Roadside infiltration systems for treatment of road runoff in Nordic countries (2024-2027)

Stormwater from road surfaces carries a wide range of contaminants, which may cause short- and long-term effects on the aquatic environment when being discharged. The sources of pollutants road runoff differ across locations and seasons.

Infiltration based solutions are commonly used for managing urban runoff and several studies have documented the performance about pollution mitigation and volume reduction. The most common solution for road runoff treatment are swales or ditches designed from a runoff capacity point of view, without pollution control originally being prioritized. The soil retention capacities of these swales are not well documented even though they represent a large ration of the stormwater treatment along roads and highways.

The pollutant retention in both engineered and non-engineered swales and ditches (including the side slope functioning as a buffer strip and infiltration area) are evaluated in this project. Commonly studied pollutants like metals as well as new emerging pollutants are found to be persistent, mobile and toxic, as they will have severe downstream impact. The project aims at increasing the knowledge and producing guidance on infiltration solutions used for pollution control along roads, with the underlying ambition of protecting water resources and controlling environmental harm.

This project is funded by NordFoU (Trafikverket, Statens Vegvesen) and is made in collaboration of Norwegian University of Science and Technology, NTNU.