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<br /> <br />Federal Emergency Management Agency <br />Washington, D.C. 20472 <br /> <br />March 14, 1997 <br /> <br />Mr. Gary W. Behlen, P.E. <br />City Engineer <br />City of Broomfield <br />P.O. Box 1415 <br />Broomfield, Colorado 80038-1415 <br /> <br />IN REPLY REFER TO: <br />Case No.: 97-08-188R <br />Community: City of Broomfield, Colorado <br />Community No.: 085073 <br /> <br />316-ACK.FRQ <br /> <br />Dear Mr. Behlen: <br /> <br />This responds to your request dated February 24, 1997, that the Federal Emergency Management Agency <br />(FEMA) issue a conditional revision to the Flood Insurance Rate Map (FIRM) and Flood Boundary and <br />Floodway Map (FBFM) for the above-referenced community. Pertinent information about the request is listed <br />below. <br /> <br />Identifier: <br /> <br />City Park Channel <br /> <br />Flooding Source: <br /> <br />City Park Channel <br /> <br />FIRM Panel Affected: <br /> <br />onOD <br /> <br />FBFM Panel Affected: <br /> <br />0220 <br /> <br />We have completed an inventory of the items that you submitted. The items identified below are required <br />before we can begin a detailed review of your request. <br /> <br />I. All of the models submitted with your request were computed using the HEC-RAS hydraulic model. <br />FEMA considers HEC-RAS a new hydraulic model. In order to use HEC-RAS the entire stream <br />from the confluence with Nissen Reservoir Channel to the upstream limit would need to be modeled. <br />Please provide a HEC-RAS model for the entire stream or a HEC-2 analysis for the duplicate <br />effective, corrected effective, pre-project conditions, and post-project conditions hydraulic models. <br /> <br />2. The report submitted with your request, entitled "City Park Channel," prepared by Rocky Mountain <br />Consultants, Inc., dated February 1997, shows the flow from the City Park Channel splitting at the <br />120th Avenue culvert. The flow in excess of the culvert capacity is subsequently diverted east along <br />the north side of 120th Avenue to where it overtops Sheridan Boulevard. Please submit a HEC-2 <br />analysis to support the delineation of the flooding area located along the north side of 120th Avenue. <br />Also, please include documentation to support the starting water surface elevation used for this HEC-2 <br />model. <br /> <br />3. The computer diskette supplied with your request appears to be blank. Weare returning the diskette <br />with this letter. Please submit another computer diskette containing working copies of all HEC-2 <br />models. <br /> <br />4. The copy of the annotated FIRM that was submitted with your request in the Rocky Mountain <br />Consultants, Inc. report appears to be incomplete. The actual portion submitted with your request is <br />attached. Please provide a copy of the annotated FIRM showing the proposed boundary delineations <br />