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FIRM Case#92-06-110P-921218Federal Emergency Management Agency Washington, D.C. 20472 _ a The Honorable Mark Wolfe Mayor of the City of Coppell P.O. Box 478 255 Parkway Boulevard Coppell, Texas 75019 Dear Mayor Wolfe: Case No.. 92.06 -1244" Community: City of Coppell, Dallas and Denton Counties, Texas Community No.: 480170 rance This is in reference to the Flood Insurancev. Rate Map (FIRM) for the City of Coppell m Mr. Kenneth M. Griffin, P. E., Coppell City Engineer, submitte the City of Coppell for the December 18, 1991, preliminary re I ed City of Coppell FIS and FIRM. We have completed our evaluation of this appeal and determined that additional supporting data are necessary in order to resolve it. These data are outlined later in this letter. In order to address Mr. Griffin's concerns completely, we would first like to outline the recent history of the City of Coppell FIS and FIRM for you. On September 22, 1988, the Federal Emergency Management Agency (FEMA) issued a preliminary revised FIS and FIRM for the City of Coppell reflecting a restudy of the Elm Fork Trinity River prepared by the U.S. Army Corps of Engineers, Fort Worth District, as well as incorporating several previously issued Letters of Map Revision (LOMRs). On January 12, 1989, the city submitted a comprehensive restudy of all of the streams within Coppell prepared for the city by Kimley -Horn and Associates (KHA). The city also requested that FEMA not finalize the September 22, 19818, preliminary FIS and FIRM, but instead issue a revised preliminary FIS and FIRM to reflect the KHA restudy, as it more accurately reflected existing floodplain conditions. However, the data and analyses in the KHA restudy were not sufficient to support a revision to the City of Coppell FIS and FIRM as required by Part 65 of the National Flood Insurance Program (NFIP) regulations. Therefore, FEMA forwarded letters requesting revised and additional data to the City of Coppell on the 1990 September 18, ; following • dates: July 3, 1989; December 7, 1989; March 30, , and November 30, 1990. :Because of the delay in submitting adequate data in support of the KHA restudy and because the then- effective FIRM for the City of Coppell was outdated, the September 22, 1988, preliminary FIS and FIRM were finalized and became effective on October 16, 1991. With an October 7, 1991, letter, Ms. M. Shohre Daneshmand, P.E., Acting Coppell City Engineer, Thus, forwarded the remaining data required to support the revision request. on December 18, 1991, the preliminary revised FIS and FIRM were issued to reflect the KHA restudy. With a June 4, 1992, letter, Mr. Griffin submitted the city's appeal of the 1991 preliminary FIRM which identified twenty separate areas of concern regarding corporate limits changes, the addition of streets and street names, and revised flood hazard information. The supporting data for this appeal included "as- built" plans, legal deeds, annexation ordinances, and several topographic maps. The requested changes to the December 18, 1991, preliminary -py-a w, m S p -6 J(—M,6, , d tj 2123/13 Federal Emergency Management Agency Washington, D.C. 20472 _ a The Honorable Mark Wolfe Mayor of the City of Coppell P.O. Box 478 255 Parkway Boulevard Coppell, Texas 75019 Dear Mayor Wolfe: Case No.. 92.06 -1244" Community: City of Coppell, Dallas and Denton Counties, Texas Community No.: 480170 rance This is in reference to the Flood Insurancev. Rate Map (FIRM) for the City of Coppell m Mr. Kenneth M. Griffin, P. E., Coppell City Engineer, submitte the City of Coppell for the December 18, 1991, preliminary re I ed City of Coppell FIS and FIRM. We have completed our evaluation of this appeal and determined that additional supporting data are necessary in order to resolve it. These data are outlined later in this letter. In order to address Mr. Griffin's concerns completely, we would first like to outline the recent history of the City of Coppell FIS and FIRM for you. On September 22, 1988, the Federal Emergency Management Agency (FEMA) issued a preliminary revised FIS and FIRM for the City of Coppell reflecting a restudy of the Elm Fork Trinity River prepared by the U.S. Army Corps of Engineers, Fort Worth District, as well as incorporating several previously issued Letters of Map Revision (LOMRs). On January 12, 1989, the city submitted a comprehensive restudy of all of the streams within Coppell prepared for the city by Kimley -Horn and Associates (KHA). The city also requested that FEMA not finalize the September 22, 19818, preliminary FIS and FIRM, but instead issue a revised preliminary FIS and FIRM to reflect the KHA restudy, as it more accurately reflected existing floodplain conditions. However, the data and analyses in the KHA restudy were not sufficient to support a revision to the City of Coppell FIS and FIRM as required by Part 65 of the National Flood Insurance Program (NFIP) regulations. Therefore, FEMA forwarded letters requesting revised and additional data to the City of Coppell on the 1990 September 18, ; following • dates: July 3, 1989; December 7, 1989; March 30, , and November 30, 1990. :Because of the delay in submitting adequate data in support of the KHA restudy and because the then- effective FIRM for the City of Coppell was outdated, the September 22, 1988, preliminary FIS and FIRM were finalized and became effective on October 16, 1991. With an October 7, 1991, letter, Ms. M. Shohre Daneshmand, P.E., Acting Coppell City Engineer, Thus, forwarded the remaining data required to support the revision request. on December 18, 1991, the preliminary revised FIS and FIRM were issued to reflect the KHA restudy. With a June 4, 1992, letter, Mr. Griffin submitted the city's appeal of the 1991 preliminary FIRM which identified twenty separate areas of concern regarding corporate limits changes, the addition of streets and street names, and revised flood hazard information. The supporting data for this appeal included "as- built" plans, legal deeds, annexation ordinances, and several topographic maps. The requested changes to the December 18, 1991, preliminary 4 FIRM for the City of Coppell proposed by Mr. Griffin, as well as our response to these changes, are discussed below. Any data still required will be summarized at the end of this letter. ,*1 Corporate Limits Mr. Griffin requested that the corporate limits for the City of Coppell shown the preliminary revised FIRM be annotated to reflect submitted annexation Ordinance Nos. 88410, 88412, 88427, and 89430, and disannexation`Ordinance No. 91504. As will be discussed later in this letter, annotations reflecting these corporate limits changes must be made by the City of Coppell on a copy of the December 18, 1991, -preliminary revised FIRM and submitted to FEMA. 061 -t-, Street Names and Locations 1Q1\0_�/ v Mr. Griffin submitted numerous plat maps and requested that streets be added X akand labeled on the preliminary FIRM for the following subdivisions: bend,,Addition, Shadow Woods Estates,.Park Meadows Sections I and:.Ii, and Carter Estates. Mr. Griffin also requested that the extension of Parkway Boulevard west of Denton Tap Road be added to the .prel,iminary, revised.- FIRM. These street additions and labels.must be made on a copy of the December -18, 1991, preliminary revised FIRM and submitted to us for review, as discussed at the end of this letter. Flood Hazard Information 3 Mr. Gr' in submitted "as- built" grading plans for the Gibbs 'Statioly and the es of Coppell /Lake —yood Estates subdivisions and requested that t 100 -year floodplain for Denton Creek be revised on the preliminary evised FIRM to reflect that information. As discussed later in this letter, these changes to the Denton Creek 100 -year floodplain must be` made on a copy of the December 18, 1991, "preliminary revised FIRM. / y Lakes of Coppell/Villages of Coppell C�, fe Mr. Griffin requested that the 100 -year floodplain for Denton Creek be revised to reflect the Lakes of Coppell/Villages of Coppell project. A conditional LOMR was issued for this project on September 8, 1992. However, the data necessary to support a revision to the FIRM upon completion of the project, as stated in the conditional LOMR, have not Xbeen submitted to FE:MA. Therefore, the FIRM for the City of Coppell ' cannot be revised to reflect this project until the required data are �"7 y��•r bm ted. \tip \•�� Elm Fork Trinity River Floodplain / Mr iffin submitted topographic information for the area south of B tline Road and requested that the area designated as Zone X be /// included in the 100 -year floodplain for the Elm Fork Trinity River. Thies revised l00 eet 'f3 "i'*1h`: tst a i► 3 December 18, 1991, preliminary revised FIRM, as discussed later in this letter. Gra evine Creek Channelization and Drop Structure Mir iffin requested that the flood hazard information for Grapevine 'Cr be revised to reflect the channelization and concrete drop �j s ructure located downstream of Interstate Highway 635. A LOMR for the :? ity of Coppell was issued to reflect this completed project on \ August 10, 1992. The effects of this LOMB will be inc_o_rporated into the final effective FIRM for the City of Coppell. _. Bi C ar Addition (�� Se <, pp� �r Mr Griffin requested that the flood hazard information for Tribut8 '� 1 of Grapevine Creek be revised to reflect fill associated with the P,�i5 ig Cedar Addition. As stated in our October 16, 1992, letter to you the effects of this project will be incorporated into ther,final:_effec- ��/ tive FIRM for the City of Coppell. Denton Tap Road Bride ('0�� r # Mr. Griffi , "requested that the flood hazards for Grapevine Creek be revised o reflect the construction of a new bridgeIat­.'Denton Tap Road. r A LO request was previously submitted for this project in a Nov tuber 20, 1990, letter from Mr. John C. Karlsruher, P.E., of Ginn, Af/ O I c. Subsequently, we responded with a January 3, 1991, letter request - r. ng additional data to support this request. Lter:soert�ya, on. November 25, 1992. After' sae , e°val tt� tGbei c �,ttii"AV(,�,` "" iete- i whether the effects of the -C- ness, we will notify you n a sep Denton Road Tap bridge can be incorporated into the finalized prelimi- ) '-- ( ^-^°X,4nary revised FIRM. �.Or0. \t . ' °a E �XIC Mr. riffin submitted "as- built" grading plans and requested that the year floodplain and FEMA- designated floodway for Cottonwood Branch be revised to reflect the Villages of Cottonwood Creek project. Additional data are necessary to incorporate this information, as discussed later in this letter. Creekview states ea r` Z Mr. G ffin requested that flood hazards for Grapevine Creek also be r rev' ed to reflect the �y`,,A conditional �`f LO was issued on July 1, 1988. However, the data necessary to support a revision to the FIRM upon completion of the project, as stated in the `r' G� onditional LOMR, were never submitted to FEMA. costa= `are 'i Villages of Cottonwood Creek 4 0�` MacArthur Boulevard Bridge N ,'�Mr. Gri in submitted "as- built" plans for the MacArthur Boulevard `brid that crosses Denton Creek and requested that the flood hazard y(� rmation for Denton Creek be revised to reflect this completed t project. As discussed later in this letter, additional data are necessary to reflect the effects of the bridge at MacArthur Boulevard. /71 Northlake Woodlands East No. 12 <;w�L Mr. Grif 'n submitted a floodplain study for this subdivision and requje wte d that the FIRM be revised as appropriate to reflect this \' ormation. We have reviewed this information and determined that the Northlake Woodlands East No. 12 subdivision is outside'th*- ,100. -year floodplain for Grapevine Creek "7`str- shown on the preliminary revised FIRM. Thus, a revision to the FIRM is not required for this subdivision. Redelineation of Floodplai.n Boundaries for all Streams t In an October 23, 1992, letter, Mr. Griffin requested that the floodplains be redelineated for each stream within the community utilizing topographic mapping provided by the City of Coppell. With this letter, Mr. Griffin submitted draft 'street and topographic,. "s F °mot a. scale;of,:2`' °ai't►' a contour interval of 10 feet.` The- City mf��oppell submitted a fnal:;set of nJ topographic maps at a scale of `1" -200' "with a contour interval of 2 feet on November 25, 1992. As discussed below, F > *111- not ip'eri°�°vif tt ` ?word= to { , �' revise the floodplain delineations based •on this topographii" �.ni?mrm ` This aior _mist performE:d by the city Additional Data Required t)v FEMA Because the City of Coppell contracted KHA to prepare the data used to support the December 18, 1991, preliminary revised FIS and FIRM, it is inappropriate for the City of Coppell to request that FEMA correct the deficiencies result- ing from the KHA analyses. In essence, the city is appealing its own study and is requesting that FF14A perform the necessary work at the expense of flood insurance policyholders nationwide. Nevertheless, one of FEMA's goals is to assure that the most accurate flood hazard information possible is presented on the FIRM for your community; thus, we will suspend processing of the preliminary revised FIS and FIRM for 90 days in order for your community to prepare the required data listed below. 1. A copy of the December 18, 1991, preliminary revised FIRM annotated to depict the revised corporate limits, added streets and street names, and revised 100- and 500 -year in hAlIna- ar' and floodwa s. All changes to floodplain boundaries must be supported by topographic information certified by a re isterRC._. professional engineer or licensed land surveyor. This annotated must also be certified by a registered professional engineer. r 5 Please note that if the floodplain boundaries are completely redelineated based on the City of Coppell's new topographic map at a scale of 1 =2001, as requested in Mr. Griffin's October 23, 1992, letter, these topographic maps must also be submitted and certified by a registered professional engineer. f 2. HEC -2 models for Denton Creek reflecting the 10 -, 50 -, 100 -, and 500 -year floods and floodway revised to- reflect the. "as-built" V MacArthur Boulevard bridge. Annotated .FlS:raporvflood profiles and the floodway data table for Denton FCzeek, ;try refhact .this., 1 revised modeling must also be submitted-. Also, the revised 100- o and 500 -year floodplain boundaries and floodway for Denton Creek must be included on the annotated FIRM, as discussed previously. �o Ie4 �,t� HEC -2 models for Cottonwood Branch reflecting the 10-, 50-, 100-, and 500 -year floods and floodway revised to reflect the Villages of Cottonwood Creek. Annotated FIS report flood profiles and the floodway data 'table for Cottonwood Branch to reflect this revised 0 �3 modeling must also be submitted. Also, the revised 100- and 500 - year floodplain boundaries and floodway for Cottonwood Branch must be included on the annotated FIRM, as discussed previously. �.� 4. or the Creek-view Estates subdivision, all data requirements of Part 65 of the NFIP regulations (copy enclosed) , as. indicated in the July 1, 1.988, conditional LOMR (copy enclosed). 1g. S _<... 5. For the Denton Tap Road bridge, all data requested in our --� January 3, 1991, letter to the City of Coppell. These items must be submitted within 90 days of the date of this letter. In order to avoid further delays in finalizing the preliminary revised FIS and FIRM, which contain more up -to -date and detailed data than Coppell's currently effective FIS and FIRM, we regret that this 90 -day period cannot be extended. Please submit the required data to Matthew B. Miller of my staff at the following address: Federal Emergency Management Agency Federal Insurance Administration Office of Risk Assessment 500 C Street, SW, Room 418 Washington, DC 20472 0 We look forward to receiving the data with the most accurate FIRM possible. this matter, please contact Matthew B Washington, D.C., at (202) 646 -3461, Enclosures necessary to provide the City of Coppell Should you have any questions regarding Miller of our Headquarters staff in r by facsimile at (202) 646 -3445. Sincerely, L'�Mt �a -L7-L-L�� William R. Locke Chief, Risk Studies Division Federal Insurance Administration cc: Ms. M. Shohre Danesh.mand, P.E. Mr. Kenneth M. Griffin, P.E. Mr. Alan D. Ratliff, Manager of the City of Coppell Mr. Phil Deaton, P.E., Carter & Burgess Ms. C. Jean Hansen, P.E., Albert H. Halff Associates, Inc. Mr. Kevin Kendrick, P.E., Unzicker, Schnurbusch Associates Mr. Robert Porter, P.E., Don Tipton Engineers Mr. Bill Wallace, P.E., Nathan D. Maier State Coordinator ?1S -Iq3 z : +O G� jam A Federal Emergency Management Agency Washington, D.C. 20472 XL 19M The Honorable Lou Duggan Case No. 88- 06 -37R Mayor of the City of Coppell P.O. Box 478 Coppell, Texas 75019 Dear Mayor Duggan: This is in reference to a February 2, 1988 letter from Mr. H. Wayne Ginn, P.E., City Engineer and Floodplain Administrator for the City of Coppell. In his letter, which was forwarded to us by our Region VI office, Mr. Ginn requested that the Federal Emergency Management Agency (FEMA) issue a con- ditional Letter of Map Revision (LOMR) for the Creek View Addition project. This project consists of channel modifications to Grapevine Creek between Moore Road and Denton Tap Road. With his February 2, 1988 letter, Mr. Ginn submitted a technical report prepared by Nathan D. Maier Consulting Engineers, Inc., entitled Floodplain Reclamation Study for the Creek View Addition Along Grapevine Creek, dated November 1987. This report included the following technical data: HEC -2 hydraulic models, dated November 10, 1987, representing existing conditions; HEC -2 hydraulic models, dated January 16, 1988, repre- senting proposed conditions; a Floodplain Reclamation Plan, dated January 1988; cross- sectional information for Grapevine Creek; and a flood profile for Grapevine Creek. Following a May 11, 1988 telephone conversation with our technical evaluation contractor, Mr. Dennis L. Johnson, P.E., of Nathan D. Maier Consulting Engineers, Inc., submitted additional HEC -2 hydraulic models, dated May 18, 1988, representing both existing and proposed conditions. Based on our review of the submitted technical data, we have determined that the proposed Creek View Addition project meets the minimum floodplain management criteria set forth by National Flood Insurance Program (NFIP) regulations. If the project were completed as proposed, a revision to the effective Flood Insurance Study (FIS), Flood Insurance Rate Map (FIRM), and Flood Boundary and Floodway Map (FBFM) for your community would be warranted. This revision would show a decrease in the Base (100 -year) Flood Elevations and the 100 -year floodplain of Grapevine Creek; however, there would be no change in the floodway width, as indicated in the submitted hydraulic calculations. Please note that future revisions to your community's FIS, FIRM, and FBFM or future restudies of the flood hazards in this area could modify this determination. This determination is based on the 100 -year flood discharges computed in the effective FIS for your community, and does not consider subsequent changes in watershed characteristics that would tend to increase flood discharges. The development of this project and other projects upstream could result in increased flood dischargers, which, in turn, could result in increased 100 -year flood elevations. Future restudies of your community's flood hazards would take into account the cumulative effects of development on flood discharges, and could therefore establish higher 100 -year flood elevations in this area. 2 This conditional LOMR is based on minimum floodplain management criteria established under the NFIP. Your community is responsible for approving all proposed floodplain developments, including the project upon which this request is based, and for assuring that necessary permits required by Federal or State law have been received. State and community officials, based on knowledge of local conditions and in the interest of safety, may set higher standards for construction or may limit development in floodplain areas. If the State of Texas or the City of Coppell has adopted more restrictive or comprehensive floodplain management criteria, these criteria take precedence over the minimum NFIP requirements. NFIP regulation Part 60.3(b)(7) requires communities participating in the Program to "assure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained." Without proper mainte- nance, such as the regular clearing of a channelized stream, channel modifi- cation projects will, in time, fail to function as designed, thereby recreating the flood hazard that they were intended to mitigate. Therefore, upon com- pletion of the project, your community must uphold its responsibility for assuring that the modified channel is maintained in order to preserve its design function. Upon completion of the proposed Creek View Addition project, your community may request a revision to the effective FIS, FIRM, and FBFM. The revision request must include supporting data outlined in the enclosed copy of Part 65 of the NFIP regulations. Please note that these supporting data must represent the conditions of the area as they exist at the time the request is submitted. Compliance with the criteria outlined in the aforementioned regulations will expedite FEMA "s review process, thus allowing the effective FIS, FIRM, and FBFM for your community to be revised as appropriate, in a timely manner. Should you have any questions regarding this matter, please do not hesitate to contact the Chief, Natural and Technological Hazards Division of the Federal Emergency Management Agency in Denton, Texas, at (817) 898 -9127 or members of our Headquarters staff in Washington, D.C., at (202) 646 -2754. Sincerely, J t*. Matticks C Risk Studies Division Federal Insurance Administration Enclosure cc: Mr. H. Wayne Ginn, P.E. Mr. Dennis L. Johnson, P.E.