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The shallow aquifer of alluvium is underlain by up to 5,000 <br /> feet of the Pierre Shale Formation. This formation yields <br /> little water to wells and its thickness limits the feasibility <br /> ' of developing water supplies from underlying aquifer such as <br /> the Dakota Sandstone. <br /> The nearest upgradient homesites are north and west of the <br /> mining site and are 1400 feet from the area to be mined. De- <br /> ' watering will have no adverse effect on wells at this distance. <br /> The closest homesitc east of the mining site is 1350 feet from <br /> mining at Stage 9. Both distance and creek discharge preclude <br /> effects on this well. Because Boulder Creek runs between the <br /> ' mining site and this homesite, creek water will act as a <br /> ' recharge to the groundwater, and dewatering will have no <br /> impact on wells at this site. No adjacent landowners will be <br /> adversely affected. <br /> Water Quality <br /> Mining at the Nelsen Pit is not likely to affect the quality <br /> of the groundwater. Analyses of water pumped from the dewatering <br /> ' trench during excavation at Stage 1 have shown that suspended <br /> solids averaged about 8 mg/liter, well below the permissable <br /> 1 average of 25 mg/liter. Oil and grease have not been noted <br /> in the water samples taken ; pH has remained within the allowable <br /> range of 6. 0 to 9. 0, usually varying between 7. 7 and 8. 1. <br /> Water Requirements - Reclamation <br /> The reclamation plan calls for the creation of 3 lakes. Total <br /> ' G-3 <br />