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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 loose <br /> sand. This material has an internal angle of friction of approximately 34 degrees and no cohesion. <br /> The Factor of Safety (FOS) for sand and gravel with a(3H:1V) 18.4 degree slope in loose sand <br /> material with an assumed internal angle of friction of 34 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 34' 0.6745 <br /> FOS = — = 2.02 <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 /> Ben Langenfeld, P.E. <br /> �,1 _ � P.E.# 0047151 <br /> r <br /> Date: <br /> Original source: Houk and Bray 1977 <br /> Base Products Gravel Pit#1 <br /> February 2018 GS-1 <br />