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RULE 6.5: GEOTECHNICAL STABILITY EXHIBIT <br /> There are no known geologic hazards on the proposed site. Based on a slope stability analysis, <br /> buildings or other structures within 200' of the Wertz Pit affected area will not be affected by <br /> mining excavation. The mine plan specifies a minimum buffer of 25-ft to the closest structure <br /> of power lines and poles. A standard slope was analyzed for stability. <br /> The material properties are derived from Table 2.5 in the SME Mining Reference Handbook', <br /> as there is no site-specific strength data of the material available. Therefore, all materials are <br /> matched to a classification from this table that best matches the materials in terms of <br /> description. The native alluvial material is best classified as sand and gravel with a mixed <br /> grain size. A layer of soil and sand lies atop the sand and gravel deposit. This material is best <br /> described as loose sand, mixed grain size. A summary of the material properties can be seen <br /> in Table GS-1. <br /> Table GS-1. Material Properties <br /> Material Unit Weight(lbs/ft) Cohesion Friction Angle <br /> Sand and gravel,mixed grain 110 0 45 <br /> size <br /> Loose sand,mixed grain size 1 99 0 34 <br /> The final reclamation (3H:1V) slope was analyzed. The final reclaimed slope crest will be the <br /> closest excavation comes to any structures. <br /> 1 . Reclamation Slopes <br /> Factor of Safety is expressed in terms of strength divided by stress as a ratio. It is arrived at by <br /> an iterative computer process where a slope failure is assumed, the strength and stress of that <br /> slope failure are calculated, and those values are compared to determine a lowest factor of <br /> safety. In the case of the Wertz Pit slope stability analysis, the Bishop's Method of Slices was <br /> the iterative calculation used, and the software GALENA was used to model slopes and <br /> calculate the factor of safety. One slope (see Figure GS-1) was analyzed to look at the factor of <br /> safety. Table GS-2 lists the analysis conducted and their respective factors of safety. <br /> GALENA data tables and analysis result figures are attached as Appendix GS-1. <br /> 1 Original source: Hoek and Bray 1977 <br /> Wertz Pit GS-, Lewicki& Associates <br /> November 2024 <br />