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-12- <br />n <br />U <br />more rapidly. Fill in this area should be brought up in relatively <br />uniform lifts across the entire valley. Based on results of our consoli- <br />dation tests, we estimate that as much as 18 inches of settlement could <br />occur within this area. A significant portion of this settlement will <br />occur during construction as the load of the fill is initially applied <br />to the underlying relatively soft soils. The amount of settlement will <br />diminish for a period of several years. To maintain the desired grades <br />between Sta. 10 and Sta. 20 along Haul Road 'D', we suggest overbuild <br />of the fill to about 3 percent of the height of the fill. <br />STABILITY ANALYSIS <br /> We made a number of different stability analyses of proposed haul <br />• <br /> road sections for this investigation. Where the haul roads are located <br />on high, dry slopes, stability is not a governing factor in this design. <br />Our investigations indicate that 1.5:1 (horizontal to vertical) slopes <br />in both cut and fill sections will be adequately stable. However, for <br />the portion of Haul Road 'D' which crosses the area underlain by rela- <br />tively soft foundation soils, flatter slopes will be required in order <br />to achieve stability. In this area, the foundation soils control the <br />stability of the fill. The lowest computed factor of safety was 1.63 <br />with no stabilizing of the soils at the toe. In our opinion, these soils <br />are sufficiently soft and the estimated time of construction sufficiently <br />short, that a higher factor of safety is desirable. We recommend that <br />a stabilizing toe fill be constructed at the base of the haul road fill <br />• at the extreme downstream end of the fill. This toe fill should be <br />