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Case 8-2 — Electric Line/Poles West of Phase 8. <br /> The proposed setback for mining is 60 feet from the electric line/poles. The <br /> mining depth was assumed to be 38 feet in this area based on bore log <br /> information in the geotechnical investigations. <br /> Case 8-3 — County Road HH.5 to the South of Phase 8. <br /> The proposed setback for mining is 75 feet from the edge of the road. The mining <br /> depth was assumed to be 29 feet in this area based on bore log information in <br /> the geotechnical investigations. <br /> Case 8-4 — Edge of Highway Realignment Parcel to the East of Phase 8. <br /> The proposed setback for mining is 50 feet from the edge of the parcel. The <br /> mining depth was assumed to be 36 feet in this area based on bore log <br /> information in the geotechnical investigations. <br /> The cross-sections located in Appendix B show the proposed mining slope geometry, <br /> estimated phreatic surface, location of the man-made structures relative to the mining <br /> slope, and location of the most critical slope failure surface for each case. <br /> V - METHODOLOGY <br /> The mining embankment configuration shown in the computer analysis represents the <br /> estimated conditions for this site. If mining conditions differ from the estimated <br /> conditions, the slope stability will need to be re-evaluated on a case by case basis. The <br /> Bishop Method was used in the computer analysis for determining safety factors. The <br /> procedure searches for circular shear failures and automatically searches for the lowest <br /> safety factor. 20,000 separate failure surfaces were analyzed for each case. The <br /> required minimum safety factors are based on the current standards detailed in the <br /> Policies of the Mined Land Reclamation Board (MLRB). <br /> VI - SLOPE STABILITY RESULTS <br /> Per the current policies of the MLRB, critical structures with assumed soil strength <br /> values require minimum factors of safety of 1.5 and 1.3 for static and pseud-static <br /> analyses respectively. Non-critical structures with assumed soil strength values require <br /> minimum factors of safety of 1.3 and 1.15 for static and pseudo-static analyses <br /> respectively. Each case analyzed used the appropriate critical or non-critical factors of <br /> safety for the structure as shown in the analysis results tables below. The calculated <br /> safety factors exceed the minimum required and can be considered indicators of the <br /> mining slope performance under the various conditions. The slopes were analyzed <br /> using full and rapid drawdown reservoir conditions. The results of the static condition <br /> and pseudo-static condition slope stability analyses are summarized in Table 2 and <br /> Table 3 below. <br /> ' West Farm Gravel Pit Expansion <br /> Slope Stability Analysis <br /> Page 4 <br />