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Dames ~ Moore <br />Flatiron Companies <br />May 17, 1982 <br />Page 5 <br />degradation as measured in the alluvium is attributable mainly to elevated <br />levels of sodium, calcium, magnesium, bicarbonate, and sulfate. <br />Registered water wells in the region are discussed on Page I-4 and on <br />Pages I-22 through I-25 of the permit application. These wells are tabulated <br />on Pages I-23 and I-24 and shown on Figure 6. <br />The regional gradient of ground-water flaw in the alluvial materials of <br />Mann Draw is to the northeast toward the Canadian River. No registered wells <br />are known to eaiat in the Mann Draw alluvium downgradient from the Bourg mine <br />or in the Canadian River alluvium for several miles downstream from its con- <br />fluence with Mann Draw. <br />The regional ground-eater gradient in the upper bedrock formations, <br />• including the sandstones in the Coalmont Formation and in the Pierre Shale, <br />is believed to be generally to the northeast, which is downdip along the <br />northeast flank of the McCallum anticline and in the direction of declining <br />topographic elevation. Locally, as shown in drill holes on the Bourg prop- <br />erty, the ground water gradient in the Coalmont Formation is west-northwest, <br />in general conformance with the topographic slope toward Mann Draw. <br />No registered wells are recorded hydrologically downgradient (northeast) <br />from the Bourg property in either the Coalmont Formation or the Pierre Shale <br />within a three-mile radius of the mine site. <br />Therefore, it is highly improbable that any existing wells located <br />dovngradient from the Bourg property will be degraded in quality due to <br />mining operations or during the post-operational period. <br />It vas previously stated that the ground-water recharge is expected to <br />be increased in the area to be covered by the East Dump. While there are no <br />• <br />- - .. -- - - <br />