The expansion of a Canadian government-owned oil pipeline from Alberta to the Pacific Coast could be delayed by nine months if regulators don’t approve a route alteration, the project’s builder said in a regulatory filing.

The expanded Trans Mountain might not be completed before December 2024 in a “worst-case” scenario where regulators force the company to stick with a plan to tunnel under land that’s important to a local indigenous community, according to a filing with the Canada Energy Regulator. The earliest the tunneling could be completed is by April, the company said.

The Trans Mountain expansion has already faced repeated delays since it began more than a decade ago, causing the price tag to more than quadruple to $30.9 billion (US$22.8 billion). The project — which would more than triple the volume of crude Alberta’s producers can pipe to the West Coast to 890,000 barrels a day — was due to start operations by the end of the first quarter.

Trans Mountain is seeking approval for a route change in British Columbia that would scrap the tunneling project in favor of an alternative that’s more intrusive — but cheaper — after running into engineering challenges. But the local Stk’emlúpsemc te Secwépemc Nation, or SSN, opposes the change, saying the change would do “irreparable harm” to its cultural and spiritual rights. The regulator has scheduled public hearings on the proposed change for this month.

Trans Mountain didn’t immediately respond to an email seeking comment. 

Prime Minister Justin Trudeau’s government bought the project from Kinder Morgan in 2018 after the company threatened to pull the plug on it amid fierce opposition in British Columbia.