2008-03-21_PERMIT FILE - C1980007A (5)

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Vest Elk Mine A small portion of the development mining area along the northwest side longwall panel 18A underlies a known area of landslide disturbance south of Highway 133 as shown on Map 1 of Exhibit 60C. As a result, the worst possible consequence associated with mining-induced subsidence in the West Flatiron lease area is that this landslide will be reactivated during mining activities causing a potential crossing of Highway 133 and an obstruction to traffic. - Based on observations made in the field both of active and inactive landslide areas before and after mining activities, MCC and it's consultant (WWE) concludes that the greatest potential for the worst possible consequence would occur during a very wet precipitation period. Such periods have been observed in the North Fork Valley as recently as the mid-1990s causing initiation or reactivation of numerous natural landslides. With few exceptions, most landslides along the North Fork Valley are relatively shallow in depth and move relatively slowly downhill_ (gravity creep) providing an opportunity for monitoring and evaluation. Monitoring of the landslide toe south of Highway 133 will provide an opportunity to assess whether reactivation of the landslide has occurred and to what extent this reactivation may have on the highway. Such monitoring will be accomplished by vertically driving steel rods into the landslide area south of Highway 133 at locations potentially subject to reactivation. These are then monitored by surveying to assess changes. Should movement be noted on these metal stakes, additional studies and surveys can be undertaken to assess where reactivation is occurring, the rate of movement, the area extent and depth of the materials that are moving, and the potential for impact to the highway. It should be noted that the portion of longwall panel 18A that is closest to the highway (approximately 600 feet horizontal distance) includes development entries, which have the smallest subsidence potential because of the room-and-pillar mining techniques used. This development mining will occur before any longwall mining activities. When longwall mining occurs in panel 18A, it will be further south (about 250 feet) with an angle of draw that will not influence the landslide area. As a result, monitoring of the landslide during development mining will serve to assess the most likely potential reactivation period, particularly during spring runoff. Material damages created by the activation of the landslide, should they occur, are expected to be limited to the physical obstruction of traffic on Highway 133. As previously stated, it is anticipated that monitoring will assist in evaluating the potential for this occurrence and minimize the health threat to individuals driving on Highway 133. Should the landslide reactivate and threaten or cross Highway 133, MCC will provide available assistance in the clearing of the highway and mitigation of the effects. WWE finds the likelihood of this occurrence to be extremely small except in abnormally 'et conditions, which will have a similar effect on numerous landslides throughout the North Fork Valley. The following are known locations within the present permit area, the South of Divide and Dry Fork pen-nit revision areas where the reactivation of a landslide could occur as a result of current or future mining: 1. Apache Rocks mining area a. North of Minnesota Reservoir darn in the SW1/4 of Section 29 10 b. Above Panels 14 and 15 in the SW'/4 of Section 26 c. On the west side of Deep Creek, above the southeasternpart of Panel 17 2.05-113 Revised June 200.1 PRIG, Rev. dfarch 2006: Rev. Apri12006 PR10: May 2006 PRIO, Vov. 2006 TR107, Sep. 2007 PR-12: Feb. 200SPR-12