Laserfiche WebLink
Report in Support of the Recertification of the <br />University of Colorado's Flood Control Levee <br />Page 11 <br />the Levee to be raised to re- establish the required freeboard. Left Hand Excavating of <br />Longmont, Colorado did the construction work, CTL /Thompson, Inc. did the testing of the new <br />fill (see Appendix E), and Robert M. Sayre, P.L.S. made the final survey of the fill. Appendix F <br />contains photographs showing the progress of the placement of the fill, and Figures 17, 19, and <br />23 and Appendix C show the final raised Levee. <br />In a similar manner, LRE identified a 1,100 -foot reach at the upstream end of the Levee that <br />needed to be raised (see Figure 10). Mr. Sayre laid out the required grades in the field. The <br />work was done by Left Hand Excavating in May 2009, and CTL /Thompson did the compaction <br />testing. On behalf of the University, Left Hand Excavating followed the same specifications for <br />the fill developed by CTL /Thompson for the downstream fill project. Photographs of the <br />maintenance work are shown in Appendix F, and the final grades are shown on the Levee <br />profiles (Figures 17 and 18 and Appendix C), and on the appropriate cross sections (Figure 24 <br />and Appendix D). <br />VIII. LEVEE FREEBOARD <br />In this report, the required minimum freeboard for the Levee is set at 3'/2 feet for the upstream <br />1,600 feet of Levee (station 135 +00 to 151 +00), while the freeboard for the remainder of the <br />upstream reach of Levee is based on three feet (station 101 +00 to 134 +00). The minimum <br />freeboard transitions from three to 31/4 feet between stations 134 +00 and 135 +00. <br />Sufficient freeboard now exists for all of the upstream reach of the Levee, as summarized in <br />Table 3 below. Above (west of) station 147 +50, the freeboard is based on a flood elevation of <br />5411.48 feet, the elevation of the main flood where it first comes into contact with the Levee at <br />station 147 +50. It is the professional opinion of the author of this report that at every location <br />between station 101 +00 and 151 +00, there is at least three feet of freeboard available over the <br />base flood profile, and that in addition, there is at least three and one -half feet of freeboard <br />between stations 135 +00 and 151 +00 (this includes all of the upstream face of the Levee). The <br />actual freeboard varies from 3.48 to 6.73 feet above the base flood. This is more than sufficient <br />to satisfy FEMA's freeboard criteria spelled out at 44 C.F.R. Section 65.10 (1). As can be seen <br />in Table 3, there is a surplus of freeboard (above the minimum required) of from 0.30 feet at <br />station 143 +00 to a maximum of 3.73 feet at station 130 +00. <br />© Leonard Rice Engineers, Inc. June 2009 — 207FIP05 <br />