A "concerned individual" brought the problems to the board's attention, spokesman Darin Barter said Thursday. A probe began in December of last year.
"We're taking it seriously," he said. "The public can be assured that there are no imminent threats or issues that would compromise safety or the environment, and we will handle this in an appropriate way."
A report by Reuters said there are up to a dozen allegations that deal with the timeliness, quality and reporting of repairs on Alberta pipelines.
TransCanada was told of the NEB's review on Feb. 27, spokesman Davis Sheremata said in an emailed statement.
"Since receiving these allegations we do know that none posed either an immediate or long-term threat to the public or our assets. Nonetheless, each and every allegation we receive is taken seriously and investigated," Sheremata said, adding that many of the problems have already been raised internally and the company has investigated or is investigating them.
"We are working diligently to gather all of the relevant information to address each of these allegations for the NEB," he said. "We share the NEB's focus on protecting the safety of the public, our workers and the environment and we are working as quickly as possible on this process to provide information."
In 2012, a different whistleblower brought forward safety concerns to the NEB. The National Energy Board investigated those issues as part of an audit that had already been planned. It was rescheduled to take place earlier when those allegations were raised.
The audit's findings, released in February of 2014, highlighted some lapses in four of the nine areas that were examined.
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