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lJ <br />SMITH WILLIAMS CONSULTANTS, INC. <br />Project: CCBV Phase 5 VLF Job No. 1125 <br />Calculation TRIe: <br />VLF Foundation Settlement Under 800 ft <br />Pre ared B : JFL Date: Februa 22 2008 <br />Checked B : DTW Date: March 14 2008 <br />to the ore at field capacity moisture content. <br />• Bedrock is modeled as aMohr-Coulomb material with a friction angle of 40 degrees and <br />zero cohesion. The unit weight of the bedrock is 140 pounds per cubic foot. <br />CALCULATIONS: <br />A finite element mesh was constructed for the section of interest. Amedium-size mesh was used for <br />the ore and bedrock, since deformations of these materials aze not critical to this analysis. To <br />provide high resolution data for the ore/structural fill interface (where the geomembrane liner is <br />located), the finite element mesh was refined to an average element size of approximately 20 feet. <br />The model was first used to calculate the foundation settlement under 590 feet of ore depth (Phase 1 <br />calculation), which is the Amendment No. 8 maximum ore height. The model deformations were <br />then re-set to zero and the incremental settlement resulting from stacking the ore to 800 feet was <br />calculated (Phase 2 calculation). <br />The model output report is attached, which includes the finite element mesh, material distribution, <br />and basic results. It is important to note that the model spans across the Phase I and Phase IV edge <br />of liner, which would reflect strain across the anchor trenches. In order to assess the potential <br />impact on the anchor trench areas, calculation points placed within the model along the surface of <br />the structural fill at the anchor trench locations. <br />CONCLUSIONS: <br />The PLAXIS model results report is attached to this calculation sheet. In order to assess the <br />potential strain on the liner, calculation points were added to the model along the ore/structural fill <br />interface under the maximum ore depth (see model output). These points aze plotted as global sheaz <br />strain versus mean stress (attached to the report). Sheaz strain was selected since this would reflect <br />extension of the geomembrane liner by foundation settlement (in two dimensions). <br />Data from the model and the calculation points show that after the VLF is loaded to 590 feet with <br />ore, the global strain on the liner is approximately 3.5 %, which is acceptable for the liner systems. <br />® After the VLF is loaded to 800 feet, the additional strain on the liner is approximately 1.5%, for a <br />total strain of 5%, which is acceptable for the VLF liner systems. The sheaz strain plots aze <br />presented in Figure 2. <br />