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HFLP-CS100624 ©_ ri Kimley -Horn and Associates, Inc June 24, 2010 • 12700 Park Central Drive Suite 1800 Dallas, Texas 75251 -1516 Mr. Kenneth M. Griffin, P.E. Director of Engineering/Public Works City of Coppell 255 Parkway Coppell, TX 75019 Re: 1550 E. Belt Line Road Elm Fork of the Trinity River Conditional Letter of Map Revision Corridor Development Certificate Dear Mr. Griffin: Kimley -Horn and Associates, Inc. (KHA) is in receipt of the Conditional Letter of Map Revision and Corridor Development Certificate submittals prepared by Cotter Associates LLC, dated June 9, 2010 and June 8, 2010, respectively, for a property located at 1550 E. Belt Line Road in the City of Coppell, Texas. KHA has reviewed the documents for adherence to the City of Coppell Floodplain Management Ordinance, National Flood Insurance Program regulations, and the Fourth Edition of the CDC Manual. KHA offers the following comments based on a review of the above referenced documents. Conditional Letter of Map Revision 1. There are discrepancies in ground geometry between the 10 -100 year and 500 - year geometry files at cross sections 873 +38 and 873 +39 in the existing and hydraulic models. The applicant should review the geometry files and revise as necessary so the ground geometry is consistent between the 10 -100 year and 500 -year geometry files. Corridor Development Certificate 2. The information on the CDC application is inconsistent with the hydraulic model output provided by the applicant. The application should be revised such that it is consistent with the information shown on the hydraulic model output. 3. There are discrepancies in ground geometry between the 1 -100 year and SPF geometry files at several cross sections in the proposed hydraulic model. The applicant should review the geometry files and revise as necessary so the ground geometry is consistent between the 1 -100 year and SPF geometry files. • TEL 972 770 1300 FAX 972 239 3820 Kimley -Horn Mr. Kenneth M. Griffm and Associates, Inc June 2 4, 2010 Page 2 Please refer to the attached markups showing the discrepancies described herein. The applicant should revise the Conditional Letter of Map Revision and Corridor Development Certificate submittals based on the above comments and resubmit to the City of Coppell for further review. The applicant should include a written response to each comment as part of the resubmittal package. KHA may offer additional comments as a result of a technical review of the revised submittal. Please don't hesitate to give me a call at 972 - 776 -1781 if you have any questions or comments regarding these comments. Sincerely, KIMLEY- HORNAND ASSOCIATES, INC. , Brad W. Pickering, P.E., CFM Project Manager Enc/ Submittal Markups Cc: Mr. Glen A. 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E_ k- (1.5 CI N .-- CO C C C RI 1. 0- u Q) 0 cr o e co c0 le---- 0) 1---ef------ *-41 Z... a) v • 1 o CO co 2 (f) <NJ a C \J 0 r•- D i . 6 .. >, E c o F- 0 o ki to ca. D 1 • -r 0 IIII di 0 LC) 0 0 0 0 0 0 0 0 a o •zr in a. .<3. ,zr cn cr (4) uotienao CDC Tracking Code: CDC APPLICATION - PART 2 Detailed Hydrologic and Hydraulic Information To be completed by Applicant or Applicant's representative and submitted to the appropriate local CDC/Floodplain Administrator. Attach additional pages as necessary. This application is considered public information and will be distributed to federal, state, and local governmental agencies as outlined in the CDC Manual. 100-YEAR FLOOD Parameter Location Pre-Project With-Project Change Downstream Boundary (DB) Discharge 45,400 cfs 45,400 n/a 0.00 n/a cross-section 86+107 Upstream Boundary (UB) 45,400 cfs 45,400 n/a 0.00 n/a cross-section 87+339 Channel Downstream Boundary 3.48 fps 3.20 fps -0.28 fps Velocity cross-section 86+107 Upstream Boundary cross-section 87+339 8.42 7.19 fps 1.23 fps Water Surface 1,148 feet downstream of DB 440.27 ft 440.27 ft 0.00 ft Elevation cross-section 84+959 (NGVD) 1,671 feet downstream of DB 440.1 ft 440.1 ft 0.00 ft cross-section 84+436 Downstream Boundary 440.38 ft 440.38 ft 0.00 ft cross-section 86+107 Mid-project 440.72 ft 440.57 ft -.0.15 ft cross-section 86+793 CDC Tracking Code: 440 elf 0. Upstream Boundary '196 — 4 - 0 ' 73P ft 06:64 ft -0.05 ft cross-section 87+339 '--- (;1 feet upstream of UB 87+428 440.90 ft 440.65 ft -0.25 ft eross 86+339 61)2.00 feet upstream of UB cross- 87+521 441.53 ft 441.32 ft -0.21 ft section 86+339 1183.00 feet upstream of UB cross 87+522 441.53 ft 441.32 ft - 0. 21 ft section 86+339 fv\ tftft ovk . •k'y Lik.k\ - 03 f 4"4 2.00 feet upstream of UB 87+541 (4413) ft 44175 4 ft -0.21 ft cross-section 86+339 Project Lands in 148.1 ac 134.9 ac 13.1 ac Floodplain Valley Storage on Project 694.76 ac 973.10ac-ft +278.34 ac Lands Total Valley Storage Change +257.80 ac Valley Storage Percent Change t hb* CDC Tracking Code: STANDARD PROJECT FLOOD (SPF) Parameter Location Pre-Project With-Project Change Downstream Boundary (DB) Discharge cross-section 86+107 89,800 cfs 89,800 cfs 0.00 cfs Upstream Boundary (UB) cross-section 83+339 89,800 cfs 89,800 cfs 0.00 cfs Channel Downstream Boundary Velocity cross-section 86+107 3.06 fps 3.06 fps 0.00 fps Upstream Bo ary cross-secti n j339 9.78 fps 7.94 fps -1.84 fps + Water Surface 1,148 feet downstream of DB Elevation cross-section 84+959 446.71 ft 446.71 ft 0.00 ft (NGVD) 1.671 feet downstream of DB cross-section 84+436 446.63 ft 446.63 ft 0.00 ft Downstream Boundary cross-section 86+107 446.76 ft 446.76 ft 0.00 ft Mid-project cross-section 86+793 446.91 ft 446.87 ft -0.04 ft ,10 0 4 to .1 t croN ti t•- Upstream Boundary ft 06 44i. 447,74. 0. ft cross-section( 339 ft 444 feet upstream of DB cross-section 86+551 446.88ft 446.87 ft 0.01 ft