The National Energy Board says its decisions and orders regarding the Trans Mountain pipeline expansion issued prior to last summer when a court overturned its approval will remain valid except where circumstances have changed.

The decision is in line with a request from the federal government-owned pipeline to restore its regulatory status in order for construction to resume during this building season.

Trans Mountain says it is reviewing the details of Friday's decision and will decide on processes and a construction schedule in the coming weeks.

The NEB, which invited comment on the issue from June 21 to July 9, says it may review any of its decisions or orders on its own, due to new information from Trans Mountain or in response to an application for review.

It says Trans Mountain must issue notices to landowners along the entire route, including those who were served previously, and publish notices in local newspapers.

The NEB says it will notify potentially affected Indigenous peoples of the detailed route approval process, adding those who have route concerns may file a statement of opposition requesting a review.

Before the Federal Court of Appeal decision last August, the NEB had approved more than 73 per cent of the detailed route and found that 64 of 98 pre-construction conditions had been fully satisfied, allowing Trans Mountain to start construction at the Westridge Marine Terminal and on certain temporary infrastructure sites and portions of the pipeline route.

The NEB reapproved the project in February after considering impacts on marine life and Ottawa gave final approval June 18 after completing consultations with Indigenous groups.