1997-07-18_REVISION - M1981302 - Laserfiche WebLink

Home Browse Search

hard. Free ground water appeared in three of the twelve holes drilled from the levee crest at 11 feet to 14 feet and in four of the six holes drilled at the toes of the levee at 3.5 feet and 4 feet. ANALYSIS In our opinion, the critical cross section of the levee is located at Station 122 + 00. The surveys provided show the steepest cross section slopes are 3:1 (horizontal:vertical). The crest width is approximately 14 feet. Figure 7 shows our interpretation of the maximum levee section including the proposed levee raise at Station 122 + 00. This is the section we used for our analysis. The elements we used to analyze the levee geotechnically where (a) an idealized soil profile from our test holes and test pits, (b) data from our laboratory tests, and (c) our field observations and our experience. The 100-year flood level and hydrograph data were given to us by Leonard Rice Consulting Water Engineers, Inc. The soil profile selected for our slope stability analysis is on Fig. 7. The soil properties of each layer used in our slope stability analysis are shown in the tables at the top of each of the slope stability analysis figures in Appendix A. Compaction of Levee Fill Test Pits 1 through 3 were drilled with a large pier hole drilling rig using a 42- inch diameter auger. The levee fill was very cobbley(rocky). The cobbles were close together but surrounded by a dense clayey, sand matrix. It was nearly impossible to pry the cobbles loose and when they came loose the matrix was loosened. We dug the holes for the sandcone density tests as nearly as possible to the standard but the closely spaced rocks made it impossible to excavate "proper" holes for the tests. The "pilot hole"for the nuclear gauge probe had to be advanced by driving a pointed steel rod into the ground with a sledge hammer. The test pit walls in the levee fill FLATIRONS COMPANY LEVEE AT DEEPE FARM PIT CTUT 26,385 3