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2.04.7 Hydrology Description <br />Cameo coal zone show that it produces very little water (Reinecke et al. <br />1991). Available information from hydraulic tests in the Mesaverde <br />formations in the Piceance Basin of Delta County support a low <br />permeability. Transmissivity values for coal beds in the lower Mesaverde <br />formation range from 1.5 to 16.7 feet2/day, with corresponding hydraulic <br />conductivity values between 0.003 to 0.03 feet/day (U.S. Geological <br />Survey 1983). <br />After several years of mining at the Red Cliff Mine, underground workings <br />will encounter saturated conditions. The Environmental Impact Statement <br />prepared by URS under the direction of the BLM contains an estimate of <br />the groundwater inflow. MODFLOW groundwater flow model was used to <br />estimate future groundwater inflows to the Red Cliff Mine within the life of <br />mine area. The modeling predicts that if the McClane Canyon mine <br />ceases dewatering in the future, it is reasonable to expect the pumping <br />rate from the Red Cliff Mine would average about 50 gpm to maintain <br />• dewatered working conditions in the mine. <br />Groundwater quality in the bedrock formations of the Mesaverde Group <br />varies greatly, depending on geology and elevation. The best water <br />quality (i.e., low total dissolved solids) occurs near mountain recharge <br />areas and the poorest quality occurs at lower elevations. The quality of <br />water is poorer with increased depth and distance from outcrops. As an <br />example, a water sample take from a 5,400-foot deep well near the central <br />portion of the Piceance Basin within the Cameo Coal Group exhibited a <br />total dissolved solids concentration of 15,500 mg/L (EPA 2004). Water <br />quality near the margins of the basin may have sufficient meteoric <br />groundwater circulation and better quality. Bedrock groundwater quality is <br />poor due to sodium bicarbonate deposits and salt beds. In general, <br />potable water wells in the area extend no deeper than 200 feet, based on <br />well records maintained by the Colorado Division of Water Resources <br />(EPA 2004). <br />• <br />Permit Application 2.04-22 06/08