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• • j <br />Ground water flow will also be disrupted by mining opera- <br />tions when the pits intercept the Sudduth coal seam, which is the <br />only significant aquifer in the area to be mined. The upper <br />Sandy member of the Pierre Formation, which underlays the coal, <br />will not be physically disrupted, but may contribute some flow to <br />the pits through faults and fractures. Both Pit 1 and P.it 2 will <br />receive ground water inflow, in amounts that should be totally <br />utilized for dust suppression at the mine. Again, the limited <br />area of the mine is small when compared to the total recharge <br />area of the North Park Basin. Consequently, the losses from pit <br />interception should be negligible and should not significantly <br />affect the storage of ground water in the deeper parts of the <br />basin. Following successful reclamation, the disrupted ground <br />water zones in Pits I and 2 should slowly return to approximate <br />pre-mining conditions. <br />Impacts to potential alluvial valley floors in the mine area <br />are directly related to surface and ground water impacts. The <br />alluvium in the North Fork of Bolton Draw that will actually be <br />physically disrupted by mining operations has not been identified <br />as an AVF. Potential alluvial valley floors downstream of the <br />permit area will not be affected by mining operations except in- <br />sofar as surface water and ground water flows might be reduced or <br />degraded. As previously discussed, the SAR hazard from over- <br />burden at the mine will potentially increase sodium levels in <br />surface and ground water flows. This may in turn increaise sodium <br />levels in the alluvium and the alluvial soil. Some of this soil, <br />such as the Spicerton series along Bolton Draw, is already <br />characterized by a high sodium content. Therefore, sodium levels <br />in water contacting these soils should be minimized as much as <br />possible. Water quality and quantity monitoring should alert the <br />operator to any degradation to the alluvium. More importantly, <br />proper handling of toxic overburden will reduce the potential for <br />such degradation. <br />-5- <br />