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entire road system by Geo -Hydro Consulting, Inc. In this report, <br />potential areas of instability on the cut slopes were identified. <br />Where possible, any fill material dug from low water crossings <br />should be used to shore up these cut slopes. An example of this <br />work is shown on Exhibit 4, Cross - Section C. The maximum angle that <br />the material should be placed is 2.OH:1.OV. Using the geometry <br />shown in this cross - section and a friction angle of 45 °, a density <br />of 105 lbs /cu.ft., a cohesion of 700 psf and a pore pressure ratio <br />of 0.5, the slope safety factor for this fill is 5.25. <br />4) In places where low water crossings must outlet on a potentially <br />unstable fill slope, large durable rock will be placed at the <br />outlet to the fill slope, if possible. <br />5) The decisions for placement of low water crossings must be based <br />on maximum hydrologic stability. If long stretches occur without a <br />crossing, large flows will build up in the inside ditch and will be <br />increasingly difficult to pass to the fill slope without problems. <br />On the other hand, some areas will not accept a concentrated flow <br />on the fill slope without erosion. These choices must be made in <br />the field based on the hydrologic basins upstream and downstream, <br />the nature of the natural drainages and the fill slopes, the road <br />slopes and other factors. <br />6) In places where a low water crossing is desired and there is no <br />need to backfill the cut material against an unstable cut slope, it <br />can still be placed against the cut slope, which will more closely <br />approach the original contour. <br />17 <br />