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Probable Hydrologic consequences <br />Ground Water (Cont.) <br />5. Impact of spoil water quality on ground and <br />surface water quality. <br />Surface Water <br />1. Effects of mining on the local geomorphology. <br />2. Effects of sediment ponds on channel <br />characteristics and downstream users. <br />TABLE 2.05.6(3) -2a (cont.) <br />CONSEQUENCES OF THE LIFE -OF -MINE MINING PLAN <br />FOR THE NEW HORIZON MINING AREA <br />Analysis Results <br />Geochemical controls on water quality suggest that the <br />water chemistry and concentrations of most elements of <br />concern are controlled by mineralogic reactions that will <br />resist changes in water chemistry. Irrigation water will <br />enter the spoil and will increase in TDS and will <br />discharge from spoil springs but the quality will be <br />essentially the same as the current overburden water <br />quality. This will occur for at least hundreds of years and <br />the spoil water quality will gradually improve to the <br />quality of the irrigation water as pyrite is oxidized and <br />dissolved solids are flushed out. <br />Meehan Draw and Glasier Draw will not be disturbed. <br />The lengths and gradients of the streams will not be <br />affected. Watershed areas will remain the same, <br />elevations and slopes will be reduced, and slope lengths <br />and time of concentration will increase. <br />Channel reaches below the frequently discharging <br />ponds, may become more incised with active <br />meandering channels and vegetation will encroach along <br />the channel edges. AVF study indicates that the <br />channels in Tuttle and Coal Canyon (and tributaries) are <br />incised into bedrock, hence neither drainage is <br />determined to have an AVF. Surface water and pumped <br />pit water impounded by the sediment ponds and <br />discharged will replace the irrigations return water flows <br />to the drainages. <br />Significance <br />No indication of significant long or short term impacts to <br />the local ground water quality. Impact to San Miguel <br />water quality is of little significance. Impacts to Tuttle <br />Draw water quality are measurable, but are of little <br />significance in terms of water use. See detailed <br />discussion in Probable Hydrologic Consequences under <br />Item 5) Potential impacts of replaced spoil on <br />groundwater quality <br />Watershed impacts will be mitigated by contour ripping, <br />mulching and prompt revegetation. The watershed <br />impacts are expected to be very minimal. Once full <br />reclamation is done on the NHN area by 2019, the site <br />will have no impact on the local geomorphology. <br />Long term channel impacts until bond release followed <br />by short term channel readjustment period when ponds <br />are removed. Impacts are of minimal significance and <br />increased vegetation should help control sediment <br />during channel readjustment period. No mitigation is <br />necessary for AVF's (negative determination). WFC has <br />water rights to more water than required for mining <br />related uses. An augmentation plan has been <br />developed for mitigating any impacts proven on <br />downstream users. <br />