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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 /> The final backfill is best classified as loose sand. This material has an internal angle of friction of <br /> approximately 34 degrees and no cohesion. The underlying material placed by dozer push to 2H:1 V <br /> is the native sand and gravel found onsite. This is classified as Sand and gravel, mixed grain size. It <br /> has an internal angle of friction of 45 degrees and no cohesion. Material properties area derived from <br /> Table 2.5 in the SME Mining Reference Handbook', <br /> A GALENA software analysis of the permanent slope condition was conducted with the above <br /> material properties and assumed a full lake. The lake level is roughly five feet below the natural <br /> topography. Final slope conditions are 3H:1 V to 10 feet below the lake level, and then 2H:1 V down <br /> to the lake bottom. The GALENA model used Bishop's method of slices iteratively to find the <br /> failure slope with the lowest factor of safety. This analysis showed a FOS of 1.39 for the lowest <br /> scenario. The minimum FOS DRMS requires for a slope near non-critical structures is 1.3. <br /> Therefore, the slope at BRS&G Pit 1 are stable in the permanent case. <br /> IN •• •C <br /> 0047151 m <br /> ONR1.E�C�� ..M <br /> Ben , P.E. <br /> P.E.# 0047151 <br /> ' Original source: Houk and Bray 1977 <br /> BRS&G Pit 1 c:,•k i,,»aAi aa �s„ i ,.ri i <br /> Alarch 2019 <br />