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10 <br />• showing the various strata is provided in Figure 4. It can be observed <br />4 that the sand deposit is essentially of uniform thickness. On the average, <br />the deposit is feet thick and dips gently eastward. <br />I The overburden is .composed mainly of sand, clay, shaly sand and <br />crossbedded sandstone, The thickness of this deposit decreases in an <br />easterly direction from 146 feet at the western boundary of the study <br />1 area and practically vanishes at Ennis Draw. In Ennis Draw the overburden <br />material has been replaced by stream sediment as shown in Figure 4. - <br />The maximum thickness of the coal seam is approximately 8 feet and <br />occurs toward the center of the project area, but subsequently thins to <br />about 2 feet at the north and east boundaries. The depth to the coal seam <br />I from the ground surface varies between 170 feet at the western boundary of <br />the site to approximately 70 feet at Ennis Draw as Shown In Figure 4, <br />1 Although the overlying sand deposit is highly permeable it does not <br />~•- contain water and, therefore, cannot be considered an aquifer. Both <br />the coal and the overburden are water bearing formations and are, there- <br />fore, the only aquifers considered in this study. <br />B. Characterization of Hydraulic Properties of Aquifers <br />Twenty-one wells have been constructed for the purposes of the <br />hydrologic study. The locations of these wells are shown in Figure 3. <br />The drilling and testing program was designed to treat the coal and the <br />overburden as individual potential aquifers. <br />A total of 10 wells were constructed to provide hydrologic data on <br />the coal seam. Wells numbered 61, 116, 132, 137, 162 and 171 are all <br />5-inch diameter wells completed in the coal. Figure 5 shows the typical <br />construction details for these wells. Four additional wells numbered <br />60, 62, 134 and l38 are 2-inch diameter wells constructed for the purpose <br />3 <br />r <br />