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GEOTECHNICAL STABILITY EXHIBIT <br /> There are no buildings or any structures outside the Breeze Basin Sand & Gravel Pit permit area <br /> which could be affected by the excavation. Sufficient buffers will be maintained to neighboring <br /> property lines. <br /> The final slope will be created during mining, and thus no backfill will be needed. The sand and <br /> gravel will be mined to a 3H:1 V slope with a loader and dozer. The native alluvial material is best <br /> classified as sand and gravel, mixed grain size. It has an internal angle of friction of 45 degrees and <br /> no cohesion. Material properties area derived from Table 2.5 in the SME Mining Reference <br /> Handbook', as there is no site specific sample data of the material available. <br /> Two models of the mining and reclaimed slopes were analyzed. One, while the mining slopes were <br /> exposed by pit dewatering, and the other the permanent condition of a lake surrounded by reclaimed <br /> slopes. <br /> 1. Mining Slopes <br /> Mining slopes, during dewatering, will have minimum safety factors below 1.5 (GALENA model <br /> Analyses 1 & 2),which is the DRMS minimum required. However,the 1.5 FOS failure circle is <br /> well within the permit boundary (marked as 0' on the X-axis of the GALENA models). No <br /> structures within 200 feet of the permit boundary will be affected by any slope failure in this <br /> condition. <br /> 2. Reclaimed Slopes <br /> Reclaimed slopes, with a lake in place, will have a minimum safety factor of 2.4. This is shown on <br /> GALENA model Analysis 4. This FOS is well above the minimum required by DRMS in this <br /> situation (DRMS FOS >1.5). Therefore, no structures within 200 feet of the permit boundary are at <br /> risk to slope failure upon reclamation of the Breeze Basins slopes. <br /> ' Original source: Houk and Bray 1977 <br /> Breeze Basin /a ry l r—,h,and kSs"ClAt 5,PIA X <br /> October 2019 <br />