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West sector

The environmental project in the west sector has been in place since September 2017. This project is being conducted in partnership with Quebec’s Ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques (MDDELCC).

In this sector, we installed a groundwater containment and treatment system. The water is contained by a hydraulic barrier of 32 pumping wells that capture contaminated groundwater and direct it to a building for treatment before it is discharged back into the river. Every 10 days, the system cleans the equivalent of an Olympic-sized swimming pool of contaminated water, which it will continue to do for the next 15 years.

In the west sector, which includes land along the Bonaventure Expressway up to the approach of the Champlain Bridge across from Île des Sœurs, groundwater that drains to the river contains contaminants such as ammonia nitrogen, polycyclic aromatic hydrocarbons (PAHs) and dissolved metals.

To address this problem, the Corporation started work in June on a containment system consisting of a hydraulic barrier with 32 wells installed along the riverbank. Through active pumping, this barrier will intercept contaminated groundwater and carry it to an on-site treatment system.

A medium to grow a biofilm with approximately the same density as water to allow bacteria to develop so that they perform nitrification in 2 phases:

  • Phase 1: Ammonia is converted into nitrite (nitrosation).
  • Phase 2: Nitrite is converted into nitrate (nitratation).

The water goes through several treatment steps before being discharged into the St. Lawrence River:

  1. The contaminated water is pumped by 32 wells installed on the site.
  2. The contaminated water is routed to a physical and chemical treatment system inside a new building.
  3. The contaminated water is then returned to an underground system for filtration and biological treatment.
  4. Finally, once quality standards are met, the clean water is discharged through a pipeline that flows directly into the St. Lawrence River.
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