2020-12-08_REVISION - M2008078 (27)

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Table 3 - Pseudo-Static Condition Slope Stability Analysis Results Description Calculated Required Factor Minimum of Safety Factor of Safety Case 3-1 -Ditch Bank West of Phase 3-Full Reservoir 2.57 1.3 Case 3-1 -Ditch Bank West of Phase 3-Rapid Drawdown 1.54 1.3 Case 3-2- Highway Parcel East of Phase 3-Full Reservoir 2.14 1.15 Case 3-2-Highway Parcel East of Phase 3-Rapid Drawdown 1.24 1.15 Case 3-3-Highway Parcel North of Phase 3-Full Reservoir 1.99 1.15 Case 3-3- Highway Parcel North of Phase 3-Rapid Drawdown 1.16 1.15 Case 4-1 -Electric Line/Poles East of Phase 4-Full Reservoir 2.32 1.3 Case 4-1 -Electric Line/Poles East of Phase 4- Rapid Drawdown 1.42 1.3 Case 4-2- Ditch Bank South of Phase 4- Full Reservoir 2.31 1.3 Case 4-2- Ditch Bank South of Phase 4- Rapid Drawdown 1.38 1.3 Case 5-1 -Conservation Easement East of Phase 5-Full Reservoir 1.92 1.15 Case 5-1 -Conservation Easement East of Phase 5-Rapid Drawdown 1.17 1.15 Case 5-2-Canal Bank South of Phase 5-Full Reservoir 2.72 1.3 Case 5-2-Canal Bank South of Phase 5-Rapid Drawdown 2.00 1.3 Case 6-1 -Conservation Easement East of Phase 6-Full Reservoir 1.97 1.15 Case 6-1 -Conservation Easement East of Phase 6-Rapid Drawdown 1.17 1.15 Case 6-2-Canal Bank South of Phase 6-Full Reservoir 2.68 1.3 Case 6-2-Canal Bank South of Phase 6-Rapid Drawdown 1.82 1.3 Case 7-1 - Elec/Gas Lines North of Phase 7-Full Reservoir 3.05 1.3 Case 7-1 -Elec/Gas Lines North of Phase 7-Rapid Drawdown 1.92 1.3 Case 7-2-Canal Bank South of Phase 7-Full Reservoir 2.23 1.3 Case 7-2-Canal Bank South of Phase 7-Rapid Drawdown 1.32 1.3 Case 8-1 - Elec/Gas Lines North of Phase 8-Full Reservoir 3.55 1.3 Case 8-1 -Elec/Gas Lines North of Phase 8-Rapid Drawdown 2.39 1.3 Case 8-2-Elec Line/Poles West of Phase 8-Full Reservoir 2.19 1.3 Case 8-2- Elec Line/Poles West of Phase 8-Rapid Drawdown 1.33 1.3 Case 8-3-County Road HH.5 South of Phase 8- Full Reservoir 2.70 1.3 Case 8-3-County Road HH.5 South of Phase 8-Rapid Drawdown 1.77 1.3 Case 8-4-Highway Parcel East of Phase 8-Full Reservoir 2.14 1.15 Case 8-4- Highway Parcel East of Phase 8- Rapid Drawdown 1.33 1.15 VII - CONCLUSIONS AND RECOMMENDATIONS Case 3-1 - The resulting safety factors of 1.85 (static) and 1.54 (pseudo-static) during a rapid drawdown condition exceed the minimum required MLRB safety factors of 1.5 (static) and 1.3 (pseudo-static) for critical structures. The resulting safety factors of 3.47 (static) and 2.57 (pseudo-static) during a full reservoir condition also exceed the minimum required MLRB safety factors for critical structures. The proposed setback of 85 feet from the edge of the ditch bank is satisfactory. West Farm Gravel Pit Expansion Slope Stability Analysis Page 6