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Water was found to mound several feet along the upstream(southern and western)edges of the west cell <br /> after installation of the slurry wall. Depending on the hydraulic connection between the Brighton Ditch <br /> and groundwater table,the ditch could potentially gain over parts of the reach nearest the west cell <br /> slurry wall. <br /> Simulations run without the presence of the Challenger Pit and Baseline Mine showed that groundwater <br /> impacts from only the Tucson South cells was much less compared to the impact of all proposed mines. <br /> Specifically,the simulations show that for the isolated Tucson South scenarios,water tends to mound <br /> instead of being drawn down. Well impacts in these isolated scenarios are predicted to be minimal. <br /> Due to the magnitude and extent of drawdown resulting from the reduction of groundwater flow to the <br /> greenhouses,the greenhouse wells are likely to be impacted,even to the extent of going dry. We <br /> recommend that alternative methods of providing the greenhouse owners with water be considered. <br /> These methods could include bedrock wells or water piped in from locations outside of the area of <br /> influence. <br /> The property inside the east cell will be completely enclosed by slurry walls, separating it from the <br /> alluvial aquifer. Water levels during mining will likely be close to bedrock as the inside of the east cell <br /> is dewatered. Water levels after mining completion will depend mostly upon water levels in the east cell <br /> reservoir. There is currently one well on this property. <br /> On the scale of this project,the alluvial and bedrock aquifers are separate hydrologic systems. Because <br /> all mining, slurry wall,and dewatering activity will take place in the alluvium,impacts on bedrock <br /> aquifer wells and the bedrock aquifer itself should be negligible. <br /> 5.0 LIMITATIONS <br /> Groundwater modeling is a useful tool for determining the magnitude of impacts to the groundwater <br /> system in an area. However,results are not absolute and local variances from simulated results are <br /> likely to occur. This groundwater model is based on the aquifer parameters that we believe to be <br /> reasonable given our current knowledge of the site. Should conditions be encountered that are <br /> significantly different from those used in this analysis or should mining activities in the area be changed <br /> significantly from those simulated,we should be contacted to evaluate the appropriateness of the <br /> existing model. <br /> August 2004 <br /> IA3919 019M OW Modd1TS RepottMcson South Rpt Draf doe <br />