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against the levee is based on hydrology which was developed by the Corps of Engineers and used by the <br /> Urban Drainage&Flood Control District, FEMA, and CWCB. <br /> In response to the additional concerns which CU has expressed in their June 10, 1997 letter to us <br /> regarding the flood hazard evaluation for the subject property, I provide the following responses: <br /> 1. CONCERN.- Whether the dike should remain in place, and, if so, whether the lower portions of the <br /> dike should he raised to a level at least four feet above the base flood elevation. RESPONSE: <br /> After reviewing all the technical data which has been presented to the Bnard, it is the CWCB staff <br /> finding that the levee system is a valuable flood mitigation measures and when it is certified by <br /> FEMA will provide flood protection to downstream property owners. Providing an additional of <br /> freeboard (total=4 feet}is a good design parameter! <br /> 2. CONCERN: Whether the dike currently offers flood protection benefit to the residences to the <br /> north of the property? RESPONSE: Yes. <br /> 3. CONCERN: Whether you support FEMA recognition of the dike for FEMA mapping purposes? <br /> RESPONSE: Yes. Due to the extensive residential development that has occurred downstream of <br /> the subject gravel pit, it appears that the dikellevee system is the most feasible flood mitigation <br /> measure. This Board does recognize that other types of flood mitigation measures may be workable <br /> also. In addition, from the engineering data that have been provided at meetings, hearings, and <br /> reports, this Board finds that the subject gravel pit,downstream developments, and roadway systems <br /> lie in the historic flow pattern of the South Boulder Creck. Hunan intervention has changed the <br /> natural flow regime many times. Therefore, structural flood mitigation measures or complete <br /> relocation of the downstream developments appear to be the only viable means of providing 100. <br /> year flood protection to the existing inhabitants of the South Boulder Creek floodplain. <br /> The Board staff will recommend endorsement of a University of Colorado,Boulder request to the CWCB <br /> for FEMA levee certification which is hated on good engineering and technical backup data. <br /> Should you have additional concerns or questions regarding the CWCB staff findings, I will happy to <br /> respund. <br /> Since ly, <br /> Larry . L'an <br /> Chi Flood Control and Floodplain Management Section <br /> encl. <br /> cc. Leslie Botham, Leonard Rice Water Eng., Inc. <br /> John Liou. FEMA <br /> Bill DeGroot, UD&FCD <br /> I Jwc trans/seca/larry/susobou2.d oc <br /> 2 <br />