The project is needed to ensure the reliability of electricity service in the coming years.
The current 49-kV power system was designed to handle less electricity demand than it is experiencing today. In fact, the maximum capacity of the power system has been exceeded. This situation makes the power system more vulnerable and increases the risk of equipment failures and major outages.
In addition, the wooden H-frames supporting the current system are aging. Note that the most recent significant outages in the region (in December 2022 and December 2023) were caused by trees falling on the 49-kV lines.
In brief, the conversion of the power system to 120 kV is designed to increase the system’s capacity so that it can meet electricity needs in the region for the next 100 years. At the same time, the new facilities will prevent equipment failures and major outages on the transmission system.
When Hydro‑Quebec develops a project, the goal is to take all these elements into account find the best balance possible. It’s a complex task, but the pursuit of this balance remains at the heart of the decisions we make throughout the project.
Some technical constraints must be respected. For example, a substation must be built on ground with sufficient bearing capacity.
Cost is also a component we consider, since the cost of Hydro‑Québec’s projects affect electricity rates.
As for environmental considerations, the project is guided by an environmental approach. Environment experts are included in the project team from the outset. The first step is to identify any major environmental constraints, sensitive elements or other environmental elements on the territory (e.g., wetlands, valued landscapes, protected farmland). The team assesses what can be done to avoid these elements or reduce the project’s impact on them as much as possible.
Finally, through our public consultation process, we collect a wealth of information (comments, concerns, ideas, advanced knowledge of the area) that also influences project development.
Several information and discussion activities were held in 2024, as part of a preliminary consultation on the project, including two meetings with the area’s residents.
Various means were used to inform the public about these meetings. For example, invitations were sent by mail, ads were placed in local papers and newsletters were sent out.
The best way to directly receive invitations to any future activities for the public is to sign up for the project newsletter (see the box below, at the very bottom).
To learn more about the activities carried out in 2024 and the comments we gathered, please refer to the review of the preliminary consultation phase, available under the Public consultation tab.
The first element to consider is the distribution system, which will connect the substation to customers (homes, schools, businesses, industries, etc.). As a general rule, the closer a substation is to the customers it serves, the better the electricity service will be (fewer outages, less voltage loss), making this an important parameter.
The host area chosen for the substation must also be close to roads, along which we can build the distribution system. Hydro‑Québec tries to avoid building distribution lines on both sides of a road, to reduce the impact on the landscape.
Finally, the location chosen will be the one with the least impact. This means we will select the site for which the presence of the substation, its 120-kV supply line and the distribution system built to serve customers have the smallest impact on the host environment.
Moving the substation farther away from the zone it will serve would have a negative impact on service quality for all the customers in the area.
The farther we move the substation from the customers it serves, the longer the distribution lines would have to be to supply the towns of Sutton and Lac‑Brome. The longer the distribution lines, the more vulnerable the power system is to outages; a negative impact that would remain present for the entire lifespan of the infrastructure (the next 100 years). This is an important element that Hydro-Québec must consider in developing the project.
In addition, when we build distribution lines, we need to clear the areas alongside roads (over a width of 6.5 to 8.5 meters on either side of a three-phase power line), which can have a significant impact on the landscape.
Moving the substation farther away from the customers it will serve also has other negative impacts on the reliability of the power system. For example, it increases voltage variations. These variations impact the capability of the power system to supply certain loads safely (which can cause damage to electronics, for example). To counter this phenomenon, several major pieces of equipment would be required.
Below is a picture of a distribution line corridor. Clearing may be required for up to 8.5 meters on either side of the line.
The surface area of the fenced enclosure around the substation equipment will be about 110 m by 150 m.
If we include the drainage ditches, retention basin and access road, the total surface area required for the substation is about 200 m by 200 m.
Hydro‑Québec is looking for a larger site, about 250 m by 250 m, to ensure we will have room to set up vegetation screens around the substation. The extra distance will also help reduce the impact of the noise coming from the substation.
Below is an aerial view of Achigan substation (in French only). It’s setup and size are similar to those planned for Brome substation.
