2014-06-16_REVISION - M1977493 - Laserfiche WebLink

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Christopher Schmitz June 2, 2014 Climax Molybdenum Company 2 1402712 001 TM01 RevO 2.0 DESIGN CRITERIA The interim OSF Loading Plan (OSF Plan) was provided to Golder by Climax on May 1, 2014. The ultimate OSF plan was previously provided on April 23, 2012. The interim OSF Plan and ultimate plan both use a footprint that is consistent with the operational requirements, post-closure requirements, and project design criteria for the facility. Based on Climax's current mine plan, the majority (approximately 70 percent) of the overburden material will consist of igneous and metamorphic rock excavated from the pit, which is either non-mineralized or contains uneconomical mineralization. The remaining approximate 30 percent of the overburden removed from the pit will consists of sedimentary rock primarily derived from the Minturn Formation shale, siltstone, and sandstone. It is common for mines to update OSF plans throughout the life of the project for a variety of reasons. These routine changes occur within the framework established by the project design criteria. Therefore, the relevant parameters in the design criteria were used to construct the ultimate OSF configurations for purposes of the stability analysis presented in Golder's OSF design report (Golder 2012). Sections constructed in this manner are intended to represent the "worst-case" cross-section geometry (i.e., steepest slopes) possible within the constraints of the design criteria. The relevant design criteria are listed below: ■ The interim OSF plan, toe limits of the ultimate OSF, and locations of the design cross sections are shown in Figure 1. ■ Operational scenario: • Inter-bench angle of repose slopes were modeled as II AH:1 V(or 36 degrees). • Operational benches were modeled as a nominal 200 feet wide. • The maximum height between benches was modeled as 200 feet. • Overall operational slopes were thus approximately 2.4H:1 V. • During operational stages, the low-grade ore stockpile, located in the southwest corner of the OSF footprint, may temporarily have angle of repose slopes in excess of 200 feet. These slopes were considered in the stability analysis. The proposed interim OSF Plan generally meets the above operational criteria slopes, with local exceptions of the operational bench widths, which vary from as narrow as 100-ft to greater than 400-ft width, resulting in a variable overall operational slope of the down gradient interim OSF between approximately 2.1 H:1 V and 2AH:1 V, with an average of approximately 2.2H:1 V. Golder considers the interim plan to be within the intent of the design criteria given that the minimum factors of safety are met. The acceptable stability factors of safety and the design earthquake conditions from Golder (2012) are summarized below: -r_ Golder 1A14\1402712\0100\0122\001 TM01 RevO\1402712 001 TM01 RM C1imaxMo1y0SFStabi1ityAna1ysis 02JUN14.docx - Associates