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<br />• very minor amount of fines. A detailed description of the a~aste rock <br />material is presented in Appendix A. The waste pile material is <br />derived from two sources: the mine development waste and the ~~re 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 var,~ locally; <br />the highest and steepest parts of the piles have angles the~t 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 ex~:eption 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. 7h ere 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 />• <br />- 15 - <br />