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i KLEINFELDER r on each slice include the slice weight, the pore pressure, the effective normal force on the base, the mobilized shear force (including both cohesion and friction), and the horizontal side forces due to earth pressures. The factor of safety is calculated by determining the ratio of the moment of resistance (cohesion and friction along the failure surface) to the moment of the driving forces about the center of the assumed circular failure surface arc. The computer program SLOPE/W was used to perform automatic searches of different potential failure surfaces and to compute a critical failure surface having the lowest factor of safety for a particular analysis condition. SLOPE/W was also used to analyze multiple wedge slip surfaces and computed a critical failure surface. The actual slope configuration will be '/4:1 (3/4 horizontal to 1 vertical) with no benches, according to discussions with Granite Construction Company. Slopes with wedge, block, and circular slip surfaces were analyzed, as shown on Plates B-1 through B-4. A summary of all the loading conditions, slope configurations, and soil profiles for the excavated slopes is shown on Plates B-1 through B-4. . 1 r 1 We have also been requested to analyze the proposed overall 1``/z:1 (1%2 horizontal to 1 vertical) reclaimed slope, which we understand will consist of silts and sands with some clays. It has been i proposed that the reclaimed material be compacted using on-site equipment consisting of scrapers, loaders, and D-9 bulldozers. Moisture conditioning of the material is not anticipated. Based on the above and on our experience at similar operations in the vicinity, we estimate that compaction of the material will range between 80 to 85 percent relative density. In order to simulate what might occur in the field, we lowered the cohesion value for the fine-grained fill to 500 psf, the friction angle to 25 degrees, and the total unit weight to 115 psf. It is our opinion that these values are of reasonable assumption for such fill, but actual test data may differ from the assumption which could result in slope flattening and/or greater compaction of the fill. The soil profile for the reclaimed soil is presented in Appendix B. A summary of computed factors of safety for all the slopes analyzed is presented in Table 2, below. We have attached all of our computer printouts to the end of this report in Appendix B. As 1 noted, the Factors of Safety for the slopes varied from 1.08 to 1.54, with the lower values i associated with seismic events. Based on observations of highway cuts, etc., in similar material, it is likely that a relatively-flat slip surface would extend from the surface downward to a point of intersection on the slope or to point of inconsistent material, such as a seam of clay or clean sands, then outward to the exposed slope. This is reflected in the failure planes shown in Appendix B which generally have large radiuses over 400 feet. As noted above, based on back calculated strength values on the existing slopes at Granite's facility, these Factors of Safety would increase by 0.2. i 20-1 108-18/20188096 Page 5 of 7 I