ANCHORAGE - The trans-Alaska oil pipeline was temporarily taken off line Tuesday after workers found a spill of as many as 500 gallons of crude oil.
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The cause turned out to be a loose fitting on a pipe, which was quickly tightened. The pipeline's operator, the Alyeska Pipeline Service Co., began the process of restarting the pipeline about six hours after shutdown, spokesman Mike Heatwole said.
The crude oil spilled from an aboveground section of the pipeline at a remote gate in the Brooks Range in northern Alaska. It was discovered Tuesday morning during routine inspections.
The cause of the spill south of Atigun Pass - at 4,739 feet the highest elevation of the 800-mile pipeline - was initially reported by state officials to have been caused by a failed weld on a threaded O-ring fitting on a bypass line.
The pipeline was carrying more than 800,000 barrels of oil when it was shut down, Heatwole said. He added that there was plenty of oil stockpiled at the marine terminal in Valdez and that tankers could continue to be loaded with oil for days with no disruption in supply.
The Valdez terminal has a storage capacity of about 7 million barrels, and was between 75 percent and 85 percent full Tuesday.
Heatwole said Alyeska workers discovered the leak at 8:20 a.m. in a 6-inch line that connects to the pipeline. The pipeline was shut down 15 minutes later, he said.
The oil that spilled covered about a 25-foot radius and spilled on to gravel. It did not reach the tundra, state officials said.
Alyeska asked BP to cut its production by about half so less oil would be flowing down the pipeline, BP spokesman Daren Beaudo said.
BP operates Prudhoe Bay on behalf of itself and other owners. BP had been asked to curb production numerous times before, Beaudo said.
Last November, the amount of oil flowing through the pipeline was intentionally slowed because of high winds in Valdez. In August, BP ordered a partial shutdown of the pipeline after discovering a leak in a corroded transit pipe at Prudhoe Bay. Production remained curtailed for weeks until repairs could be made.
In fact, the pipeline has been shut down dozens of times since startup. The reasons are varied, ranging from routine maintenance to vandalism to earthquakes. On Oct. 4, 2001, a man shot the pipeline, causing a 300,000 gallon spill and a shutdown that lasted more than 60 hours. On Nov. 3, 2002, a powerful earthquake forced the shutdown of the pipeline for more than 66 hours.