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Hydrogeological Evaluation of Sunday Mines Group <br />Geologic and Hydrologic Conditions <br />areas where significant fracture zones are more likely to be associated with the fault. <br />These are areas where the fault zone would be more likely to affect groundwater flow. <br />2.4.3 Direction and Rate of Groundwater Flow <br />2.4.3.1 Area of Underground Workings <br />Although the regional direction of groundwater flow is towards the Dolores River, <br />the direction and rate of groundwater flow in the area of the Sunday Mines Group is <br />perturbed by the presence of the underground mine workings and integral activities <br />associated with mining such as dewatering and ventilation. Available data regarding <br />the rate and direction of groundwater flow in the interconnected Sunday-Carnation- <br />St. Jude-West Sunday mine workings, and the Topaz Mine underground workings <br />suggests the following: <br />¦ The direction of groundwater flow in the vicinity of the West Sunday Mine <br />underground workings is into the mine; <br />¦ The direction of groundwater flow in the area of the Sunday mine underground <br />workings has been into the mine during periods of active dewatering prior to 1991 <br />and during recovery of the water table since 1991--it is unknown if groundwater is <br />still flowing into the Sunday mine; and <br />¦ The direction of groundwater flow in the areas of the Topaz, Carnation, and St. <br />Jude mines is currently unknown. <br />Mine water encountered in the underground mines is not pumped to the surface and <br />discharged. All of this water is used within the mines for dust control and drilling <br />purposes. It is currently thought that this water evaporates and is exhausted from the <br />mine in the ventilation circuit. This process can result in removal of large quantities of <br />water from underground mines (Younger et al. 2002). This process causes the <br />underground mines to act as a local groundwater sink, which causes local <br />perturbations in the regional groundwater gradient. Mine dewatering is currently <br />conducted at the West Sunday Mine, although mine water and associated <br />groundwater inflows are also reported at the Carnation, Sunday and Topaz mines. <br />The most recent phase of mine dewatering at the West Sunday Mine started in early <br />2008. The rate of dewatering is estimated to be 400 gallons per day (approximately 0.3 <br />gallons per minute) (S. Davies, West Sunday Mine Foreman, personnel <br />communication 2008). Prior to the most recent phase of mine dewatering, the water <br />level in the West Sunday mine was approximately 5,438.1 ft. amsl. Dewatering at a <br />rate of approximately 0.3 gallons per minute for a period extending from early 2008 to <br />the present has resulted in lowering of the water table by approximately 14 feet to the <br />current level of approximately 5,424.2 ft. amsl. Detailed information regarding water <br />within the West Sunday underground mine is presented in Appendix A. <br />L' <br />cm 2-16 <br />T:\64986-Denison Mines\Task Order 3 - DMO Sampling and Analysis Plan\Task 3.14 - Hydrogeology RepoMfinal sunday hydro reporNexITINAL Sunday Hydrogeology Report.doc