Environmental risk assessment of dredged material disposal

Disposal of dredged material can release hazardous substances into the marine environment. At the same time, clear and consistent criteria for assessing these risks are often lacking. This project develops new threshold values, dispersion models and a practical tool to support authorities and ports in environmental risk assessment.

Dredging is necessary to keep shipping lanes and ports safe, but sediments often contain contaminants such as metals, polycyclic aromatic hydrocarbons (PAHs) and organotin compounds like TBT, which can negatively affect marine ecosystems.

Despite this, scientifically robust and widely accepted criteria for assessing environmental risks are often missing. Assessments are frequently carried out without dispersion modelling and without comparing predicted concentrations to effect-based threshold values, leading to inconsistent decisions.

The project develops a new methodology that combines ecotoxicological threshold values, hydrodynamic modelling and environmental legal analysis. A key output is a user-friendly digital tool where users can input contaminant levels and disposal volumes to estimate environmental concentrations and associated risks.

The results will contribute to more transparent, consistent and environmentally sound decisions on dredged material disposal.

The project is coordinated by IVL Swedish Environmental Research Institute, in collaboration with Chalmers University of Technology, the University of Gothenburg and DHI, in close dialogue with authorities and ports.