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GEOTECHNICAL STABILITY EXHIBIT <br /> There are no buildings or any structures outside the permit area which could be affected by the <br /> excavation. Sufficient buffers will be maintained to neighboring property lines. <br /> From Table 2.5 in the SME Mining Reference Handbook, the backfill is best classified as sand <br /> and gravel, mixed grain size. This material has an internal angle of friction of approximately 45 <br /> degrees and no cohesion. <br /> The Factor of Safety (FOS) for sand and gravel with a (3H:1 V) 18.4 degree slope in loose sand <br /> material with an assumed internal angle of friction of 45 degrees can be approximated by <br /> evaluating the internal angle of friction as follows: <br /> FOS = Tangent of Internal Angle of Friction <br /> Tangent of Actual Angle of Failure Surface <br /> Tan 450 1.0 <br /> FOS = _ = 3.0 <br /> Tan 18.40 0.3326 <br /> The minimum safety factor in the permanent case is 1.5, therefore the 3H:1 V slopes will be safe <br /> as the final condition. <br /> Skelton Pit Lewicki&Associates <br /> January 2022 <br />