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foot, respectively. Porosity and permeability characteristics of this aquifer were not calculated <br />due to the depth of the sandstone and lack of corresponding data from other locations within the <br />Formation. Storage coefficient for one well, Taylor No. 1, was 0.066, but should only be <br />considered a factor for that well and not the Formation as a whole since no reference data is <br />available. <br />The proposed mining operations aze not expected to decrease the water quality or quantity of the <br />Trout Creek aquifer. Since the Trout Creek sandstone menmber underlies the deepest coal seam to <br />be mined by 800 feet, it is estimated that Colowyo's operations should not impact this aquifer in <br />any manner. <br />Underlying the Iles Formation is the Mancos Shale, a unit 5,000 feet thick, consisting of marine <br />shales and limestones. This unit is impermeable and creates the confining base for the Trout <br />Creek sandstone aquifer. <br />Continued operations in the active pits from 1981 to present support the assertion that little water <br />exists above the coal stratum to be mined. What water does exist has only been experienced <br />under perched conditions. Seeps encountered during operations have been consumed by the face <br />or evaporated from the floor of the pit. Excavation to the lower coal seams has produced dry <br />conditions, indicating there is no lateral nor vertical continuity in the connection between the Iles <br />and the Williams Fork Formations; so the probability of aquifer cross- contamination is <br />negligible. <br />The quality of ground water within the permit site has been rated poor by the USGS and <br />designated for limited agricultural use only. The chemical composition of the area's water was <br />tested by the USGS in 1978 and found to be somewhat saline, alkaline and hard (see <br />pages 2.04.7-12 and 13 in the Permit and Table 1). PH varies from 7.2 to 8.4. The USGS report <br />indicates that concentrations of trace nmetals razely exceed health limits. Specific conductivity <br />averages 1440-1390 mmhos with a range between 720 and 2700 mmhos; exceeding EPA <br />43 Revised October 30, 1997 <br />