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Christy Woodward <br />September 17, 2008. <br />Page 3 <br />Groundwater in Area of Underground Workings <br />Groundwater is currently encountered in active underground workings at the West Sunday <br />and Topaz mines, at a depth of approximately 700 feet below ground surface. Approximately <br />0.3 gallons per minute of groundwater is currently pumped from the base of the West Sunday <br />mine to a temporary storage sump located within the mine. This low rate of groundwater <br />pumping is adequate to dewater working areas within the West Sunday mine, and is <br />indicative of generally low permeability within rock units hosting the thine. Currently, no <br />water is discharged to the surface. This water is used in drilling activities that occur <br />underground within the West Sunday, St. Jude, Carnation and Sunday mines. In addition, <br />groundwater is reported to be present in a historic portion of the existing workings at the <br />Sunday Mine. However, this area is not currently accessible because of lack of ventilation and <br />hazardous ground conditions. <br />The hydrogeologic framework in the area of the underground,workings is presented <br />diagrammatically in Figure 2. This cross-section shows lithologic units based on US <br />Geological Survey data (Cater 1955), the approximate extent of underground workings in the <br />Sunday Mines Group, and the interpreted location of the water table. The Salt Wash Member <br />of the Morrison Formation is the primary rock unit hosting vanadium-uranium <br />mineralization and is the target unit for min' ng operations. The location of the water table is <br />interpreted based on observations of saturated conditions in the lmvermost portion of the <br />West Sunday and Topaz Mines and reported groundwater %vithin inaccessible areas of the <br />Sunday Mine. The water table is interpreted to be parallel to topography in areas beyond the <br />known observation points. 'A groundwater divide is interpreted to be coincident with the <br />topographical divide between Disappointment Palley and Big Gypsum Valley. Based on the <br />current interpretation, groundwater flow is generally' towards the southwest in the <br />underground mine area. <br />Several features shown on Figure 2 are important in relation to understanding potential <br />effects to groundwater from the underground workings. The Salt Wash Member of the <br />Morrison Formation is underlain by the Summerville Shale. Although local hydrological <br />characteristics of the Summerville Shale are unknown, it is likely that the rock unit forms a <br />confining unit based on the lithological descriptions of Cater (1955). This confining unit <br />would restrict downward migration of groundwater from the Salt Wash Member into <br />stratigraphically loiter aquifers. The Salt Wash member is overlain by shale of the Brushy <br />Basin member of the Morrison Formation, which is also likely to be a confining layer. <br />Therefore, groundwater in the mine area would be expected to move laterally within the Salt <br />Wash Member in the down-gradient direction towards Disappointment Valley. <br />Based on conditions observed in the mine, groundwater within the Top Rim sandstone is <br />unconfined, although confined conditions may exist down gradient from the current extent of <br />the underground workings. It is unknown if all rock units beneath the Top Rim sandstone are <br />saturated. Therefore the unconfined aquifer in the current mine area may be a perched