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LONDON MINE <br /> M-2023-015 <br /> Rule 6.5 <br /> Geotechnical Stability Exhibit <br /> The two permitted site areas contain no geologic conditions that would present geotechnical hazards, <br /> either during operation or after reclamation, and there are no offsite surrounding lands which could be <br /> adversely affected by geotechnical conditions during the proposed activities in the permit area. All <br /> materials to be affected are pre-mined or were moved previously;there will be no excavation below the <br /> surface of native materials. <br /> Slope Gradients <br /> The slope gradients on the South London Stockpile area presently range from 0%(level)to 40%. The <br /> level portion is on the top of the waste dump;the steepest portion is on the outslope of the dump, <br /> which is an angle-of-repose gradient which has existed stably for many years.The natural gradient on the <br /> undisturbed hillslope surrounding the South London Stockpile averages 20%. Since the waste rock to be <br /> removed from this site was placed directly on the original hillslope,the site will again attain an <br /> approximate slope of 20%after mining has ceased and the site is reclaimed. <br /> The gradients in the Sorting Plant area range from 25 to 45% in the upper portion, and 2 to 30%in the <br /> lower portion. Steepest slopes are found on the cut slopes and fill slopes of the old roadways;these <br /> have demonstrated their stability over the years that they have existed. Some of the roads will be used <br /> in this operation and will be maintained. The gentler gradients on this site are in the lower portion <br /> where the stockpiling, sorting, and other mining activities will be carried out. The operating pad and <br /> pond area in the lower portion are currently nearly flat, and will be cleared and graded to level for the <br /> mining phase. Suitable controls will be installed at the outer edge of the pad area,to contain runoff and <br /> rolling material. The outslope of the pad and pond area (above and facing Mosquito Creek) are largely <br /> outside the permit boundary and will not be disturbed. <br /> Material Description <br /> The waste rock to be moved and sorted, and then placed for permanent disposal ranges in size up to two <br /> inches, and contains a significant amount of fine material less than 0.1 inch. It is angular and,when <br /> emplaced for final disposal, is able to be compacted and remain in place. <br /> The operations pad is composed of native material and old waste rock. Its texture and size ranges are <br /> similar to the upper waste rock stockpile that will be handled during mining; it behaves similarly to the <br /> waste rock and can be easily stabilized during mining and for reclamation. <br /> Material Placement <br /> Reclamation will involve permanent placement of sorted waste rock and final grading of other site <br /> surfaces. Materials will be moved by loader and dozer, deep fills placed in lifts,shaped, and compacted. <br /> No slopes will exceed 30%, and all areas will initially have appropriate sediment/runoff controls installed. <br />