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&Ig <br /> Seepage Analysis <br /> The ground configuration necessary to create seepage instability must have <br /> the water level on the creek side above the ground surface on the land side. Also the <br /> water must remain high on the creek side long enough for the water to flow down- <br /> gradient through the soils from the creek side and the landside. Seepage analysis <br /> assuming a permeability of 100 for the foundation soils and a maximum head of 8 feet <br /> shows that a particle of water would take approximately 60 hours to move 1 foot <br /> through the foundation just below the levee. Since the time for most of the flood <br /> waterto pass is 20 hours, we conclude seepage is not a problem. The time frame is <br /> much too short to establish flow through the levee or foundation. <br /> Results of our pinhole tests for the levee fill and foundation soils show that the <br /> materials are rated as ND-1 or ND-2 and are non-dispersive. These results indicate <br /> that piping will not be a problem. <br /> Freeboard <br /> In our opinion the existing levee is densely compacted and has been in place <br /> long enough that consolidation of the levee and foundation due to the weight of the <br /> levee has occurred. The additional load imposed by the maximum proposed 2.4-foot <br /> raise of the levee will be small, less than 300 psf. This added load will cause <br /> negligible additional settlement of the levee and its foundation, therefore, loss of <br /> freeboard due to the proposed raise will be insignificant. <br /> LEVEE RAISE <br /> Two short sections of the levee crest need dressed to provide at least 3 feet <br /> of freeboard. The maximum thickness of new levee fill will be 2.4 feet. Soils similar <br /> to the soils from which the existing levee was constructed (see Figs. 8 and 10) can <br /> be used. The added fill should have 100 percent finer than 6 inches and it should be <br /> FLATIRONS COMPANY <br /> LEVEE AT DEEPE FARM PIT _ <br /> CTL?25,385 6 <br />