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. As mentioned above, a small portion of the development mining area along the northwest side <br />~ longwall panel 18A underlies a known area of landslide disturbance south of Highway 133 as <br />shown on Map 1 of Exhibit 60C. As a result, the worst possible consequence associated with <br />mining-induced subsidence in the West Flatiron lease azea is that this landslide will be <br />reactivated during mining activities causing a potential crossing of Highway 133 and an <br />obstruction to traffic. <br />Based on observations made in the field both of active and inactive landslide azeas before and <br />after mining activities, MCC and it's consultant (WWE) concludes that the greatest potential for <br />the worst possible consequence would occur during a very wet precipitation period. Such <br />periods have been observed in the North Fork Valley as recently as the mid-1990s causing <br />initiation or reactivation of numerous natural landslides. <br />With few exceptions, most landslides along the North Fork Valley; are relatively shallow in depth <br />and move relatively slowly downhill (gravity creep) providing an opportunity for monitoring and <br />evaluation. Monitoring of the landslide toe south of Highway 133 can provide an opportunity to <br />assess whether reactivation of the landslide has occurred and to what extent this reactivation may <br />have on the highway. Such monitoring will be accomplished by vertically driving steel rods into <br />the landslide area south of Highway 133 at locations potentially subject to reactivation. These <br />are then monitored by surveying to assess changes. Should movement be noted on these metal <br />stakes, additional studies and surveys can be undertaken to i assess where reactivation is <br />occurring, the rate of movement, the area extent and depth of thematerials that are moving, and <br />• the potential for impact to the highway. <br />It should be noted that the portion of longwall panel 18A that is closest to the highway <br />(approximately 600 feet horizontal distance) includes development entries, which have the <br />smallest subsidence potential because of the room-and-pillaz mining techniques used. This <br />development mining will occur before any longwall mining activities. When longwall mining <br />occurs in panel 18A, it will be further south (about 250 feet) with an angle of draw that will not <br />influence the landslide azea. As a result, monitoring of the landslide during development mining <br />will serve to assess the most likely potential reactivation period, particularly during spring <br />runoff. <br />Material damages created by the activation of the landslide, should they occur, are expected to be <br />limited to the physical obstruction of traffic on Highway 133. As pieviously stated, it is anticipated <br />that monitoring will assist in evaluating the potential for this occurrence and minhnize the health <br />threat to individuals driving on Highway 133. Should the landslide reactivate and threaten or cross <br />Highway 133, MCC will provide available assistance in the clearing of the highway and mitigation <br />of the effects. WWE finds the likelihood of this occurrence to be extremely small except in <br />abnormally wet conditions, which will have a similaz effect on numerous landslides throughout the <br />North Fork Valley. <br />Impact ofHi,~hway Construction <br />Based on a review of aerial photographs taken before highway construction and on communication <br />• with Bob Barrett of CDOT, two appazently dormant landslides were located east and west of the <br />mouth of Box Canyon. In November 1996, however this azea is covered by extensive slides with <br />2.05-130 March 1005PR11 Iqi) <br />M- 7 <br />