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7.1.3 West Sunday Mine <br />The local geological framework of the West Sunday Mine affected area is shown on <br />Figure 7 -4. In general, this geology of the area is similar to that previously described <br />at the St. Jude, Carnation, and Sunday mines. However, the affected area of the mine <br />is located in a different location in relation to the faults bounding the valley and the <br />displaced geologic formations. The affected area of the West Sunday mine lies on the <br />Brushy Basin Member of the Morrison Formation and the Burro Canyon Formation. <br />Several faults are present in the general vicinity of the mine affected area; however, <br />the faults are located upslope from the affected area. <br />7.1.4 Topaz Mine <br />The Topaz Mine is located approximately 1 mile west of the other Sunday Group <br />mines, and the local geological framework is somewhat different. The affected area of <br />the Topaz mine is shown on Figure 7 -5. This affected area directly overlies the Salt <br />Wash Member of the Morrison Formation, which is the unit that hosts uranium - <br />vanadium mineralization at the mine. The Salt Wash Member consists of sandstone <br />with interbedded red shale and a few local beds of limestone. A fault is present in <br />proximity to the Topaz Mine affected area, which displaces rock units on the north <br />side downward as observed previously at the other Sunday Group mines. This fault <br />juxtaposes the Brushy Basin shale on the north side of the fault against the Salt Wash <br />member on the south side of the fault. <br />Additional information regarding the geological framework in the area of the Topaz <br />mine affected area is shown on the geologic map (Figure 7 -1). The relative density of <br />faults in the area west of the Topaz Mine is higher than areas adjacent to the other <br />Sunday Group mines. This may be related to increased structural complexity <br />associated with the intersection of the Big Gypsum Valley anticline with geologic <br />structures associated with the Dolores River. Although the density of faults is higher, <br />the faults show the same general pattern of displacing rock units on the north side of <br />the fault downward towards Big Gypsum Valley. The surface geology shown in <br />Figure 2 -1 also shows that the Salt Wash Member of the Morrison Formation crops <br />out west - northwest of the Topaz mine adjacent to the Dolores River. <br />7.2 Potential Aquifers in Area of Sunday Mines Group <br />In order to better define the local hydrogeologic framework, the hydrogeologic units <br />defined by Weir et al. have been subdivided. These subdivisions are summarized in <br />Exhibit 7 -1. <br />It is likely that groundwater flows laterally within the sandstone aquifers in a <br />direction that is generally towards the Dolores River. However, local flow directions <br />in direct vicinity of the mines are likely modified by the complex structural geology of <br />area, and groundwater in the vicinity of the mines may take a complex route in the <br />process of moving generally towards the Dolores River. A hydrogeologic divide is <br />interpreted to be present coincident with the topographic divide between Big <br />Gypsum and Disappointment Valleys with groundwater north of the divide staying <br />C \Users 1cwoodward\Desktop \Sundays \FINAL - Environmental Protection Plan Sunday Mines Revised January 2012 docx <br />Section 7 <br />Groundwater Information <br />7 -2 <br />