ANCHORAGE - The operator of the trans-Alaska pipeline said Wednesday it is assessing how to safely remove crude oil from a damaged storage tank as it works to restart the pipeline after a spill at a pump station.
Up to several thousand barrels of crude spilled from the pipeline Tuesday and into the tank, which overflowed into a containment area. The containment area, a yard lined with an impermeable barrier and surrounded by a berm, apparently captured all the oil.
Main line power remains off at the site about 100 miles south of Fairbanks, as response officials assess whether vapors rising from the oil could be ignited.
Michelle Egan, a spokeswoman for pipeline operator Alyeska Pipeline Service Co., said she could not predict when the pipeline might be restarted.
"It's going to take as long as we need to do it correctly and safely," she said.
Oil companies operating on Alaska's North Slope were ordered to reduce production to 16 percent of their regular output. Alyeska has storage capacity for that reduced North Slope oil production through mid-Thursday, Egan said, and it's possible pumps on the main pipeline could be restored by then, allowing oil to flow at regular levels.
The 800-mile trans-Alaska pipeline carries crude oil from Prudhoe Bay to Valdez, where tankers pick it up and deliver it to refineries.
Analysts expected the temporary shutdown to have a minimal effect on oil prices and gasoline supplies.
While the shutdown may have been a "supportive factor" in the 4-percent rise in crude oil prices Wednesday, "I don't think it was an overwhelming factor," said Phil Flynn, a senior market analyst for PFGBest. "The market is pretty well supplied right now, and we probably could miss it for a short time."
Last month, the 48-inch diameter pipeline moved an average of 645,113 barrels per day - about 12 percent of the estimated 5.5 million barrels a day that are produced domestically.
Tuesday's spill occurred during a planned pipeline shutdown and testing of the pump station's fire command system. Power failed, and a vent in the main pipeline opened, as it is designed to do, to prevent pressure from building too high in the main line.
Oil flowed into a partially filled 2.3-million-gallon tank. However, the tank filled, and oil spilled through vents near the top of the tank and into the containment area.
Tom DeRuyter, on-scene spill coordinator for the Alaska Department of Environmental Conservation, said Wednesday the tank was damaged and deformities could be seen near its top.
Alyeska, he said, has assembled a team to assess how oil can be safely drawn down from the tank. A second team will assess how power can be restored to the pump station, which will allow cleanup to begin.
The state is putting no pressure on the company to begin the cleanup, since all the spilled oil seems to be contained on top of the liner.
"You don't want to get anybody hurt," DeRuyter said.
A primary hazard is the heavier-than-air vapor rising from the spilled crude. Vapors can ignite, explode, and spark a fire back to their source.
"The stuff that makes gasoline explosive is the stuff that makes crude oil explosive," DeRuyter said.
Vapors tend to hang over the oil but can be spread by wind. Alyeska is monitoring air to detect if gas has traveled beyond the tank farm.
Associated Press Writer Becky Bohrer in Juneau contributed to this report.