Electrical transmission lines are very widely used to transmit high-frequency signals over long or short distances with minimum power loss. One familiar example is the down lead from a TV or radio aerial to the receiver. Transmission lines are sets of wires, called conductors, that carry electric power from generating plants to the substations that deliver power to customers. At numerous substations on the transmission system, transformers step down the power to a lower voltage and deliver it to distribution lines.
The materials are transported to each tower site. The parts are carefully distributed and the construction materials needed for each tower are left directly on the site where the tower will be built.
The construction team begins by clearing the project area. The workers carefully set aside the topsoil, which will be reused. During excavation for the foundations that will stabilize the tower, pumping may be required to remove the water and dry the site. The size of the excavation site depends on the type of soil and the type of tower. Anchors depend on the type of tower installed
The project area must be adapted to the type of tower that will be built. Because this step requires the use of heavy machinery, all the necessary precautions are taken. For example, in wetlands, steel plates are sometimes placed on the ground to accommodate the machinery and preserve the environment.
Once the tower is assembled on the ground, it is raised using a telescopic crane. The raising of a tower in the Matapédia region.
The conductors are unreeled and strung section by section from tower to tower. There is a cable drum with a reel and tensioner at one end and a puller and take-up reel at the other. In this step, workers make sure that the voltage levels in the conductors are within acceptable limits and that there is adequate clearance between the ground and the cables. Our practices are adapted to account for sensitive and special environments.
Counterpoise wires are installed to ground each tower and protect the line from lightning. A counterpoise wire is actually an underground conductor that ensures the electrical connection between some or all of the line’s towers and the ground.
When minor excavation and filling work is required, mitigation measures are implemented. For example, counterpoise wires are not installed near wetlands to avoid heavy machinery traffic and excavation.
Once a project is complete, Hydro-Québec always restores the site by:
- removing all the debris and waste
- levelling the ground
- dismantling the temporary accesses (roads, bridges, culverts)
- repairing any infrastructure that was damaged during the work (roads, fences, etc.)
- seeding or planting whenever necessary based on the characteristics of the site (shoreline, wetland, etc.)
When the work is carried out on private land, Hydro-Québec meets with the landowners to ensure they are satisfied with the restoration. It takes responsibility for any damages that may have occurred as part of the work and compensates the landowners according to project regulations.