WASHINGTON (Reuters) - Enbridge's massive oil pipeline spill in Michigan in 2010 was caused by a complete breakdown of company safety measures, while its employees performed like "Keystone Kops" trying to contain it, the National Transportation Safety Board said on Tuesday.
The rupture of Enbridge's pipeline spilled more than 20,000 barrels of heavy crude into Michigan's Kalamazoo River in July, 2010.
"This investigation identified a complete breakdown of safety at Enbridge," NTSB Chairman Deborah Hersman said in a statement.
"Their employees performed like Keystone Kops and failed to recognize their pipeline had ruptured and continued to pump crude into the environment."
The NTSB said the main failure of the pipeline was due to multiple small "corrosion-fatigue cracks" that grew over time to create a breach in the pipe over 80 inches long.
The rupture, which spilled crude unchecked for 17 hours, has raised concern about pipeline safety in North America, including Enbridge's planned oilsands pipeline from Alberta to the British Columbia coast, as well as TransCanada's Keystone pipeline in the United States.
"How can we trust Enbridge to build two pipelines safely across nearly 800 rivers and streams in Alberta and British Columbia?" asked Nikki Skuce at ForestEthics Advocacy, an environmental group. "This company cannot be trusted with our wild salmon rivers."
Enbridge said in a statement it believed its personnel were trying to do the "right thing" at the time.
"As with most such incidents, a series of unfortunate events and circumstances resulted in an outcome no one wanted," said Patrick Daniel, Enbridge's chief executive.
The U.S. pipeline regulator in early July slapped a $3.7 million fine on Enbridge, the largest it has ever imposed.
The Pipeline and Hazardous Materials Safety Administration, or PHMSA, said its probe uncovered two dozen regulation violations related to the leak on Enbridge's Line 6B near the town of Marshall, about mid-way between Detroit and Lake Michigan.
The accident shut down the pipeline for more than two months and spawned a massive cleanup that the company has estimated will cost more than $700 million.
Following the Enbridge spill and other major pipeline accidents, the Transportation Department enhanced its oversight last year.
Last December, Congress passed a pipeline safety bill that raised maximum fines and authorized an increase in the number of pipeline inspectors.
NTSB said their investigation found that Enbridge failed to accurately assess the integrity of the pipeline, including analyzing cracks that required repair.
"Following the first alarm, Enbridge controllers restarted Line 6B twice, pumping an additional 683,000 gallons of crude oil, or 81 percent of the total amount spilled, through the ruptured pipeline," the agency said.
The NTSB said there was a "culture of deviance" at Enbridge where personnel were not adhering to approved procedures and protocols.
"Enbridge knew for years that this section of the pipeline was vulnerable yet they didn't act on that information," said Chairman Hersman.
The NTSB also cited PHSMA, the pipeline regulator, for weak oversight and said it reiterated one recommendation to PHMSA and issued 17 new safety recommendations as a result of the probe.
The Keystone Kops slapstick comedies were popular in Hollywood's silent-film era and featured an incompetent police force fighting crime.
Reporting by Russ Blinch and Timothy Gardner; Editing by David Gregorio and Bob Burgdorfer