Frequently asked questions
Why was Hertel substation chosen as the starting point for the line?
Hertel substation is a robust facility, connected to the main 735-kV transmission system, which has enough space to fit the new equipment required to convert alternating current to direct current. All the new equipment will be installed on Hydro-Québec property at Hertel substation, located on Chemin Lafrenière, in La Prairie.
Why an underground line?
Hydro-Québec carries out studies for all its generation (generating stations) and transmission (lines and substations) projects. These studies simultaneously examine environmental, social, technical and economic criteria. With all these aspects considered, transmission projects usually call for the construction of overhead lines.
However, with the Hertel–New York interconnection, the geological conditions of the study area, the technology selected as well as its reasonable cost allows for the simple undergrounding of the line over a long distance, without the addition of other electrical equipment on the ground.
How does Hydro-Québec determine the route for an underground line?
In an underground line project, although environmental considerations are always taken into account, the line routing criteria have mainly to do with technical factors (underground space, presence of other infrastructure, clearance, etc.). The environmental impacts are mostly related to the construction work.
First, the environmental experts conduct a brief survey of the study area to determine corridors that would be suitable for the installation of the underground line. Once these corridors are determined, potential line routes can be studied.
In developing the potential routes, Hydro-Québec applies the following criteria:
- Run the line along an existing linear axis (road, railway, etc.) to limit impacts on property
- Ensure easy access to the jobsite to reduce inconvenience
- Preserve woodlands wherever possible
- Limit the impacts of construction on local residents
Will the line be buried directly in the ground?
The line will be buried directly into a 1-metre wide trench, at a depth of approximately 1.5 metres.
The construction methods used will allow us to bypass obstacles (e.g., streams, drainage systems) by using specific techniques, such as directional drilling.
Will there be restrictions on land use after the line has been commissioned?
Once the line is commissioned, traffic can resume in the right-of-way and famland can be cultivated again.
What is direct current?
Direct current is unidirectional, which means the electrons always move in the same direction. A good example is a battery, where a chemical reaction triggers a movement of electrons in one direction inside the conductor: from the negative to the positive terminal of the battery. Alternating current is when electrons move back and forth.
The technology used to transmit direct current is not the most common. However, in projects such as this one, it can be advantageous for transmitting electricity over long distances or connecting systems that aren’t synchronized.
How are the concerns expressed during public consultation activities integrated?
The concerns expressed are integrated to the studies and analyses under way and will improve the selected route.
How can citizens submit their questions or concerns about the project?
Questions or concerns can be submitted by calling the Info-project line at 1 877 653-1139 or by writing to firstname.lastname@example.org.
Does an underground direct current line create electric and magnetic fields (EMFs)?
EMFs generated by direct current are considered static: their intensity and direction do not vary every second.
Static electric fields
Static electric fields exist in nature. They can fluctuate considerably with the vagaries of nature—increasing in storms and diminishing in fine weather. In addition, a powerful electric field is required to keep the cells of living organisms alive.
Underground direct-current lines do not generate electric fields. Each conductor is covered with insulation and a metal sheath that completely blocks the electric field.
Static magnetic fields
The Earth is surrounded by a permanent static magnetic field that can be detected with a compass. This magnetic field is generated by continuous electric currents produced by the movement of molten metal in the Earth’s core.
The Earth’s magnetic field can be locally disturbed by large metal structures, such as buildings or transportation vehicles.
Operation of the line will alter the Earth’s magnetic field over several metres on either side of the line. This will diminish very rapidly, however, and maximum intensity of the magnetic field will not exceed normal values found elsewhere on the planet.
Effets des champs électriques et magnétiques statiques sur la santé
There are no known harmful effects associated with exposure to low-intensity static magnetic fields such as the magnetic field of the Earth or those measured near DC power lines.
The limit recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for exposure to static magnetic fields is 400,000 µT (continuous exposure for the general population). On the basis of the project configuration, the magnetic field emissions of the DC line will not exceed 20 µT.