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We have concluded the existing levee with the proposed 2.4-foot maximum <br /> levee raise meets the FEMA slope stability requirements. The theoretical Bishop <br /> factors of safety for the levee at the critical section under the analysis conditions <br /> required by FEMA are in the following table. <br /> TABLE A <br /> Condition' Theoretical Bishop Factor of Safety <br /> Creekside Landside <br /> Before Flood 4.0 4.0 <br /> Sudden Drawdown 3.8 N/A <br /> Critical Flood Stage 6.6 4.6 <br /> Earthquake 3.5 3.5 <br /> Since this levee exists end of construction is not applicable. <br /> Results from our direct shear tests from samples of the levee fill and <br /> foundation soils show an internal angle of friction of 33 degrees and a cohesion of <br /> 160 psf for the foundation soils and a friction angle of 33 degrees with a cohesion <br /> value of 47 psf for the levee fill (Figs. 13 and 14). For our slope stability analysis, we <br /> assumed a friction angle of 45 degrees and a cohesion of 200 psf for both the <br /> foundation soils and the levee fill. We believe this assumption is valid for the <br /> following reasons: (a) the soils are very rocky and very sandy and gravelly, and (b) <br /> the test procedure for the direct shear requires the removal of particles larger than <br /> 1/4-inch thus the strengthening affects of the bigger gravels and cobbles is lost. <br /> Much of the strength of a cobbley soil comes from the "locking" effect of the cobbles <br /> trying to "roll over" each other when the material is sheared. <br /> FLATIRONS COMPANY <br /> LEVEE AT DEEPE FARM PIT <br /> CTLrr 25,305 5 <br />