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potential to dewater the associated perched groundwater reservoirs. <br />Localized dewatering of both the strata effected by mining operations and <br />perched reservoirs associated with abandoned underground mine workings <br />will result in localized reductions in the level of the piezometric <br />surface. The resulting cone of depression will induce groundwater flow <br />into the mine workings as the hydrologic system adjusts to re- establish <br />a balanced piezometric surface. A shift in groundwater flows toward the <br />Southfield Mine workings may result in localized disruption or alteration <br />of natural flow patterns. <br />Underground operations will also result in a significant void space which, <br />as a result of gradual seepage and other inflows, will upon abandonment <br />form an additional perched groundwater reservoir . Based upon projected <br />mining plans, potential groundwater storage capacity within the ultimate <br />limits of the Southfield Mine workings will be approximately 5,700 acre <br />feet (1370 acres x 7 feet x 60 percent recovery) . This maximum volume <br />would be reduced by any ground subsidence or natural caving which might <br />• occur resulting in some reduction in total groundwater storage capacity. <br />Localized reduction of the piezometric surface due to groundwater inflows <br />to active mine workings is unavoidable. However, reduction of the <br />piezometric surface in the interval to be mined is expected to be both <br />minor and localized due to the relatively low permeability of the <br />stratigraphic units and prevailing direction of groundwater flow. With <br />mine workings located down - gradient from recharge areas and covering a <br />limited areal extent, natural groundwater flows will tend to maintain <br />and /or re- establish the normal piezometric surface as mining is completed <br />and dewatering is discontinued in inactive areas. Effects on the perched <br />groundwater reservoirs represented by overlying abandoned mine workings <br />may be more significant dependant upon the nature and extent of <br />subsidence. EFCI, as part of ongoing operations will attempt to minimize <br />subsidence to the extent possible while maximizing recovery of available <br />coal resources. Subsidence will be controlled by limitations on <br />extraction, maintenance of barrier pillars, and proper mining and roof <br />• control methods. Effective control of subsidence will limit fracturing <br />of overlying strata and consequent drainage through subsidence fractures. <br />2.05.6 -32 <br />