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Westhaven-CS140327;pp HALFF March 27, 2014 AVO 28875 W005 Mr. Kenneth M. Griffin, P.E. Director of Engineering and Public Works City of Coppell PO Box 9478 Coppell, Texas 75019 Re: Review of Floodplain Study Submittal by Kimley-Horn and Associates, Inc. — Cottonwood Branch Floodplain Study Dear Mr. Griffin, We have completed an initial review of the Cottonwood Branch Floodplain Study prepared by Kimley-Horn and Associates, Inc., dated March 11, 2014, and received on March 17, 2014. This general review consists of checking the submittal package for completeness and compliance with the City of Coppell floodplain ordinances, regulations, and policies. The following comments are a result of this initial review: 1. Per City of Coppell floodplain ordinance, the finished floor should be a minimum of two (2) feet above the Flood Insurance Study (FIS) base flood elevation or to one (1) foot above the design flood elevation, whichever is higher. Based on the floodplain workmap and hydraulic model results provided, the finished floor of the proposed structure does not meet this criterion if the proposed finished floor is set to 474.5 feet. Please revise and resubmit. 2. The proposed project seems to have no significant impact on water surface elevations on Cottonwood Branch. 3. The proposed project seems to have no significant impact on velocities on Cottonwood Branch. 4. Valley storage loss on Cottonwood Branch due to the project does not exceed the maximum allowable of 15%. Based on this information, Halff Associates recommends conditional approval. Full approval can be granted once Item 1 above has been addressed. HALFF ASSOCIATES, INC. 1201 NORTH BOWSER ROAD TEL (214) 346-6200 WWW. HALFF.COM RICHARDSON, TX 75081-2275 FAX (214) 739-0095 ;pp HALFF This review was performed for the benefit of the City of Coppell. This is not a detailed engineering review of any construction plans, and Halff Associates, Inc. assumes no liability for the adequacy of the planning, design or construction of the project. Do not hesitate to call me at 214-346-6245 if you have further questions or comments concerning this review. Please include the reference "AVO 28875 W005" on all correspondence. Sincerely, HALFF ASSOCIATES, INC. Russell P. Erskine, P.E., CFM Project Manager cc: Brad Pickering, P.E., CFM Kimley-Horn and Associates, Inc.