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