The Crown corporation behind the Trans Mountain pipeline expansion says it may not complete the project before December 2024 if a regulator does not approve its request for a route deviation.

Trans Mountain Corp. says the new time frame is a worst-case scenario that could add close to $86 million in cost overruns to the final project price tag. 

Trans Mountain Corp. had hoped to have the pipeline in service in early 2024 but has run into engineering difficulties related to the drilling of a tunnel in B.C.

It wants to alter the route slightly for a 1.3-kilometre stretch of pipe, as well as the construction method.

But it faces opposition from the Stk’emlupsemc te Secwepemc Nation, whose traditional territory the pipeline crosses and who had agreed to the originally proposed route and construction method.

The Canada Energy Regulator will hear arguments from both Trans Mountain and the First Nation at a hearing in Calgary next week.