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DR1101-CS121213 E! HALFF December 13, 2012 AVO 27953 Regulatory Branch,CESWF-PER-R U.S.Army Corps of Engineers PO Box 17300 Fort Worth,Texas 76102-0300 Attn: Mr. Darvin Messer RE: Cypress Waters Project by Billingsley Company(Project No.: SWF-2012-00111) Dear Mr. Messer: Irving Flood Control District—Section III (IFCD-3) is a levee protected area located west of the Elm Fork of the Trinity River, south of Grapevine Creek, and directly east of the proposed Cypress Waters proposed development by the Billingsley Company. The levee protects what is known as Valley Ranch, a residential area, and is operated and maintained by IFCD-3. On behalf of IFCD-3, Halff Associates reviewed the Public Notice for the Cypress Creek Project (SWF-2012-00111) proposed by the Billingsley Company. Irving Flood Control District—Section III has no comments on this public notice since the proposed work shown in this document does not directly impact IFCD-3. However, IFCD-3 does have a few concerns based on statements made within this public notice pertaining to work associated with the North Lake Dam and future work in the North Lake area which should be addressed prior to further design and development. These items include: 1. On Page 3, 2nd paragraph,will the City of Coppell (owner of the dam and spillway) update the current dam breach analysis for the main dam/spillway to reflect the lowering of the lake? Will the proposed revisions and results be presented to the Texas Commission of Environmental Quality (TCEQ)? Due to the modification, how will the hydrology and hydraulics of Grapevine Creek be impacted? 2. Besides the main dam, a second dam exists, known as the Saddle Dam, located on the east side of North Lake and immediately adjacent to IFCD-3. Does the City of Coppell own this structure as well? If not,who does? IFCD-3 has concerns about this structure and the safety and welfare of the estimated 30,000 residence that would likely be impacted if failure of this structure was to occur. We are unaware of any previous dam breach analysis or evaluations of this structure. If the functionality of this structure is unchanged due to the lowering of the water behind the dam, IFCD-3 requests that a study/evaluation of the Saddle Dam, including the development of an Emergency Action Plan be provided for review and approval. The structure should also be permitted with the State of Texas (TCEQ), if it is not already. 3. IFCD-3 requests that a copy of the Operations and Maintenance Plan for the Saddle Dam be provide to the District for review and approval. HALFF ASSOCIATES,INC. 1201 NORTH BOWSER ROAD TEL (214)346-6200 WWW.HALFF.COM RICHARDSON,TX 75081-2275 FAX (214)739-0095 HALFF 4. As the North Lake area develops, any potential impacts to IFCD-3 should be clearly defined and will be subject to review and approval prior to development. This review was performed on the behalf of Irving Flood Control District—Section 3. This is not a detailed engineering review of any construction plans, and Half Associates, Inc. assumes no liability for the planning,design or construction of the project. Do not hesitate to call me at (214) 346-6245 if you have further questions concerning this review. Sincerely, HALFF ASSOCIATES, INC. 7 & & PEA Russell P. Erskine, P.E., CFM Project Manager Dallas O. Burke,Operations Manager IFCD-3 Bill Walker, Billingsley Company Garry Fennel, City of Irving Steve Parker, City of Dallas Kenneth Griffin, City of Coppell