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• <br />L <br />0 <br />Cyprus Western's mine plan for the Foidel Creek Mine does not <br />anticipate significant impacts to the Twentymile Sandstone <br />aquifer. The regulations at 30 CFR 817.41 require groundwater <br />monitoring. <br />Increases in TDS levels is an unavoidable impact since there is <br />no method currently available to remove dissolved solids. <br />Studies indicate that dilution of TDS concentrations increases <br />with increasing distance from the source and with time. <br />A drawdown effect will occur in the Wadge overburden aquifer as <br />water flows into the mine. Water supply wells completed in the <br />Wadge overburden aquifer are owned by Cyprus Western and its <br />subsidiaries. Should impacts occur to other wells. Cyprus <br />intends to mitigate the loss with water it holds under senior <br />water rights. <br />Surface Water <br />Groundwater from the Wadge overburden aquifer may no longer <br />discharge into Fish Creek as mining progresses beneath the <br />stream. The overall base flow of .Fish Creek would not <br />necessarily change since mine effluent waters will be treated to <br />meet water quality requirements in NPDES Permit CO-0027154 and <br />released into Fish Creek. keeping the quantity of water in Fish <br />Creek approximately the same. Water quality in Fish Creek would <br />be affected in the same manner asdescribed under the groundwater <br />section. <br />Effects of subsidence could possible occur at the surface. <br />These impacts would be mitigated by requirements of 30 CFR <br />817.121. <br />Impacts from this proposed lease modification would not be <br />significant within the confines of Tracts A and B and would be <br />cumulative to those impacts associated with the adjacent surface <br />mining and the mining of the underground coal already under <br />federal and private lease. <br />Vegetation <br />Since the proposed lease area would be mined by underground <br />methods. no significant adverse impacts would occur to the <br />vegetation even if subsidence occurs on the surface. <br />Wildlife <br />No significant impacts would occur to wildlife since no surface <br />disturbance is planned. In addition. no significant impact <br />would be expected from the anticipated subsidence. <br />Soils <br />No significant impacts would occur to soil resources under the <br />Proposed Action.