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Factor of Safety — Ratio of forces resisting movement to those driving <br /> movement. <br /> Slope Failure — the movement (sliding or collapsing) of rock and/or soil in <br /> response to gravitational stresses, often under the influence of a rainfall or <br /> seismic activity. <br /> Slope Stability — the resistance of inclined surface to failure by sliding or <br /> collapsing. <br /> Slope Stability Analysis — performed to assess the safe design of a human- <br /> made or natural slopes (e.g. open-pit mining, excavations, embankments, road <br /> cuts, etc.) and the equilibrium conditions. <br /> 30.2 — Declaration of Purpose <br /> The Division of Reclamation, Mining and Safety Minerals Program (Division) issues this <br /> memorandum to promote the orderly development of the state's natural resources while <br /> considering the industry's "standard of care" relative to Factors of Safety with the intent <br /> to: <br /> i. Protect and promote the safety and general welfare of the people of Colorado, <br /> ii. Ensure reclamation of lands affected by mining to beneficial use, and <br /> iii. Aid in the protection of aquatic resources and wildlife. <br /> 30.3 — Background <br /> In the past, the Division has typically accepted a factor of safety (FS) greater than 1 .0 <br /> for slope stability analyses to demonstrate "that such structures shall not be damaged <br /> by activities occurring at the mining operation" pursuant to Rules pertaining to <br /> permanent man-made structures and geotechnical stability: Construction Materials <br /> Rules 6.3.12(b) and 6.4.19(b) and 6.5 and Hard Rock Rules 6.3.12(b), 6.4.20(b) and <br /> 6.5. This practice was based on the oversimplified concept that a slope with a FS > 1 .0 <br /> is stable. This is technically true IF there is a comprehensive and <br /> complete understanding of all the geologic, hydraulic, land use, and other conditions <br /> that influence the forces and stresses determining whether or not the slope in question <br /> can or will fail. However, this is very rarely possible or feasible, particularly in a mining <br /> application. An FS must account for uncertainties (geologic setting, groundwater <br /> conditions, mining parameters, etc.), and the selection of an appropriate FS for slope <br /> stability should consider the following factors: <br /> 1 . Magnitude of damages (potential risk to human safety, environmental impact and <br /> property damage), <br /> 2. Reliability of geologic information such as the proximity to faults, orientation of <br /> jointing, and subsurface soil and water data, <br /> Effective May 16,2018 MLRB Policies Page 11 <br />