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Federal Emergency Management Agency Washington, D.C. 20472 CERTIFIED MAIL RETURN RECEIPT REQUESTED IN REPLY REFER TO: Case No.: 95.08.041P The Honorable Leslie Durgin Mayor, City of Boulder P.O. Box 791 Boulder, Colorado 80306 Community: City of Boulder, Colorado Community No.: 080024 Panel Affected: 08013C0415 F Effective Date of This Revision: JUN 0 5 \995 102.I.A.C Dear Mayor Durgin: This is in response to a request for a revision to the effective Flood Insurance Study (F1S) and National Flood Insurance Program (NFIP) map for your community. Specifically, this responds to a letter dated March 22, 1995, from Mr. David J. Love, P.E., Love & Associates, Inc., regarding the effective FIS report and Flood Insurance Rate Map (FIRM) for Boulder County, Colorado and Incorporated Areas. Mr. Love submitted data to support a November 18, 1994, letter from Ms. Karen S. Medde, P.E., Civil Engineer I, Department of Public Works, City of Boulder. Ms. Medde requested that we revise the effective FIRM to show the effects of channel modifications and culvert construction under 47th Street and Foothills Parkway along Wonderland Creek. All data required to complete our review of this request were submitted with letters dated March 22 and April 4, 1995, from Mr. Love; letters dated November 18, 1994, and January 10 and February 7, 1995, from Ms. Medde; and a letter dated December 13, 1994, from Mr. Gene M. Morris, Love & Associates, Inc. Because this Letter of Map Revision (LOMR) shows the effects of a publicly sponsored flood. control project that reduces flooding to existing development, fees were not assessed for the review. We have completed our review of the submitted data and the flood data shown on the effective FIRM, and have revised the FIRM to modify the elevations, floodplain and floodway boundary delineations, and zone designations of a flood having a I-percent probability of being equaled or exceeded in any given year (base flood) along the reach of Wonderland Creek from approximately 600 feet upstream of Kings Ridge Boulevard to just upstream of the Burlington Northern Railroad. The Special Flood Hazard Area (SFHA) increased and decreased along this reach of Wonderland Creek as a result of the replacement of a single culvert under 47th Street with triple box culverts that pass under both 47th Street and Foothills Parkway and channel modifications. The base flood is contained within the triple box culverts. The maximum decrease in SFHA width is approximately 600 feet, and occurred approximately 300 feet downstream of 47th Street. This reduction is due to the elimination of the Zone AO (depth 1 foot) SFHA. The maximum increase in the SFHA width is approximately 50 feet, and occurred approximately 900 feet upstream of Kings Ridge Boulevard along the north side of the creek. The maximum decrease in base flood elevations (BFEs) is 8 feet through the box culverts. In the channel, the maximum decrease in BFEs is 1.6 feet approximately 360 feet downstream of 47th Street. The maximum increase in BFEs is 1.1 feet just downstream of the Burlington Northern Railroad. The City of Boulder notified all affected property owners by public notice published in the Boulder Daily Camera and stated that no insurable structures are affected by the increase in BFEs.