Location Alternative Considerations
The planning phase for a highway section usually involves consideration of a number of alternate highway locations, which often require construction across or along streams and floodplains. During the planning phase, evaluate the effects that location alternatives would have on stream systems. (See the Project Development Process Manual for more details.) Include a preliminary hydraulic study of the various alternatives because the type and cost of drainage facilities required can determine location selection. As project development
proceeds, you may find that locations selected without adequate hydraulic consideration to floodplain encroachments and extensive channel modifications are unacceptable.
Consider the environmental effects, risks, and costs of required drainage facilities in the final selection of an alternative. Analysis of alternative alignments may reveal possibilities for reducing construction costs, flood damage potential, maintenance problems, and adverse environmental impacts.
Detailed information and survey data are seldom available for an in-depth hydraulic study during the planning phase; however, it is possible to ascertain basic requirements and consequences of a particular location or alignment and the relative merits of alternatives.
Topographic maps, aerial photography, stream gage data, floodplain delineation maps, and a general knowledge of the area often provide the basis for preliminary evaluations of
alternatives.
Phase Planning Assessments Consider the following factors:
♦ water quality standards
♦ stream stability
♦ heavy debris discharge
♦ highly erodible banks
♦ fish and wildlife resources
Chapter 7 — Channels Considerations and Design Criteria
Assessments may require the cooperative efforts of Area Office designers and Division personnel as well as others with experience on similar projects or specialized expertise in the particular area. Design all projects to comply with Federal and State regulations. As such, it is necessary to consider the implications of the following:
♦ Federal Emergency Management Agency National Flood Insurance Program (FEMA NFIP)
♦ U.S. Corps of Engineers (USACE) 404 permit
♦ U.S. Fish and Wildlife requirements
♦ Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System permit requirements
♦ EPA NPDES permit for industrial activity (construction)
♦ EPA Endangered Species Act provisions
Refer to the Project Development Process Manual for more information on the above regulations.
Environmental Assessments
Consult the Environmental Procedures in Project Development Manual for environmental concerns. (See Texas Parks and Wildlife Department (TPWD), Clean Water Act (CWA), in the Environmental Procedures in Project Development Manual.) Consider stream channel modification only after examining all other alternatives. Regulatory requirements invoked by stream channel modifications can be substantial.
Consider the U.S. Fish and Wildlife Service (USFWS) review requirements where review may result in recommendations to avoid, minimize, or compensate for the adverse effects to wildlife habitat.
Refer to the Environmental Procedures in Project Development Manual for more
information. It is prudent to plan measures to avoid, minimize, or compensate for stream modifications.
Justify the selection of a stream modification alternative. Consult with resource agencies early in design planning, and include these consultations in the Environmental Assessment Statement (EAS) or Environmental Impact Statement (EIS) with supporting documentation.
(See the Environmental Procedures in Project Development Manual for more details.) The EA should also contain compensation plans for replacing any removed habitats. Avoid or minimize adverse effects, or implement mitigation plans to the best of your ability when transportation projects impact riparian corridors as described in the Fish and Wildlife Coordination Act (FWCA). (See Environmental Procedures in Project Development Manual for more information.) If the department cannot offer mitigation for riparian corridor impacts, offer an explanation as justification in the environmental documentation.
Chapter 7 — Channels Considerations and Design Criteria
Consultations with Respective Agencies
During the planning phase, contact Federal, State, and local agencies in regard to plans or land uses such as the following that could affect the highway drainage design:
♦ dams and reservoirs
♦ irrigation
♦ flood control levees or channel modifications
♦ navigation
♦ floodplain management
♦ zoning
♦ recreational use
♦ fish or wildlife management
Consult the four agencies having regulatory authority over navigation and construction activities in waters of the United States and agencies with special expertise, such as in the limits and classification of wetlands, for preliminary information that may affect location decisions. The four agencies are as follows:
♦ U.S. Coast Guard (USCG), U.S. Department of Transportation
♦ U.S. Army Corps of Engineers (USACE), Department of Army
♦ Federal Highway Administration (FHWA)
♦ Environmental Protection Agency (EPA) See References for contact information.
Stream Channel Criteria
Stream channel criteria include the following:
♦ Evaluate the hydraulic effects of floodplain encroachments for the peak discharges of the design frequency and the 100-year frequency on any major highway facility.
♦ Avoid relocation or realignment of a stream channel wherever practicable.
♦ If you deem relocation necessary, the cross-sectional shape, plan-view, roughness, sediment transport, and slope should conform to the original conditions insofar as practicable.
♦ You may need some means of energy dissipation when velocities through the structure are excessive or when the original conditions cannot be duplicated.
♦ Provide stream bank stabilization, when appropriate, to counteract any stream
Chapter 7 — Channels Considerations and Design Criteria well as the local site. Refer to “Stream Stability at Highway Bridges,” FHWA-IP-90- 014 for guidance.
♦ Provide a sufficient top width with access for maintenance equipment for features such as dikes and levees associated with natural channel modifications. Provide turnaround points throughout and at the end of these features.
Federal Emergency Management Agency (FEMA) Requirements
Consider FEMA rules and procedures early in the project planning stages.
Program application for permits and approvals by Federal and State agencies having
regulatory authority over streams early in the project development process. (See the Project Development Process Manual for more details.) An increasing number of federal and state permits are required for construction activities that may involve navigation and water quality. Authorization of structures for work in navigable waters of the United States is required by Sections 9, 10, and 11 of the River and Harbor Act of 1899 (30 Stat. 1151, 33 U.S.C. 401, 403, and 404), and Section 404 of the Clean Water Act of 1977 (33 U.S.C.
1344). (See the Project Development Process Manual for more details.)
The issuance of any of the above permits is contingent on receipt of a water quality certificate or waiver of certification from the State in which the work is to be done. This certification assures that the proposed project will not violate effluent limitations and water quality standards established pursuant to Section 401 of the Clean Water Act (33 U.S.C.
1341) as amended. (See the Project Development Process Manual for more details.) Many federal and state agencies have statutory authority to issue permits or approve construction plans for the purposes of erosion and sedimentation control, floodplain management, utilization of natural resources, environmental protection, and coastal zone management.
Assure compliance with our agreements with FHWA, USFWS, Texas Natural Resource Conservation Commission (TNRCC), and Texas Parks and Wildlife Department under the FWCA and each respective Memorandum of Understanding (MOU). Check on jurisdictional status with USACE and USCG. (See References for more information on contacting these agencies and the Project Development Process Manual for more information on policies and coordinating with these agencies.)
Section 3