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interconnected with the West Sunday /St. Jude /Carnation /Sunday underground <br />workings. Dewatering and ventilation of the Topaz mine has occurred on an <br />intermittent basis since development of the mine. It is currently unknown if <br />groundwater in the area of the Topaz mine is contiguous with groundwater in the <br />area of the interconnected West Sunday /St. Jude /Carnation /Sunday underground <br />workings. It is possible that the 140 ft. difference in the water table is a result of <br />dewatering and consumptive groundwater use resulting from mining in the <br />interconnected West Sunday- Carnation -St. Jude - Sunday mine workings. It is also <br />possible that the water observed in the Topaz mine is associated with a local perched <br />zone of groundwater within the Salt Wash Member. <br />7.4.2 Surface Affected Areas <br />This section addresses the direction and rate of groundwater flow in the vicinity of <br />the affected areas of the Sunday Mines Group. In these areas, the rate of groundwater <br />flow cannot be estimated empirically and therefore, this section presents estimates <br />based on analytical evaluations of available data. The rate of groundwater flow is <br />discussed here in terms of the average linear groundwater velocity. The average <br />linear groundwater velocity is a function of the hydraulic gradient, the effective <br />porosity, and the hydraulic conductivity (Dominico and Schwartz 1980). Data <br />presented in Exhibit 7 -2 for estimated hydraulic conductivity is based on the intrinsic <br />permeability analyses of Jobim (1962). This section presents estimates of the rate of <br />groundwater flow using the estimates of Jobim (1962), estimates of hydraulic gradient <br />based on relative observed water elevations in exploration drill holes and the Dolores <br />River, and values for effective porosity that are estimated using empirical <br />relationships described by Chilinger (1963). <br />Groundwater generally flows westerly from the areas of surface disturbance towards <br />the Dolores River. Therefore, the gradient can be estimated by comparing the <br />elevation of groundwater observed in exploration drill holes at the Carnation /Sunday <br />and Topaz Mines with the elevation of the Dolores River at potential groundwater <br />discharge points in Big Gypsum Valley. Exhibit 7 -2 shows the observed groundwater <br />elevations at the Carnation /Sunday Mine and Topaz Mine affected areas and the <br />potential discharge point at the Dolores River, the distance from the mines to the <br />potential discharge points, and the estimated hydraulic gradients. The distance used <br />in this estimate is the direct line of site distance between the mine affected areas and <br />the Salt Wash Member outcrops along the Dolores River in Big Gypsum Valley. This <br />provides a conservative estimate of the hydraulic gradient, because the actual <br />groundwater flow paths are likely longer than assumed. In addition, groundwater <br />may be compartmentalized within relatively isolated fault blocks in some areas, <br />which would affect the actual groundwater flow rate. <br />C \Users\cwoodward\ Desktop \Sundays \FINAL - Environmental Protection Plan Sunday Mines Revised January 2012 docx <br />Section 7 <br />Groundwater Information <br />7 -7 <br />