Assess the ecotoxicological risk and health risk of sites with contaminated sediment as part of restoration projects

Context and project description

Several sites in the St. Lawrence contain contaminated sediments and may need to be restored. All decisions on this matter are based on an assessment of the quality of the sediments according to a series of established criteria. In some cases where the level of contamination is highest, we must add an assessment of the risk represented by these sediments, as much for the environment as for the people who are exposed to them. However, this complementary analysis requires specific tools (toxicity tests, study of benthic communities, etc.) not described in the current assessment guide at Environment and Climate Change Canada and Quebec's Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques. Furthermore, there is no assessment process specifically associated with the risk to human health. We must refer to criteria regarding contaminated soil, for which the physiochemical characteristics are different than those of sediments.

This project goes together with two other projects on the management of contaminated sediments. It aims to develop a relationship model and a standardized approach to the assessment of the ecotoxicological risk (first step) and the risk to human health (second step) created by the restoration projects. The approach will start from a database created in the last phase of the SLAP for the deposit of dredging sediments in open water in the river section. It will first be adapted to the contaminated sites, then expanded for the brackish water of the estuary and sea water. 

Results

An analysis of actual cases made it possible to complete part of the first stage of this project, which involved assessing the ecotoxicological risk associated with contaminated sediment sites. The two cases used are the contamination of the Chaudière River following the Lac-Mégantic rail disaster, and the development of an evaluation approach for projects involving the transfer of port facilities. The first project stage will be finalized during the 2016–2021 phase of SLAP. The second stage was initiated in parallel and involves the design of tools for assessing the human health risks posed by contaminated sediments. It, too, will be completed during the 2016–2021 phase.

Participating departments

Government of Canada

  • Environment and Climate Change Canada
  • Health Canada
  • Public Works and Government Services Canada

Government of Quebec

  • Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques
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