"The 12-km route will see the pipe, which ranges in diameter from 2.2 to 3.2 metres, tunnelled for two kilometres".

They have not decided over the tunnelling technology yet, writes Tricity news.

https://www.tricitynews.com/local-news/metro-vancouvers-mega-water-main-dig-through-coquitlam-due-to-start-in-2022-3932181