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Gateway BP (1.1)-CS 910314 COMMISSION ROBERT H, DEDMAN, CHAIRMAN RAY STOKER, JR. WAYNEB. DUDDLESTEN STATE DEPARTMENT OF HIGHWAYS AND PUBUC TRANSPORTATION P.O, BOX ~7 }{arch 14, 1991 MAR 18 1991 ~' ~ ,,,, .~ . ENGiNEER-DIRECTOR ARNOLD W. OLIVER, P.E. CONTACT: Control 2374-7 I.H. 635 Dallas County Mr. Pat Acker Albert H. Halff Associates, 8616 Northwest Plaza Driv~ Dallas, Texas 75225 Dear Mr. Acker: Reference is made to your letter of trans.ntttal requesting permission to grade Grapevine Creek and place rock riprap within the right-of-way of I.H. 635 in the City of Coppell. The State has no objection to your proposed work. Please contact Mr. Milton Gurecky, Roadway Maintenance Supervisor in Lewisville, 214/436-1546, 24 hours prior to beginning work. OhS Engineer DEPARTMENT OF THE ARMY FORT WORTH DISTRICT, CORPS OF ENGINEERS P. O. BOX 17300 FORT WORTH. TEXAS 76102-0300 November 14, 1990 Operations Division Office Operations Branch SUBJECT: Project Number 198800444 Ms. Jean Hansen Albert H. Halff Associates, 8616 Northwest Plaza Drive Dallas, Texas 75225 IDC. Dear Ms. Hansen: Thank you for your letter of October 23, 1990, concerning construction of bridge crossings and erosion control improvements on Grapevine Creek in Dallas County, Texas. Your project has been assigned Project Number 198800444; all future correspondence concerning your project should include this number. Failure to reference the project number on future correspondence will result in a delay. Your project has been reviewed in accordance with Section 404 of the Clean Water Act under which the U.S. Army Corps of Engineers regulates the discharge of dredged and fill material into waters of the United States including adjacent wetlands. Based on your description of the proposed work and all information available to us, we have determined that your project will involve such discharges and will require prior Department of the Army authorization under Section 404 of the Clean Water Act. Two general permits are applicable to your project. These permits have been issued on a nationwide basis for discharges into waters of the United States. The first nationwide permit authorizes minor road crossing fills including all attendant features, both temporary and permanent, that are part of a single and complete project for crossing of a non-tidal waterbody, provided that the crossing is culverted, bridged or otherwise designed to prevent the restriction of, and to withstand, expected high flows and provided further that discharges into any wetlands adjacent to the waterbody do not extend beyond 100 feet on either side of the ordinary high water mark of that waterbody. A "minor road crossing fill" is defined as a crossing that involves the discharge of less than 200 cubic yards of fill material below the plane of ordinary high water. The crossing -2- may require a permit from the United States Coast Guard if located in navigable waters of the United States. District Engineers are authorized, where local circumstances indicate the need, to define the term "expected high flows" for the purpose of establishing applicability of the nationwide permit. The other general permit applicable to your project authorizes discharges of dredged or fill material into non-tidal rivers, streams, and their lakes and impoundments, including adjacent wetlands, that are located above the headwaters and other non-tidal waters of the United States, including adjacent wetlands, that are not part of a surface tributary system to ~ interstate waters or navigable waters of the United States (i.e., isolated waters) provided the activity does not cause the loss or substantial adverse modification of one or more acres of waters of the United States. For discharges which will cause the loss or substantial adverse modification to one or more acres of waters of the United States, written Department of the Army authorization will be required prior to initiation of work. The only requirement in the use of this permit is that the person responsible for the project must ensure that the work is in compliance with the above stated specifications and the conditions, and best management practices listed on the enclosure. Failure to satisfy these conditions invalidates the authorization and may result in a violation of the Clean Water Act. The verification for the construction of an activity under this nationwide permit will be valid until the nationwide permit is modified, reissued, or revoked. All of the nationwide permits are scheduled to be modified, reissued, or revoked prior to January 13, 1992. It is incumbent upon you to remain informed of changes to the nationwide permits. The U.S. Army Corps of Engineers will issue a public notice announcing the changes when they occur. Furthermore, if you commence, or are under contract to commence, this activity before the date that this nationwide permit is modified or revoked, you will have twelve months from the date of the modification or revocation to complete the activity under the present terms and conditions of the nationwide permit. This permit should not be considered as an approval of the design features of any activity authorized or an implication that such construction is considered adequate for the purpose -3- intended. It does not authorize any damage to private property, invasion of private rights, or any infringement of federal, state, or local laws or regulations. Thank you for your interest in our nation's water resources. If you have any additional questions concerning our regulatory program, please contact Mr. Stan Walker at the address above or telephone (817)334-3551. Chief, Enclosure Copies Furnished: Mr. Rollin MacRae Texas Parks and Wildlife Department 4200 Smith School Road Austin, Texas 78444 Office Opera~ anch Mr. Robert M. Short U.S. Fish and Wildlife Service Ecological Services Stadium Centre Building, 711 Stadium Drive, Suite 252, Arlington, Texas 76011 East Mr. Jerry Saunders U.S. Environmental Protection Agency Region VI, 1445 Ross Avenue Dallas, Texas 75202 NATIONWIDE PERMIT CONDITIONS FOR CERTAIN ACTIVITIES REQUIRING DEPARTHENT OF THE ARNY AUTHORIZATION The following special conditions must be followed in order for the nationwide permit(s) to'be valid: (1) That any discharge of dredged or fill materia! will not occur in the proximity of a public water supply intake. (2) That any discharge of dredged or fill material will not occur in areas of concentrated shellfish production unless the discharge is directly related to a shellfish harvesting activity. (3) That the activity will not jeopardize a threatened or endangered species as identified under the Endangered Species Act (ESA), or destroy or adversely modify the critical habitat of such species. In the case of Federal agencies, it is the mgencies' responsibility to comply with the requirements of the ESA. If the activity may adversely mffect any listed species or critical habitat, the District Engineer must initiate Section ? consultation in accordance with the ESA. In such cases, the District Engineer may: (i) initiate Section ? consultation and then, upon completion, authorize the activity under the nationwide permit by adding, if appropriate, activity specific conditions, or (ii) prior to or concurrent with Section ? consultation he may recommend discretionary authority or use modification, suspension, or revocation procedures. (4) That the activity shall not significantly disrupt the movement of those species of aquatic life indigenous to the waterbody (unless the primary purpose of the fill is to impound water). (5) That any discharge of dredged or fill material shall consist of suitable material free from toxic pollutants (see Section 307 of the Clean Water Act) in toxic amounts. (6) That any structure or fill authorized shall be properly maintained. (?) That the activity will not occur in a component of the National Wild and Scenic River System; nor in & river officially designated by Congress as a "study river" for possible inclusion in the system, while the river is in an official study status. (8) That the activity shall not cause an unacceptable interference with navigation. (9) That, if the activity may adversely affect historic properties which the National Park Service has listed on, or determined eligible for listing on, the National Register of Historic Places, the permittee will notify the District Engineer. If the District Engineer determines that such historic properties may be adversely affected, he will provide the Advisory Council on Historic Preservation an opportunity to comment on the effects on such historic properties or he will consider modification, suspension, or revocation. Furthermore, that, if the permittee before or during prosecution of the work authorized, encounters a historic property that has not been listed or determined eligible for listing on the Nation&l Register, but which may be eligible for listing in the National Register, he s~all immediately notify the District Engineer. {10) That the construction or operation of the activity will not impair reserved tribal rights, including, but not limited to, reserved water rights and treaty fishing and hunting rights. (11) That in certain states, an individual state water quality certification must be obtained or waived. ({2) That in certain states, an individual state coastal zone management consistent7 concurrence must be obtained or wmived. (13) That the activity will comply with regional conditions which may have been added by the Division Engineer. (14) That the management practices listed below shall be followed to the maximum extent practicable. MANAGEMENT PRACTICES In addition to the conditions specified in the nationwide permit, the following management practices shall be followed, to the maximum extent practicable, in order to minimize the adverse effects of these discharges on the aquatic environment. Failure to comply with these practices may be cause for the District Engineer to recommend, or the Division Engineer to take, discretionary authority to regulate the activity on an individual basis or regional basis. (1) Discharged or dredged or fill material into waters of the United States shall be avoided or minimized through the ,,se of other practical alternatives, (2) Discharges in spawning areas during spawning seasons shall be avoided, (3) Discharges shall not restrict or impede the movement of aquatic species indigenous to the waters or the passage of normal or expected high flows or cause the relocation of the water (unless the primary purpose of the fill ia to impound waters). (4) If the discharge creates mn impoundment of water, adverse impacts on the aquatic system caused by the accelerated passage of water and/or the restriction of its flow shall be minimized. (5} Discharge in wetlands areas shall be avoided. (6) Heavy equipment working in wetlands shall be placed on mats. (7) Discharges into breeding areas for migratory waterfowl shall be avoided. (8) All temporary fills shall be removed in their entirety. FURTHER INFORMATION (1) District Engineers are authorized to determine if an activity complies with the terms and conditions of m nationwide permit unless that decision must be mede by the Division Engineer'.. (2) Nationwide permits do not obviate the need to obtain other Federal, state or local authorizations required by law. (3) Nationwide permits do not grant any property rights or exclusive privileges. (4) Nationwide permits do not authorize any injury to the property or rights of others. (5) Nationwide permits do not authorize interference with any existing or proposed Federal project. The Honorable Lou Duggan Mayor of the City.of Coppell P.O. Box 4?8 Cop~ell, Texas. Federal Emergency Management Agency Washington, D.C. 20472 Case ~86-06-47R Dear Mayor Duggan= This is in reference to a letter dated May 29, 1986, and technical data submitted by Mr. Ed Powe11, P.E., former City Engineer for the City of Cop~ell, Texas. In his letter, which was forwarded to us by our Region VI office, Mr. Powell requested that the Federal Emergency Management Agency (FEMA) issue a conditional Letter of Map Revision for a proposed channel modification and bridge construction project along Grapevine Creek between Coppell Road and Interstate Highway 635. This proposed project involves realignment of the Grapevine Creek channel including construction of a grass-lined channel with the base width varying from ?0 to 200 feet, construction of a concrete drop structure downstream of Interstate Highway 635, and construction of a bridge at Freeport Parkway. Technical data submitted in support of this request included a report entitled 'Conditional Letter of Map Revision Request for Grapevine Creek in Coppell, Texas,' prepared by Albert N. Halff Associates, Inc. This report contained a description of methodologies used and hydraulic backwater models for existing and proposed conditions. Additional technical data were submitted on several occasions at our request~ all required data to process this request were received by March 18, 1987. During the course of review, we were informed that the channel modification between Coppell Road and Freeport Parkway and the construction of the Freeport Parkway bridge were completed. Mr. B. Anatole Falsgan of Albert H. Halff Associates, Inc., submitted hydraulic analyses, which reflected the completed portion 9f the project and requested that F~4A review these analyses and issue a Letter of Map Revision. In reviewing the analyses, we noted that excessive velocities exist in the earthen channel between the downstream end of the completed channel modifications and the Freeport Parkway bridge, which could result in severe erosion and undercutting of both the bridge structure and the modified channel during flooding events. FEMA will not porform a revision at this time to the effective Flood Insurance Study (FIS), Flood Boundary and Floodway Map (FBFM), and Flood Insurance Rate Map (FIRM) for the City of Coppell to reflect the completed portion of the channel ~odification and bridge construction project due to the unstable conditions created by the partially completed project. Our regional office has been notified of the stability problem with the completed portion of the project, and will be contacting your community in an effort to resolve this problem. We have reviewed the data submitted for the entire channel ~odifica{~on'~f~: bridge construction project, and have determined that the project as a whole meets the minimum floodplain management criteria of the National Flood In- surance Program. The drop structure that is proposed between the completed channel modification and the Freeport Parkway bridge would appear to create stable channel conditions during flood events. If the entire project is completed' as proposed, a revision to the effective FIS, FEFM, and FIP~ for the 2 City of Coppell will be warranted. Base (100-year) Flood Elevations and floodway boundaries for Grapevine Creak would be revised as depicted in the aforementioned report. Please note that future revisions to the PIS, FBFM, and FIRM or restudies of the flood hazards in this area could modify this de- termination. This determination is based on the ]00-year flood discharges computed in the effective PIS for the City of Coppell, and does not consider subsequent changes in watershed characteristics that would tend to increase flood dis- charges. The development of this project and other projects upstream could result in increased flood discharges, which, in turn, could result in in- creased ] 00-year flood elevations. Future restudies of your community's flood hazards, which would take into account the cumulative effects of development on flood discharges, could establish higher 100-year flood elevations in this area. This conditional Letter of Map Revision is based on minimum floodplain man- agement criteria established under the National Flood Insurance Program. The City of Coppell is responsible for approving all proposed floodplain develop- ments, including this request, and for assuring that necessary permits re- quired 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 Program requirements. It should be noted that National Flood Insurance Program regulation 44 CFR 60.3(b)(7) requires communities to 'assure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained.' This provision is incorporated into your community's existing floodplain management regulations; consequently, upon completion of the project, re- spoD~ibility for maintenance of the modified channel will rest with your c ommuni ty. Upon completion of the entire project as proposed, your community may request a revision to the effective PIS, FBPM, and FIRM. The revision request should be submitted to our Region VI office and must include the data listed below= 'As-built' plans of the channel modification and bridge construction project, certified by a registered engineer. 20 A written description of the methodology used to determine hydrologic and/or hydraulic parameters, if different from the effective. FIS~gnd FIRM. .~. -.. Revised water-surface profiles of the 10-, 50-, 100-, and 500-year floods reflecting =as-built~ conditions, including a zone determi- nation. The methodology and starting parameters for the revised profiles should be consistent with the present effective FIS, i.e., same discharges and hy~raulic model, unless the parameters have been 3 superseded by more current and technically superior data and analyses. (FEMA approval should be obtained before deviating fro~ the effective FIS parameters. ) Since only a portion of the existing profiles is being revised, the upstream and do wnstreamportions of the revised profiles should coincide with the effective FIS profiles, i.e., hydraulic calculations should be continued upstream and downstream of the revised area until water-surface elevations coincide with those in the effective FIS. Two floodway hydraulic backwater models. The first should be a duplication of the original baseline model used in the effective FIS. This is required to ensure that the original data has been duplicated correctly. The second model should incorporate the completed project and include any other channel modifications or encroachment that have occurred in the floodplain since the original floodway was delineated. If, however, additional cross sections are used in the second model to provide a more detailed analysis of the completed project and its effects on flood hazards, an intermediate model incorporating the additional cross sections should also be submitted. This model must reflect floodplain conditions as they existed at the time that the original floodway was delineated and, therefore, it is important that any cross sections added to the original model describe those con- ditions. In addition, any improvements to the original modeling technique may be incorporated into this intermediate model. This model will then become the new baseline model and will be used to accurately measure the effects of the completed project. am The methodology and ~arameters for the revised floodway should be consistent with the effective FIS, i.e., equal conveyance reduction to establish encroachment limits, unless changes as s~ecified in item 3a have been approved by FEMA. be Since only a portion of the floodway is being revised, it must tie into the effective FIS floodway by duplicating the results of the original baseline model at cross sections upstream and downstream of the project. The revised floodway must carry the waters of the base (100- year) flood without increasing the water-surface elevations of that flood by more than 1.0 foot over the original baseline model at any point. If additional cross sections have been incorporated, then revised floodway elevations also may not exceed base flood elevations calculated in the new baseline model by more thanl.0 foot. In all cases, the revised.flo~o~._way elevations may not exceed revised base flood elevations b~' mo~ than 1.0 foot. Delineation of the 100- and 500-year flood boundaries, the 100-year floodway boundary, and the locations and alignment of cross sections and flow line used in the hydraulic model. This information should be shown on a map of suitable scale and tol)ographic definition to provide reasonable accuracy. All items should be labeled for easy cross-referencing to hydraulic model and summary data. Source data and engineering documentation for the previously mentioned items, as well as a bibliographic list of other sources of information We have enclosed documents entitled Conditions and Criteria for Ma~ Revisinn~ and Conditions and Criteria for Floodwa~ Revisinn,, which further describe the nature and extent of the material needed to support a request to revise an effective FIS, FBFM and FIRM. Compliance with the criteria outlined in these documents will expedite FEMA's review process, thus allowing the effective FIS, FBFM, and FIRM 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 ~azards Division of the Federal ~mergency Management Agency in Denton, Texas, at (817) 898-9127 or members of our Headquarters staff in Washington, D.C., at (202) 646-2754. Sincerely, Chief, Risk Studies Division Federal Insurance Administration Enclosures cc: Mr. B. Anatole Falagan Mr. Patrick Lee Acker, Albert H. Halff Associates, Inc. Ms. Shohre Daneshmand, Civil Engineer, City of Coppell