This week's oil spill from the trans-Alaska pipeline totaled about 5,000 barrels, making it the third-largest spill ever from the 800-mile pipeline.
The new estimate of the spill size Friday compares with earlier estimates from the company that runs the pipeline that "up to several thousand" barrels spilled.
That company, Alyeska Pipeline Service Co., restarted the pipeline just before 5 p.m. Friday. Alyeska kept the pipeline shut down for more than three days after discovering the spill at Pump Station 9 near Delta Junction on Tuesday.
The shutdown forced North Slope oil companies to slash production to 8 percent of normal to keep the limited oil-storage capacity near the oil fields from filling while Alyeska dealt with the spill.
Lack of storage capacity at Pump Station 9 contributed to Tuesday's spill. During a routine maintenance check, power went out, causing a valve to open and channel oil into a storage tank, which overflowed. Oil streamed into a bermed secondary containment area. That containment area is lined with an impermeable liner and state and company officials say no oil escaped from the area.
The size of this week's spill from the pipeline is topped only by two other accidents on the pipeline:
• In 1978, sabotage at Steele Creek caused about 670,000 gallons - 16,000 barrels - to leak.
• In 2001, a Livengood man shot the pipeline with a high-caliber rifle, causing 258,000 gallons - 6,143 barrels - to spew from the line before Alyeska could secure a clamp over the hole.
This week's spill involved an estimated 5,000 barrels, Alyeska and the state Department of Environmental Conservation said.
With the pipeline restored to full operation, Alyeska told the producers at the North Slope's complex of oil fields to return to delivering oil at their normal rates of production, said Alyeska spokeswoman Michelle Egan.
The pipeline normally carries about 650,000 barrels a day, about 10 percent of U.S. oil production.
Alyeska had anticipated starting the pipeline by noon Friday but that was delayed when regulators from the federal Pipeline and Hazardous Materials Safety Administration issued a "corrective action order" - a series of steps Alyeska needed to take - to make sure the pipeline was safe. The federal go-ahead came at about 4 p.m. Friday.
The state DEC said cleanup of the spilled oil is well under way.
Alyeska and the pipeline are owned by BP, Conoco Phillips, Exxon Mobil, Koch Industries and Chevron.
The pipeline was shut down for 79 hours and 40 minutes this week, Alyeska said. For every day it was down, it disrupted about $45 million in North Slope production and about $13 million in state revenue. Alaska Revenue Commissioner Pat Galvin this week said the state wouldn't have a big revenue problem because it anticipates down times and production has been far ahead of projections so far this year.
Alyeska said a crew of about 125 people is on site continuing to manage the cleanup and restart. The pump station is usually staffed by about six people, Egan said.Find Megan Holland online at adn.com/contact/mholland or call 257-4343. Reporter Elizabeth Bluemink contributed to this story.
By MEGAN HOLLAND