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D.6.8 Stability <br />• D.6.8.1 General <br />Two dimensional stability analyses have been performed <br />on the main tailings embankments, collection pond berm, and <br />impoundment dikes for the maximum sections and under critical <br />loading conditions. The stability analyses were performed using <br />the PC STABL4 computer program developed at Purdue University. <br />This program is capable of computing factors of safety for <br />circular, random, and planar slip surfaces by using limit <br />equilibrium methods. The two techniques used for the slope <br />stability analyses are listed below: <br />u Simplified Janbu method of slices for the random <br />generation of circular slip surfaces (PC STABL4 <br />option CIRCLE); and <br />• u Simplified Janbu method for wedge slip surfaces <br />(PC STABL4 option BLOCK). <br />The following sections discuss the methods and results <br />of the stability analyses in more detail. <br />D.6.8.2 Main Embankment <br />The main embankment has an upstream slope of 2.5H:1V. <br />This slope was chosen to minimize embankment fill volume, while <br />satisfying stability requirements. The stability of the <br />upstream face will increase with time as tailings are deposited <br />and buttress the slope. The downstream face of the embankment <br />is characterized by a uniform slope of 3H:1V. This slope <br />gradient chosen to meet stability and reclamation <br />considerations. <br />U <br />D-60 <br />