2025-06-23_REVISION - M1980244 (92)

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Cripple Creek&Victor Gold Mine I Valley Leach Facility Expansions ■ Detailed Design for Permitting NewFields Project No.475.0106.064• March 2024 diameter and five(5) perforated twenty-four(24) inch and twenty-eight (28) inch diameter HDPE primary header pipes. Pipe connection and spacing details can be referenced on Drawing A025. As shown on Detail R on Drawing A025, two (2) feet of DCF cover shall be maintained on all HVSCS pipes larger than 6 inches. The smaller 4-inch diameter tertiary CPe collection pipes are spaced and arranged to direct flow into secondary and primary header pipes that will direct flow to the PSSA. The piping system has been sized to accommodate the maximum solution application flow rate of .0055 gallons per minute (gpm) per square feet(ft2) with a factor of safety of 1.5. The calculations have accounted for acceptable pipe deformations from being located beneath the loads of up to 800 feet of ore. Additionally, the pipes were spaced to reduce the hydraulic head on the liner system to 2 feet or less. Detailed calculations for the sizing of the various pipes can be referenced in Appendix D. As the HVSCS pipes leave the VLF2 Phase 4 limits, the primary pipes will transition from perforated to solid and routed to the 9550-foot bench located above ADR2. These pipes will empty the process solution into a tank. Under normal operating conditions, the process solution will then be routed directly to ADR2 where the minerals will be extracted from the solution and recycled onto the VLF. However, in upset conditions when ADR2 cannot accept a solution, the • process solution will be directed to an infiltration gallery constructed on the 9550-foot bench. The process solution within the VLF1 Phase 6 HVSCS will route flow to the VLF1 Phase 6 PSSA area and into the Solution Recovery System (SRS), as discussed in Section 4.4.3. 4.6.2. VLF2 Phase 4 Infiltration Gallery The Theis equation was used to evaluate single and total well field infiltration rates of the infiltration gallery above ADR2. Numerical modeling to assess groundwater mounding was performed in HYDRUS for a period of 24 hours. The gallery consists of a series of fifty-four (54) gravity fed, 4-inch diameter, 0.100-inch slotted PVC wells, spaced 38 feet perpendicular and 60 feet parallel to the bench. A blank section of PVC pipe will extend down 30 feet from the land surface to the top of the screened interval, followed by screen down to the elevation 50 feet above the liner. More information on the infiltration gallery modelling can be found in Appendix C. 4.6.3. Low Volume Solution Collection System The VLF1 Phase 6 PSSA design includes a system of 4-inch diameter perforated CPe pipes called the Low Volume Solution Collection System, located between the upper and lower layers of the 100-mil LLDPE geomembrane within the 3-foot layer of LVSCF material. The LVSCS will direct solution,via gravity,to the sloped riser pipes located below the HVSCS SRS.The riser pipes consist I Page 15