05.6(6)(e)(ii)(A-C), in Exhibit 19C, and in Exhibit 52. Monitoring personnel (e.g. hydrology, <br />subsidence survey) are regularly in the field throughout the permit area and note observations of <br />cracking, landslides, rockfalls, or other natural and/or subsidence hazards or impacts. Roads will be <br />repaired through regrading or filling if adversely affected by subsidence. Should cracking or <br />blockage of a trail or an unimproved road that is open for use (i.e. is not blocked, reclaimed, or <br />otherwise "closed" from use) occur from subsidence, the damage would be repaired (i.e. fill crack, <br />buttress, install drains, or remove blockage etc.) or the area barricaded or blocked to prevent access. <br />MCC will also place an informational sign along the primary public access to the USFS lands for <br />mining and/or natural hazards awareness.