Agenda - Council - 01/27/2009 - Laserfiche WebLink

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CERTIFIED MAIL RETURN RECEIPT REQUESTED The Honorable Tom Gamec Mayor, City of Ramsey 7550 Sunwood Drive Northwest Ramsey, MN 55303 Dear Mayor Gamec: Federal Emergency Management Agency Washington, D.C. 20472 September 25, 2008 IN REPLY REFER TO: Case No.: 08- 05 -2729R Community: City of Ramsey, MN Community No.: 270681 104 This responds to a request that the Department of Homeland Security's Federal Emergency Management Agency (FEMA) comment on the effects that a proposed project would have on the effective Flood Insurance Rate Map (FIRM), Flood Boundary and Floodway Map (FBFM), and Flood Insurance Study (FIS) report for your community in accordance with Part 65 of the National Flood Insurance Program (NFIP) regulations. In a letter dated March 27, 2008, Mr. Duane Hansel, P.E., Bolton and Menk, Inc., requested that FEMA evaluate the effects that a revised hydrologic and hydraulic analysis, updated topographic information, and the proposed project would have on the flood hazard information shown on the effective FIRM, FBFM, and FIS report along Trott Brook from approximately 1,600 feet upstream of Ermine Boulevard Northwest Culvert to approximately 700 feet downstream. The proposed project includes replacement of an existing 72 -inch reinforced concrete pipe culvert at Ermine Boulevard Northwest Crossing with a 1 -feet wide by 6 -feet high box culvert. The area affected by this request is in a flood zone designated Zone Al, a Special Flood Hazard Area (SFHA), an area subject to inundation by the base (1- percent - annual- chance) flood, with Base Flood Elevations (BFEs) determined. All data required to complete our review of this request for a Conditional Letter of Map Revision (CLOMR) were submitted with letters from Mr. Hansel. We reviewed the submitted data and the data used to prepare the effective FIRM and FBFM for your community and determined that the proposed project meets the minimum floodplain management criteria of the NFIP. The submitted existing conditions HEC -RAS hydraulic computer model, dated February 23, 2008, based on updated hydrology, was used as the base conditions model in our review of . the proposed conditions model for this CLOMR request. We believe that, if the proposed project is constructed as shown on the topographic work map entitled "City of Ramsey, Anoka County, Minnesota, Ermine Boulevard Northwest Proposed FIRM/Floodway," prepared by Bolton and Menk, Inc., dated February 2008, and the data listed below are received, a revision to the FIRM and FBFM would be warranted. The effective hydrology for Trott Brook was computed using regression equations, resulting in a base flood discharge of approximately 660 cubic feet per second (cfs) for the project reach. A Hydraulic Engineering Center Hydrologic Modeling System (HEC -HMS) hydrologic computer model was used to determine revised discharges for Trott Brook from its headwaters in Anoka County to its lowest extent in Sherburne County. The revised hydrology was prepared by Barr Engineering and approved by the Minnesota Department of Natural Resources. There are significant differences between the revised