Saint-Grégoire mechanical ventilation station

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Following the government’s announcement of new lockdown measures, essential worksite activities will continue as decided by the contractor in charge of each site.

For more information on our services and all COVID-19 preventive measures in place at the STM click here.

Construction of the Saint-Grégoire mechanical ventilation station

Project summary

The construction of the Saint-Grégoire mechanical ventilation station, located on the street of the same name, is part of our program to refurbish our métro facilities and equipment. The new building will be located in the parking lot of the École des métiers de l’équipement motorisé de Montréal.

Duration of the work: December 2020 to summer 2023

Description of the work: Construction of a new mechanical ventilation station

Métro impacts: No

Bus impacts: No

Impact on customer trips

The project has no impact on customer trips.

Impact on local residents

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During the week of December 7, our general contractor will begin preparing the worksite. Therefore, the contractor will close off the worksite and install fences, the site trailer as well as the equipment needed to carry out the work.  

During the worksite set up phase, we will proceed to drill the pilings, which is necessary in order to install the retaining walls during the excavation work. This phase of the work will generate noise in the vicinity of the worksite; however, the work should be completed prior to the Holidays.

Then, after the Holidays, the ground level excavation work will begin. This work will be carried out using mechanical equipment.

Measures taken to minimize inconveniences during construction


Any construction work likely to generate noise will be scheduled during the hours allowed by municipal regulations, 7 a.m. to 7 p.m., Monday to Friday, and 10 a.m. to 6 p.m., Saturday, inclusive


While the majority of the work will take place Monday through Friday, it may be necessary for it to continue on Saturdays and possibly, but more rarely, on Sundays in order to meet the project deadline. Should this happen, any extensions will be announced on this page, and an electronic newsletter will be sent out to subscribers.


Anti-dust sheets will be installed on the worksite partitions.


Once the work is complete, we will create a small grassy area near the new building to make it more inviting. Three park benches will also be installed on site.

The worksite is a considerable size. We have to dig into the rock bed to create a vertical shaft to a depth of 21 metres. We will then excavate a 64-metre tunnel, removing a total of 6,790 cubic metres of bedrock from the site. After that, we will install a waterproofing membrane over the tunnel to protect it from water infiltrations. Next comes the concrete, which will form the tunnel and underground building. Finally, fans and their accompanying electrical equipment will be installed. All of these steps vary in terms of duration and impact, such as noise and dust.

Once the work is complete, the mechanical ventilation station will comply with all City of Montréal noise by-laws. Huge noise suppressors will mitigate the noise from the fans, installed below ground level, to ensure quiet for residents living nearby. The noise will not exceed 50 decibels, a level comparable to that of a household dishwasher.

Learn more about the project

A mechanical ventilation station is a large infrastructure located between two métro stations that is equipped with two powerful fans designed to extract hot air from the métro system through inlets fitted with air vents. Ventilation stations built for the original métro system extract around 60,000 cubic feet of air per minute, while the new ventilation systems extract around 240,000 cubic feet per minute. Huge noise suppressors mitigate the noise from these fans to ensure quiet for residents living close to a ventilation station.

  1. Preparation of worksite
    Fencing off the worksite
    Setting up the worksite and installing equipment
  2. Excavation at ground level
  3. Excavation in the rock bed
    Micro-blasting will be required to break into the rock bed. In this case, it is the fastest, most efficient way to proceed. Another option would have been jackhammering. However, given the volume of rock to be excavated, jackhammering would be less efficient, would take significantly more time, and be much more disruptive as the noise is constant.
  4. Installation of a membrane to ensure water-tightness of all infrastructures
  5. Concrete work for ventilation station
    Concrete work for all infrastructures
  6. Installation of mechanical and electrical equipment, as well as architectural finishes and exterior design
    Delivery of equipment to work site
    Installation of equipment
    Performance testing on mechanical equipment
    Construction of ventilation station’s external structure

For more information on mechanical ventilation stations, visit the page in the Major Projects section

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The project in images

This work is made possible through funding from the Ministère des Transports du Québec.

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