The City of Montreal hired EBC Inc. and McNally Construction Inc. to build a water main in a tunnel along Jarry Street between 24th Avenue and Champ-d’Eau Street.
The project involves building six access wells, digging a tunnel with a tunnel boring machine (TBM), installing a large water main in the tunnel, filling the annulus of the pipes with cellular concrete, building nine concrete structures, and connecting the structures to the existing network by installing pipes in open trenches.
Adapting to an urban environment
- EBC faced several major challenges while working on the construction site located in a very busy area of Montreal. The team had to implement measures to manage noise, dust, and vibrations and control traffic. To minimize inconveniences to residents and ensure everyone’s safety, the EBC-McNally team implemented several preventive and control measures, such as erecting noise barriers, monitoring vibration and noise in real time, using blasting mats made of blast-protection fabric, and using sophisticated equipment and working methods adapted to the environment.
Building a tunnel without excavating the street
To obstruct traffic as little as possible and for resident convenience, EBC used a TBM so they could dig the tunnel without having to excavate the street. This method also shelters workers from the weather, which is important given the harsh winters in Quebec.
Although the method has many advantages, the EBC team encountered a number of problems but were able to solve them with innovative solutions specific to each one. For example, to reduce vibrations during blasting, our experts adjusted the depth of the charges and used a tighter blasting pattern. An expert monitored vibrations from the blasts and if they were too strong, he would adjust the plans for the next blasts.
Furthermore, to control fly rock and reduce blast waves, blasting mats and a protective cover were placed over the berm and tunnel shafts.
Using expertise to work in a confined space
One of the biggest challenges the team faced on the Jarry Tunnel project was digging a 4.04 km tunnel using a TBM that was only 2,235 mm in diameter! The tight working space inside the tunnel made daily operations difficult. Qualified teams worked in shifts, always supervised by an experienced foreman to make sure the work was carried out safely. Before work on the tunnel began, the team developed safe working procedures taking each of the constraints into consideration.
- Used a 2,235 mm wide TBM to dig a 4.04 km tunnel
- Dug 6 access shafts between 10 and 17 m deep through rock
- Laid 4,075 m of 1,200 mm wide pipe and 80 m of 600 mm wide pipe
- Carried out blasting work in an urban area
- Monitored and reduced vibrations and noise from blasting