ANCHORAGE - The state has asked federal regulators to step in and help investigate the rupture of a high-pressure natural gas pipeline at Prudhoe Bay.
The Sept. 29 rupture broke apart the steel pipe and flung a piece of metal across the tundra in the nation's largest oil field. No one was hurt.
The state Petroleum Systems Integrity Office has begun an investigation.
The agency has asked a federal agency, the Pipeline and Hazardous Materials Safety Administration, to assist.
"The state's in charge of the investigation. We're supporting them," said Dennis Hinnah, who heads the pipeline administration's Anchorage office.
The pipeline administration began to ramp up its Alaska work following leaks from corroded, BP-operated pipelines in 2006. Ultimately, those incidents led to BP's Alaska subsidiary to plead guilty to a federal misdemeanor pollution crime. The company was put on probation for three years and fined $20 million in penalties.
Since the spills, the pipeline administration has ordered BP to improve pipeline monitoring and upkeep. BP is required to file monthly status reports. The cause of the last month's pipeline rupture remains undisclosed.
The pipeline carried natural gas to a well pad for injection underground. When the pipe ruptured, safety systems shut down the flow of gas automatically, BP spokesman Steve Rinehart said.
The rupture forced the shutdown of some wells producing about 5,000 barrels a day. That's less than 1 percent of total North Slope production.