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V_'A <br />WIX <br />SMITH WILLIAMS CONSULTANTS, INC. <br />Project: Phase 5 VLF Job No. 1125 <br />Calculation Title: Arequa Phase 5 VLF Stability Calculations <br />Prepared B : Justin Hall Date: 3/19108 <br />Checked B : John Lupo Date: 3119108 <br />peak acceleration that quickly decays to lesser accelerations. Consequently, the duration that a mass <br />is actually subjected to a unidirectional, peak seismic acceleration is finite, rather than infinite. The <br />pseudo-static analyses conservatively model seismic events as constant acceleration and direction, <br />i.e., an infinitely long pulse. Therefore, it is customary for geotechnical engineers to take only a <br />fraction of the predicted peak maximum acceleration when modeling seismic events using <br />pseudo-static analyses. Two-thirds the peak ground acceleration generated from the maximum <br />credible earthquake (Hynes and Franklin, 1984), was used in the analysis. For the Phase 5 VLF <br />within Arequa Gulch, the horizontal coefficient of ground acceleration were 0.14g and 0.08g for <br />operational and closure conditions, respectively. <br />• Cross section geometry was delineated from SWC designed ore stacking configurations and existing <br />ground topography from CC&V, revised from photography completed 9/28/06. The areas of <br />revision were based in part from survey data supplied from Foresight West Surveying, Inc. 5/9/07. <br />LAI <br />E <br />• The geomembrane liner for the phase 5 VLF will consist of 80-mil single sided textured Linear Low <br />Density Polyethylene (LLDPE). <br />The material properties used in the analyses were based on previous laboratory testing, field <br />investigations, experience with similar materials, and based on previous amendments. Descriptions <br />of the materials and the basis for the shear strength are summarized below: <br />Material properties summarized in the below table are described by a linear Mohr-Coulomb failure <br />envelope. <br /> <br />Materials Moist Unit <br />Weight <br />c Saturated <br />Unit Weight <br />c Effective <br />Friction Angle <br />(deg) Cohesion <br />(pst) <br />Cross Section <br />Cresson Ore 110 118 40 0 A B C D E,F,G,H I <br />Foundation Soil 120 125 26 0 A,B D E F G,H I <br />Structural Fill 120 125 38 0 A B C D E F I <br />Rockfill Waste Dump) 120 125 * 0 C <br />Ph.5 Liner/Soil Interface 120 125 18 0 A B C D E F <br />Ph.IV Liner/Soil Interface 120 125 18 0 I <br />Ph.I11 Liner/Soil Interface 120 125 18 0 H <br />Ph.II Liner/Soil Interface 120 125 15 1600 H ,G <br />Ph.l Liner/Soil Interface 120 125 24 100 G <br />See 1 able uelow <br />The rockfill material was modeled with a nonlinear shear/normal strength envelope (Leps, 1970) <br />and is summarized in the table below.