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Flood Control Levee August 2, 1999 Page <br />• Entities affiliated with the Flatiron Sand and gravel Company obtained p rMis ion from the <br />land owner to force flood waters eastward toward South Boulder Creek by means of a levee. <br />Leonard Rice Consulting Water Engineers, Inc. (LRCVVE) designed a flood control levee for <br />the Flatiron Sand and Gravel Company %n 1979, As part of this design, LRCVVE conducted <br />a study of the flood plain and floodway of South Boulder Creep and wrote a report which <br />became part of Flatiron Sand and Gravel Company" s "Application for a Special Permit for <br />Floodplain Construction- South Boulder Creel ." The study rn lud d a definition ofthe 100 - <br />year flood plain and floodway using Boulder County floodway criteria and the updated <br />USAGE flood hydrology. <br />After review and comments by the staffs of the City of Boulder, Boulder Open Space and <br />Boulder County, the Boulder County Planning Commission granted the special permit to <br />construct the levee, and the Flatiron Sand and Gravel Company built it in 1980. <br />(Appendix . <br />Topographic mapping I I o ' with two-foot contours) was prepared in anticipation of an <br />upcoming flood plain study from aerial photographs taken November 1, 1980. The resulting <br />snap clearly shows that the levee vas constructed by that date. The mapp g is part of <br />Appendix 4. <br />A flood -plain study was begun on or before 1979 by the USA B, and it was completed by <br />engineering consultant Greenhorns and 'll lara� Inc. (G&O) for the Urban Drainage and <br />Flood Control District and Boulder County. The final report South Boulder Creep Mood <br />Hazard Area Delineation, was published July 1986 (Appendix . It utilized the updated <br />flood hydrology and the 1980 topographic mapping. The study recognized the levee as a <br />completely effective flood control facility; the levee's upstream and downstream reaches <br />determine the western boundary of the flood plain. The upstream, middle and downstream <br />reaches of the levee are defined later in this report. <br />FEMA's FIRM for Boulder County was updated to include the results of the G&O study on <br />July 15, 1988. The western edge of the flood plain boundary is determined by the levee. <br />Pertinent portions of the current FIRM and Flood Insurance Study (FIS) for Boulder County <br />are contained in Appendix 5. <br />The first City FBMA reap to identify the flood potential of South Boulder Creep in this area <br />was the second revision to the FIRM, which becarne effective August 4,198 8. The western <br />limit of the flood plain followed the outline of the G &o study of July 1986. Pertinent <br />portions of the current FIRM and FIS for the City of Boulder are contained in Appendix 5. <br />The gravel raining company placed large - diameter riprap on the face of the levee from about <br />S CA station 133+00 to station 148+50. <br />, LE ARD RicF_...C.0..N.5.ULT1NG WATER ENGINEERS, INCI <br />