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Major faults in the area have o general north to northwest trend and are <br /> mapped as normal faults. Regional deformation of the sedimentary rocks took place <br /> during the Laramide Orogeny of the Rocky Mountain region. Deformation of bedrock <br /> is the result of tectonic uplift, sinking or tilting of underlying blocks of crystalline <br /> basement rocks similar to those exposed in the Park Range. <br /> The axis of the Washakie-Sand Wash structural basin is locally disturbed by <br /> smaller folds and faults. The most prominent folds include the Tow Creek Anticline, <br /> Fish Creek Anticline, Twe~JFymile park S~cline and an unnamed anticline that <br /> originates o few miles west of the town of Oak Creek and trends northwesterly along <br /> the southwest side of Twentymile Park. <br /> Ground-Water Hydrology - A total of 10 holes were drilled within the <br /> Moffat Area of the Edna Mine, and two holes were drilled in The Wesf Ridge vicinity. <br /> Well 05-03-0005 was drilled on the west side of Trout Creek and used in this study. <br /> No bedrock wells were established in the Oak Creek watershed since no mining will <br /> occur there. Geologic information and/or overburden quality data were obtained <br /> from all of these holes. Selected holes were cased or otherwise used directly in the <br /> hydrologic investigation. These wells are IC, OS-01-0004, 05-01-0005, OS-01-0010, <br /> EBRI and EBR2. Exhibit 2.5-2 shows the location of these wells. In addition to the <br />• wells established as part of this study, wells constructed in previous studies were <br /> utilized (Watec, 1978; D'Appolonia, 1977). <br /> Of particular interest in this study are the water bearing properties of the <br /> overburden, the Wadge cool seam, and The immediate underburden. Potential water <br /> bearing scrota within the areas to be mined (i.e., east and south of Trout Creek) dip <br /> to the west and northwest and rise sharply away from The stream. The elevations <br /> of the strata of interest along the top of the ridge near The eastern and southern <br /> boundaries of the permit area are above the elevation of major drainages in the Oak <br /> Creek watershed. In fact, the Trout Creek sandstone, well beneath the Wodge coal, <br /> outcrops in the Oak Creek watershed near the top of the ridge that roughly parallels <br /> the eastern and southern boundaries of the permit area. Exhibits 2.5-15, 2.5-16 and <br /> 2.5-17 are east-west cross-sections on Oak Creek (see Exhibit 2.5-10 for locations) <br /> that show the westernly dip of the strata. The strata shown on these sections ore <br /> below the Trout Creek Sondstone which is, in turn, below the Wodge shown on Exhibit <br /> 2.5-18 in an east-west cross-section. The Trout Creek Sondstone is believed to be <br /> the first unit below the Wadge Coal with any significant potential as an aquifer. It <br /> is estimated from data on The Trout Creek outcrop along Oak Creek, that the Trout <br /> Creek Sandstone is 150=225 feet below the Wadge Coal in the Edna Mine area. To <br />Revised 7-81 2.5-46 <br />