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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> summarizes key information on groundwater occurrence in the mines and mine area. For <br /> locations of the discussed observations, see Figure 8-1. <br /> Denison's groundwater information sources consisted of underground surveys of groundwater <br /> occurrence, two vent hole measurements, and a nine-hole drilling program conducted in the <br /> spring of 2009. Groundwater information subsequent to 2009 was obtained by EFR and PRM <br /> and is limited to data obtained from four monitoring wells installed in 2012 and 2013 and six <br /> vent hole measurements in 2019 and 2020. <br /> , <br /> 8.2.1 Denison Data <br /> Mine Observations <br /> Groundwater was observed and surveyed at the Topaz, West Sunday, and Sunday Mines in the <br /> form of flooded workings. Figure 3-1 shows the location of these observations, which are listed <br /> below. <br /> • Sunday Mine groundwater elevations were measured at sites DLS-1 at the deeper mine <br /> (South Area) workings and DLS-2 at the shallow mine workings (North Area). At DLS-1, <br /> a groundwater elevation was measured and observed at several other locations within <br /> the interconnected workings at an elevation of 5,389.7 ft amsl on February 24, 2009. A <br /> large area of deeper workings in the South Area was flooded at that time. At DLS-2, the <br /> water elevation was measured at 5,477.8 ft amsl on February 24, 2009. Workings in the <br /> North Area underlie the main portal area by approximately 200 to 320 ft. It is suspected <br /> that the water at the DLS-2 location was pumped there from the flooded workings at the <br /> DLS-1 location, as the DLS-2 location was not included in the final Hydrogeologic <br /> Evaluation report (CDM, 2009). <br /> • West Sunday Mine water elevations were measured at sites DLS-3 and DLS-5 on <br /> February 24, 2009. Denison also reported measurements taken at DLS-4 by Union <br /> Carbide Corporation in 2006. The water elevations at these locations were 5,448.7.7 <br /> (DLS-3), 5,438.1 (DLS-4), and 5,424.2 (DLS-5)ft amsl on the dates noted. The DLS-4 <br /> location is about 200 ft outby (towards the portal) of DLS-5 in the same drift. Seepage at <br /> the DLS-4 location was described as originating from the back and sill. <br /> • Topaz Mine water elevations at two locations, DLS-6 and DLS-7, were 5,574.92 and <br /> 5,644.95 ft amsl, respectively, on February 24, 2009. However, the DLS-7 site was a <br /> Western Water 8 Land, Inc. 23 <br />