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GEOTECHNICAL STABILITY EXHIBIT <br /> There are no buildings or any structures outside the permit area that could be affected by <br /> excavation. Sufficient buffers will be maintained to neighboring property lines. <br /> From Table 2.5 in the SME Mining Reference Handbook, backfill is best classified as loose sand. <br /> 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:1 V) 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 /> FOS = Tan 34' _ 0.6745 _ 2.02 <br /> Tan 18.4° 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 /> f� <br /> • Ben Langenfeld, P.E. <br /> 7153 P.E.# 0047151 <br /> -a�,• /�j' .'� �' <br /> Date: l;IZ <br /> Garrett Pit ,. <br /> February 2018 GS-I <br />