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Cripple Creek&Victor Gold Mine <br /> Valley Leach Facility Expansions ■ <br /> Detailed Design for Permitting <br /> NewFields Project No.475.0106.064• <br /> March 2024 <br /> 5. GEOTECHNICAL EVALUATION <br /> A geotechnical evaluation was completed to assess the global stability and potential settlement <br /> of the proposed VLF Expansion Phase 4 and 6 slopes and facility. The results of the evaluations <br /> are discussed in the following sections. <br /> 5.1. Stability Evaluation <br /> Stability analysis was completed using the computer program SLIDE2 v.9. The results of <br /> Morgenstern-Price and Spencer method of slices were implemented within SLIDE2 to evaluate <br /> the factor of safety, confirm convergence within the model, and ensure accuracy of results. <br /> Circular and non-circular failure forms were evaluated. Non-circular failure forms were found to <br /> produce more conservative results and are presented herein. <br /> Minimum acceptable factors of safety for static and pseudostatic conditions are 1.40 and 1.15, <br /> respectively. This acceptance criterion meets the requirements of both the Colorado Division of <br /> Reclamation Mining and Safety (DRMS) guidelines and the Newmont Tailings and Heap Leach <br /> Facility Management Standard and remains consistent with previous evaluations. The model <br /> development, material properties, and results of the stability analyses are expanded on in the <br /> 11111 following sections and presented in Appendix E. <br /> 5.1.1. Model Development <br /> A total of five cross sections were evaluated for the VLF Expansion. The cross sections depict the <br /> regions with the greatest elevation difference between the stacked ore and base grade. The <br /> specific locations were selected to represent the most critical conditions where the VLF reaches <br /> its highest point along both outward and inward facing foundation contours. The stability <br /> sections were created by superimposing the as-built liner surfaces, existing VLF surface, and <br /> proposed VLF Expansion surfaces. <br /> Subsurface conditions beneath the VLF Expansion were discussed in Section 2.5. In general, <br /> existing boreholes and test pit logs, geophysical velocity profiles, as well as the geologic model <br /> provided by CC&V were used to develop the subsurface stratigraphy. Groundwater under the <br /> VLF was not modeled as it is very deep and is not expected to influence the facilities stability. <br /> Phreatic conditions within the facility were modeled at approximately 0.5 feet above the LLDPE <br /> liner, representing a fully drained VLF with minor accumulation of solution along the base <br /> geomembrane. <br /> • <br /> Page 17 <br />