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<br />.,iT. ~ <br /> <br />e <br /> <br />e <br /> <br />2 <br /> <br />In response to your concerns, we reviewed our backup information to assess how the FHAD was <br />incorporated onto the FIRM. Based on our review, we agree that the berm was incorrectly shown <br />on the FIRM as providing base flood protection. In addition, as you indicated, we agree that there <br />is a flood hazard associated with the split flow that breaks out of South Boulder Creek upstream of <br />Highway 36 and follows a northwest path. <br /> <br />Upon receipt of data to correct the berm mapping error and to identify the flood hazard associated <br />with the split flow, we will revise the FIRM for Boulder County, Colorado and Incorporated Areas, <br />as warranted. The submitted data should include existing conditions topographic information and <br />hydraulic analyses of existing conditions for the Flatirons gravel mining area and the split flow that <br />breaks out just upstream of Highway 36 along South Boulder Creek. Please note that during a <br />telephone conversation with a representative of o'!f Technical Evaluation Contractor on <br />November 19,1997, Mr. Alan Taylor, City of Boulder, indicated that topographic information in the <br />vicinity of the berm and for the split flow area along South Boulder Creek is available. <br /> <br />Please note that we will not be suspending the use of the FHAD or revising the FIRM and FIS to <br />reflect the conditions of the 1978 FIS and 1979 FIRM, as you requested. Because the FHAD was <br />based on revised hydrologic and hydraulic analyses and not based solely on the effects of the berm <br />in question, it would not be appropriate for. FEMA to ignore the information developed for the <br />FHAD and republish the information from the 1979 FIRM. <br /> <br />You also requested that FEMA require the Colorado Department of Transportation (CDOT) to <br />perform and submit a detailed impact analysis of the U.S. Highway 36 median crash barrier. The <br />Taggart study indicates the barrier was built during 1968-1969. Therefore, the barrier should have <br />been considered during the review of the study performed for the 1978 FIS and 1979 FIRM. The <br />City of Boulder or Boulder County may wish to contact CDOT officials to determine if any such <br />analysis has been performed and obtain the results of that analysis. Boulder County may submit <br />information on the barrier and/or an analysis of its effects on the flooding in support of a map <br />revision request. <br /> <br />In addition, you requested that we require the Flatiron Property gravel mining operator and property <br />owner to perform and submit a detailed impact analysis of the earthen berm and gravel mining pit <br />with respect to pre-berm and pre-mining conditions and grades using the R. W. Beck study as a <br />baseline. It is not clear from the submitted information that the flood hazard for the Flatiron <br />Property has changed as a result of the gravel mining operation. Again, the City or County may wish <br />to contact the gravel mining operator to determine if any such analysis has been performed and <br />obtain the results of that analysis. Otherwise, Boulder County may perform the analysis and submit <br />the results of the analysis for our review in support of a map revision request. <br /> <br />You asked that FEMA not certify the existing Flatiron Property berm as providing protection from <br />the base flood, pending the resolution of problems with the results of the FHAD and a complete <br />review of the impacts of the berm on flood hazards. You also requested that FEMA seek community <br />approval before certifying levees within your jurisdiction. Upon receipt of any map revision request <br />and required documentation cited in Part 65 of the NFIP regulations, we will make a determination <br />