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optimistic of assumed shear strength parameters. <br />Based upon the results of our analyses, we would recommend <br />that the proposed fan f~ortal should not be located in the area <br />immediately to the west of the existing entry portal (Section A) <br />due to the severe potential for active instability in that area. <br />J We would instead recommend that the fan portal remain at the site <br />of the existing fan portal to the east of the existing main entry <br />portal. Proposed new construction for an intake portal should be <br />located immediately to the east of the existing main entry portal <br />in as close proximity as possible in order to take advantage of <br />the better stability conditions present ire tt,e area of exposed <br />t bedrock at that location. The bench immediately in front of the <br />J existing main entry portal may be widened from its present 20 <br />feet (plus or minus) to 40 feet through stabilization of the <br />existing sandstone outcrop above the portal area utilizing <br />J grouting and rock bolting. The area immediately below the <br />sandstone outcrop will be protected utilizing a tieback retaining <br />wall system. We would recommend that this treatment be extended <br />to both the existing main entry portal and the proposed intake <br />I portal. In the vicinity of the existing fan portal to the east, <br />l the bench area shall be improved in order to maintain a 30-foot <br />1 dimension and the portal area will be protected with a more <br />flexible gravity type of retaining system. The use of a crib <br />I wall or gabion wall is being investigated. The use of such <br />flexible retaining systems will permit some degree of <br />1 intermittent movement within the landslide debris at that <br />location without causing the structure to lose its retaining <br />12 <br />