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Continued. <br />1.0). The criteria for minimum safety factors for operations are 1.3 for static conditions <br />and 1.1 for seismic conditions (DRMS, 2015). <br />Seismic loading conditions were modeled using a pseudo -static approach, conservatively <br />assuming a pseudo -static coefficient of 0.14 g. This is consistent with the stability <br />evaluations presented in the MLE2/Amendment 10. <br />3.3 Model and Cross -Sections <br />The following material profile was used in the models (from top to bottom): <br />• Ore and Drain Cover Fill: Spent ore and DCF placed within the PSSA were <br />modeled as a single material type as their shear strength properties are assumed to <br />be similar. <br />Composite Liner System: The composite liner system within the PSSA consists of <br />(from top to bottom): (i) 2 -feet of DCF; (ii) 100 -mil smooth LLDPE primary <br />geomembrane; (iii) 3 -feet of low volume solution collection fill; (iv) 100 -mil single - <br />sided textured LLDPE secondary geomembrane; and (v) 1 -foot soil liner fill. The <br />liner system was modeled considering a single 1 -foot thick layer with a shear <br />strength corresponding to the critical interface which could correspond to either the <br />secondary geomembrane / soil liner fill interface or the primary geomembrane / <br />drain cover fill interface. <br />• Foundation Material: Based on the results of previous geotechnical investigations, <br />the VLF foundation material consists of a relatively high strength foundation material <br />representing competent bedrock materials or granular native soils. <br />Two cross-sections were developed based on current conditions of the PSSA. Section A <br />is representative of exposed drain cover fill with no ore stacked on 2.51HI:1 V slopes. <br />Section B is representative of spent ore placed partially into the PSSA. Section B was <br />developed by comparing the design grading plan of the PSSA to a Lidar survey of the <br />area dated June 3, 2015. The locations of the cross-sections evaluated are presented <br />on Figure 1. <br />3.3 Evaluation Criteria and Material Parameters <br />Consistent with the SGVLF design, Table 1 presents criteria and material properties <br />pertinent to this stability evaluation. Further discussion of material strength properties are <br />discussed below. <br />Table 1 - Criteria and Material Properties for Stability Evaluation <br />Parameter <br />Value <br />Ore and DCF shear strength <br />0'= 40°, zero cohesion <br />Composite liner interface shear strength <br />0' = 23.59, zero adhesion <br />Foundation materials shear strength <br />0' = 409, zero cohesion <br />Operational design earthquake acceleration <br />0.14 <br />Minimum operational factor of safety static <br />1.3 <br />Minimum operational factor of safety (pseudo -static) <br />1.1 <br />Page 3 of 7 <br />