Small crack in pipeline may have delayed detection of spill off California coast

Video of the ruptured pipeline that spilled tens of thousands of litres of crude oil off Southern California shows a thin crack along the top of the pipe that could indicate a slow leak that initially was difficult to detect, experts said Thursday.

The 33-centimetre narrow gash could explain why signs of an oil slick were seen Friday night but the spill eluded detection by the pipeline operator until Saturday morning, said Richard Kuprewicz, a private pipeline accident investigator and consultant.

"My experience suggests this would be a darned hard leak to remotely determine quickly," Kuprewicz said. "An opening of this type, on a 27-kilometre underwater pipe is very hard to spot by remote indications. These crack-type releases are lower rate and can go for quite a while."

When pipes experience a catastrophic failure the breach typically is much bigger, what's referred to in the industry as a "fish mouth" rupture because it gapes wide like the mouth of a fish, he said.

Amplify Energy, a Houston-based company that owns and operates three offshore oil platforms and the pipeline south of Los Angeles, said it didn't know there had been a spill until its workers detected an oil sheen on the water Saturday at 8:09 a.m. local time. The cause of the spill is under investigation by numerous agencies as the cleanup continues along miles of shoreline on the Orange County coast south of the ports of Los Angeles and Long Beach, Calif.

That data shows the Rotterdam Express, a German-flagged ship nearly 305 metres long, was assigned to anchorage SF-3, the closest to where the pipeline ruptured off Huntington Beach. The ship made three unusual movements over two days that appear to put it over the pipeline.

The U.S. Coast Guard is investigating whether a ship's anchor might have hooked and bent the pipeline. Amplify has said publicly that no more than 477,000 litres leaked. But it also told federal investigators the total amount may only be 111,300 litres.