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The ditch and power poles, being the nearest structure to the existing activity, are the focal point <br /> of the geotechnical stability analysis. It should be noted that the power poles and the ditch are <br /> very close to each other, with power poles directly abutting the south side of the ditch. In several <br /> location,the ditch has been routed through a culvert to protect the power poles from any bank <br /> erosion along the ditch. These facts regarding the power poles and the ditch's proximity were <br /> noted by DRMS during the last inspection. <br /> 2. Geotechnical Analysis—Worst Case Slope Identification <br /> The geotechnical stability analysis began with a review topographic survey of the pit and surveys <br /> of the location of each power pole, the ditch, and each ditch culvert. A set of sections was <br /> developed along the south side of the permit boundary and several possible worst case sections <br /> were identified for further review: <br /> 1. Station 6+30: A power pole is located very close to one of the culverts at this station, (<5 <br /> feet away) and the topsoil berm toe is within 20 feet of the culvert. The berm toe is closer <br /> to the culvert at Station 8+80', so no evaluation will be conducted for this section. <br /> 2. Station 8+80': A power pole is located within two feet of the ditch culvert at this station <br /> and the topsoil berm toe is within 15 feet of the culvert. The berm's slope stability will be <br /> evaluated. <br /> 3. Station 11+40': A power pole is within five feet of the edge of the ditch. The topsoil <br /> berm in this area is not present as it is the location of the site access. Similarly, the access <br /> ramp that proceeds down into the pit is of such a shallow slope that evaluating it for slope <br /> stability is unnecessary. Other sections are worse scenarios. <br /> 4. Station 38+20': The power pole is roughly 15 feet away from the edge of the ditch. The <br /> topsoil berm is roughly five feet tall relative to the ditch and at a slope of roughly 6H:IV. <br /> The internal slope within the pit, however, is closer to 2H:IV, and within 100 feet of the <br /> power pole and ditch. The highwall slope stability will be evaluated. <br /> 5. Station 61+50': The ditch is not present in this section. The power pole is within 100 feet <br /> of the active mining highwall. Therefore the mining highwall's slope stability will be <br /> evaluated. <br /> Each of these sections can be seen on the attached Map C-4. <br /> Three slope stability analysis will be conducted: Station 8+80 (topsoil berm), Station 38+20 <br /> (mining highwall), Station 61+50 (active mining highwall). <br /> 3. GALENA Model <br /> For each identified worst-case slope identified above a GALENA slope stability model was <br /> developed. This model was based on the following inputs: <br /> Material' Classification Density(lb/CF) Friction Angle Cohesion(lb/sq/ft.) <br /> Topsoil Loose sand, 99 34 0 <br /> mixed grain size <br /> Aggregate Sand and gravel, 110 4,5 0 <br /> mixed grain size <br /> 'Table 2.5,page 17,SME Mining Reference Handbook.2002.Originally Houk and Bray 1977 <br />