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• generally be confined to the mine and immediately adjacent areas by <br />relatively low permeability of the effected intervals and limited <br />hydrologic connection with other stratigraphic units. <br />Minor changes in groundwater quality will not effect any groundwater users <br />since all existing groundwater use in the immediate area is limited to <br />units which are stratigraphically above the interval to be mined. There <br />is some regional use of groundwater from the Trinidad Sandstone, however, <br />this unit is hydrologically separated from the interval to be mined by <br />significant thicknesses of relatively impermeable strata as previously <br />described in this section. It should be noted that anticipated changes <br />in groundwater quality will not be so significant as to preclude <br />beneficial use of affected groundwater resources. This contention is <br />supported by the common regional practice of utilizing groundwater <br />resources stored in abandoned underground coal mines. <br />Surface placement of coal refuse has the potential to affect groundwater <br />• quality as a result of infiltration and leaching of coal refuse materials. <br />Analyses of coal refuse materials as described in Exhibit 9, Comparison <br />of Refuse and Soil Suitabilities, indicate somewhat elevated values of <br />SAR, sodium, iron and manganese when compared with soil and overburden <br />materials. Leaching of coal refuse materials has the potential to cause <br />a shift in the groundwater chemical type towards a sodium sulfate water <br />type and may also cause minor increases in concentrations of iron, <br />manganese and TDS. These potential impacts are expected to be minimized <br />by specific operational measures utilized during construction and <br />reclamation of the permanent coal refuse pile. These measures include; <br />o Controlled placement and compaction of refuse materials <br />o Establishment of an underdrain system <br />o Regrading of completed refuse pile areas to provide effective <br />surface drainage <br />o Topsoil replacement <br />o Reclamation of the completed coal refuse pile <br /> <br />2.05.6-23 <br />