Enbridge Inc. said on Saturday it did not know when it would restart a U.S. oil pipeline that ruptured and leaked crude oil in Wisconsin a day earlier.
The Calgary, Alberta-based pipeline operator said it had not yet determined the cause of the oil spill from the 318,000 barrel-a-day pipeline known as Line 14. The company added it returned Lines 6A and 61 to service early on Saturday, but had not determined when it could restart Line 13.
"(The U.S. Transportation Department's Pipeline and Hazardous Materials Safety Administration) is investigating the cause of the Enbridge crude oil pipeline failure in Wisconsin," spokesman Damon Hill said in an e-mail on Saturday, adding that an inspector had been sent to the location of the pipeline failure.
Line 14 is one of four lines that ship mainly Canadian crude via Lakehead, a 2.5 million barrel-per-day network that is the principal route for the country's exports.
The news will not help Enbridge build public trust in its network, which has come under scrutiny following several high-profile incidents, including a spill in Alberta last month and the massive leak in Michigan two years ago.
Just weeks ago, the U.S. National Transportation Safety Board delivered a scathing report of Enbridge's handling of the July 2010 rupture of its Line 6B near Marshall, Michigan, which led to more than 20,000 barrels of crude leaking into the Kalamazoo River.
The NTSB said it found a complete breakdown of company safety measures, and that Enbridge employees performed like "Keystone Kops" trying to contain it. The rupture went undetected for 17 hours.
U.S. pipeline regulators fined it $3.7-million (U.S.) for the spill, their largest ever penalty.
The incidents have caused furor just as the company seeks approval for its $6-billion Northern Gateway pipeline to Canada's West Coast from Alberta amid staunch opposition from environmental groups and native communities that warn against oil spills on land and in coastal waters.
Enbridge said Line 14 was a 24-inch diameter pipe that was installed in 1998, making it a relatively new line.
In most cases, smaller pipeline leaks can be repaired quickly allowing operations to resume pumping, although regulators may require significant work if they find any cause for alarm. Following the leak two years ago, the line was shut for over two months.
No injury was reported on Friday at the line, which is near Grand Marsh, Wisconsin, Enbridge said.