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West Elk Mine Landslides It could be expected that the changes in stress and strain of the near-surface strata and possible neaz-surface fractures associated with the predicted subsidence could reactivate or initiate landslides. The landslides listed below are all naturally-occurring features, which become unstable during periods of increase precipitation. A review of aerial photographs that were taken in 1963 show that the slides listed below were more stable at that time than they are now. Mr. Dunrud observed that many of the existing landslides, including the landslides north and south of Minnesota Reservoir became unstable and moved during the period of high precipitation in the mid 1980s. The landslides on the southeast side of West Flatiron and on the west side of Deep Creek in the Apache Rocks azea appeaz to have been unaffected by longwall mining beneath the azeas. It therefore appeazs apparent that wet seasons affect landslides more than does longwall mining. During very wet periods, however, landslides that aze already unstable may locally be triggered by mine subsidence. The following are known locations within the present permit area and the South of Divide pernut revision azea where the reactivation of a landslide could occur as a result of current or future mining: Apache Rocks mining area a. North of Minnesota Reservoir dam in the SW'/a of Section 29 b. Above Panels 14 and 15 in the SW'/< of Section 26 c. On the west side of Deep Creek, above the southeastern part of Panel 17 2. Box Canyon mining area a. Above projected Panels 18 and 19 on the east side of Box Canyon in the N% of Section 14 b. Two landslides above projected Panels 19 and 20 on the west side of Box Canyon in the W% of Section 14 c. Above the barrier pillars between the Box Canyon and Apache Rocks longwall rnining ganels in the SE'/< of Section 22 3. South of Divide mining area: a. An extensive landslide located south of Minnesota Reservoir above the northern part of projected Panel E9 in the NW'/a of Section 32 Rockfall As discussed in Section 2.04.6, Geology Description and later in this section, there are exposed rock faces on steep slopes where the potential for rockfall exists within the permit azea. Theoretically, mining-induced changes in stress and strain and fracturing could trigger additional rockfall from the many sandstone cliffs. Areas of rockfall potential, such as the flanks of West Flatiron within the Apache Rocks and Box Canyon permit azeas are currently monitored for rockfall whether it is naturally occurring or mining-induced. As with landslides, due to the lack of structures and limited human activity within the permit azea, present and future land uses will not be significantly impacted. 1.05-100 Revised November 1004 PRIO