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J SUMMARY <br />Project Location: The project (Bear Mine No. 3) is located at <br />the site of the old existing Clark Mine <br />workings at Somerset, Colorado. in Gunnison County. <br />Project Description: <br />two possible locatio <br />the project will <br />conveyor, stacking <br />facilities. <br />The project will involve the construction <br />of a new intake portal and/or fan portal at <br />ns. In addition to portal area construction, <br />also involve construction of a crusher, <br />tube, and other miscellaneous surface <br />Scope of Report: The purpose of this report is to provide the <br />1 results of an investigation and a computer- <br />assisted limit equilibrium slope stability analysis addressing <br />existing stability conditions in portal areas and access road <br />area, and the impact of proposed construction and proposed <br />reclamation condition on the existing stability conditions. <br />Results of Analysis: With the exception of the slope above the <br />main portal area and the vicinity of <br />Section A, all sites have an existing condition of marginal <br />stability (indicated factors of safety between approximately 1.1 <br />and 1.3>. The main entry portal area was found to be stable due <br />to the window of exposed bedrock present in that area. Section A <br />appears to remain unstable based on the results of analysis of <br />the mathemtical model. even with the most optimistic of assumed <br />shear strength parameters. <br />Recommendations: Based upon the results of our analyses, we <br />I would recommend that the proposed fan portal <br />not be located in the area immediately to the west of the <br />existing entry portal. due to the severe potential for active in- <br />1 stability in that area. We would instead recommend that the fan <br />portal remain at the site of the existing fan portal to the east <br />of the existing main entry portal. Proposed new construction for <br />an intake portal should be located immediately to the east of the <br />I existing main entry portal in as close proximity as possible in <br />order to take advantage of the better stability conditions <br />present in the area of exposed bedrock at that location. The <br />I bench immediately in front of the existing main entry portal may <br />be widened from its present 20 feet (plus or minus) to 40 feet <br />through stabilization of the existing sandstone outcrop above the <br />poctal area, utilizing grouting and rock bolting. The area <br />immediately below the sandstone outcrop will be protected <br />utilizing a tieback retaining wall system. This treatment should <br />be extended to both the existing main entry portal and the <br />' proposed intake portal. In the vicinity of the existing fan <br />portal to the east, the bench area should be improved in order to <br />maintain a 30-foot dimension and the portal area will be <br />1 protected with a more flexible gravity type of retaining system. <br />These measures should result in a small increase in stability <br />1 <br />