Iron-Enhanced Swale Ditch Checks for Phosphorus Removal

Principal Investigator(s):

John Gulliver, Professor Emeritus, 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 the Minnesota Pollution Control Agency (MPCA) and meet permit requirements. This research is measuring the performance of iron-enhanced ditch checks in roadside swales as a novel stormwater treatment system developed specifically for capturing phosphate and toxic metals from roadway runoff in both urban and agricultural environments. Permeable check dams enhanced with iron filings have been developed and tested in the laboratory through a project funded by the Local Road Research Board (LRRB), and check dams have been designed and built through a project funded by the MPCA. The long-term effectiveness of these new enhancements, however, is yet to be investigated. This research is: 1) documenting the field performance of an iron-enhanced swale ditch check for three years, 2) determining the dissolved phosphorus and metal retention in the filter insert and in the entire ditch check, and 3) identifying maintenance needs of the ditch check. Results from this study can be used to design treatment practices for use along roadways throughout Minnesota and the United States. Results can also be used to estimate load reductions in Total Maximum Daily Load studies for future installations of iron-enhanced swales.

Project details:

  • Project number: 2017009
  • Start date: 06/2016
  • Project status: Completed
  • Research area: Environment and Energy
  • Topics: Environment

Reports or Products: