Management tools for contaminated sediment

The assessment of the extent of sediment contamination makes it possible to target sectors where the quality of St. Lawrence sediments is of concern. The environmental issues represented by these sectors are related to the exposure of aquatic organisms and humans to contaminated sediments. More specifically, the exceedances mentioned in the Criteria for the Assessment of Sediment Quality in Quebec and Application Frameworks: Prevention, Dredging and Remediation (2007) will make it possible to identify the areas of potential concern, to define them and to assess the environmental risks. By assessing exposure and effects on ecological and human receptors, it will also be possible to target sites that pose specific issues.

This project also aims to promote exchanges between stakeholders  by taking over the activities of the integrated management committee for dredging and sediments, which is more oriented towards research.

All knowledge gained in this project will also be used to improve, update, or initiate new sediment assessment and management guidelines as needed.

The assessment of the sediment quality is performed in comparison with the criteria for assessing the quality of Quebec’s sediments. However, comprehensive assessment also requires the use of more specific tools for informing management decisions.

In the previous phases of the SLAP, our team determined the method to assess the risk related to the release of dredging sediments in free water for the St. Lawrence freshwater ecosystems. Furthermore, the analysis of actual cases allowed the development of risk assessment tools to be initiated for contaminated sediment sites. In order to assess the effects of this discharge on aquatic wildlife, the team analyzed the contaminants present in the sediments and then studied their effects by performing, among other, toxicity tests in the laboratory and studies on the invertebrate communities present in the St. Lawrence River. 

During this SLAP phase, our team pursue its work throughout the St. Lawrence River. The creation of the necessary risk assessment tools for the ecosystems is completed as the risks of contaminated sediments on human health, which was initiated at the same time as the previous phase.

This project aims to locate aquatic sites where the chemical quality of the St. Lawrence River’s sediments is of concern in accordance with the Criteria for the Assessment of Sediment Quality in Quebec and Application Frameworks: Prevention, Dredging and Remediation (2007). To do so, an analysis of the existing data and data collection on-site will be performed. This work will allow the extent of the different sectors of concern to be identified, assess their degree of contamination and to perform an initial assessment of the risk that contaminated sediments can have for the aquatic environment and its use (fishing, swimming, drinking water, etc.). The documentation of these contaminated sites guide new data collection, determine the necessary environmental interventions, and set their order of priority to better guide future actions, if necessary.

Sediment quality is assessed through comparison with numerical criteria. However, comprehensive assessment also requires the use of more specific tools for informing management decisions. First, the development of an assessment methodology for characterizing the ecotoxicological risk of projects in sediment management will assist in gauging the ecotoxicological risk associated with sediment management. Next, the project will enable development of a methodology for assessing the risk to human health through use of sediment exposure criteria and definition of the exposure pathways specific to the sites with contaminated sediment.

Read the backgrounder for this project. Read also the Ecological Risk Assessment of Open-Water Sediment Disposal to Support the Management of Freshwater Dredging Projects guide.

The project involves defining toxicity tests that can be used to assess the potential impact of sediment dredging or dumping in the brackish waters of the St. Lawrence downstream of Île d'Orléans.

Read the backgrounder for this project.

 A review of the Criteria for the Assessment of Sediment Quality in Quebec allows a targeting of the sectors of the St. Lawrence where sediment quality is an issue of concern. The issues in terms of various types of exposure to contaminated sediment, both for the ecosystem and humans, will be defined. Finally, the definition and documentation of these issues could assist in prioritizing actions throughout the St. Lawrence and focusing the various restoration activities carried out within specific sectors. 

Read the backgrounder for this project.

This framework will serve in defining the necessary timing and conditions for sediment decontamination as well as determining the various solutions to the problems identified. This project will assist in prioritizing sectors associated with the greatest potential benefits of sediment restoration efforts for the ecosystem while also taking into account current regulations and the impact of decontamination (environmental benefits and socioeconomic factors) in terms of cost.

Read the backgrounder for this project.