Synthesis of Information Related to Highway Problems. Topic 43-06. Pollutant Load Reductions and Total Maximum Daily Load (TMDL) Compliance for Highways

The Federal Water Pollution Control Act (Clean Water Act) empowers the Environmental Protection Agency (EPA) to require that states set water quality standards for all waterways. For waterways that do not meet these standards due to an excessive pollutant load, the states are required to determine the maximum amount of the pollutant that can be introduced to a waterway and still meet water quality standards. This level of pollutant loading is called the total maximum daily load or TMDL. For many years states have been developing water quality standards, listing impaired waters and developing TMDLs for those impaired waters; but now the EPA is requiring that the TMDL loads be met and impaired waters be restored. This requirement is coming to state Departments of Transportation (DOTs) through the National Pollutant Discharge Elimination System (NPDES) permitting process for municipal separate storm sewer systems (MS4s) and stormwater runoff. Because TMDL implementation is so new for DOTs, strategies to meet them tend to rely on traditional stormwater control practices which involve constructing a facility that will provide on-site treatment of stormwater such as bioretention, sand filters, or retention ponds. The drawback to these types of controls is they are expensive to design and construct, they compete for right-of-way that is often needed for other purposes, and expensive to acquire. They require intensive maintenance to ensure continued pollutant removal efficiencies and may not be effective at removing targeted pollutants for a particular waterway. Also, revenue for DOT capital and operations activities is at a premium and many necessary programs are competing for fewer dollars. To determine effective and practical methods of meeting TMDL requirements for highways and to provide needed flexibility given land and budget constraints, this study will document current effective practices of stormwater treatment and pollutant load reduction strategies for highway applications. The study will provide a summary of information for effective practices as identified by the state DOTs, including: 1) descriptions of applicability to highways, 2) design standards, 3) site development criteria, 4) potential impacts to the environment or cultural resources, 5) types of pollutants treated, and effectiveness of treatment, 6) costs associated with implementation, and 7) maintenance requirements. Information will also be sought on techniques and strategies to reduce external inputs of pollutants into the DOTs stormwater system and barriers to such practices. There will be a discussion of what can be achieved by strategies designed to address the most common pollutants of concern (e.g., nitrogen, phosphorus, zinc, copper, bacteria, chloride, temperature, and sediments). Information will be gathered through literature review and in-depth interviews among selected state DOTs. The selected states will be those that have mature or advanced TMDL programs, taking into account geographic and pollutant diversity. There will be special interest in innovative and non-traditional methods. The consultant will propose at least 10 states to be interviewed in their work plan.


  • English


  • Status: Active
  • Contract Numbers:

    Project 20-05, Topic

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    National Cooperative Highway Research Program (NCHRP) Synthesis

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC    20001
  • Project Managers:

    Williams, Jon

  • Start Date: 20110701
  • Expected Completion Date: 0
  • Actual Completion Date: 0
  • Source Data: RiP Project 29021

Subject/Index Terms

Filing Info

  • Accession Number: 01463277
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 20-05, Topic
  • Files: TRB, RiP, USDOT
  • Created Date: Jan 3 2013 2:20PM