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• For the future expansion of both waste piles, two expansion schemes have been assumed. Expansion plan "A" is shown on Plate 6, Waste Piles, "A" Expansions. Corresponding cross-sections of this ex- pansion are shown on Plates 8 and 9. On the east side of the creek, expansion "A" assumes an increased height of the pile to approximately elevation 6,115 feet. It also asswnes a very slight extension toward the north but no expansion towards the south. As discussed in Section 4.3, the southernmost end of the existing east waste pile should be removed for stability purposes. Expansion plan "A" on the east side of the creek represents some additional 70,000 yd3 or approximately 2.5 years of additional operation. For the west side of the creek, it was assumed that: the pile will be extended toward the north, with the maximum elevation ~~f the top of the pile at 6,725 feet. On the south side of the west pile, a minor extension into the present storage yard and increased height pile to elevation 6,755 feet has been assumed. The expansions comprise ad- • ditional yardages of 81,000 yd3 on the north end (3 years of oper- ation) and 104,000 yd3 on the south side (4 years of operation). Expansion "B" is shown on Plate 7, Waste Piles, "B" Expansions, and in the cross-sections (Plates 8 and 9). This expansion assumes a further increase of the height of the east pile providing additional volume of 73,000 yd3 (2.5 years of operation) and a considerable extension toward the south on the west side of the creek. Increased height to elevation 6,755 feet also is assumed on this side. It can be seen that considerable storage volume is available on the west side when the pile is extended toward the south. The reason for such an important volume of storage is because of the significant width of the Ralston Creek alluvial valley at this location. Some 275,000 yd3 (approximately 10 years of operation) could be obtained if Expansion plan "B" is implemented. • - 17 -