The trans-Alaska pipeline -- the spine of the state's oil-dependent economy -- is back on the job this week after a series of expensive and disruptive emergency shutdowns.
But now is not the time to celebrate, the pipeline operator and regulators said Tuesday.
Like a patient recovering from surgery, the pipeline is still in critical condition.
In fact, the potential remains for another major shutdown in the dead of winter.
The main concern is the temperature of oil in the pipeline. At some locations, the oil temperature is well below freezing, and Alyeska Pipeline Service Co. needs to get bring it back to normal or risk major damage to the 800-mile line.
Also, the pipeline system has lines at other locations that might be similar to the leaky one on the North Slope that triggered the shutdowns starting Jan. 8. Alyeska's newly minted chief executive, Tom Barrett, said Tuesday he has ordered an inventory of the other lines. If needed, the company will take immediate steps to deal with them, he said.
The leak and shutdown came in the first full week on the job for Barrett, whose previous high-level jobs included overseeing the Coast Guard in Alaska and running the nation's pipeline safety agency in Washington, D.C.
Alyeska warned Tuesday that its studies show that ice can form in the pipeline at a flow rate of 500,000 barrels a day or less. The pipeline's reduced flow as of midday Tuesday was about 510,000 barrels per day.
Ice or waxy buildup generated during the shutdown could clog and damage the pumps that push oil down the line to the Valdez tanker port, Barrett said. That could harm a pump to the point that it doesn't function, forcing another pipeline shutdown for emergency repairs.
Two shutdowns to address the leaking pipe lasted a total of 142 hours. Oil companies drastically ramped back output from North Slope oil fields due to limited storage, disrupting what normally would have been about $300 million worth of oil production.
One federal regulator in Alaska said Tuesday that it will be at least another week to week and a half before he feels assured that the pipeline has returned to normal.
"We want to make sure that everything gets back up to temperature," said Nolan Heath, an acting authorized officer for the U.S. Bureau of Land Management, one of the agencies that regulates the pipeline.
Barrett said company workers are adding heat to the pipeline in some locations by recirculating oil in the pump stations, and it is positioning workers at the pump stations to monitor the pumps for potential clogging or damage.
The risk of damage to the pipeline system will drop substantially within the next four to five days, as the flow of oil ramps back up to its normal level of about 630,000 barrels a day, but the risk won't disappear for another 14 to 15 days, according to Alyeska.
The challenges of restarting the pipeline in extreme cold at reduced flow levels are a foreshadowing of the line's future, Barrett said.
As less oil flows through the line, that oil stays in the pipeline longer, and the temperature of the slower-moving oil declines. If it drops to 32 degrees, ice can form in the line.
The lowest oil temperature seen along the pipeline so far was at Pump Station 6 in Interior Alaska, where it had dropped to 29 degrees, according to Barrett.
On Tuesday, Sen. Mark Begich, D-Alaska, called for a congressional hearing on the future of the 33-year old pipeline, which carries about 11 percent of domestic oil production.
With the flow of the oil from North Slope fields declining, "we need to focus on how we keep this vital piece of infrastructure healthy, whole and an economic asset," Begich said in his letter requesting a Senate Commerce Committee hearing this spring.
THE LINE THAT LEAKED
The pipe discovered leaking at Pump Station 1 on Jan. 8 fed oil into a booster pump building.
Alyeska knew about corrosion in some other pipes at that building in 2008 and 2009, but the problems weren't severe enough to require repairs, Barrett wrote in a letter Tuesday to U.S. Rep. Edward Markey, D-Mass.
Last week, Markey wrote to Alyeska that he was worried about the decision to restart the pipeline before the leak was fixed. He also demanded more information about the leak's cause.
Despite Markey's and others' concerns, the leak was contained in the building without causing a spill outside on the tundra, company officials and regulators said. Bypass piping was installed over the weekend, but the leaky pipe hasn't been removed yet. Barrett said Tuesday in an interview that Alyeska still doesn't know whether the leak was caused by corrosion or some other problem.
Those questions will be answered as quickly as possible, he said, noting the importance of dealing with the similar pipes in other places.
A big problem with the line that leaked is that it was buried in the ground and encased in concrete, making it difficult to inspect, according to Alyeska. Two years ago, when the company was studying the condition of piping at Pump Station 1, it decided not to inspect the line. The only way to inspect it was to chip away the concrete, and that was deemed too risky, the company said.
Instead, the company scheduled the line for replacement with an above-ground pipe. Construction on the new line was to begin this year, company officials said.
Heath, the BLM officer, said the regulatory agencies that oversee the pipeline were given a chance to review the company's plans for the piping at Pump Station 1.
It seemed to be a good plan at the time, Heath said.
"In this case, it caught up with them before it got replaced," he said.
Find Elizabeth Bluemink online at adn.com/contact/ebluemink or call 257-4317.
By ELIZABETH BLUEMINK