Pie-IX

In the coming months, we’ll be starting excavation work to make way for new infrastructure for the Blue line extension.

The excavation method will vary depending on the type of work being done. The surface excavation work will involve controlled microblasting, whereas most of the excavation for the underground tunnel will be done using a tunnel boring machine, or TBM. At both types of worksites, there will also be some mechanical excavation. The vibrations produced by the different excavation methods will be measured on an ongoing basis using seismographs. These devices will be installed at various points throughout the excavation zones and will be used to continuously monitor the vibration levels and make sure they fall within legal limits.

Essential preventive measures

To prepare for upcoming excavation work, the STM has tasked ABS with inspecting buildings that meet at least one of the following criteria:

• Located within 75 metres of any surface-level excavation work

• Located within 30 metres of the tunnel axis

The inspections will serve to compile an inventory of the structures surrounding the worksites for the Blue line extension. The findings of the inspections will also be used to establish the maximum vibration levels for each site. Although these inspections are a precautionary measure, they are essential in the unlikely event that the work causes any damage.

As a further precaution, any building within 100 metres of a worksite where there will be microblasting will receive a carbon monoxide detector a few weeks before the excavation work starts.

Each building inspection lasts approximately 15 to 30 minutes. Photos are taken of the building interior and exterior. The photos are mostly close-ups of the foundations, walls, ceilings, and floors and serve to document the building’s condition prior to the start of the excavation work.

The pre-construction inspection is a common precautionary measure for major construction sites. It protects you in the unlikely event that your property suffers any damage during work on the Blue line extension.

Controlled microblasting is used on several major STM worksites, depending on the type of rock to be excavated. To learn more, watch the video in the FAQ section of our Blue line extension page.

In 2020 and 2021, two archeological potential studies were conducted at the sites of several future structures. This is standard procedure whenever we break ground on a project of this scale that requires excavation. Three future métro stations were identified for targeted interventions, at Pie-IX, Viau and Saint-Michel. These sites were chosen because they are located along the watershed of the Ruisseau du Pont à l’Avoine, a now-dried stream that existed until the 1950s. It flowed south to join the Ruisseau Molson and into the St. Lawrence.

• The sites of the future métro stations at Pie-IX and Viau will be studied as they are likely to show signs of former Indigenous occupation.
• The site of the future Saint-Michel power station, located beside the métro station of the same name, is potentially significant to European Quebec history, since it was occupied more recently in the early 20th century. A delivery company occupied the space until the 1960s, when the building was destroyed by fire.

How are the digs conducted?

An expert archeological firm has been hired to conduct the digs. After analyzing the sites and leading archeological potential studies, the archeologists will choose locations for inventory trenches. The trenches will be roughly one metre deep and will allow the researchers to physically evaluate the site’s potential.

What do you do if there is a find?

If anything is found, the trench where it is discovered will be enlarged, and additional probes will be done to evaluate its archeological features. An inventory is also conducted as needed.

Have you ever found any historical artifacts?

At the site of the future Pie-IX (working name) métro station, archeologists unearthed a stone wall and a wooden beam. Although these vestiges show that the site was occupied at the beginning of the last century, they were not of significant heritage value. An archaeological inventory was carried out to document the precise location of the ruins. The inventory included a qualitative and quantitative identification, ensuring the protection and safeguarding of the vestiges’ data.

Yes, the shopping centre will be able to remain in operation during the expected construction period of the new Pie-IX station. However, it will be partially deconstructed to prevent any interference with worksite or shopping centre operations.

The STM acquired the building on December 1, 2021, following the expropriation process started earlier in the project timeline.

The property will be managed by STM subsidiary Transgesco. A recognized company specializing in this area has also been mandated to manage shopping centre operations.