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FS9906-CS000204Federal Emergency Management Wash on. D.C. 20,72 FEB 0 2000 CERTIFIED MAIL RETURN RECEIPT REQUESTED The Honorable Candy Sheehan Mayor, City of Coppell 255 Parkway Boulevard Coppell, TX 75019 Dear Mayor Sheelan: IN REPLY REFER TO: Case No.: 00-0-138R Community: Ct. ~ 104 -8 C~TY CITY t'OFMAC~# This responds to a request that the Federal Emergency Management Agency (FEMA) comment on the effects that a proposed project would have on the effective Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS) report for your community in accordance with Pan 65 of the National Flood Insurance Program (NFIP) regulations. In a letter dated October 27, 1999, Mr. Ronald W. Morrison, P.E., C.F.M., Senior Hydrologist, Morrison Hydrology Engineering, Inc., requested that FEMA evaluate the effects that proposed placement of fdl along Cottonwood Branch and proposed excavation associated with proposed construction of Coppell High School would have on the flood hazard information shown on the effective FIRM and FIS report. The proposed fall will be placed from approximately 545 feet upstream to approximately 1,805 feet upstream of Parkway Boulevard, and the proposed excavation will occur from approximately 100 feet upstream to approximately 1,805 feet upstream of Parkway Boulevard. This request also included more detailed topographic information to reflect existing channel conditions from approximately 2,445 feet upstream to approximately 2,675 feet upstream of Parkway Boulevard. All data required to complete our review of this request for a Conditional Letter of Map Revision (CLOMR) were submitted with letters from Mr. Morrison. We reviewed the submitted data and the flood data used to prepare the effective FIRM for your community and determined that the proposed project meets the minimum floodplain management criteria of the NFIP. The submitted existing conditions HEC-2 hydraulic computer model, dated October 18, 1999, based on updated wpographic information, 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 endfled "Conditional Letter of Map Revision for Cottonwood Creek, at the Coppell High School, City of Coppell, Texas," contained in the report entitled "Flood Study in Support of a Conditional Letter of Map Revision for Cottonwood Creek at Coppell High School, Coppell, Texas," prepared by Morrison Hydrology Engineering, Inc., dated October 25, 1999, and the data listed below are received, a revision to the FIRM would be warranted. As a result of the more detailed topographic information, the elevations of the flood having a 1-percent chance of being equaled or exceeded in any given year (base flood) for Cottonwood Branch increased compared to the effective base: flood elevations (BFEs). The maximum inciease in BFE, 2.24 feet, occurred approximately 545 feet upstream of Parkway Boulevard. As a result of the proposed placement of fill, the BFEs will decrease compared to the existing conditions BFEs for Cottonwood Branch. The maximum decrease in BFE, 1.83 feet, will occur approximately 545 feet upstream of Parkway Boulevard. As a result of the more detailed topographic information and proposed project, the BFEs will increase and decrease compared to the effective BFEs for Cottonwood Branch. The maximum increase in, BFE, 0.41 foot, will occur approximately 545 feet upstream of Parkway Boulevard. The maximum decrease in BFE, 0.59 foot, will occur approximately 1,060 feet upstream of Parkway Boulevard. The width of the Special Flood Hazard Area (SFHA), the area that would be inundated by the base flood, will decrease compared to the effective SFHA width, and the width of the regulatory floodway will increase in some areas and decrease in other areas compared to the effective floodway width. Upon completion of the project, your community may submit the data listed below and request that we make a final determination on revising the effective FIS report and FIRM, Effective March 1, 1999, FEMA ~evised the fee schedule for reviewing and processing requests for conditional and final modifications to published flood information and maps. In accordance with this schedule, the fee for your map revision request will be $3,400 and must be received before we can begin processing your request. Payment of this fee shall be made in the form of a check or money order, made payable in U.S. funds to the National Flood Insurance Program, or by credit card. The payment must be forwarded to the following address: Federal Emergency Management Agency Fee-Collection System Administrator P.O. Box 3173 Merrifield, VA 22116-3173 · As-built plans, certified by a registered professional engineer, of all proposed project elements · Community acknowledgment of the map revision request Certification that all fill placed in the currently effective base floodplain and below the proposed BFE is compacted to 95 percent of the maximum density obtainable with the Standard Proctor Test method issued by the American Society for Testing and Materials (ASTM Standard D-698) or an acceptable equivalent method for all areas to be removed from the base floodplain A copy of the public notice distributed by your community stating its intent to revise the floodway, or a statement by your community that it has notified all affected property owners and affected adjacent jurisdictions · A letter stating that your community will adopt and enforce the modified floodway Hydraulic analyses, for as-built conditions, of the base flood; the floods having a 10-, 2-, and 0.2-percent chance of being equaled or exceeded in any given year; and regulatory floodway if they differ from the proposed conditions models After receiving appropriate documentation to show that the project has been completed, FEMA will initiate a revision to the FIRM and FIS report. Because the BFEs would change as a result of the project, a 90-day appeal period would be initiated, during which community officials and interested persons may appeal the revised BFEs based on scientific or technical data. '3 The basis of this CLOMR is, in whole or in pan, a channel-modification project. NFIP regulations, as cited in Paragraph 60.3(b)(7), require that communities assure that the flood-carrying capacity within the altered or relocated portion of any watercourse is maintained. This provision is incorporated into your community's existing floodplain mnnngement regulations. Consequently, the ultimate responsibility for maintenance of the modified channel rests with your community. This CLOMR is based on minimum ~oodpla'm management criteria established under the NFIP. Your community is responsible for approving all floodplain development and for ensuring all necessary permits required by Federal or State law have been received. State, county, and community officials, based on knowledge of local conditions and in the interest of safety, may set higher standards for comt~uction in the SFHA. If the State, county, or community has adopted more restrictive or comprehensive floodplain management criteria, these criteria take precedence over the minimum NFIP criteria. If you have any questions regarding floodplain management regulations for your community or the NFIP in general, please contact the Consultation Coordination Officer (CCO) for your COmmllnity. hlforfilation on the CCO for your community may be obtained by contacting the Director, Mitigation Division of FEMA in Denton, Texas, at (940) 8984127. If you have any technical questions regarding this CLOMR, please contact the FEMA Map Assistance Center, toll free, at 1-877-FEMA MAP (1-877-336-2627). Sincerely, Alan A. Joh~ Hazards StUd n, P.E., Project Engineer Branch Mitigation Directorate For: Matthew B. Miller, P.E., Chief Hazards Study Branch Mitigation Directorate Enclosure(s) CC; Mr. Kenneth M. Griffm, P.E. Director of Engineering and Public Works City of Coppell Mr. Ronald W. Morrison, P.E., C.F.M. Senior Hydrologist Morrison Hydrology Engineering, Inc.