2013-12-17_PERMIT FILE - C1992081 (13)

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the Yampa River floe. The alternative eater source to Walker Ditch water right has offset eat r i ounded b Ch also been offered as an ediment onds (total t e mp y e wo p s capacity is 3.4 acre-feet) at the loadout, vi [h a eater right for 90 acre-tee[/year and a prof ectetl alluvial cell pumpa ge of 35 to 40 acre feet/year, the re is more than enough water from this eater right to offset both potential eater use impacts caused by the operation of the loadout. The 1)alker Ditch water is ideal for the mitigation because most of the water in the ditch is derived from the Yampa River and is thus very comparable in chemical quality (o fhe eater it is augmenting. There will be some minor loss in the recharge potential of the loadout area, because the heavy equipment traffic will cause some additional degree of compaction to the ground surface which will reduce the vertical infiltration capacity. The effects of this on [he Dry Creek alluvial aquifer should be negligible because 1) the surficial area involved is very small, 2) [he main form of recharge to [he Dry Creek alluvial aquifer is from channel flow transmission losses through the stream bed and lateral inflow tram permeable bedrock units, and 3) the vertical hydraulic conductivity of the alluvial terrace material is naturally toe because the material is poorly sorted. Ground Weter Duality Leachate generated from coal stockpiled at the loadout can potentially infiltrate [he alluvium and add dissolved chemical loads [o the Dry Creek alluvial aquifer. The impact to the Dry Creek alluvial Water quality from loadout coal stockpile Leachate should be insignificant because: 1) the stockpile surficial area is small and quantities of Leachate generated from the stockpiles should be limited, 2) compaction of [he ground surface from heavy equipment traffic ui ll reduce the vertical permeability of the alluvium and limit the amount of Leachate that will infiltrate the alluvium, 3) coal chemistry paste extracts do not suggest that high concentrations of dissolved constituents (conductivities ranging from 200 to 800 umh os/cm) will be generated, 4) coal column leach tests yielded Lou TDs and metals concentrations (see Table 15-1 and Attachment 15-2), and 5) [he existing alluvial eater quality (refer to Tab 7, Hyd rolo9 it Description) is very poor and indicates [hat the eater is unsuitable for use as irrigation or stock eater. To substantiate the aforementioned, the folloui ng alluvial eater quality impact analysis Was performed. The analysis to assess the eater quality impacts requires: 1) determining the saturated cross sectional alluvial area; 2) calculating an alluvial flow gradient; 3) 7 Revised 04/18/94 (R-ol