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West Elk Mine <br />evidence of surface cracking would lend strong validafion to the premise that longwall mining <br />has had minimal surface impacts at West Elk Mine. <br />Landslides <br />It could be expected that the changes in stress and strain of the near-surface strata and possible <br />near-surface fractures associated with the predicted subsidence could reactivate or initiate <br />landslides. The landslides listed below are all naturally occurring features, which become <br />unstable during periods of increase precipitation. A review of aerial photographs that were taken <br />in 1963 show that the slides listed below were more stable at that time than they aze now. Mr. <br />Dunrud observed that many of the existing landslides, including the landslides north and south of <br />Minnesota Reservoir became unstable and moved during the period of high precipitation in the <br />mid 1980s. The landslides on the southeast side of West Flatiron and on the west side of Deep <br />Creek in the Apache Rocks area appeaz to have been unaffected by longwall mining beneath the <br />azeas. It therefore appears appazent that wet seasons affect landslides more than does longwall <br />mining. During very wet periods, however, landslides that aze already unstable may locally be <br />triggered by mine subsidence. <br />The following are known locations within the present permit area and the South of Divide permit <br />revision azea where the reactivation of a landslide could occur as a result of current or future <br />mining: <br />1. Apache Rocks mining azea <br />a. North of Minnesota Reservoir dam in the SW'/< of Section 29 <br />b. Above Panels 14 and 15 in the SW'/< of Section 26 <br />c. On the west side of Deep Creek, above the southeastern part of Panel 17 <br />2. Box Canyon mining area <br />a. Above projected Panels 18 and 19 on the east side of Box Canyon in the N'/~ of Section <br />14 <br />b. Two landslides above projected Panels 19 and 20 on the west side of Box Canyon in the <br />W%2 of Section 14 <br />c. Above the bamer pillars between the Box Canyon and Apache Rocks longwall mining <br />panels in the SE'/< of Section 22 <br />3. South of Divide mining azea: <br />a. An extensive landslide located south of Minnesota Reservoir above the northern part of <br />projected Panel E9 in the NW'/< of Section 32 <br />Rockfall <br />As discussed in Section 2.04.6, Geology Description and later in this section, there aze exposed <br />rock faces on steep slopes where the potential for rockfall exists within the permit area. <br />Theoretically, muting-induced changes in stress and strain and fracturing could trigger additional <br />rockfall from the many sandstone cliffs. Areas of rockfall potential, such as the flanks of West <br />Flatiron within the Apache Rocks and Box Canyon pernut areas aze currently monitored for <br />• rockfall whether it is naturally occurring or mining-induced. As with landslides, due to the lack of <br />1.05-100 RevisedJ~me 1005 PRIG <br />