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(11 j-id6o, — � <br /> Geotechnical Stability Exhibit <br /> The permanent slopes in place at White River City will be 3H:1 V or shallower as shown on Map <br /> F of the approved permit. <br /> From Table 2.5 in the SME Mining Reference Handbook', the backfill is best classified as loose <br /> sand,mixed grain size. This material has an internal angle of friction of approximately 34 degrees <br /> 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 /> ignoring the cohesion component of the stability and simply evaluating the internal angle of <br /> 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 18.40 0.3326 <br /> The permanent slopes at the White River City Pit will be stable, and not risk any neighboring <br /> structures. <br /> •1W <br /> oi0 "Ni <br /> c,.. . � "EIVED <br /> + <br /> s 47 1 ,, <br /> 1.2 JUL 1 2017 <br /> 000*0 tiNr'�� <br /> of Reclamation, <br /> NALVrinIng& <br /> 'Original source:Houk and Bray 1977 <br /> White River City GS-1 +, f+v.L: n.1.1 1•.ristr 3't;< <br />