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Limited data are available to describe the hydraulic characteristics of the sandstones in the <br />Williams Fork and Iles Formations because most of the sandstones in the Williams Fork <br />Formation contain only limited quantities of groundwater. These sandstones have not been <br />penetrated by water wells; therefore, no data are available to describe their characteristics. <br />However, Colowyo has completed two water wells into deeper sandstones beneath the coal to <br />be mined on the property. Aquifer tests completed on these two wells yielded data that can be <br />used to determine average hydraulic conductivities of these sandstones. <br />The Colowyo Taylor Creek No. 1 (see Map l0) is approximately 825 feet deep and produces <br />40 gpm on a continuous basis. A 24-hour aquifer test was completed on the well and the <br />drawdown data collected at specific times during the test are shown in Figure 1. An analysis <br />of the data by the Theis nonequilibrium method reveals that the average transmissivity of [he <br />sandstone is 206 gallons per day per foot (gdf) in the vicinity of the well. The average <br />hydraulic conductivity was computed to be 3.4 gallons per day per square foot. The storage <br />coefficient presented on Figure 1 is 0.066, but should be considered as a representation of <br />storage conditions in the pumped well. There were no observation wells available to calculate <br />storage of [he formation. The same condition was true for the Taylor Creek No. 3 Well. <br />Taylor Creek No. 3 (see Map 10) was drilled to a depth of 2,284 feet to test the deep <br />sandstones of the Iles Formation. Three hundred feet of perforated casing was set between <br />1,335 feet and 2,284 feet. After the well was completed, a 24-hour aquifer test was <br />conducted. An analysis of the data indicated the average transmissivity to be 40 gallons per <br />day per foot. The average hydraulic conductivity was 0.13 gallons per day per square foot. <br />The drawdown data for Taylor Creek No. 3 is shown in Figure 2. <br />• <br />2.04.7-8 <br />