Third link: drilling in the river this summer

Third link: drilling in the river this summer< /p> UPDATE DAY

Preliminary work for the third link will take place this summer with the completion of eight boreholes that will probe the seabed of the St. Lawrence River up to 80 meters deep. 

Transport Minister Francois Bonnardel and Third Link Project Office Director Dale Robinson confirmed this to the Journal yesterday. 

< p>“It shows that we are doing the work. We want to carry out this project which is important for Lévis and the people of Quebec. This is an extremely serious first step, to seek out the scientific and technical data that will lead us to make the right decisions for the future,” said the Minister.

A barge specially equipped to carry out geotechnical surveys is moored in the center of the river, between Quebec and Lévis, near the crossing sector. The cores that will be taken from the bottom of the river will make it possible to learn more about the nature of the soil in which the future tunnel will be dug. 

In the rock < /p>

Already, 20 boreholes have been drilled as part of preliminary work, 13 on the North Shore, five on the South Shore and two in the St. Lawrence River.

“Preliminary data indicate that it is rock in which the tunnel boring machine will be placed”, confirmed Mr. Robinson.  

Some experts were concerned about the possible presence of a very deep and filled underwater gorge sediment at the bottom of the river, on the route. According to Mr. Robinson, this has not been observed until now.

But if the tunnel boring machine were to encounter unconsolidated deposits, this would not jeopardize the project, according to him. “Whether it's sediment or rock, we are able to make the necessary design. ” 

The depth of the rock brings additional constraints, for the slopes of the tunnel, underlines the engineer.

“The geological aspect between Quebec and Lévis means that technically, it is a project that requires advanced expertise. »

These eight new boreholes will “conclude this crucial phase of the project”, say officials.

At this point, the river has a depth that varies from 30 to 55 meters. The boreholes will probe 65 and 80 meters below seabed level. They will take place from July to October. 

Day and night 

The barge was specially adapted for this work. A team of 15 to 20 workers work there. It has 75 m high anchor piles and suitable lifting towers. Drilling is done day and night.

“To my knowledge, this type of drilling has never been done. It's still quite special, at the technical level, it's something important, “said Dale Robinson. 

The Ministry of Transport is delaying in presenting the studies on the third link.

One of them, dating from 2020 and presenting the potential effects of the project on land use planning, remains inaccessible to the public.

Minister Bonnardel reiterates that he will make public all the elements of the project “in due time”. He promises an annual update in the spring. 

As for the mayor of Quebec, Bruno Marchand, who is asking for more information before taking a position on the project, the minister affirms that “the challenge is to reassure”. He promises to “respond to concerns”.  

20 boreholes already drilled

  • 13 on the South Shore
  • 5 on the North Shore
  • 2 in the river

8 drillings to come

  • In the river, at a depth between 65 and 80 m in the seabed, from July to October 2022

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