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~' <br /> <br />J.E. Stover & Associates -13- May 31, 1996 <br />Bowie No. 2 Mine <br />for the Mount Gunnison No. 1 and Sear No. 3 mines. The history <br />of operations of both of these same mines can provide unfortunate <br />examples of the difficulty caused by geotechnical hazards. The <br />Bear No. 3 lost its ventilation capability and had to <br />rehabilitate its portal bench and haul road due to debris flow <br />and landslide activity. The Mount Gunnison No.l has suffered <br />numerous expensive slope movement events impacting its portals, <br />electric substation, conveyors, refuse pile, and haul roads. <br />The following comments apply specifically to the indicated <br />surface facilities. <br />Haul Road Along the Railroafl Bed - Drainage <br />26. BRL proposes to build this road without a sediment control <br />facility. Further, BRL requests a variance because a <br />portion of these facilities lie within 100 feet of the <br />Right-of-Way for old State Highway 133. Old Highway 133 <br />appears to provide access for several of the neighboring <br />residents as well as the Bowie No. 2 mine. If Highway 133 <br />were compromised emergency access might be eliminated to the <br />mine and the neighbors. BRL will have to provide detail <br />concerning the existing drainage conveyances along and under <br />old Highway 133 to demonstrate that changes within the mine <br />permit area, which affect water retention and routing will <br />not overload the existing ditches and culverts and <br />compromise the old Highway. Further, BRL will have to <br />specify which alternative sediment control devices and <br />techniques will be implemented and at what specific <br />locations. <br />Haul Road Reclamation <br />27. BRL states; "The haul road from old State Highway 133 to the <br />portal area will not be totally reclaimed." As with all the <br />roads, benches and surface facility disturbances at this <br />challenging site, BRL will have to propose specific <br />reclaimed configurations for all areas. Cuts and <br />embankments proposed to be retained as part of the reclaimed <br />configuration will have to be analyzed to demonstrate their <br />structural and geomorphic stability. Particular attention <br />will have to focused upon the drainage facilities because of <br />the deleterious effects of introduction of water to <br />landslide landforms. In the case of the Mount Gunnison No. <br />1 mine, stability analyses determined that many of the <br />retaining walls along roadways and portal bench cuts need to <br />be backfilled in place to attain stable final reclaimed <br />slopes. <br />