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CHAPTER III <br />SUMMARY OP CONCLUSIONS AND RECOMMENDATIONS <br />A. GENERAL <br />C Site investigations and engineering analyses were performed ors the roposed <br />open pit mine of Colowyo Coal Company near Craig, Colorado. It must be <br />emphasized that the conclusions in this report are derived from a prelim- <br />inary investigation based on research and analysis of obtained field <br />data and of some assumed conditions that could be expected at the site. <br />The possible nonrepresentativeness of the geologic cross section studied <br />precludes firm general conclusions regarding the field geologic structures <br />and the overall pit slope stability. The tentative conclusions presented <br />I herein are subject to future confirmation or revision as the pit excava- <br />tion is accomplished. <br />B. CONCLUSIONS <br />L 1. Geology <br />The proposed oven pit lies in a stratigraphic sequence of Upper Cretaceous <br />~_ rocks which are in the lower part of the Williams Fork formation of the <br />Mesa Verde group. The rock throughout the area of concern consists of <br />l interbedded sandstone, siltstone, mudstone, sandy shale, shale, and <br />coal. Prominent joint sets in the area observed at the outcrops generally <br />L strike parallel to and/or normal to the strike of the bedding. The dips <br />of the joint sets are generally greater than 80°. No evidence of faulting <br />L was observed on the site. There exists some perched ground water associated <br /> with coal beds. However, the information on ground water developed in <br />L this study is sketchy and <br />" <br />" inconclusive. The fact that an underground mine <br /> in the <br />G <br />Seam was dry, i ndicates that the ground water level is prob- <br /> ably located below the "H" Seam. <br />L <br /> <br />• <br />• <br />W.aWRHIER Project 0807 III-1 <br />& ASSHCIAiE~ <br />