PERMFILE128342 - Laserfiche WebLink

Home Browse Search

area on the south side of the berm is filled, additional waste rock will be used to raise the starter berm. This operation will continue until the south waste rock disposal facility reaches its maximum elevation of 8,650 ft. The outer (north) side of the berm will be developed using 50-ft high angle of repose lifts with 75-ft bench setbacks far an average overall ' slope of 3H:1V. The initial and final facility plans are shown on Figures D.3-1 and D.3-2. Sections for the initial and final facilities are shown on Figure D.3-3. The initial stage will start accepting tailings following mill startup, currently anticipated at 1/2 year after heap leach startup. The ultimate south waste rock disposal area will store all the tailings generated as part of the San Luis Project. D.3.5 Stability The stability of the waste rock disposal areas has been evaluated using judgement based on past experience with similar facilities in conjunction with computerized slope stability analytical methods. The computer program used, P~;STABL4, was I developed at Purdue University and is described in detail by Carpenter (1985). The circular (CIRCLE2) subroutine was used to evaluate the stability of the waste ro~:k disposal facilities. In addition, each facility was evaluated for long- term static and pseudostatic loading conditions ror both the ' construction configuration and the reclaimed configuration. A maximum pseudostatic coefficient of 15 percent gravity (0.15 g) was used for horizontal acceleration. The analyses assumed that due to the nature of the waste rock and the pile configuration, a phreatic surface would not develop. The results of the stability analyses for the south waste rock dump are summarized on Figure D.3.5-1. The analyses indicate that the minimum long-term static fa ctor of safety I (FOS) for the critical slip circle associated with the full height slope is approximately 2.0 for the as-constructed D-23