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<br />P,opon:d Hrdrotogicaf Ma,fwrig Plan for,M1a tkr tfari,on Md¢ 2 <br />use right on the Highlfne Canal which would be used to mitigate the potential 26 acre foot <br />impact on surface water right users from pit inflow drawdown. <br />Impact on groundwater rights. No surface or groundwater rights 4ave been identified within <br />the New Horiwn 2 mine azea. Therefore, there wt71 be no direct impact from the proposed <br />mining plan on any local water rights. <br />Imtmct of spoil material on psoundwater flow and recharge. The mine pit will remain open <br />only until flte coal has been removed. Following the short-tens water Level decline on the <br />groundwater system as a result of pumpage of groundwater inflow to the pit, a potential <br />long-term impact to the local groundwatu flow is the period of time necessary for <br />resatmation of the spoil material and reestablishment of a flaw gradient Spot material at <br />the New Horizon mine will be replaced using techniques which will restore permeabtlities <br />of the material. Thus, 'the mining operation will not diminish vertical or horizontal <br />permeabflities but may increase these permeab0ities. As a result, there should be no <br />significant impacts from the mining operation on groundwater flow and recharge rates. The <br />time period required for the spoil material to resaturate should be grcady reduced because <br />of the irrigation recharge as We mined area will be revegetated for an irrigation type of post <br />mining land use. <br />• ~ Containment of pit inflow and impacts on water euality. All runoff and pit pumpage from <br />disturbed areas will be routed through sedimemation pond 007. The pond is designed and <br />constructed to impound runoff and pit pumpage from areas distmbed by mining and provide <br />sufficient residence time to insure that the pond discharge water chemistry meats the effluent <br />requirements specified in the NPDFS Permit A review of the chemical and flow data <br />indicates that the potential for a~ discharge from Pond 007 to exceed receiving stream or <br />federal standards is minimal. Past history of mine operations at Ote Nucla Mine indicate <br />very few exceedances of the standards over the years of operations. As previously discussed, <br />highest pit inflow is predicted to occur in ywr 5 at apprmdmately 5,600 cubic feet per day. <br />To assess the impact of this inflow on Calamity Draw and the San Miguel water quality, it <br />was assumed that the entire flow was discharged and that the TDS level for the overburdea <br />aquifer was representative of the chemical load. The duration of the water quality impacts <br />is relatively short term (S years) and the significance of the impact is negligible as TDS <br />increases in the range of 0.08 to 1.5 percent are projected. These projected changes in TI),S <br />levels tvfll in no way affect the present and potential uses of the surface water and aze so <br />small that.they may not be measurable. <br />Tm~act of spoil water quality on the sound and surface water quality. The available data <br />indicate that a small proportion of the overburden may produce acid through the otddation <br />of pyrite. Based on laboratory tests on overburden cores, calcite is almost ubiquitous. <br />Calcite serves two functions. First, it buffers the pH of the water, which overall tends to <br />10 <br />• <br />Attachment 2.04.7-5-34 <br />