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WL D UFF RMR Aggregates, Inc. <br /> U N ❑ E R G R 0 U N C Rock Failure Analyses and Stabilization Report <br /> ENGIN E E R I N G,I N C Mid Continent Limestone Quarry <br /> Table 4. Slope Stability Design Standard <br /> Minimum Factor of Safety <br /> Consequence of Failure/ Generalized,Assumed, Strength Measurements <br /> Analyses or Single Test Strength Resulting from Multiple <br /> Measurements Tests <br /> Non-Critical Structures - <br /> 1.3 1.25 <br /> Static <br /> Non-Critical Structures— <br /> Pseudostatic 1.15 1.1 <br /> Critical Structures -Static 1.5 1.3 <br /> Critical Structures— <br /> Pseudostatic 1.3 1.15 <br /> For the RMR Aggregate site, the failure path of the slope could impact quarry facilities on the bench, <br /> and potentially impact life safety, therefore the structures were considered Critical. Static analyses <br /> were performed, together classified in Table 4 as "Critical structures—static". The slope stability <br /> analyses were performed using some historic data provided by the client, but the model input <br /> parameters were largely informed by empirical values that were confirmed through our backanalysis, <br /> classified as "Generalized, assumed, or single test strength measurements" in Table 4. Therefore, a <br /> FOS of 1.5 was considered as the minimum acceptable FOS for the project. <br /> As a cross check, other mine-industry references commonly used for recommendation of an <br /> acceptable minimum value for FOS include a table of minimum FOS for slope scale vs. consequence of <br /> failure from the Acceptance Criteria chapter in the Guidelines for Open Pit Slope Design manual, <br /> reproduced here as Table 5. <br /> Table S. Typical Mine Design Criteria for Slopes <br /> Wesseloo &Read, 2009$ <br /> Consequence of Failure <br /> Slope Scale <br /> Low Medium High <br /> Bench FOS >_ 1.1 <br /> Inter-Ramp FOS >_ 1.15-1.2 FOS >_ 1.2 FOS >_ 1.2-1.3 <br /> Overall FOS >_ 1.2-1.3 FOS >_ 1.3 FOS >_ 1.3-1.5 <br /> $Wesseloo,J. and Read,J. (2009). Chapter 9-Acceptance Criteria. In: Guidelines for Open Pit Slope Design,J. Read and P. <br /> Stacey(eds),pp 221-236. CIRSO publishing.496p. <br /> Page 11 <br /> 535 16th STREET,SUITE 620 1 DENVER,CO 80202 1 (303)732-3692 1 WWW.KILDUFFUNDERGROUND.COM <br />