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very minor amount of fines. A detailed description of the waste rock <br /> material is presented in Appendix A. The waste pile material is <br /> derived from two sources: the mine development waste and the ore sorter <br /> reject. According to the data provided by Cotter Corporation, approxi- <br /> mately half of the material is formed by the mine development waste, <br /> and the other half is produced as the ore sorter reject. <br /> The waste material has been deposited on both sides of the creek <br /> in the past. It covers most of the width of the alluvial valley and at <br /> certain locations, it has also been deposited on valley slopes. The <br /> waste is hauled to the waste piles with trucks and spread out with a <br /> track type bulldozer. The side slopes of both waste piles vary locally; <br /> the highest and steepest parts of the piles have angles that are ap- <br /> parently close to the angle of repose. Slopes around 35° have been <br /> found at several locations. According to Cotter Corporation represen- <br /> tatives , no preparation of the foundations for the piles has been <br /> performed. No measures have been implemented to modify the natural <br /> drainage systems in the area of the waste piles, with the exception of <br /> possible minor relocations of Ralston Creek. On the west side of the <br /> valley, a road has been constructed between the toe of the pile and <br /> Ralston Creek. At approximately the central part of the east pile, the <br /> road crosses the creek and follows the east side. There is very little <br /> space between the toe of the southern part of the east pile where the <br /> creek flows directly below the colluvial slopes and the creek itself. <br /> There is no alluvium developed on this side of the valley. <br /> The stability analyses of the existing piles and the consider- <br /> ation of future pile configurations required estimates of pile expan- <br /> sions in the future. Cotter Corporation representatives provided us <br /> with estimates of future production of the waste for the expected life- <br /> time of the mine of 15 to 20 years. According to these data, approximate- <br /> ly 15,000 to 20,000 tons of mine development waste and approximately the <br /> same tonnage of the ore sorter reject waste will be produced each year. <br /> - 15 - <br />