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PURPOSE AND SCOPE: <br />The purpose of this report is to provide results of an investi- <br />gation and analysis of stability conditions for the proposed abandon- <br />ment of the west portal area at the Bear Mine site. Information on <br />the existing and proposed configuration of slopes was obtained from <br />plan and profile sheets provided by Ute Engineering and Surveying Co. <br />in Delta, Colorado. <br />There are several different types of instability which may affect <br />cut and fill slopes. These include large-scale mass instability {land- <br />slide type movement), ravelling or sloughing, and erosion. The stabil- <br />ity analyses performed as part of this investigation deal only with the <br />large-scale mass instability or landsliding type of problem. The fac- <br />tors of safety provided refer only to this type of instability. We <br />have assumed that the other aspects of instability of the proposed <br />portal abandonment project have been sufficiently covered by ethers. <br />GENERAL SITE CONDITIONS AND PROJECT CHARACTERISTICS: <br />The site is located approximately one-half mile east of Somerset, <br />Colorado, in Gunnison County. A General Location Diagram in map form <br />will be found in the Appendix of this report. <br />The topography of the site tends to be moderate to steeply slop- <br />ing in a northerly direction. Major drainage in the vicinity of the <br />site consists of the North Fork of the Gunnison River and trends in <br />a westerly direction. <br />Physiographically, the site lies essentially at the margin between <br />the Colorado Plateau Physiographic Province and the Southern Rocky <br />Mountain Physiographic Province. The site lies in an area containing <br />Cretaceous Age sediments such as the Mesa Verde group and the Mancos <br />-2- <br />