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Transit Mix <br /> 12/30/16 <br /> Page 2 <br /> Two stability cases were analyzed for the embankment: 1) Long Term Steady-State, and 2) <br /> Long Term Pseudo-static. Long Term Steady State considers the extended term stability of the <br /> dam embankment at the design elevation (full wash fines pond elevation 5,807 ft and steady <br /> state seepage condition) and the soil strength is characterized by the effective stress <br /> parameters in drained conditions. Pseudo-static introduces seismic loading to the long term <br /> steady state model. A maximum downstream slope height of 30 feet was selected for analysis. <br /> For the slope stability analysis, the phreatic surface was generated using SEEP/W. The analysis <br /> considered the maximum reservoir pool. The embankment dam and foundation soil properties <br /> are based on conditions encountered during Brierley's subsurface investigation and laboratory <br /> results. Mohr-Coulomb strength criterion framework was utilized to define soil and bedrock <br /> strengths. Mohr-Coulomb assumes an inherent cohesion in over-consolidated fine-grained or <br /> cemented soils and bedrock. The strength properties used in each analysis are based on <br /> available soil classification laboratory test results and engineering judgement and experience. <br /> The engineering properties are summarized in the table below. <br /> Table 1. Engineering Pro erties for Slope Stabilit I Analysis <br /> Embankment Wash Eolian Coarse Pierre <br /> Property Fill Fines Foundation Alluvium Shale <br /> Material Bedrock <br /> Unit We ig ht c 130 90 125 135 135 <br /> Cohesion 100 0 100 0 500 <br /> Effective sf <br /> Stress Friction(degrees) 35 10 32 35 30 <br /> Slope stability modeling results for the Long Term Steady-State condition is shown in Figure 1. <br /> BRIERLEY <br /> ASSOCIATES <br /> Creating Space Underground <br />