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FIRM Case#6-89-236-891213Federal Emergency Management Age �o Washington, D.C. 20,172 DEC 13 MY DEC 7 19$9 fi;ml•y.H�►N �, /i,. Dallas, T•Yas The Honorable Mark Wolfe Mayor of the City of Coppell P.O. Box 478 Coppell, Texas 75019 Dear Mayor Wolfe: This is in reference to the Flood We are currently processing three Flood Insurance Rate Map (FIRM); Case Nos.: 6 -89 -236, 6- 90 -21, and 89- 06 -31R Community: City of Coppell, Dallas and Denton Counties, Texas Community No.: 480170 Insurance Study (FIS) for your community. requests concerning your community's FIS and the status of each request is outlined below. Kimley -Horn Restudy of all Streams We have completed our review of the September 11, 1989 hydraulic report prepared by Kimley -Horn and the revised Cottonwood Branch model submitted by Kimley -Horn on October 20, 1989, and have determined that the submitted models represent hydraulic conditions in the City of Coppell more accurately than those used to prepare the September 22, 1988 preliminary FIRM. Therefore, the preliminary FIRM will not be finalized. Rather, we will issue a revised preliminary FIRM based on the submitted restudy. However, please note that this revision cannot be completed until the modeling for the 10- and 50 -year flood frequencies for all streams is submitted. A revised Cottonwood Branch model utilizing the nine field - surveyed cross sections by Nathan D. Maier Consulting Engineers, Inc., for the proposed Shadow Woods Estates (discussed later in this letter) must also be submitted before the revision can be completed. In addition, we ask that you submit an updated corporate limits map for the City of Coppell to assure that the revised preliminary FIRM will be as accurate as possible. Please submit the data to our technical evaluation contractor, Dewberry & Davis, 8401 Arlington Boulevard, Fairfax, Virginia 22031, to the attention of Mr. Dave Lushbaugh, Management Engineering and Technical Services Division. Your community will receive a revised preliminary FIS and FIRM approximately two months after our receipt of the aforementioned data. Until this revision is finalized, your community should reasonably use the information developed in the submitted technical report for floodplain management purposes in accordance with Subparagraph 60.3(b)(4) of the National Flood Insurance Program regulations (copy enclosed). Proposed Parkway Boulevard Bridge This conditional Letter of Map Revsion (LOMR) request for the proposed Par.lcway Boulevard Bridge on Cottonwood Branch was prepared by Jerry Parche Consulting Engineers. The existing conditions model for Cottonwood Branch is now in agreement with the Kimley -Horn restudy existing conditions model in the 2 project area. We are currently completing our review of this conditional LOMR request. The results of our review will be conveyed to your community in a separate letter. Proposed Shadow Woods Estates With an October 6, 1989 letter, Mr. Russell Doyle, P.E., City Engineer for t11e City of Coppell, submitted, for informational purposes only, a June 9, 1989 technical report prepared by Nathan D. Maier, Consulting Engineers, Inc., concerning the proposed Shadow Woods Estates floodplain modification project along Cottonwood Branch. The project is a 22 -acre residential development to be built on fill outside the 100 -year floodplain shown on FIRM number 480170, panel 0005, dated February 15, 1984. The existing conditions HEC -2 model for this project utilized nine original field - surveyed cross sections not included in the Kimley -Horn restudy. As discussed earlier in this letter, and in an October 24, 1989 telephone conversation with our technical evaluation contractor, Mr. Ronald W. Morrison of Kimley -Horn agreed to incorporate the nine additional field - surveyed cross sections into the Cottonwod Branch restudy model. However, since the proposed Shadow Woods Estates project is outside the effective 100 -year floodplain and was submitted for informational purposes only, no further action will be taken concerning the project. We thank you for submitting this information. 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 Matthew B. Miller of our Headquarters staff in Washington, D.C., at (202) 646 -3461. Sincerely, MWk_%JJt -Q J h 5 L. Matticks Chief, Risk Studies Division Federal Insurance Administration Enclosure cc: Mr. Russell R. Doyle, P.E. Mr. Michael Boyd, Nathan D. Maier Consulting Engineers, Inc. N Mr VJ ona Mr. Jerry Parche, P.E., Jerry Parche Consulting Engineers § 60.3 (41 FR 46975, Oct. 26, 1976. Redesignated at 44 FR 31177. May 31. 1979, and amended at 48 FR 29318. June 24. 1983; 48 FR 44552, Sept. 29, 1983; 49 FR 4751, Feb. 8, 1984; 50 FR 36024, Sept. 4, 19851 §60.3 Flood plain management criteria for flood -prone areas. The Administrator will provide the data upon which flood plain manage- ment regulations shall be based. If the Administrator has not provided suffi- cient data to furnish a basis for these regulations in a particular community, the community shall obtain, review and reasonably utilize data available from other Federal. State or other sources pending receipt of data from the Administrator. However, when special flood hazard area designations and water surface elevations have been furnished by the Administrator, they shall apply. The symbols defining such special flood hazard designations are set forth in § 64,3 of this subchap- ter. In all cases the minimum require- ments governing the adequacy of the flood plain management regulations for flood -prone areas adopted by a particular community depend on the amount of technical data formally provided to the community by the Ad- ministrator. Minimum standards for communities are as follows: (a) When the Administrator has not defined the special flood hazard areas within a community, has not provided water surface elevation data, and has not provided sufficient data to identify the floodway or coastal high hazard area, but the community has indicated the presence of such hazards by sub- mitting an application to participate in the Program, the community shall: (1) Require permits for all proposed construction or other development in the community, including the place- ment of manufactured homes, so that it may determine whether such con- struction or other development is pro- posed within flood -prone areas; (2) Review proposed development to assure that all necessary permits have been received from those governmen- tal agencies from which approval is re- quired by Federal or State law, includ- ing section 404 of the Federal Water Pollution Control Act Amendments of 1972.33 U.S.C. 1334; 44 CFR Ch. 1 (10 -1 -87 Edition) (3) Review all permit applications to determine whether proposed building sites will be reasonably safe from flooding. If a proposed building site is in a flood-prone area, all new construc- tion and substantial improvements shall (i) be designed (or modified) and adequately anchored to prevent flota- tion, collapse, or lateral movement of the structure resulting from hydrody- namic and hydrostatic loads, including the effects of buoyancy, (ii) be con- structed with materials resistant to flood damage, (iii) be constructed by methods and practices that minimize flood damages, and (iv) be constructed with electrical, heating, ventilation, plumbing, and air conditioning equip- ment and other service facilities that are designed and /or located so as to prevent water from entering or accu- mulating within the components during conditions of flooding. (4) Review subdivision proposals and other proposed new development, in- cluding manufactured home parks or subdivisions, to determine whether such proposals will be reasonably safe from flooding. If a subdivision propos- al or other proposed new development is in a flood -prone area, any such pro- posals shall be reviewed to assure that U) all such proposals are consistent with the need to minimize flood damage within the flood -prone area, (ii) all public utilities and facilities, such as sewer, gas, electrical, and water systems are located and con- structed to minimize or eliminate flood damage, and (iii) adequate drain- age is provided to reduce exposure to flood hazards; (5) Require within flood -prone areas new and replacement water supply systems to be designed to minimize or eliminate infiltration of flood waters into the systems: and (6) Require within flood -prone areas (i) new and replacement sanitary sewage systems to be designed to mini- mize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters and (ii) onsite waste disposal systems to be located to avoid impairment to them or contamination from them during flooding. (b) When the Administrator has des- ignated areas of special flood hazards 216 Federal Emergency Management Agency (A zones) by the publication of a com- munity's FHBM or FIRM, but has nei- ther produced water surface elevation data nor identified a floodway or coastal high hazard area, the commu- nity shall: (1) Require permits for all proposed construction and other developments including the placement of manufac- tured homes, within Zone A on the community's FHBM or FIRM; (2) Require the application of the standards in paragraphs (a) (2), (3), (4), (5) and (6) of this section to devel- opment within Zone A on the commu- nity's FHBM or FIRM: (3) Require that all new subdivision proposals and other proposed develop- ments (including proposals for manu- factured home parks and subdivisions) greater than 50 lots or 5 acres, which- ever is the lesser, include within such Pr n als base f1oQ_d�levation_data; Obtain, review and reasonably utilize any base flood elevation and floodway data available from a Feder- al. State, or other source, including data developed pursuant to paragraph (b)(3) of this section, as criteria for re- quiring that new construction, sub- stantial improvements, or other devel- opment in Zone A on the community's FHBM or FIRM meet the standards in paragraphs (c)(2), (c)(3), (c)(5), (c)(12), (d)(2) and (d)(3) of this section ;__ (5) Where base flood elevation data are utilized, within Zone A on the community's FHBM or FIRM: (i) Obtain the elevation (in relation to mean sea level) of the lowest floor (including basement) of all new and substantially improved structures, and (ii) Obtain, if the structure has been floodproofed in accordance with para- graph (c)(3)(ii) of this section, the ele- vation (in relation to mean sea level) to which thNe structure was flood - proofed, and (iii) Maintain a record of all such in- formation with the official designated by the community under § 59.22 (a)(9)(iii); (6) Notify, in riverine situations, ad- jacent communities and the State Co- ordinating Office prior to any alter- ation or relocation of a watercourse, and submit copies of such notifications to the Administrator; § 60.3 (7) Assure Lhat the flood carrying ca. pacity within the altered or relocated portion of any watercourse is main- tained: (8) Require that all manufactured homes to be placed within Zone A on a community's FIIBM or FIRM shall be installed using methods and practices which minimize flood damage. For the purposes of this requirement, manu- factured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. Methods of an- choring may include. but are not to be limited to, use of over -the -top or frame ties to ground anchors. This require- ment is in addition to applicable State and local anchoring requirements for resisting wind forces. (c) When the Administrator has pro- vided a notice of final flood elevations for one or more special flood hazard areas on the community's FIRM and, if appropriate, has designated other special flood hazard areas without base flood elevations on the communi- ty's FIRM, but has not identified a regulatory floodway or coastal high hazard area, the community shall: (1) Require the standards of para- graph (b) of this section within all Al- 30 zones, AE zones, A zones, AH zones, and AO zones, on the community's FIRM; (2) Require that all new construction and substantial improvements of resi- dential structures within Zones Al -30, AE and AH zones on the community's FIRM have the lowest floor (including basement) elevated to or above the base flood level, unless the community is granted an exception by the Admin- istrator for the allowance of base- ments in accordance with § 60.6 (b) or (c); (3) Require that all new construction and substantial improvements of non- residential structures within Zones Al -30, AE and AH zones on the com- munity's firm (D have the lowest floor (including basement) elevated to or above the base flood level or, (ii) to- gether with attendant utility and sani- tary facilities, be designed so that below the base flood level the struc- ture is watertight with walls substan- tially impermeable to the passage of water and with structural components having the capability of resisting hy- 217 93 -154 0 -87 -8