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2004 Geobgic Hazard Field Observations <br />South of Divide Mining Area <br />• <br />Minnesota Reservoir is outside of the area of mining influence of the nearest location of the mine <br />r 1 <br />l J <br /> <br />workings in the South of Divide mining azea Therefore, subsidence due to longwall mining in <br />the currently projected mine workings will not impact the reservoir. Even by using a 45-degree <br />angle of draw, which is 25 degrees greater than the maximum angle measured in the West Elk <br />mining area, the nearest mine workings (the main haulageway) and projected longwall panels E2, <br />E3, and E9 are at least 500 feet farther away than a buffer zone established by the most <br />conservative 45 degree angle of drew. <br />It is estimated that any mine-generated seismic activity will not affect Minnesota Reservoir or the <br />landslides located north and south of it There is no historical evidence that mine-induced <br />seismic activity has effected landslides in the area of West Elk Mine. The landslides on Jumbo <br />Mountain, located above mined longwall mining panels, for example, were unaffected by any <br />mine-generated seismic activity that may have occurred In addition, earth tremors have never <br />been felt above actively mined longwall panels during annual subsidence visits for the past nine <br />Ye~- <br />The landslide on the south side of Minnesota Reservoir is located above the northern part of <br />longwall panel E9. However, based on the historical evidence on Jumbo Mountain, no <br />subsidence or seismic impacts on the slide are expected. The landslides, some of which were <br />located directly above longwafl panels 8 and 9, were not noticeably affected, even in yeazs of <br />above-normal precipitation. <br />Seven general rocldall azeas are located in the South of Divide mining area (Map 1). Many of <br />these azeas are located neaz remote drill roads and agricultural access roads that have only limited <br />to very limited local traffxc. Should rocldalls occur on these remote roads, these areas could be <br />easily cleated before local traffic is impacted. Evidence of naturally occurring rockfalls, such as <br />remnant boulders at the base of steep slopes or in the run-out zones of these areas with a rockfall <br />potential, should be documented prior to mining. <br />831-032.621 Wright Water Engineers, Inc Page 2 <br />November 2004 <br />