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Villages C P3&4-CS 920428· ^ FILE COPY Federal Emergency Management Agency Washington, D.C. 20{72 CERTIFIED NAIL IN REPLY REFER TO: RETURN RECEIPT REQUESTED 316 Hr. Don A. Tipton Date: April 28, 1992 Don A. Tipton, Inc. Case No.: 92-06-037R 6330 Belt Line Road Community: City of Coppell, Texas Suite C _ Community No.: 180170 Carland, Texas 75043 Re: Villages o£ Coppell-Phases 3 and 4 Dear Hr. Tipton: This is in response to the request for a conditional Letter of Nap Revision (LOMR) for the Villages o£ Coppell-Phases 3 and 4, in the City of Coppell, Texas, dated April 10, 1992. We have completed an inventory of the items you submitted to support this request. The results o£ our inventory are sv~unArized on the enclosed "Data Request Checklist." All of the items indicated by an "X' in Column 1 are needed before we viii begin our review; items indicated in Column 2 have already been received. I£ only items in Column 2 are, noted, no additional items are required at this time; there£ore, we will, begin our review. However, additional items may be requested at a later date. The Federal Emergency Management Agency (FEMA), has ".implemented a reimbursement procedure to recover costs associated with revleving prOposed projects, thus reducing the expense to taxpayers. The initial fee, if indicated on the checklist, is the minimum charge associated with our reviewing a project of this type. However, additional costs could be required after review and before issuing a conditional LOMR, depending on the complexity of the review required. You will be notified of the estimated total processing cost ii it is anticipated that, due to the extent of the review required, the total cost viii exceed $1,500. In that situation, our review would be suspended pending our receipt of written authorization from you to proceed. Any items indicated in Column 1 of the checklist should be submitted to the following address: Federal Emergency Management Agency Federal Insurance Administration Office of Risk Assessment 500 C Street, SW., Room 422 Washington, D.C. 204?2 Attention: Ms. Fay L. Davis For identification purposes, the case number referenced above should be included on any check or money order; these should be sent by Registered Mail, Return Receipt Requested. Please note that any initial fee already submitted will be applied to this request only if we receive all items indicated in Column 1 of the checkl£st within 90 days of the date of this letter. After 90 days, the request will be treated as an origlnal submittal and will be subject to all submittal/payment procedures, £ncluding the initial fee. However, should you wish to withdraw your request for a conditional LOHR at this time, you may submit a ~ritten request for return of data and reimbursement o£ any £nltial fee already submitted by wr£t£ng to the address given above with£n 90 days. To ass£st you in preparing the required data, we have enclosed a copy of Parts 65 and 72 of the National Flood Insurance Program and Related Regulations. Part 65 describes the FEHA policy concerning revisions to Flood Insurance Study maps; Part 72 describes the reimbursement procedures. If you have any questions concerning FEHA policy, or the National Flood Insurance Program in general, please call Mr. Alan Johnson of our Headquarters staff in Wash£ngton, D.C. at (202) 646-3403. Sincerely, William R. Locke Chief, Risk Studies Division Federal Insurance Administration Enclosures cc: The Honorable Mark Wolfe Mayor, City of Coppell Mr. Ron Morrlson Morrison Hydrology/Engineering, Inc. Mr. Kenneth Griffin, P.E. City Engineer Federal Emergency Management Agency Washington, D.C. 20472 DATA REQUEST CHECKLIST FOR CONDITIONAL LETTER OF HAP REVISION Requestor: Hr. Don A. Tipton Case No.: 92-06-037R Community: City of Coppell, Texas Date: April 28, 1992 Re: Villages of Coppell - Phases 3 and ~ The items checked below in Column 1 are required to process your request £or a conditional Letter of Hap Revision (LOHR). .Items checked in Column 2 have been received and should not be resubmitted unless specifically requested. (2) (2) Required Received N/A 1. Written description of the scope of the proposed project and the methodology used to analyze the project's effects. 2. Hydraulic backwater models of the 1D0-year flood for the following: N/A a. Existing conditions (cross sections to reflect conditions prior to construction of the project). N/A b. Proposed conditions (same cross sections as the existing conditions model, reflecting the proposed project). 3. Hydraulic backwater models of the 10-, 50-, 100-, and 500-year floods for the following: N/A a. Duplicate of the effective Flood Insurance Study (FIS) model. N/A b. Existing conditions (effective FIS model including cross sections through the project site; cross sections should reflect conditions prior to construction of project). N/A c. Proposed conditions (existing conditions model reflecting the proposed project). 4. Floodway hydraulic backwater models of the following: N/A a. Duplicate of effective. N/A b. Existing conditions. N/A . c. Proposed conditions. (1) (2) Required Received N/A 5. Copy of the Flood Insurance Rate Map with the project area indicated. N/A 6. Topographic mapping of the entire area covered by the proposed conditions model, indicating the locations of all cross sections used in the hydraulic model and delineating the proposed 100-year floodplain boundary. 7. Topographic mapping of the entire area covered by the proposed conditions model, indicating the locations of all cross sections used in the hydraulic model and delineating: N/A a. The proposed 100- and 500-year floodplain boundaries. N/A b. The proposed floodway boundary. X 8. A concise description of the nature and extent of the requested revision. X 9. Evidence that the Chief Executive Officer (CEO) of the affected community, or an official designated by the CEO, was asked to submit the request. (See Section 65.4 of the NFIP regulations.) N/A 10. A general description of the proposed hydrologic conditions on which the conditional revision request is based. (See Paragraph 65.6(c)(1)(i) of the NFIP regulations.) X 11. A general description of the proposed hydraulic conditions, including channel modifications or other projects, on which the conditional revision request is based. (See Paragraph 65.6(c)(2)(i) of the NFIP regulations.) N/A 12. New hydrologic analysis, including a brief description of the methodology used, for the -year flood(s) for (See Paragraph 65.6(a)(?) of the NFIP regulations.) (1) (2) Required Received N/A 13. Evidence that the appropriate local, State, or Federal agency ) has approved the new hydrologic analysis, including the resulting peak discharge values. X 14. Printouts (including full input and output listings) from a calibration model, produced by the requestor, that duplicates the hydraulic computer model used to determine the 10-, 50-, 100-, and 500-year water-surface elevations shown for Denton Creek and Elm Fork Trinity River in the effective FIS report and on the effective FIRM. (See Paragraph 65.6(a)(8) of the NFIP regulations.) The calibration model may be either the FIS model, reproduced on the requestor's equipment, or a model that yields computed water-surface profiles thac duplicate the flood profiles shown for Denton Creek and Elm Fork Trinity River in Cbe effective FIS report. X 15. Printouts (including full input and output listings) from a calibration model, produced by the requestor, that duplicates the hydraulic computer model used co determine the limits of the 100-year floodway shown for Denton Creek and Elm Fork Trinity River on the effective Flood Boundary and Floodway Map (FBFM)/FIRM. (See Paragraph 65.6(a)(8) of the NFIP regulations.) The callbra~ion model may be either the FIS floodway model, reproduced on ~he reques~or's equipment, or a model that yields the computed floodway widths and wa~er-surface elevations presented in the Floodway Data Table for Denton Creek and Elm Fork Trinity River in ~he effective FIS report. (1) (2) Required Received 16. Printouts (includlng full input and output listings) from a revised hydraulic model for the 10-, 50-, 100-, and 500-year water-surface elevations on Denton Creek and Elm Fork Trinity River. The revised model must be created from the calibration model (Item 14) and must meet the requirement(s) listed below. X Th~ model must be based on the same peak discharge values used in the calibration model (Item 14). The model must be based on the peak discharge values determined in the new hydrologic analysis (Item 12). X The model must account for the effects of the proposed hydraulic conditions on which the conditional revision request is based. In addition, the revised model must account for the effects of any encroachments that have occurred in the 100-year floodplain since the FIg hydraulic model was developed and must cover a sufficient length of Denton Creek and Etm Fork Trinity River so that the water-surface elevations computed at cross sections upstream and downstream of the revised reach will match those shown at the same cross sections on the Flood Profiles in the effective FIg report within approximately 0.5 foot. All changes to the input data in the calibration model (Item 14) must be highlighted on the printouts. (See Paragraph 65.6(a)(8) of the NFIP regulations.) N/A 17. A hydraulic analysis, including a brief description of the methodology used, for the 100-year flood on . (See Paragraph 65.6(a)(9) of the NFIP regulations.) (2) (2) Required Received X 18. Printouts (including full input and output listings) from a revised hydraulic model for the 100-year floodway on Denton Creek and Elm Fork Trinity River. The revised model must be created from the calibration model (Item 15) and must meet the requirements listed below. X Th~ model must be based on the lO0- year peak discharge value(s) used in the calibration model (Item 15). The model must be based on the lO0- year peak discharge value(s) determined in the new hydrologlc analysis (Item 12). X The model must account for the effects of the proposed hydraulic conditions on which the' conditional revision request is based. In addition, the revised model must account for the effects of any encroachments that have occurred in the lO0-year floodplain since the FIS floodway model was developed and must cover a sufficient length of Denton Creek and Elm Fork Trinity River so that the water-surface elevations and floodway widths computed at cross sections upstream and do~mstream of the revised reach will match those sho~n at the same cross sections on the Flood Profiles and Floodway Data Table in the effective FIS report. The revised model must be based on the equal conveyance reducclon method unless agreements have been made with affected property owners that an alternative method would be used. The net effect of the proposed hydraulic conditions, the encroachments that have occurred since the floodway model was developed~ and the revised floodway limits must not increase the computed (1) (~) Required Received 100-year water-surface elevations by more than 1.0 foot above those computed in the calibration model (Item 14) or those computed in the revised model (Item 16), whichever are lower. (See Paragraph 65.7(b)(4) of the NFIP regulations.) X 19. A statement from the community (or State, as appropriate~ that it is aware of the proposed floodway and has no objections. N/A 20. Corporate limit map and/or annexation ordinances that reflect the current community boundaries. X 21. A topographic map that shows the proposed 10-, 50-, 100-, and 500-year floodplain and lO0-year floodway boundaries, the locations and alignments of all cross sections used in the revised hydraulic models (Items 16 and 18), stream alignments, road alignments, and the community boundaries. The revised 100- and 500-year floodplain and 100-year floodway boundaries must tie into those shown on the effective FIRN and FBFM upstream and downstream of the revised reach. The scale and topographic definition of the map must be sufficient to provide reasonable accuracy, and the map must be certified by a registered professional engineer. (See Paragraphs 65.6(a)(11) and 65.7(b)(5) of the NFIP regulations.) X 22. Construction plans, certified by a registered professional engineer, for all project elements, specifically a grading plan for the reclamation area. (1) (2) gequlred ;ecelved 23. The following data concerning the ability of the proposed to be built along to meet the minimum design and maintenance requirements established for levee systems in Section 65.10 of the NFIP regulations: N/A a. Freeboard -- Evidence which shows that the levee(s) will meet the minimum freeboard requirements set forth in Paragraph 65.10(b)(1) of'the NFIP regulations. N/A b. Closures -- Evidence which show that all drainage structures that will penetrate the levee(s) vii1 be fitted with closure devices that (1) will be structural parts of the levee(s) during operation and (2) are designed according to sound engineering practicer as set £orth in Paragraph 65.10(b)(2) of the NFIP regulaClons. N/A c. E~banlu~ent Protection -- An engineering analysis which demonstrates that no appreciable erosion of the levee embankment(s) can be expected during the 100-year flood. The analysis must be performed according to the guldelines set forth in Section 65.10(b)(3) of the NFIP regulations. N/A d. Stability -- An engineering analysis that evaluates the stability of the levee embankment(s) and foundation(s). The analysis must be performed according to the guidelines set forth in Paragraph 65.10(b)(4) of the NFIP regulations. (1) (2) Required Received N/A e. Settlement -- An engineering analysis that assesses the potential for and magnitude of losses of freeboard that may result from settlement of the levee(s) and that demonstrates that the minimum required freeboard will be maintained. The analysis must be performed according to the guidelines set forth in Paragraph 65.10(b~(5) of the NFIP regulations. N/A f. Interior Drainage -- An engineering analysis of the potential hazards associated with floodwaters that originate on the landward side of the levee(s) and that would be prevented by the levee(s) from flowing into · The analysis must be performed according to the guidelines set forth in Paragraph 65.10(b)(6) of the NFIP regulations. N/A, 24. Other: X 25. Community acknowledgment of the conditional LOMR request (form enclosed for community's use~ if desired). (1) (2) Required Received 26. Initial fee for conditional LOMR a. Review of new hydrology 9245 b. New bridge or culvert (no channelizaCion) $490 X c. Channel modifications only $560 d. Channel modification and new bridge or culvert $735 e. Levees, berms, or other structural measures $945 f. Structural measures on alluvial fans $2~800 g. Fee exemption certification in compliance with Section 72,5 of National Flood Insurance Program regulations h. Additional initial fee $560 The items checked in Column 1 should be sent to the following address: Federal Emergency Management Agency Federal Insurance Administration Office of Risk Assessment 500 C Street, SW., Room 422 Washington, D.C. 204?2 Attention: Ms. Fay L. Davis Any initial fee for the request, in the form of a check or money order made payable to the National Flood Insurance Program, should be sent by Registered Mail, Return Receipt Requested. The case number referenced above should be included on the check or money order for identification purposes. CLOMR CHECKLIST ADDENDUH (1) (2) Required Received N/A 27. Data which show that any primary frontal dune (as defined in Section 59.1 of the NFIP regulations ) that is to be considered an effective barrier to the 100-year flood surge and associated wave action is either a natural dune or an artificial (designed and constructed) dune that is well established and has long standing vegetative cover. It must also be shown that the cross sectional area of the portion of the dune seaward of the dune crest, measured perpendicular to the shoreline above the 100-year stillwater elevation, is greater than 540 square feet. As an alternative to the data described above, authoritative historical documentation may be submitted which shows that the primary frontal dune at a specific site has withstood previous 100-year storm surges and associated wave action. (See Section 65.11 of the NFIP regulations. ) 28. The following data concerning the proposed placement of fill in the [lO0-year floodplain of ~ where no regulatory floodway has been established/regulatory floodway of ], which we have determined could cause a rise in the computed 100-year water-surface elevations greater than that allowed by Section 60.3[(c)(10)/(d)(3)]. (See Section 65.12 of the NFIP regulations. ): N/A a. Co~tulity Request -- A request from the affected community for the Federal Emergency Management Agency' s conditional approval of the proposed change, accompanied by the appropriate initial fee or a request for an exemption from the · fee, whichever is appropriate. (See Item of this checklist.) N/A b. Evaluation of Alternatives -- An evaluation of alternative actions would not result in a rise in the computed 100- year water-surface elevations greater than (1) (2) Required Received that allowed by Section 60.3[(c)(10)/(d)(3)]. The evaluation must demonstrate that the alternatives are not feasible. N/A c. Legal Notice -- Documentation of indlvldual legal notice to all property owners affected by the proposed action~ both w_/thin and outside the community, that explains the effect of the proposed action on their properties. N/A d. Concurrence of Other Co--unities -- Evidence that the CEOs of other communities affected by the proposed action concur in that action. N/A e. Certification Concerning Structures -- Certification that no structures are in the areas that will be affected by the increased 100-year water-surface elevations. N/A f, Flood Klevatlon Revision Request -- A request for a revision Co the existing computed 100-year water-surface elevations, submitted according to the procedures outlined in Section 65.6 of the NFIP regulations. The required technical supporting data are listed as Items of this checklist. N/A g. Floodway Revision Request -- A request for a revision to the regulatory floodway, submitted according to the procedures outlined in Section 65.7 of the NFIP regulations. The required technical supporting data are listed as Items of this checklist. (~) (2) Required Received 29. The following data concerning the effect of on the alluvial fan Special Flood Hazard Area: N/A a. Engineering analyses that quantify the design discharges and the volumes of water, debris, and sediment associated with the lO0-yea_r flood at the apex of the fan under current watershed conditions and under potential adverse conditions (e.g., deforestation of the watershed by fire). The potential for debris flow and sediment movement must be assessed with an engineering method acceptable to the Federal Emergency Management Agency. The assessment should consider the characteristics and availability of sediment in the drainage basin above the apex and on the alluvial fan. N/A b. Engineering analyses which show that will accommodate the estimated 100-year peak discharge, consisting of the total volume of water, debris, and sediment determined in Item a. above, and the associated hydrodynamic and hydrostatic forces. N/A c. Engineering analyses which show that has/have been designed to withstand the potential erosion and scour forces. N/A d. Engineering analyses or evidence which shows that will provide protection against flows that migrate or suddenly move to the project site from other portions of the fan. (~) (2) ;equired ;eceived N/A e. Engineering analyses that assess the methods by which concentrated floodwater and the associated sediment load will be disposed of and the effect of those methods on adjacent properties. N/A f. Engineering analyses which demonstrate that flooding from local runoff, or sources other than the fan apex, will be insignificant or will otherwise be accommodated by appropriate flood control or drainage measures, N/A g. Evidence that the effect of on flood hazards in all areas of the fan (including those not protected by ) and the design and maintenance requirements for the various elements of were reviewed and approved by the community, State, or local agency that has jurisdiction over flood control activities in the community. X 30. An engineering analysis that demonstrates that the proposed fill slope protection will be adequate to protect against the impact of floodwaters moving at velocities expected to occur during the lO0-year flood.