Why is this project necessary?

Hydro-Québec plans to build a 315/25-kilovolt (kV) substation and a 315-kV supply line in Saint-Eustache to meet the growing needs of Saint-Eustache, Deux Montagnes and Sainte-Marthe-sur-le-Lac. La Trappe substation (in Oka) and Saint-Eustache substation, which currently supply the area, no longer provide the capacity and reliability required to support the urban development underway.

What are the technical characteristics of the project?

The new Patriotes substation will be located on Boulevard Albert-Mondou in Saint-Eustache’s industrial sector. The selected site is located west of the Adesa Montréal premises and south of the right-of-way for the Réseau de transport métropolitain (RTM) railway. The Patriotes substation will be built with three transformers that will lower the voltage from 315 kV to 25 kV for distribution to customers. Another transformer may be added at a later time to meet the growth and development of the regional county municipality (MRC) of Deux-Montagnes. The area of the substation will be 32,000 m2.

The substation will be supplied by a new 315-kV line, about 5.2 km long, which will connect it to the existing 315-kV line located north of Boulevard Arthur Sauvé. The new line will be located entirely within the boundaries of Saint Eustache’s agricultural zone. It will be held up mainly by reduced footprint lattice towers, designed to limit the loss of farmland. Four-legged towers will be used where the line changes directions.

Please refer to the information bulletin to consult a map of the selected route and substation site and a graph showing the types of towers that will be used.

Has Hydro-Québec studied other scenarios to meet the growing demand for electricity in the region?

Hydro-Québec studied three electric scenarios for meeting growing demand in the municipalities of Saint-Eustache, Deux-Montagnes and Sainte-Marthe-sur-le-Lac. The selected scenario will improve service quality for Hydro-Québec customers in the target area and support the region’s growth into 2060 and beyond.

The other scenarios were not optimal in terms of distribution system configuration.

Did Hydro-Québec consult with the public on this project?

Information and consultation activities were carried out between June 2015 and September 2017. Hydro-Québec set up many opportunities for dialogue with the region’s elected officials and administrators, representatives from various community organizations, and affected landowners and residents:

  • We organized meetings with elected officials and municipal administrators representing residents, as well as with regional and local organizations.
  • Information bulletins, mailings, advertorials in local newspapers, social media posts and press releases were used to disseminate information at each of the project’s key stages.
  • In March 2017, we held public consultation activities, including two open house sessions. Opinions were collected through an opinion submission form and online survey.
  • The public can obtain more information about the project by calling the Info project line (toll-free phone line).

Consultation activities were held with local organizations, affected landowners and residents living near the route variants. Through these exchanges, Hydro-Québec gained a better understanding of issues related to urban development, landscape, agricultural vitality, agritourism and other local realities.

After conducting technical and environmental studies, Hydro-Québec developed two line route variants (A and B) and two possible sites for the substation, which were presented to the local community to gather any concerns. The more favorably received variant was route B, to which Hydro-Québec made significant adjustments to take into account the community’s concerns, improve the line’s integration into the landscape and reduce the final project’s impact on the community as much as possible.

What did Hydro-Québec do to reduce the project’s impact on the region’s landscape and farmland?

To replace a tower rather than add a new one, route B was moved west of the Autodrome St-Eustache. This change also reduces the clearing of deciduous forest by 50% compared to the initial route B.

Hydro-Québec will be purchasing two properties on Boulevard Arthur-Sauvé and Chemin de la Rivière Nord to keep the future line far from neighboring homes and ensure that the route is as linear as possible. An increased proportion of reduced-footprint towers will be used so that the line will better integrate into the landscape.

Improvements to the alignment and distribution of towers will also help reduce the visual impact of the line for residents living on the roads that run along the Rivière du Chêne. In addition, selective clearing will be carried out in the ecological corridor of the Rivière du Chêne to preserve as much vegetation as possible.

Do the electric and magnetic fields (EMFs) emitted by power lines have any health impacts?

When public health authorities analyzed all the studies carried out in the past 30 years, they concluded that there are no harmful health effects associated with EMFs. As of 2014, the position of public health authorities on electric and magnetic fields emitted by power lines is the following:

[Translation from the original French] “There is no scientific basis for adopting an exposure limit to extremely low frequency (ELF) electric and magnetic fields (EMFs) that would be lower than established guidelines or standards. Therefore, the Committee is not proposing an exposure limit to magnetic fields, nor a minimal distance to be maintained from an exposure source, nor an exclusion zone for new constructions of certain facilities (hospitals, daycares, etc.) near high-voltage power lines (HVPL).”

Source : http://publications.msss.gouv.qc.ca/msss/document-001126/

In addition, the magnetic field levels recorded near the future line are very are low. Some electric household appliances give off more intense fields than those emitted by a high-voltage power line.

Will the line or substation be noisy?


Once substation construction is complete, the noise levels emitted by the substation will range between 35 dBA and 39 dBA at the property’s boundaries. These noise levels are below the criterion of 70 dBA (LAeq) set by the Ministère du Développement durable, de l’Environnement et la Lutte contre les changements climatiques (MDDELCC) in its briefing note 98-01 on noise. Furthermore, the city of Saint-Eustache’s regulation on noise (no 1496; 2015b) does not set any limit for noise on industrial properties.

Given the significant distance between the substation and the nearest homes—located south of Highway 640 (Sainte-Marthe-sur-le-Lac)—permanent residents should not be impacted by the noise from the substation, since it will not be perceptible from their homes.


A high-voltage line produces noise, primarily due to the corona effect around the conductors. This effect is produced by electric micro-discharges at rough points on a conductor’s surface. The noise can be described as a continuous hum combined with a light buzzing.

Under certain humidity and precipitation conditions such as rain, fog, wet snow and freezing rain, the noise may be louder. In the Montréal region, these conditions occur approximately 20% of the time.

The noise study conducted showed that the noise emitted by the 315-kV line will be in line with municipal (regulation 1496 regarding noise) and provincial (briefing note 98-01 of the MDDELCC) requirements regardless of weather conditions.

At the level of the homes closest to the planned right-of-way, the noise created by the new line will be below 40 dBA, regardless of weather conditions. In dry weather, the noise emitted by the line is 15 dBA to 25 dBA lower than the noise emitted when the conductors are wet. It will therefore not be audible. When the conductors are wet, the noise coming from the line may be audible. However, anticipated noise levels are below the current ambient noise perceived from the homes closest to the planned right-of-way.

What is the timeframe for construction?

The construction of the substation, which will take longer than the construction of the line, will begin in spring 2019, with commissioning slated for summer 2020. Construction of the supply line will extend from fall 2019 to summer 2020.

When construction begins, a project news bulletin with detailed information on the project will be sent to residents in the surrounding area. Relevant information is also available on the Web site.

What will be the project’s impact?

Most of the work for the project will be carried out on farm land. The impact of the construction of 14 towers will be compensated and mitigated in accordance with the compensation and mitigation measures set out in the Hydro-Québec–UPA Agreement on the Siting of Power Lines on Farms and in Woodlands [PDF 842 Kb].

During construction, Hydro-Québec will also make sure to limit disturbances (including noise) for landowners and residents living near the future line, to implement rigorous safety measures at public road crossings and to carry out site restoration after construction.