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Eventually, springs and seeps will emanate from the topographically lowest points <br />of the reclaimed pits. These waters will be characterized by high levels of iron, <br />manganese, total dissolved solids, and possibly boron. Unless this water is <br />intercepted by holding ponds, it will add flow to the unnamed drainage directly <br />below the mining area and eventually to Hubberson Gulch and Dry Creek. This flow <br />may be expressed as surface flow, or as an increased (elevated) water table, <br />dependent upon local conditions. It is projected that the concentrations of these <br />parameters will decrease with time as the readily dissolvable elements are leached <br />until an equilibrium level is reached. Further discussion of this is found under the <br />Surface Water Effects of the Probable Hydrologic Consequences section. <br />Ground Water Effects (South Extension Area Addendum) <br />Probable hydrologic consequences to the ground water regime as a result of mining <br />the Wadge, Sage Creek and Wolf Creek coal seams within the south extension area <br />have been assessed. Localized effects to the hydrologic system will include: <br />1) The drawdown of ground water, due to pit dewatering. For the Wadge ground <br />water system, the largest estimated radial distance will occur in the overburden <br />aquifer, where a one -foot drawdown is predicted to occur approximately 151 <br />feet from the mined area after one year of pit inflow and approximately 285 feet <br />from the area after four years of inflow. For the Sage Creek/Wolf Creek <br />systems, the estimated drawdown in the overburden is predicted to occur <br />approximately 333 feet from the mined area after one year of pit inflow and <br />approximately 1,441 feet from the area in year 2011. No pre-existing water <br />sources with registered water rights including water wells were identified in the <br />south extension area. The maximum radius of influence for one foot of <br />drawdown over the predicted life of mine for the south extension area will not <br />extend beyond the permit area boundary. Because drawdown will be limited to <br />areas within the permit boundary, there is no anticipated impact to adjacent <br />water users due to drawdown. <br />2) The establishment of a relatively unconfined aquifer of poor quality in the <br />backfilled pits. Spoil discharge may increase the TDS of the overburden ground <br />water system by as much as 261 % (Wolf Creek overburden) and the coal ground <br />water system by as much as 238% (Wadge Coal). With respect to both the <br />overburden and coal seam ground water systems, elevated levels of TDS and <br />individual constituents will be localized. The impact of localized water quality <br />degradation in the coal and overburden aquifers is minimal, given that the <br />aquifers do not yield volumes sufficient for irrigation purposes, baseline ground <br />water quality in these systems is marginal to unsuitable for stock watering <br />and/or irrigation, and there are no wells completed in the overburden or coal <br />units in the mine vicinity. <br />23 <br />