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HAWK'S NEST MINE <br />PERMIT STIPULATION N0. 18 <br />Permit stipulation number 18 (OSP1 stipulation number 17) requires <br />a stability analysis of any cut slope or fill slope adjoining roadways <br />at the Hawk's Nest Mines which exceed the maximum regulatory slope limits <br />contained within Rule 4.03. As shown on the drawi;igs of mine roads <br />which accompanied the permit application, several cut and fill slopes <br />exceed the maximum regulatory slope limits; however, none exceed a slope <br />of 1:1 or 1000. It was decided therefore, to do a "worst case" analysis <br />to demonstrate that soil material forming cut slopes and used as fill <br />material have a safety factor greater than the minimum required by Rule <br />4.03. Paterial used as fill is the same as that in the cut slopes and <br />is the soil found along the slopes occupied by the mine. This material <br />is assumed to be substantially uniform from East Mine to West Mine based <br />on similarity of geology, aspect and slope. <br />Attached is a report describing the lab analysis of the material <br />sampled and the calculations used to determine the safety factor. The <br />results show a cut slope safety factor range of 7.5 for a 100 slope <br />10 feet high to a safety factor of 2.4 for a 100 slope 40 feet high. <br />For fill slopes of 100$ the safety factor is 2.46 at 10 feet deep to <br />2.12 at 30 feet deep. Those cut and fill slopes at the mine which exceed <br />the maximum of Rule 4.03 average less than 10 feet which produces a <br />higher safety factor. This analysis demonstrates that the cut and fill <br />slopes in question meet the requirements of Rule 4.03. <br />