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monitoring show that impacts to the ground water aquifers are precluding its use, Peabody <br /> will provide alternate water sources of comparable quantity and quality. <br /> Also discussed in Attachment 16-1 of Tab 16 are the 11 surface water rights that could be <br /> potentially affected by pit inflow drawdowns. An augmentation plan, which utilizes the <br /> 114 acre foot consumptive use right Peabody has with the Highline Canal, has been <br /> developed to mitigate the potential 26 acre foot impact to surface water right users from <br /> pit inflow drawdowns. The reader is referred to Attachment 16-1 to Tab 16 for a more <br /> detailed description of the quantities of water to be augmented, the associated <br /> calculations and the plan. The impacts to surface water users will be minimal and of <br /> little significance, as an augmentation plan has been developed that will insure that <br /> those quantities lost will be replaced. <br /> Removal of Wells and Ponds by Mining. No surface or ground water rights have been <br /> identified within the Nucla permit revision boundary for the Nucla East mining area (refer <br /> to Figure 2 of Attachment 16-1 to Tab 16). Thus there will be no direct impact from the <br /> proposed mining plan on any local water-righted facilities. <br /> Impact of Replaced Spoil Material on Ground Water Flow and Recharge Capacity. The pits <br /> will remain open only until the coal has been removed. Following the short-term impacts <br /> (water level declines) on the ground water system as a result of pumpage of ground water <br /> inflow to the pits, a potential long-term impact to the local ground water flow is the <br /> period of time necessary for resaturation of the spoil material and reestablishment of a <br /> flow gradient. <br /> A wide range in permeabilities for spoil material can occur, depending on how it is <br /> placed. Rahn (1976) reported that spoil material replaced using a dragline in one <br /> instance and a scraper in another, yielded hydraulic conductivities of 35.3 ft/day and 0.4 <br /> ft/day, respectively. Van Voast and Hedges (1975) concluded that greater porosities and <br /> hydraulic conductivities will result from volume changes (approximately one-fourth <br /> greater) between spoil material in its original compacted, stratified state, and in its <br /> rearranged state following replacement, regardless of the method of placement used. <br /> Spoil material at the Nucla and Nucla East mining areas will be replaced using several <br /> techniques. Some spoil movement at either mining area will be accomplished using cast <br /> blasting. The remaining mining at the Nucla mining area will be conducted with scrapers <br /> 17-27 Revised 04/11/88 <br />