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SUNDAY MINE COMPLEX-HYDROGEOLOGIC REPORT <br /> The Cutler Formation is sparsely exposed in the region surrounding the study area. Cater <br /> estimated that a few hundred feet of the formation is exposed in the Hamm Canyon quadrangle. <br /> The Redwall aquifer is considered the most continuous aquifer in San Juan County, Utah, <br /> immediately west of the study area. The Redwall aquifer consists of Leadville Limestone and <br /> permeable intervals of the Molas, Pinkerton Trail, and Honaker Trail Formations (all <br /> Pennsylvanian-age sedimentary rocks). The limestone portion of the aquifer is over 500 ft thick <br /> near the Grand Canyon. The aquifer is considered of low porosity and permeability, and is most <br /> prolific in areas where the rocks have been fractured or solution channels are present (Lowe, <br /> 1996). <br /> Considering the great thickness of strata that separates the Salt Wash Member from these <br /> aquifer units, the P, C, and Redwall aquifers are not considered relevant to the hydrogeology of <br /> the SMC. <br /> Confining Units <br /> Confining units that separate the above-described aquifers consist primarily of the Mancos <br /> Shale which overlies the D aquifer, the Brushy Basin Member of the Morrison Formation which <br /> overlies the M aquifer, the Summerville Formation which overlies the N aquifer, and the Chinle <br /> Formation and Moenkopi Formations which overlie the C aquifer. The thicknesses of these <br /> formations are discussed in Section 4.0. The confining units consist of fine-grained sediments <br /> and share the hydraulic properties of low permeability and low transmissivity. Below the Cutler <br /> Formation, the Permian-age Hermosa Formation also acts as thick confining and impermeable <br /> unit consisting of mostly of salt beds. <br /> Groundwater Flow <br /> Weir and others (1983) studied the hydrology of the Dolores River basin and eastern Paradox <br /> basin, which includes the SMC area. In the area of Big Gypsum Valley and Disappointment <br /> Valley, these studies reported that the aquifers that made up the "upper ground-water system" <br /> (those strata younger than confining beds of the Paradox Member of the Hermosa Formation, <br /> i.e. salt-containing beds)were generally unconfined, with the exception of confined portions of <br /> the 0 aquifer units. They reported artesian conditions in Dakota Sandstone wells in <br /> Disappointment Valley. This is supported by the well log for the BLM well (Hotchkiss well, permit <br /> 150887) that showed water levels rose well above the zone where water was encountered. <br /> Western Water& Land, Inc. 20 <br />