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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> • Holes SC-0109, SC-0209, SC-0309 and SC-0809 were drilled into the Top Rim <br /> Sandstone or other units of the Salt Wash Member near the northwest extent of the <br /> North Area workings (see Figure 3-1). Water levels measured in these holes ranged <br /> from 5,472 to 5,494 ft amsl. Denison interpreted water elevations at these wells to be <br /> related to groundwater compartmentalization due to faulting in the area. <br /> • Holes SC-0409 and SC-0509 and SC-0709 were interpreted to have been drilled into the <br /> Entrada Formation and water elevation measurements of 5,363, 5,348, and 5,402 ft <br /> amsl, respectively were reported. <br /> • Hole SC-0909, an offset of Hole SC-0609, was drilled near the Topaz portal, and <br /> indicated a groundwater elevation of 5,353 ft amsl, which later decreased to 5,345 ft <br /> amsl. <br /> 8.2.2 EFR and PRM Data <br /> EFR conducted a monitoring well installation program in 2012 and 2013 with the approval of the <br /> BLM and the DRMS. The purpose of the wells was to supplement hydrogeological data for the <br /> remanded Environmental Assessment (EA) administered by the BLM, and to provide required <br /> water quality background data as required by the DMO designation under DRMS. Four wells <br /> were installed; one shallow well to investigate the potential occurrence of leachate from the <br /> Topaz Mine waste dump (MW-TPZ), and three to monitor water quality in the Salt Wash <br /> Member hydraulically downgradient of the mine sites (MW-SUN1, MW-SUN2 and MW-SUN3) <br /> (see Figure 8-2). <br /> Water levels at the monitoring well sites were collected prior to sampling events; well MW-TPZ <br /> has been dry since it was initially installed. Table 8-1 and Graphs 8-1 thru 8-3 show the plotted <br /> water level data from the wells. <br /> Vent shafts S-4, S-8 and S-15 associated with Sunday Mine were measured for water levels in <br /> October 2019. The calculated water level elevations for these shafts are 5,485, 5,496, and <br /> 5489.7 ft amsl, respectively. As shown in Table 8-1, these elevations are 83 to 87 ft higher than <br /> elevations indicated by CDM in 2009 and reflect the additional groundwater inflow into the <br /> Sunday Mine workings over the 10-year period. Figure 8-1 shows the projected potentiometric <br /> surface (and flooded zones) for the Sunday Mine using the most recent vent shaft water level <br /> measurements. <br /> Western Water& Land, Inc. 25 <br />