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I I I I I I I I I I I I I I I I I I I the downstream soli that will be against the dam toe. No downstream soli dead load or lateral earth pressure was used In the stability determination. The factor of safety for this case was found to be 1.54 for sliding and 1.75 for overturning. This case was examined to determine If the dam would be safe after an extreme event had caused erosion at the downstream toe, For the UNUSUAL condition this ecenarlo Indicated a factor of safety of 2.15 for sliding and 1.43 for overturning. All cases analyzed Indicate factors of safety greater than the minimum required. Only the Usual condition shown for Station I +26 for the sliding between lifts Indicates a lower than required factor of safety, This case Is misleading because the added lift length due to the I H to I V lower section Is not Included In the calculation, The sliding for this case between the foundation and RCC Indicates a factor of safety of 4.0 at the base and which Includes the total 11ft length. Thle would Indicate that the factor of safety between lifts would be greater than 4.0 as the cohesion between lifts used Is greater than between the RCC and the rock, The calculations for Station 1+26 are Included In the appendix as an example of the analyses conducted. STA. CASE FOUNDATION OVERTURN TENSILE SLIDING SLlDlNG F.S, STRENGTH F.S. BETWEEN F.S. RQD @ LIFT LIFTS (PSI) 0+26 USUAL 9.37 2,93 0 6.11 It 6' UNUSUAL 6,08 1.30 6 4.68 It 6" EXTREME 7.42 2.47 0 6.36 It 6' 1+25 USUAL 4,00 1.67 0 2.86 It 66' UNUSUAL 2.76 1.39 0 2.17 It 66' EXTREME 2.63 1.38 6 2,11 It 66' 2+26 USUAL 8.31 2.80 0 7.06 It 10' UNUSUAL 6,16 1.80 16 4,64 It 26' EXTREME 6.71 2,24 0 4.60 0 6' TABLE 2 CALCULATED FACTORS OF SAFETY Foundation rock cohesion = 2600 psf. Friction Angle = 46' RCC cohesion = 20 psi, Friction Angle = 46' Vertical &. Horizontal Earthquake Coefflcient = O.lg PAGE 4 Peterson Lake Dam Design Report