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Park, Peter-CS 970305· Federal Emergency Management,Agency Washington, D.C. 204:72 ..: ....... CERTIFIED MAIL IN REPLY REFER TOY ' " ~TURN ~CEIPT ~QUESTED Case No.- 97-06-239R ............... - ~e Honorable Tom Morion Commu~W: Ciw of Coppell, Texas Mayor, Ciw of Coppell Co~u~W No.: 480170 255 Par~ay Boulevard Coppell, Texas 75019 104 Dear Mayor Moron: ~ res~n~ m a r~uest ~at ~e F~erfl Emergency M~agemem Agency (FEMA) commem on ~e effec~ · at a pro~ proj~t would have on ~e effe~ive Flood Imur~ce Rate Map (FIRM) for your comm~iw, in accordance wi~ Pan 65 of ~e Nafionfl ~ood Imurance Progr~ (NFIP) re~afiom. In a letter dated Febma~ 7, 1997, Mr. Ke~e~ Gri~n, P.E., Director of Engineering and Public Wor~, Ciw of Coppell, requested ~at FEMA evfluate ~e effecm ~at proposed excavation and fill in ~e floodway ~hge along ~e western overb~ of Elm Fork of TrOw River j~t ups~e~ of S~dy L~e Road would have on ~e effective FIRM. The proposed project is also alo~ ~e sou~ern overba~ of Demon Creek, which is under ~uence of ~e bac~a~r effec~ ~om Elm Fork of Trhi~ River ~ough ~e project mca. In addition, ~is request included a more derailed hydraulic anflysis ~at hco~rated more derailed topographic information to reflect existing watershed con,flora. ~e Ciw of C~rollton, Texas is flso affected ~y ~is conditiona! revision request. MI dam r~u~ ~ complete our review of ~is request for a Condifionfl ~uer of Map Revision (CLOMR) were submitted wi~ Mr. Griffm's lener. We have completed our review of the submitted data and the flood data used to prepare the effective FIRM tbr your community'. The submitted corrected effective conditions HEC-2 hydraulic computer model, dated July 22, 1996, based on updated topographic intbrmafion, 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 submitted map, entitled "Grading Plan, 18.9 AC. Sandy Lake Road Property, City. of Coppell, Texas," dated January 30, 1997, prepared by Nathan D. Maier Consulting Engineers, inc., and as described in the report, entitled "Floodplain Hydraulics Study, Elm Fork Trinity River," dated July 30, 1996, also prepared by Nathan D. Maier Consulting Engineers, Inc., a revision to the FIRM would be warranted. The submitted corrected effective analysis incorporated more detailed topographic information to reflect; existing watershed conditions. The elevations of the flood having a 1-percent chance of bei~ equaled or exceeded in any given year (base flood) increased by a maximum of 0.02 foot and decreased by a maximum of 0.01 foot, compared to the effective base flood elevations (BFEs). The submitted proposed conditions analysis incorporated the effects of the proposed project. The BFEs w~li increase by a maximum of 0.02 foot and decrease by a maximum of 0.05 foot, compared to the BFEs computed in the corrected effective analysis. The increase in BFE is because of fill in the floodway fringe. As a result of the proposed conditions analysis, the BFEs will increase and decrease compared to the effective BFEs. The maximum increase in BFE, 0.01 foot, will occur just,upstream of Sandy Lake Road. The maximum decrease in BFE, 0.03 foot, will occur approximately 3,800 feet upstream of Sandy Lake Road. 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 by a maximum of approximately 1,000 feet, approximately 400 feet upstream of Sandy Lake Road. 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 FIRM. · Effective October 1, 1996, FEMA revised the fee schedule for reviewing and processing requests for modifications to published flood information and maps. Under this schedule,' FEMA established flat review and processing fees for most types of requests. All requests dated October 1, 1996, or later will be processed under this new schedule. The tee for your map revision request will be $2,300 and must be received before we can begin processing your request. Paymem 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 lr~urance Program, or by credit card. The payment must be forwarded to the tbllowing 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 from your community and the City of Carrollton · 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 · Hydraulic analyses, for as-built conditions, of the base flood, the 0.2-percent-annual--chance flood, and regulatory floodway, if they differ fi.om the proposed conditions models After receiving appropriate documentation to show that the project has been completed, FEMA will initiate a revision to the FIRM. This CLOMR is based on minimum floodplain 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 construction 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. "3 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 community. Information on the CCO for your community may be obtained by contacting the Director, Mitigation Division of FEMA in Denton, Texas, at (817) 898-5127. If you have any technical questions regarding this CLOMR, please contact Mr. Alan Johnson of our staff in Washington, DC, either by telephone at (202) 646-3403 or by facsimile at (202) 646-4596. Sincerer. ~Hazard Identification Branch Mitigation Directorate cc: The Honorable Gary Blancet Mayor, City of Carrollton Mr. Kenneth Griff'm, P.E. Director of Engineering & Public Works City of Coppell Mr. Mark D. Walter, P.E. Nathan D. Maier Consulting Engineers, Inc.