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Section 2: Federal Laws, Regulations, and Agencies Governing Hydraulic Design

This section provides an overview of the federal regulatory environment as it relates to hydraulic considerations for TxDOT projects. It is not, however, an exhaustive list of all federal regulations that may pertain to highway drainage.

The following subsections discuss:

It is possible to comply with the Federal requirements regarding the encroachment of a highway on a floodplain and still risk future legal liabilities because of the impact of the highway on the floodplain and the stream. Hydraulic engineers should review these potential liabilities and ensure that their evaluation is considered in design of highway projects.

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National Flood Insurance Program

The National Flood Insurance Program (NFIP) was established under the National Flood Insurance Act (NFIA) in 1968 to reduce future flood losses through local floodplain management. NFIP requires participating cities, counties, or states, to adopt floodplain management ordinances containing certain minimum requirements intended to reduce future flood losses.

Special Flood Hazard Areas (SFHAs) are depicted on Flood Insurance Rate Maps (FIRMs) or Flood Hazard Boundary Maps (FHBMs) that have been prepared by Federal Emergency Management Agency (FEMA) for each participating community. The participating community is responsible for informing FEMA of any alterations or changes to the floodplain. TxDOT requires that designers inform the participating community through its Floodplain Administrator (FPA) of any changes to the floodplain or its parts via FPA notification.

The following list identifies some typical conditions that must be checked for consistency with the requirements:

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  • Replacement of existing bridge with smaller opening area, e.g., shorter length, deeper deck, higher or less hydraulically efficient railing.
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  • Replacement of bridge and approach roadway with an increase in the roadway profile.
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  • Safety project involving addition of safety barrier.
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  • Rehabilitation or maintenance of roadway resulting in a higher profile.
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  • Highway crossing at a new location.
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  • Longitudinal encroachment of highway on floodplain (with or without crossing).

For more information on the NFIP, see Chapter 5 of this manual.

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Executive Order 11988

Executive Order 11988, May 24, 1977, requires each federal agency, in carrying out its activities, to take action (1) to reduce the risk of flood loss, to minimize the impact of floods on human safety, health and welfare, and to restore and preserve the natural and beneficial values served by floodplains; (2) to evaluate the potential effects of any actions it may take in a floodplain, to ensure its planning programs reflect consideration of flood hazards and floodplain management; and (3) to submit a report to the Council of Environmental Quality (CEQ) and the National Water Resources Council (WRC) on the status of procedures and the impact of the Order on the agency’s operations. This executive order applies mostly to state buildings in the floodplain, but also requires TxDOT to consider alternatives that will not impact the floodplain. U.S. Department of Transportation Order 5650.2 contains DOT policies and procedures for implementing E.O. 11988.

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National Environmental Policy Act

The National Environmental Policy Act (NEPA) was passed in 1969, 42 United States Code (USC) 4321-4347, to establish a national policy to protect the environment.

For more information on NEPA, see the TxDOT Environmental Manual.

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Rivers and Harbors Act

The U.S. Army Corps of Engineers (USACE) began regulating activities in navigable waters with the Rivers and Harbors Act of 1899.

For more information on the Rivers and Harbors Act, see the TxDOT Environmental Manual and the TxDOT Bridge Project Development Manual.

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Clean Water Act

The Clean Water Act (CWA) of 1972, 33 USC 1251-1387, was enacted to maintain and restore the chemical, physical, and biological integrity of the waters of the U.S. The broader jurisdiction under this law includes not only navigable waters, but also most waters of the country and adjacent wetlands. Provisions of the CWA are enforced by the Texas Commission on Environmental Quality (TCEQ) and the USACE.

A water discharge permit or coordination is required whenever a project directly or indirectly impacts water resources. For more information on the CWA, see the TxDOT Environmental Manual.

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  • Section 402 National Pollutant Discharge Elimination System In 1990, the EPA published 40 CFR Part 122, which contains regulations for the National Pollutant Discharge Elimination System (NPDES) storm water discharge permits. The purpose of this legislation is to improve the quality of the nation's rivers, lakes, and streams. NPDES regulations are administered by Environmental Protection Agency (EPA) and TCEQ through the Texas Pollutant Discharge Elimination System (TPDES) and the Construction General Permit (CGP).

    The CWA makes it unlawful to discharge storm water from most construction sites in Texas, unless authorized by the TPDES CGP. Unlike an individual permit that authorizes discharge activities for a specific location, the general permits are for a specific activity (i.e. construction). The operator seeking authorization to discharge storm water is required to comply with the terms of the permit.

    For more information on the CGP, see the TxDOT Environmental Manual.

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  • Section 404 Regulatory Program Section 404 of the Clean Water Act (CWA) establishes a program to regulate the discharge of dredged and fill material into waters of the U.S., including wetlands. Section 404 makes it unlawful to discharge dredged or fill material into waters of the U.S. without first receiving authorization from the USACE. Activities that typically require authorization include placement of culvert pipes, bridge piers, riprap, or any other alteration to the stream including relocation.

    The Section 404 Program can issue the following permits:

Some types of permits do not require individual review and approval by the USACE, while others may take several years to process and require extensive mitigation for impacts to Waters of the U.S. The type of permit that will be required depends on the degree of impact. Projects that impact less than 0.10 acre below the ordinary high water mark of the water body, and do not impact any wetlands, can often be authorized without individual review by the USACE.

For more information on the Section 404 Regulatory Program, see the TxDOT Environmental Manual.

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  • Section 401 Water Quality Certification 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 CWA, 33 USC 1341, as amended. Under Section 401, TCEQ is authorized to certify that federally issued permits will meet the state's water quality standards. TCEQ regulates this section under the USACE permit program and requires the installation of temporary and permanent storm water best management practice devices (BMPs) that have been approved by TCEQ. Environmental documents should include a general description of the measures that will be taken to minimize the potential for impacts to receiving waters under Section 404 and a discussion regarding compliance with Section 401 of the Clean Water Act.

    For more information on Section 401 Water Quality Certification, see the TxDOT Environmental Manual.

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23 Code of Federal Regulations 650 Subpart A

When a TxDOT project with participation by the FHWA involves an encroachment on the 1% Annual Exceedance Probability (AEP) (100-yr event) floodplain, the location and design of the project must comply with FHWA Policy 23 CFR 650, Subpart A. Compliance with this regulation is required when a proposed project includes a new or expanded encroachment on a floodplain regulated by FEMA, or contains the potential for adversely impacting private property or insurable buildings on or near a floodplain.

The FHWA has prepared a non-regulatory supplement, 23 CFR 650, Subpart A, Attachment 2, which explains the requirements for coordination with FEMA and the local community responsible for administering the NFIP under different floodplain encroachment scenarios. Chapter 5 of this manual explains TxDOT procedures for compliance with these requirements.

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23 Code of Federal Regulations 650 Subparts C and H

The January 2005 updated regulation, 23 CFR 650, Subpart C, underscores FHWA guidance regarding Plans of Action (POA) for scour critical bridges. TxDOT scour issues and countermeasure designs are handled by the Bridge Division, Geotechnical Section. Refer to the TxDOT Geotechnical Manual for more information. The regulation 23 CFR 650, Subpart H requires coordination with the United States Coast Guard (USCG) and USACE in providing adequate vertical and horizontal clearance for navigation on navigable waterways and is covered in the TxDOT Bridge Project Development Manual.

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Memoranda of Understanding (Federal)

Some projects may be governed or affected by a Memorandum of Understanding (MOU). An MOU is an executed understanding between TxDOT and other state or federal agencies. The purpose of an MOU is to guide both parties concerning their roles and responsibilities necessary to achieve effective coordination of project activities. MOUs are used to expedite the review process and minimize the required documentation for such items as:

TxDOT has not negotiated MOUs for hydraulic design with any federal agencies.

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