Stormwater Considerations for Newly Developed/Redeveloped Roadway Projects

Roads are a source of imperviousness generating stormwater in landscapes across the United States. There are a variety of pollutants found in stormwater from roads including metals like copper, zinc, and lead as well as sediments and trash. Unmaintained rights of way can also release sediments if stormwater becomes channelized thereby causing erosion. Stormwater runoff can come into contact with these pollutants and be conveyed into nearby waterbodies with little or no treatment. The excess volume and velocity of stormwater coming from these roads can also cause flooding and stream scouring.Roads are designed to convey stormwater offsite quickly to preserve the roadway surface and prevent deterioration. Yet there are still many things that departments of transportation can do in their rights of way to achieve these important transportation objectives while also protecting local water quality. Incorporating green infrastructure techniques into roadway designs, for example, can provide cost-effective solutions to stormwater management with multiple water quality-based and vegetation-based benefits for communities.EPA has been considering updating the Clean Water Act's stormwater program to take a more proactive approach to stormwater management. Specifically, EPA has been considering establishing a retention-based performance design standard for stormwater discharges from newly developed and redeveloped sites, including roadway projects. EPA is also considering expanding ways to encourage municipal separate storm sewer systems (MS4s) to work together to develop watershed approaches. An overview of these considerations will be presented as well as flexibilities for sites, local governments, and state governments.