Cause and scope of oil spill at Prudhoe Bay remain a mystery

NORTH SLOPE: Multiple entities look into the leak of a pipeline containing oil-gas-water mix.

December 2, 2009 

The spill was from an 18-inch, three-phase common line carrying a mixture of crude oil, produced water and natural gas. The edge of the contamination is visible in the photo.

J. EBEL / ALASKA DEPARTMENT OF ENVIRONMENTAL CONSERVATION

More than 100 local, state, federal and oil industry employees have responded to a BP oil spill discovered early Sunday on Alaska's North Slope.

The spill covers about three-quarters of an acre. Cleanup supervisors have called in help from multiple agencies and have those on scene operating under intense safety measures as they begin to clear away the mess and investigate what happened.

Officials say they still don't know the basics: What caused the spill from the pipeline, which had been shut down weeks earlier because of ice plugs? How much oil leaked out onto the snow-covered tundra? All of that is being investigated, said spokesman Steve Rinehart of BP Exploration (Alaska) Inc.

A unified command team was formed to deal with the leak, which doesn't happen for minor spills, said Weld Royal, spokeswoman for the state Department of Environmental Conservation. The team includes representatives from BP, DEC, the U.S. Environmental Protection Agency and the North Slope Borough. As of Tuesday, 108 people were working on a response to the spill, including 75 on the Slope and 33 in Anchorage. DEC alone enlisted 27 employees.

The spill comes at a difficult time for BP, which is on probation after pleading guilty in 2007 to a misdemeanor violation of the federal Clean Water Act. That charge stemmed from a spill of more than 200,000 gallons of oil in 2006 from a corroded pipe. The corporation paid $20 million in fines and restitution and is in its third and final year of probation under a plea deal.

The circumstances of the latest spill are being watched by the federal probation office in Anchorage.

Mary Frances Barnes, BP's probation officer, said she could not say whether there would be repercussions.

"I am monitoring it, and it's too early to tell," Barnes said. "It's still in the investigative stage."

BP's Rinehart said he could not address the company's legal troubles. "No comment on any of that," he said.

The pipeline that leaked transported a mix of oil, natural gas and water from a drill pad to the Lisburne Processing Center, he said. There, the crude oil was separated and sent down a transit line.

The corrosion issues in 2006 were with transit lines that have since been replaced, Rinehart said.

The line now at issue was last inspected in 2008, and also was inspected in 2003 and 1998, Rinehart said. But he said BP wouldn't provide a copy of the inspection report.

"This is not information that we routinely share," he said. He said BP's inspections of welds and other key elements of the oil field infrastructure were "on schedule" but wouldn't discuss any specifics, including whether BP was dealing with a backlog.

"We have an active, aggressive inspection program that has ramped up steadily from roughly 30,000 in 2005 to 100,000 this year," Rinehart said.

Two or three weeks ago, BP stopped operating the line because of ice plugs that had formed in low-lying spots, Rinehart said. The line was still being checked daily. A worker making routine rounds spotted the leak at about 3 a.m. Sunday.

Some residual material was still in the line when, for reasons not yet known, it began to leak. By Monday the flow had slowed, and by Tuesday it had stopped, Rinehart said.

The hole that emitted the oil is not visible, and BP has not yet found it, he said.

The investigation and cleanup efforts are being done methodically with concern for worker safety, according to BP and the DEC.

An oily mist spewed from the pipeline and spread over about one-half acre. Crews began scooping up that contaminated snow Monday night. By Tuesday night, all 80 cubic yards of oil-misted snow had been hauled away.

But cleaning up the main spill area closer to the pipeline is a trickier proposition. Engineers were concerned the suspected ice plugs might cause pressure differences along the line, which could lead to unexpected movement of the pipe and pose a risk to workers.

The leaking pipe was strapped more securely to its pipe frame on Tuesday to keep it from moving, Royal of the DEC said. Still, cleanup crews are supposed to generally stay outside a 10-foot safety zone for now, she said.

Workers are building an ice pad to store equipment and supplies, including front-end loaders, generators and lights. There's less than an hour of daylight at Prudhoe Bay this time of year.

It's difficult to measure how much oil spilled until the cleanup is done, Royal said. One method uses a snow melting machine, which allows crews to isolate the oil from snow and ice. A snow melter is at the scene, she said.

The command team plans to conduct a briefing for reporters today.


Find Lisa Demer online at adn.com/contact/ldemer or call 257-4390.

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