A section of Enbridge's Line 21 pipeline from Norman Wells, N.W.T. to Zama, Alta., is due to be replaced starting in June, at an estimated cost of $53 million, pending approval from the National Energy Board.
Actual drilling would begin in August. The company expects to be finished by November.
New filings with the board show how Enbridge intends to drill a new section 100 metres below the Mackenzie River, about 10 kilometres from Fort Simpson.
The company plans to drive materials bound for the north shore to Hay River and barge them to the site from there. Materials bound for the south shore will be driven in along a temporary road.
The new pipeline segment will run for 2,500 metres before rejoining the existing pipeline south of the river.
The existing pipeline will remain in the ground after it is decommissioned.
Line 21 was shut down in November over concerns about the riverbank's stability.
Impact on Norman Wells oil field
Following that, Imperial Oil ramped down its production in the field, finally shutting in its facility entirely last week.
The company says it is continuing "surveillance and maintenance operations" for now, but won't say whether it will restart production once the pipeline is repaired. Spokesperson Lisa Schmidt would only say the company is "continuing to work with [Enbridge] on their plan to replace the pipeline at the Mackenzie River crossing."
An Enbridge spokesperson said the project "still requires regulatory and customer approval and ultimately, it's up to the National Energy Board as to whether it goes ahead."