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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 /> 5.2.1. Model Development <br /> Potential settlement was evaluated for critical sections beneath the VLF Expansion that include <br /> portions of the facility that will be expanded over VLF2, the VLF1 slopes surrounding the PSSA, <br /> and the portion of the facility constructed over the backfilled Elkton Pit. The sections evaluated <br /> are shown on Figure 1 in Appendix E. <br /> Three VLF Expansion sections were selected for settlement evaluation.Section A presents an area <br /> of substantial ore stacking on top of fill materials. This section represents the area of largest <br /> differential settlement and strain. Section D presents an area of substantial pit backfill and ore <br /> stacking over top of the full pit profile. The PSSA section presents a typical cross section of the <br /> double lined pond and was selected for evaluation to ensure the PSSA volume is not reduced by <br /> settlement. <br /> RS2 uses an advanced meshing algorithm to generate a base mesh for the model. The mesh <br /> density for the presented models was further refined and increased in locations where stress <br /> concentrations were expected. The model used grid element sizes ranging from as large as 60 <br /> feet in areas outside of the Elkton Pit, to less than 1 foot in locations of stress concentrations <br /> such as the abrupt transitions from intact bedrock to backfill near the Elkton Pit walls. Variations <br /> 111 <br /> in grid size were investigated, and the final grids utilized in the presented models were found to <br /> be sufficiently dense to develop accurate estimates of long-term settlement. <br /> 5.2.2. Material Properties <br /> Material properties used in the settlement evaluation were developed in the VLF2 Phase 3 design <br /> (NewFields, 2020) and are summarized in Table 5.3 and further discussed below. <br /> Table 5.3—Material Properties <br /> Unit Subgrade Modulus <br /> Compactive Poisson <br /> Material Effort Weight Ratio Isotropic Tangent Modulus <br /> (pcf) (ksf) m a <br /> Ore(Existing and Proposed) N/A 120 0.2 700 N/A N/A <br /> • <br /> High 130 0.4 N/A 225 0.5 <br /> Pit Backfill and Fill <br /> Low 120 0.3 N/A 150 0.5 <br /> Foundation(Sand and Gravels) Low 125 0.4 N/A 225 0.5 <br /> Foundation(Bedrock) N/A 150 0.4 le+6 n/a n/a <br /> • <br /> Page 22 <br />