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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> 2009. On average, water levels in the mines have risen approximately 0.7 feet per month over the <br /> last 11 years. <br /> Other information reviewed included the results of nine groundwater exploration drill holes installed <br /> by Denison in 2009 to investigate groundwater occurrence in the SMC mine area near the mine <br /> workings. Several holes drilled into the Top Rim unit or other units of the Salt Wash showed <br /> elevations of approximately 5,480 feet amsl. The estimated extent of the flooded mine workings in <br /> 2009 is shown in Figure 8-1 in Appendix A. <br /> Water Chemistry <br /> An analysis of water chemistry shows that MW-SUN1 groundwater is of a sodium-potassium <br /> sulfate type, MW-SUN2 groundwater is of a sodium-potassium bicarbonate type, and MW- <br /> SUN3 groundwater is of sodium-potassium bicarbonate-sulfate type. Piper Plots (see Plots 11-2 <br /> to 11-4 in Appendix C) generally indicate an evolution in water chemistry along the flow path <br /> from a more bicarbonate water type to a sulfate water type. Common ion concentrations of spot <br /> samples collected from underground sites fall within the chemical trends of the monitoring well <br /> data, but these data should not be directly comparable to the well data since mining operations <br /> likely impacted these samples. <br /> Field parameters showed all wells to have groundwater of high pH, with averages ranging from <br /> 10.73 in well MW-SUN1 to 8.84 in MW-SUN2, to 9.57 in well MW-SUN3. The relatively high pH <br /> may be controlling the solubility of metals. With the exception of arsenic, uranium and <br /> vanadium, most minor and trace metals were not detected in the monitoring well water <br /> analyses. <br /> The underground wells installed by Denison in 2009 in the West Sunday Mine indicate how <br /> water chemistry can vary dramatically from strata to strata within the Salt Wash Member. In <br /> these wells, the wells screened in the sandstone unit contained arsenic, molybdenum, uranium <br /> and vanadium concentrations magnitudes greater than the well screened in an underlying <br /> siltstone unit. <br /> Table 10-5 presents the constituents that exceed Colorado Basic Standards for Ground Water <br /> (BSGWs) in the groundwater sampled. The main constituents of concern are considered to be <br /> uranium and the radiological parameters of gross alpha, gross beta, radium-226, radium-228, <br /> and thorium-230. Vanadium has an agricultural standard of 0.1 mg/L. As Tables 10-3, 10-4, and <br /> 10-5 illustrate, uranium, vanadium and gross alpha are exceeded 8, 10, and 12 times, <br /> Western Water& Land, Inc. xi <br />