Toulnustouc hydroelectric power project

VINCI Construction Grands Projets was mandated by Hydro-Québec to build the Toulnustouc hydroelectric power plant. The project includes excavation work, heavy engineering concreting, electricity, and architecture.


The project is located approximately 1,000 kilometres north of Montreal, on the north shore of the St. Lawrence River in the Côte-Nord administrative region. Excavation work includes the discharge channel, the concreting includes the power plant, and the installation of the steel framework of the plant’s superstructure includes architectural work for the plant. In addition, heavy engineering includes the design, supply and installation of the overhead crane, draft tubes, monorail and penstock shielding.

Technical overview

This project is special due to various constraints. Weather conditions were harsh (the average temperature in January was minus 23°C). During the concrete work throughout the winter, we installed wood-frame shelters and oil heaters in order to maintain temperatures at a minimum of 10°C during the curing period. Added to this constraint was the isolated site location, which made the provision of materials difficult, all under a very tight schedule.
The project’s geological conditions were characterised by a mountain interspersed by numerous continuous cleavage planes, often very close to one another, poorly crystallised and welded, with almost vertical dips and a slope towards the excavation interior.
Construction of the 1.2-kilometre long river discharge channel includes excavation of 93,000 m3 of overburden and 67,000 m3 of rock. Additionally, 35,000 m3 of stone was placed on geotextile membrane to stabilise the slopes and the bottom of the discharge channel.
And from an environmental standpoint, we set up a wastewater catch basin prior to discharge into the river.

The Toulnustouc hydroelectric plant has an average annual production rate of 2,660 GW/h. Equipped with two generating units, the plant will provide a flow of 350 m3/s and an installed capacity of 526 megawatts.


The Toulnustouc hydroelectric plant was inaugurated on August 18, 2005, north of Baie-Comeau. Premier Jean Charest and the CEO of Hydro-Québec, Thierry Vandal, took part in the ceremony.
With an expected capacity of 526 megawatts, the plant produces 2,660 GW/h annually.
This hydroelectric plant produces electricity using water flow as the driving force.
Hydroelectric plants produce approximately a quarter of the planet’s electricity output. With its access to abundant water reserves, Hydro-Québec produces almost all of its electricity using water. This means its hydroelectric plants produce energy while helping to reduce greenhouse gas emissions.

Project participants


Project management

Key figures

Implementation dates
September 2002 to July 2005

455,000 m3

24,620 m3

Steel reinforcement
1,600 t

Hydroelectric project