Hugh Harden, vice-president of operations and engineering, said updated estimates were that less than five barrels, or about 800 litres, of oil leaked from the line breach discovered Wednesday about 40 kilometres south of Merritt, B.C., where the line follows the Coquihalla Highway through the Cascade Mountains.
"It's quite a minor release. No real permanent impact on the environment — there was no wildlife harmed and the public was minimally impacted," Harden said as crews completed the clean-up of the spill.
The company hoped to have the approval of the National Energy Board to restart the flow by Friday afternoon.
The leak was discovered around 10 a.m. Wednesday by a crew doing routine maintenance work.
"One of our crew members... noticed a small pooling of what appeared to be oil," company spokesman Andy Galarnyk said.
The pipeline was shut down and a crew dispatched, he said. All regulatory agencies were notified, and by late Wednesday, the National Energy Board had observers on site and the repair was underway.
The energy board said the public and the environment were not at risk.
A Kinder Morgan oil spill response team of two dozen people was at the scene within a couple of hours, but Galarnyk said it is unclear how long oil had been leaking.
"My understanding was that the control centre did not receive an alarm, so in terms of whether it was a very slow leak that just bubbled to the surface, that's part of the investigation that's underway at this point," he said.
The federal energy board said the company is responsible for clean-up and site remediation.
"There is no immediate safety concern for local residents and precautions are being taken to ensure continued public safety," the watchdog agency said in a statement.
B.C. Environment Minister Mary Polak did not respond to a request for comment.
The province recently announced its opposition to the Northern Gateway oil pipeline proposal, due in part to concerns about a spill. The province has not taken a position on Kinder Morgan's proposed expansion.
The Trans Mountain line ships 300,000 barrels per day of various petroleum products from Alberta to the B.C. Lower Mainland and Washington State.
Kinder Morgan expects to file an application with the energy watchdog later this year to almost triple the capacity, and include shipment of diluted bitumen, a heavier, molasses-like oil that critics claim is harder to clean up.
The proposal is controversial, and critics were quick to seize upon the spill.
Sarah Cox, the head of Sierra Club B.C., said the leak — however small — highlights the dangers of oil pipelines.
"We find it alarming that it took them a few days to detect the leak," she said.
The expansion would mean more oil coursing through the pipelines on land, and an additional 400 oil tankers a year plying the B.C. coast.
"Where oil moves, it spills," Cox said. "It's only a matter of time before there is a bigger spill."
Since 2005 there have been four ruptures on the Trans Mountain line, she said, including a 2007 construction accident that rained down 230,000 litres of oil on a Burnaby neighbourhood.
Ben West, of the group ForestEthics, said the incident serves as a reminder that "it's not a matter of if spills will happen, but when they will happen."
The spill occurred days before a federal panel begins hearing final arguments in its review of the Northern Gateway pipeline, another controversial proposal that would transport oil from Alberta to a tanker port in Kitimat, B.C.
Harden said the company will conduct its own investigation to determine how long the pipe had been leaking. The rupture is related to damage to the pipe when it was constructed more than five decades ago, he said, and is not related to the age of the pipe.
In the meantime, Harden said ongoing inspections continue.
"I think it's a demonstration that our inspection process is actually working, and finding these defects before they become major," he said. "But at the end of the day, no release is acceptable for our company."
- By Dene Moore in Vancouver