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evaluated. If the worst case scenario proved to be stable, then the other embankments with lesser <br />height and shallower slopes should be stable. ~ • <br />A force limit equilibrium stability analysis was completed using the SLOPE/W software package. A <br />Morgenstern Price analysis was used in conjunction with a search routine to estimate the lowest safety <br />factor for the embankment. This method satisfies both moment and force equilibrium of a given <br />analysis. <br />For the worst case scenario, embankment geometry with the following characteristics was used: <br />• Embankment Crest Width: 5 feet <br />• Downstream Slope Height: 9 feet <br />• Downstream Slope Angle: 2H:1 V <br />• Upstream Slope Height: 8 feet <br />• Upstream Slope Angle: 2H:1 V <br />• Height from Spillway Invert to Upstream Slope Toe: 5 feet <br />This geometry is illustrated by SLOPE/W output shown on Figure 13-A, Stock Tank Stability. <br />The embankments will be constructed from spoil material produced during mining. This material is • <br />placed in controlled lifts and compacted. Based on this fact, observations of the on-site spoil piles, and <br />typical strength values for spoil material, the following strength properties were assigned to the <br />embankment. <br />• Spoil: ~= 38°, cohesion = 0 psi <br />• Unit Weight: 120 pcf <br />Based on the above stated assumptions, safety factor of 1.56 was calculated by the limit equilibrium <br />analysis. Rule 4.05.918116) states that the stock tanks require a safety factor of 1.3. Therefore, these <br />structures should perform adequately during the life of mine. In addition, stock tanks will be located so <br />that there are no potential safety hazards to downstream structures; therefore, if a failure did occur, <br />there would be minimal risk to life and property. <br />• <br />~~ <br />7> Revised 8/03 <br />