Upgrading the power transmission system between Aqueduc and Saraguay substations
- Region
- Montreal
- Status
- Under construction
- Type
- Transport
- Expected commissioning
- 2040
Hydro‑Québec is carrying out a project to build transmission lines in the north‑south axis of the island of Montréal, between the Saint‑Laurent and LaSalle boroughs, in addition to converting three substations.
Work around Hampstead substation
Hydro‑Québec is currently carrying out major work in the Hampstead substation area.
For more information, consult the FAQ section and the Project News bulletin in the Documentation section.
Project description A stronger network for Montréal’s West Island
To meet the growing energy demand in Montréal’s west end, we are upgrading the existing 120‑kV transmission lines which connect Aqueduc and Saraguay substations, to convert them to 315‑kV.
We are also building Rockfield substation in Lachine, and the Hampstead substation will be replaced with the new Côte‑Saint‑Luc substation to increase system capacity in these boroughs.
Construction work on the new line is already underway along the existing line route.
Details of the line route
Based on the community’s recommendations and technical, environmental and social constraints, Hydro‑Québec selected the route with the least impact [PDF 73.2 Kb].
The community at the heart of the project
The community at the heart of the project design stage
We always strive to ensure that our projects have the least possible impact. In this case involving a critical area of Montreal, in 2018 we implemented a collaborative approach which is currently ongoing, designed to meet the needs of the municipalities with regard to quality of life and the promotion of biodiversity.
This approach included more than 100 meetings, the establishment of decision‑making and technical committees, discussions with residents, as well as open‑house events.
We would like to extend our thanks to everyone who participated in these discussions!
Our environmental commitment
We apply a rigorous approach to understand the environment, predict the impacts of projects and implement mitigation and monitoring measures to reduce the effects of infrastructure construction and operation on nature and the quality of life in communities. To learn more, consult the Register of Environmental Assessments ‑ [in French Only] on the website of the ministère de l’environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP).
Consult the summary of the collaborative approach used with the host environment 2019‑2023 [PDF 6.3 Mb ‑ in French only].
Project schedule
-
2018‑2023
Preliminary consultation of organizations affected, collaboration with the community, study area and environmental process.
-
2024‑2025
Permitting, work plan, detailed engineering and procurement.
-
2026‑2029
Construction of a 315‑kV line between Saraguay (Saint‑Laurent) and Hampstead (Côte‑Saint‑Luc) substations.
Construction of the 315/25 kV Côte‑Saint‑Luc substation.
-
2031‑2034
Construction of the Rockfield substation (315/25 kV) in Lachine and replacement of the 120‑kV line with a 315‑kV line extending to the Côte‑Saint‑Luc substation.
-
2040
Replacement of the 120‑kV transmission line with a 315‑kV line between the Rockfield substation (315/25 kV) in Lachine and the Aqueduc substation in LaSalle.
FAQs
Based on the tests conducted, the new line’s magnetic field will be weaker than that of the existing line because the cables will be further from the ground and the current flowing in the cables will be weaker.
As for the electric field, it will increase slightly but will remain well below the recommended exposure limit. It will therefore comply with international standards at all times and will be perfectly safe. Want to know more?
Consult our website about electric and magnetic fields.
The existing line is an overhead line. Overhead lines have many advantages compared with underground lines: they last twice as long, their transmission capacity is higher and they are less expensive. In addition, they are much simpler to build and repair, when necessary.
For all these reasons, an overhead line was selected for this project.
The noise level from 315‑kV lines is below that of current lines.
The work will be announced in advance and signage will be set up if temporary traffic disruptions are necessary. The work will take place between 7 a.m. and 7 p.m. Other mitigation measures will help us minimize the impact on residents’ quality of life.
Following the line and substation construction work, Hydro‑Québec and its municipal partners will work together to establish a green corridor along the rights‑of‑way to improve quality of life for residents. The aim is to promote biodiversity, connectivity and sustainable mobility, particularly in Montreal‑Ouest and in the borough of Saint‑Laurent.
Hydro‑Québec will aim to keep as many trees as possible in the rights‑of‑way.
The work will be carried out in compliance with noise regulations and will subject to rigorous monitoring, including:
- A noise management plan with continuous monitoring
- The use of low‑noise equipment whenever possible
- Mitigation measures to minimize disturbances
Please note:
- The noisiest activity is pile driving (June 2026). It lasts approximately one month.
- Noise will be intermittent, with quieter periods.
- For the transmission towers, the noise will be temporary and limited to each site.
- The noise levels will gradually decrease over the course of the summer.
Hydro‑Québec is implementing several measures to ensure safety and minimize disturbances.
Safety and monitoring
- Secure fencing installed around the work
- Safe pedestrian walkways
- Seismographs to monitor vibrations
Noise and vibrations
- Work on weekdays only (with some exceptions)
- Noisy work during specific hours (7 a.m. to 7 p.m.)
- Monitoring by an independent firm
Traffic and logistics
- Strictly enforced designated truck routes (no truck traffic on Avenue Fleet)
- Signaller at the Boulevard Cavendish intersection
- Appropriate signage
Area cleanliness
- Watering to reduce dust
- Regular street cleaning
Stringent measures are in place to protect nearby residences, including:
- Geotechnical studies carried out before the start of work
- Ongoing vibration monitoring
- Immediate suspension of work if a critical threshold is reached
- Installation of safe shoring systems
Some vibrations may be felt, but they are under supervision and will not affect building foundations.
Some trees had to be removed to ensure safety and technical compliance around Hampstead substation.
With respect to revegetation:
- Options are limited due to the presence of private property.
- Discussions are underway with property owners to determine replanting options.
Documentation
- Environmental impact study on the Environmental Assessment Register ‑ [in French Only]
- Press release March 2025 ‑ Agreement signed between Hydro‑Québec and Canadian Pacific Kansas‑City for the for the Saraguay‑Rockfield project [PDF 85 kBkilobyte]
- Review of the collaborative community approach 2018 to 2025 [PDF 10.18 MBmegabyte]
- Open house activities held in 2023 [PDF 127 kBkilobyte]
- Montréal-Ouest and Hydro‑Québec working committee November 2019 [PDF 31 kBkilobyte]
- Bulletin for Saint‑Laurent and Mont‑Royal ‑ 2023 [PDF 408 kBkilobyte ‑ in French Only]
- Bulletin for Hampstead and Côte des Neiges ‑ 2023 [PDF 418 kBkilobyte]
- Bulletin for Montreal-Ouest ‑ 2023 [PDF 458 kBkilobyte]
- Bulletin for Lachine ‑ 2023 [PDF 383 kBkilobyte]
- Project presentation bulletin ‑ 2019 [PDF 1.4 MBmegabyte ‑ in French Only]
Contact us
We’re committed to keeping the lines of communication open. Please send us your questions and comments about the project.
Info‑Project line: 1 866 388‑1978