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A-2 J J 1 1 ll 1 1 will exit the slope. Other constraints, such as an elevation beneath which the failure surface is not permitted to pass, as might be used to represent a competent bedrock, are used to limit the failure surface to within required limits. The program then randomly generates circular failure surfaces within the defined limits and calculates the safety factors. The lowest safety factors and details of the corresponding circles are printed out to enable evaluation of the reason- ableness of the solutions. In the case of the initial waste rock storage pile, it was considered that the critical failure surfaces would probab- ly lie entirely within the waste rock. Failure surfaces were therefore constrained to lie entirely within the waste material, with exit points at the toe of the pile and in the vicinity of its crest. In order to verify that this type of failure is critical, subsequent analyses were performed in which the failure surface was permitted to penetrate the foundation material. Toe exit points were defined at various distances downslope from the toe of the pile to insure that the critical surface for a deep-seated type of failure had been located. These analyses confirmed that foundation failures are less critical than failures entirely within the waste material. Safe- ty factors increased with increasing distance of the toe exit goint from the toe of the slope. Several representative sections have been analyzed to evaluate the stability of the initial waste rock storage pile and its foundation. These stability sections have been developed to represent the critical (least stable) sections through the pile. They are taken at the maximum height of the pile (assum- ing width at the base of 200 ft.) and extend longitudinally through the pile so that the elevation of the pile increases slightly behind the crest; for transverse sections the elevation of the pile would decrease behind the slope crest, making trans- ceaNwRO cauu~nrw, iNC.