State, BP investigate cause of latest Prudhoe Bay oil spill

PAD SPRAYED: The 6-inch pipe carried oil, water and natural gas.

December 22, 2009 

A new spill has occurred at the Prudhoe Bay oil field, the Department of Environmental Conservation said Tuesday.

The spill was discovered Monday by a BP oil field operator doing a routine inspection at a drill site. It was coming from a 6-inch pipeline carrying a mixture of oil, water and natural gas, officials said.

BP spokesman Steve Rinehart said the break occurred where the production line left the well house.

"That break triggered the automatic shut-off valve of the well," he said.

The force of the release destroyed the back of the well house and blew open its front doors. When the pipe separated, it misted the surrounding area.

The DEC said about 17,000 square feet of the well's gravel pad was sprayed with oil, as well as an undetermined area of tundra.

The cause and amount of the spill were not immediately known.

Rinehart said it appears to be a small spill "because it happened and ended quickly."

A BP spill response team was sent Monday to delineate the contaminated area, state officials said. Two DEC staffers who were in Prudhoe Bay also have been sent to the well pad at Drill Site 6 to evaluate the spill. Two more DEC responders were on the way Tuesday.

DEC said 38 cubic yards of contaminated snow had been removed. More contaminated snow was stockpiled at the site and was awaiting transport Tuesday afternoon to a disposal facility.

BP operates Prudhoe Bay, North America's largest oil field.

Last month, one of the North Slope's biggest spills -- 46,000 gallons of oil, water and natural gas -- was reported at the Lisburne oil field, another BP-operated site. That spill occurred when an 18-inch pipeline split on Nov. 29.

Officials believe ice plugged up the line and likely caused a 2-foot-long split at the bottom of the pipe, allowing oil and water to spray out across a three-quarter-acre of tundra. Most of the oil and water congealed in a large pile under the pipe.

Cleanup involved bringing in steaming equipment to loosen the frozen material, loading it into buckets and totes and taking it to another area where it was being melted and measured.

State officials say the Nov. 29 spill was one of the worst by volume since the March 2006 spill of more than 200,000 gallons of crude at Prudhoe Bay -- the biggest spill ever on the North Slope.

BP is on probation for the 2006 spill after pleading to a misdemeanor conviction and paying $20 million in fines and restitution. That spill was blamed on corrosion in a pipeline. The company acknowledged at the time that its corrosion prevention program was not doing enough to keep pipes from corroding in the aging Prudhoe field.

BP denied allegations from prosecutors that a culture of cost-cutting was hurting the quality of maintenance on the network of pipelines at Prudhoe Bay.

"We maintain high standards of safety and operational integrity," Rinehart said when asked about the most recent spill.

BP manages the Prudhoe Bay field on behalf of itself and production partners, Exxon Mobil Corp., Conoco Phillips and Chevron USA Inc.

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