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Pitch Reclamation Project • Sediment Control Embankment November. 2002 <br />estimated factors of safety. A few stability analyses were run using a set of alternate shear strength <br />parameters to check the sensitivity of the revised shear parameters with respect to the calculated factor <br />of safety. The alternative values consider a slightly stiffer core material. However it was found that the <br />change in core material shear parameters did not impact the calculated factors of safety for the <br />downstream slopes. The critical surfaces (least value factor of safety) remained within the downstream <br />shell of the embankment and did not pass through any portion of the core. <br />The three cases listed on the following page are considered representative of the field <br />• <br />r1 <br />conditions for this evaluation: 1) the full height of the downstream slope, 2) the upper portion of the <br />slope from [he base of the wetted are up to the crest, and 3) the mid slope section bounded by the <br />upper and lower limits of the wetted area on the downstream face. The phreatic surface for these <br />stability runs were based on the upper and lower piezometer readings, and the assumed phreatic <br />surface used in the design analysis. <br />Table 3: Case 1 -Slope at Full Height <br />Phreatic Surface Design Parameters Revised Parameters Intr. Parameters* <br />Design Location 1.4 1.2 NA <br />Low Perched Level 1.2 1.1 1.1 <br />High Perched Level 1.2 1.06 1.06 <br />Table 4: Case 2 -Slope from Crest to Base of Wet Area <br />Phreatic Surface Design Parameters Revised Parameters Intr. Parameters* <br />Design Location 1.3 1.2 NA <br />Low Perched Level 1.3 1.2 NA <br />High Perched Level 1.2 1.1 NA <br />The Homestake Mining Company <br />The Glasgow Engineering Group, /rrc. <br />