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-31- <br />The model used by Empire Energy Corporation for the present inflow projections <br />for the Eagle No. 9 Mine is contained on pages III-68 to III-78 of the permit <br />application. The calculations of mine inflows and their affects on over and <br />underlying rock aquifers, and the Yampa River/Big Bottom stream/alluvial <br />system were calculated assuming depletion will occur in the coal seam and two <br />White Sandstones aquifers during mining. An earlier inflow study conducted by <br />the applicant (Appendix III-Sc in the application) indicates that inflows to <br />the Eagle No. 9 Mine are through the roof and floor strata as well as through <br />the coals. <br />The expansion in the Eagle No. 5 and No. 9 mine workings will result in <br />streamflow depletions in the Yampa and Williams Fork Rivers during and after <br />mining. Streamflows in the rivers will be depleted through two means; 1) the <br />reduction of baseflow to streams by drying up the discharge areas of aquifers <br />over and underlying the coal seams; and 2) the induced withdrawals of surface <br />and alluvial ground waters from stream/alluvial systems at outcrops and <br />subcrops, flaws through the affected over and underlying aquifers, and <br />resultant discharges to the mine workings. <br />During mining, the overall depletion of river flows will be minuscule, since <br />most of the mine inflow waters will have to be pumped to the surface and <br />eventually discharged to the rivers after treatment. Minor losses of water <br />will result from water consumed by increased humidity in mine ventilation air, <br />moisture adsorbed on the coal leaving the mine, evaporation in treatment <br />ponds, and potentially through use in the surface operations of the mines. <br />However, the total loss to the flows in the Yampa and Williams Fork Rivers <br />will not cause material damage to the quantity of surface water for uses <br />downstream on the Yampa River. The Yampa River is under-appropriated and thus <br />there is sufficient flows in this river below the Eagle Mines to sustain <br />downstream uses. <br />There is a potential far the largest streamflow depletion to occur after <br />mining. After the underground coal mining activities have stopped the mine <br />workings and overlying and underlying depleted aquifers will begin to fill and <br />reestablish pre-mining water levels. During this period of ground water level <br />rebound, the mine inflow waters will not be discharged to the surface and then <br />to the rivers. Thus, depletions of surface waters from stream/alluvial <br />systems will not be augmented by mine water discharges. These depletions will <br />continue until such time as an equilibrium is reestablished between the <br />surface and ground water systems. <br />The Eagle No. 5 and No. 9 mine workings may impact the quality of ground and <br />surfaces water during mining and following the closure of each mine. The roof <br />strata in the zone of caving, the floor strata, and the coal seams will be <br />subjected to chemical weathering and leaching, if in contact with mine inflow <br />waters. The chemical weathering and leaching will lead to ground water <br />quality degradation. The degree of water quality degradation will depend on; <br />1) the geochemistry of the affected strata; 2) the thickness of affected <br />strata in the zone of caving exposed to mine waters; 3) the particle or <br />