Hertel‑New York interconnection line


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Description of work

Underground line

The construction method selected for the underground line is the following. At the edge of the road, we will dig a trench measuring approximately 1 metre wide and a minimum of 1.2 metres deep. In this trench, we will build a concrete-encased duct bank which will house the two electric cables. We will also construct underground joint bays made of prefabricated concrete measuring about 3-m wide by 12-m long throughout the length of the line, at regular intervals of 1.5 km, depending on the obstacles encountered along the way.

Other construction methods will also be used based on the obstacles to cross (e.g., streams, railways or drainage systems), including specific techniques, such as directional drilling.

Underground line construction steps

Teams hired by Hydro‑Québec to carry out the work secure the site and install signage to ensure the safety of workers and road users.

The trench is excavated in the road right-of-way. The fill is carried to a specialized disposal site.

A concrete-encased duct is installed. It contains the conduits in which the line’s two electric cables will be inserted.

An underground prefabricated concrete joint bay is installed every 1.5 km along the route for the installation of cable joints. The ducts connect to these joint bays.

The cables are pulled and handled from the joint bays. A crane deposits the cable reel and guides the cable to the target duct. The cable junctions are made, the joint bays are filled with sand and then concrete is used to close it all in.

If the duct runs along a road right-of-way, the trench is filled with new material before the road surface is repaired, in line with requirements. If the duct runs through soil, the soil is piled and then put back in place once the work is complete. In this way, there are no residual impacts once the construction work is over!

Connection at the crossing point

Once the line crosses over from land to water, directional drilling will be used. At the Canada–U.S. border, the underwater cables from the U.S. partner will be pulled into the ducts of the borehole, where they will be protected at the bottom of the Rivière Richelieu.

Line operation

Equipment to be installed in each of the converters at the ends of the line, in Québec and New York, will allow us to detect and locate any electrical faults and correct them as quickly as possible. If the line is damaged, it will be de-energized instantly.

Addition of a converter at Hertel substation

The conversion equipment will be installed in a new 5,000-m2 building on Hydro‑Québec property.

The electrical equipment needed to connect the converter to the 735-kV system will be installed within the existing substation and planned expansion area.

Hertel substation, in La Prairie

Interactive map of work