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Whirlwind Mine Groundwater Characterization Report <br /> Information on hydrogeologic conditions underlying the Salt Wash is lacking. However, the <br /> underlying Summerville formation is approximately 100 ft thick, consists of mudstone and shale, <br /> and is considered of relatively low permeability. <br /> A hydrogeologic conceptual model for the study area describes a limited groundwater system <br /> with aerial recharge primarily on Beaver Mesa to the west of the Whirlwind Mine and historical <br /> mine sites. Recharge is likely less than 10 percent of annual precipitation. Groundwater that <br /> accumulates in the hydrostratigraphic units flows down stratigraphic dip to the northeast. <br /> Discharge of groundwater occurs at natural springs, subflow into Quaternary alluvium, <br /> colluvium, and landslide deposits, evapotranspiration, and past discharge from formerly free- <br /> draining mines. Currently, groundwater conditions in the mine area do not attain adequate head <br /> nor have sufficient transmissivity on a broad scale, to contribute flow to area drainages. <br /> The report concludes with comments on the fate of groundwater in the Whirlwind Mine (which <br /> includes both Whirlwind Decline and the Packrat Mine). Key issues and concerns are <br /> addressed. Briefly, upgradient groundwater sources will not be impacted by mining operations <br /> and downgradient groundwater sources are not expected to be impacted because of aquiclude <br /> conditions in the Salt Wash and planned implementation of one or more bulkheads that will <br /> isolate upgradient aquifer sources to the mine workings where the groundwater originates. <br /> This report will be amended as additional knowledge of the mine area's hydrogeology becomes <br /> available. <br /> Western Water& Land, Inc. E-7 <br />