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by holding ponds, it will add flow to the unnamed drainage directly below the mining <br />area and eventually to Hubberson Gulch and Dry Creek. This flow may be expressed <br />as surface flow, or as an increased (elevated) water table, dependent upon local <br />conditions. It is projected that the concentrations of these parameters will decrease <br />with time as the readily dissolvable elements are leached until an equilibrium level is <br />reached. Further discussion of this is found under the Surface Water Effects of the <br />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 the <br />Wadge, Sage Creek and Wolf Creek coal seams within the south extension area have <br />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 feet <br />from the mined area after one year of pit inflow and approximately 285 feet from <br />the area after four years of inflow. For the Sage Creek/Wolf Creek systems, the <br />estimated drawdown in the overburden is predicted to occur approximately 333 <br />feet from the mined area after one year of pit inflow and approximately 1,441 feet <br />from the area in year 2011. No pre-existing water sources with registered water <br />rights including water wells were identified in the south extension area. The <br />maximum radius of influence for one foot of drawdown over the predicted life of <br />mine for the south extension area will not extend beyond the permit area <br />boundary. Because drawdown will be limited to areas within the permit <br />boundary, there is no anticipated impact to adjacent water users due to <br />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 and/or <br />irrigation, and there are no wells completed in the overburden or coal units in the <br />mine vicinity. <br />Surface Water Effects <br />Seneca II-W Findings Document 40 ('1982057 <br />Permit Renewal No. 5 December 9, 2010