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RULE 2 PERMITS <br /> present has supported the conclusion that little water exists in the sedimentary sequence and that <br /> where water is encountered it is limited both vertically and laterally and under perched conditions. <br /> In addition, the excavation has been dry in the lower seams where the sandstones show a greater <br /> lateral continuity and would be expected to contain more water in storage than the upper seams. <br /> 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 Formation <br /> contain only limited quantities of groundwater. These sandstones have not been penetrated by <br /> water wells; therefore, no data are available to describe their characteristics. However, Colowyo <br /> has completed two water wells into deeper sandstones beneath the coal to be mined on the property. <br /> Aquifer tests completed on these two wells yielded data that can be used to determine average <br /> hydraulic conductivities of these sandstones. <br /> The Colowyo Taylor Creek No. 1 (see Map 10B) is approximately 825 feet deep and produces 40 <br /> gpm on a continuous basis. A 24-hour aquifer test was completed on the well and the drawdown <br /> data collected at specific times during the test are shown in Figure 2.04.7-1. An analysis of the <br /> data by the Theis nonequilibrium method reveals that the average transmissivity of the sandstone <br /> is 206 gallons per day per foot(gdf)in the vicinity of the well. The average hydraulic conductivity <br /> was computed to be 3.4 gallons per day per square foot.The storage coefficient presented on Figure <br /> 2.04.7-1 is 0.066,but should be considered as a representation of storage conditions in the pumped <br /> well. There were no observation wells 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 10B) was drilled to a depth of 2,284 feet to test the deep sandstones <br /> of the Iles Formation. Three 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 was conducted. An analysis of the <br /> data indicated the average transmissivity to be 40 gallons per day per foot. The average hydraulic <br /> conductivity was 0.13 gallons per day per square foot. The drawdown data for Taylor Creek No. <br /> 3 is shown in Figure 2.04.7-2. <br /> The results of the two tests indicate that the hydraulic conductivities of the sandstones below the <br /> coals to be mined are low and variable. Because the hydraulic conductivities are low, little <br /> groundwater is transmitted through the sandstones and discharged to the surface as springs or as <br /> base-flow in creeks. Groundwater that is encountered on the property moves extremely slowly. <br /> Recharge and Discharge <br /> Aquifer tests conducted on the two Taylor Creek wells revealed low average hydraulic <br /> conductivities for the sandstones. Because the hydraulic conductivity values are relatively low, <br /> recharge rates are also low. Recharge to a groundwater system can be estimated by determining <br /> discharge from that groundwater system. The U. S. Geological Survey (USGS) installed a <br /> continuous recording stream gage at the mouth of Goodspring Creek. Analysis of the data reveals <br /> that the average groundwater discharge over the entire Goodspring Basin is on the order of 0.2 to <br /> 0.35 inches per year. Since over a long period of time groundwater recharge equals groundwater <br /> discharge,the recharge rates for the Taylor Creek Basin are also on the order of 0.2 to 0.35 inches <br /> pc' ycai. These iecliaigc Tates are 1.0 to 1.5 percent of the annual precipitation across the property. <br /> Rule 2 Permits 2.04-15 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />