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0 <br />• GEOLOGIC CONDff70NS <br />Geologic conditions were interpreted from review of previous investigations'•Z~' <br />review of geologic maps°, and visual observations of mine excavations. We also <br />reviewed core logs and were provided structure maps indicating the floor elevations <br />of coal seams. The X-Seam floor elevations are shown on Fig, 3. <br />Bedrock at the mine site consists of interbedded sandstone, siltstone shale <br />and coal of the Williams Fork Formation. The sandstone and siltstone layers <br />predominate with shale comprising less than 10 percent of the sequence. In the <br />West Pit and Streeter Pit areas the bedrock bedding dips about 5 degrees toward <br />the north-northeast. The rock jointing is closely parallel and/or normal to the strike <br />of the bedding. Joint spacing typically is on the order of 1 to 3 feet or more. Zones <br />of the rock are more highly fractured. The dip of joints is typically greater than 80 <br />degrees. No evidence of faulting has been observed during previous investigations <br />• or mining operations. <br />Localized folds or rolls occur in the bedrock resulting in localized variations <br />in the strike and dip. The X-Seam Floor elevations shown on Fig. 3 are based upon <br />a considerable number of bore holes performed by Colowyo which show a relatively <br />uniform dip of 4.8 degrees, striking north to north-northeast in the area of the West <br />Pit initial box cut. <br />The Wahler study concluded "that the groundwater level is probably located <br />below the "H" Seam". Operations of the East Pit have experienced limited seepage <br />of water from the working face over 18 years. The seepage has generally been in <br />isolated areas and occurs more frequently in shallow areas in response to seasonal <br />conditions. Drilling performed by Colowyo to evaluate coal reserves after the Whaler <br />study has not consistently indicated groundwater above the F-Seam. <br />r1 <br />~ J <br />COLOWYO COAL COMPANY, L. P. <br />crux za,ses 3 <br />