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GRAND JUNCTION <br />• LINCOLN - DeVOR1+J, Inc. <br />GEOTECHNICAL ENGINEEILS -GEOLOGISTS <br />¢... <br />1441 Motar St. TEL: (970) 242-8968 <br />Grand Junction, CO 81505 FAx: (970) 242-1561 <br />January 26, 2007 <br />J.E. Stover & Associates, Inc. <br />1?.O. Box 60340 <br />Grand Junction, CO 81506 <br />Re: Slope Stability Analysis, Road Fill and Portal Fill <br />Roadside Mine, Cameo, CO <br />Gentlemen: <br />At the request of J.E. Stover & Associates, we have sampled the proposed new fill materials from the soil <br />borrow area at the old Load Out Facility. We have conducted laboratory testing of these borrow <br />materials and have utilized the properties of the proposed borrow materials for computation of slope <br />stability for the proposed fills at the Roadside Mine. <br />• An electronic file was provided to Grand Junction Lincoln DeVore by J.E. Stover (Exhibit 6C and 26). <br />These files were used to construct the model of the slope stability computations. Grand Junction Lincoln <br />DeVore also utilized aerial photography from the Mesa County GIS website, USGS 7-1/2 minute <br />mapping, and in-house records from Lincoln DeVore, Inc., GEX Colorado, Coal Refuse Pile (onsite), <br />1980. <br />An enlarged map (Stover, Exhibit 6C) is presented in this report as Figure 1. Graphical depictions of our <br />modeling are presented as Figures 2 and 3. <br />The analysis indicated that the new embankments will have a sufficient factor of safety (FS) equal to or <br />greater than 1.3. The analysis output has been set to give the factor of safety (FS) to three significant <br />places. Final determinations should "round" the factor of safety (FS) to only one or possibly two signifi- <br />cant places. <br />STTE DESCRIPTION <br />The proposed fills at the Roadside Mino are to cover the existing fill surface, provide a new access road <br />up to the old Mine Entry elevation, and to provide a second fill to cover the Mine Entry. <br />The lower fill will be placed on existing man-made fill and the existing access road. The existing man- <br />made fill has been in place for over 30 yeazs. The new lower fill will have a height of approximately 80 <br />feet from the toe to the upper surface. The upper ftll will have a height of approximately 60 feet from the <br />• toe of the main fill mass to the upper studied surface. Both slope fill masses have been assumed to be <br />reasonably wmpacted (at least 90% of a standazd proctor, ASTM D-698), and the fugal fill surface will <br />have a slope no steeper than 2:1 (horizontal:vertical)- The slopes were studied, asswning that no <br />benching of the original fill slope or natural surfaces occurred. It is our recommendation that nominal <br />PR-3 A14-8-1 <br />(New Ot/07) <br />