2025-06-23_REVISION - M1980244 (23)

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Docusign Envelope ID:45B9721 C-FDE2-4821-B686-80BBC79CA6DD while the infiltration gallery is in operation, the movement of fluid should be sufficient to prevent freezing inside any distribution equipment and the wells themselves. • b. What is the minimum distance from the crest of the 9550-foot lift that the first row of wells can be placed to be within the limits of the modeling and design. The minimum distance from the crest of the 9550'bench that the first row of wells can be placed is 15 feet as measured horizontally from the top of the screen to the daylight surface at the equivalent elevation on the 9500'to 9550'slope face. Due to the slope, this distance increases with increasing depth down hole, and thus the collar can be placed as close to the face as logistically possible without causing hydraulic issues at the bench face. The 15-foot spacing from the screened intervals horizontally to land surface is determined from the HYDRUS modeling of a single infiltration well, which shows the zone of saturation around the well limited to an approximate 15-foot radius. Figure 44-1 shows the 15- foot radius around the infiltration wells in profile view along a section that is perpendicular to the bench slope face, demonstrating that it does not intersect with the existing land surface. c. How is the system designed to either prevent siltation or plugging of the screen intervals or discuss how the facility will be maintained and wells replaced as necessary. Siltation or plugging of well screens should only be possible when the system is operating. When the system is not operating, it is anticipated that the piping system and well casings will be empty. Without fluid moving fine grained material into the well screen, plugging should not be a concern. Given the duration of operation of the system being on the order of single digit days per year, plugging as a result of flow into the system should also not be a concern. 45. Within Section 5.1.1, it states that cross sections to be analyzed were chosen based upon the maximum differences between stacked ore and base grade. Please provide additional documentation confirming that the cases presented are the most conservative possible 411 cases. This may be provided in the form of additional cases or other documentation confirming the conservatism of the provided cases.As presented in Appendix E, Cross Section D passes over what appears to be the access into the Elkton Pit in a southwest to northeast direction showing a maximum backfilled depth of approximately 175'; the Division requests at least one additional cross section analysis is provided which shows the main area mined of the Elkton Pit with the greatest extent of backfill in a west to east direction. An additional cross-section has been included in Attachment 10(Section D Prime) to analyze the main mined area of the Elkton Pit, capturing the greatest extent of backfill in a west-to-east direction as requested. However, the Elkton Pit is no longer included in the permit application and the additional section is still included to close out this comment. Additionally, the analyzed cross sections were selected to represent the most critical possible cases based on the maximum differences between the stacked ore and the base grades. Below is a detailed explanation of each analyzed section: • Section A: Represents the maximum heap height within the VLF 2 Phase 4 facility, ensuring that stability is assessed under the most extreme loading conditions for this phase. • Section B: While not the most critical section, this analysis was included to verify the stability of the upstream side of the facility, providing confidence in lateral stability. • Section C: Evaluated to confirm that the VLF2 Phase 4 facility will not fail into the VLF1 Phase 6 facility, ensuring structural integrity between adjacent phases. • Section D: Represents the maximum heap height within the VLF1 Phase 6 facility, ensuring the highest loading condition for the phase is accounted for. • Section E:Assess the upstream side of the VLF 1 Phase 6 facility, capturing potential stability • concerns associated with its location and surrounding conditions. SSR Mining Inc. PAGE 12/19