Assessing and Improving Pollution Prevention by Swales

Principal Investigator:

John Gulliver, Professor, Civil, Environmental and Geo-Engineering

Project Summary:

Swales and/or drainage ditches for linear road projects have excellent potential for stormwater treatment. They can infiltrate water into the soil, filter sediments and associated pollutants out of the water, and settle solids to the bottom of the swale. Currently, however, there is little information that can be used to gain pollution prevention credits with State of Minnesota agencies and meet permit requirements of watershed districts and other municipalities. This research will 1) document the pollution prevention available through infiltration into the soil of swales and develop practical soil modifications that will make it possible to utilize existing right-of-way to meet permit requirements, and 2) develop methods to remove dissolved phosphorus and heavy metals in swales. Maintenance requirements will also be documented, demonstrating another advantage in using swales for pollution prevention and for runoff volume control. Drainage ditches should be utilized to their full pollution prevention potential before building other, more expensive stormwater treatment practices. This research will document the swale potential of drainage ditches and credit them for the pollution prevention they are already achieving, guide the conversion of drainage ditches into swales that can remove dissolved constituents, and provide the information necessary to develop design standards for swales along our linear road projects. Results from this study could be used to design systems for use along roadways throughout Minnesota and the United States. Results could also be used to estimate load reductions due to infiltration in total maximum daily load (TMDL) studies for future installations of roadside swales.


Project Details:

  • Start date: 07/2010
  • Project Status: Completed
  • Research Area: Environment and Energy
  • Topics: Environment