The company that runs the trans-Alaska pipeline remains under federal investigation and is in the middle of major changes after an internal probe this summer raised serious concerns about how it handled a major pipeline leak and emergency shutdown in May.
Alyeska Pipeline Service Co.'s internal review blamed the May 25 accident -- the third-largest oil spill in the pipeline's history -- on a technical glitch, potential design failures and a series of human mistakes.
The review said the spill of about 190,000 gallons of oil at a pump station near Delta Junction fits into part of a pattern of similar "significant" pipeline incidents over the past three years. Despite internal probes of those cases, the findings "have not been communicated well throughout the organization," according to the report written by Alyeska's six-member investigative team.
To this day, federal regulators are still requiring Alyeska to keep additional workers at the pump station around the clock, inspecting for leaks or other problems.
The internal report was completed in June and shared with state and federal regulators in July but it wasn't shared with the public until last week, when a pipeline watchdog, Richard Fineberg, posted on the Web a redacted version that he obtained from state officials.
State and federal pipeline regulators did not respond this week to requests for comment about Alyeska's findings. The federal Pipeline and Hazardous Materials Safety Administration is probing the accident and has not issued any findings yet.
Alyeska has been unable to determine what caused the technical glitch that led to the spill, company spokeswoman Michelle Egan said this week.
While the reason for the glitch remains unclear, the June report explains what happened: When Alyeska was running a battery of fire-system tests, a breaker tripped open and prevented the backup power from kicking in when workers cut off the main power supply. The power failure caused valves on a large oil storage tank to open -- an automatic event that prevents the 800-mile pipeline from over-pressuring during outages.
In this case, the flow of oil was already shut down for testing and over-pressuring was not an issue. But because the valves were open, oil began filling the tank. Workers in Anchorage and Delta Junction focused on restoring power without noticing that the tank was filling up. The tank soon overtopped, spilling oil into a lined containment area.
The spill created an explosive hazard for workers and forced a three-day pipeline shutdown. The 800-mile pipeline carries North Slope oil production to the tanker port in Valdez.
But why did the power system fail? The answer remains unclear. During the accident investigation, Alyeska was unable to get the breaker on the backup power system to trip again, despite multiple attempts.
Fineberg, the pipeline watchdog who posted the report on his website, said the company's admission that it didn't learn from previous accidents raises questions about its ability to fix this one.
"They claimed they were going to stop these events from happening. It clearly did not work," he said.
He said he remains deeply concerned that the company hasn't explained why its backup power -- an important component during emergencies -- didn't work.
Egan said this week that the company is redesigning its backup power system at its operating pump stations to prevent this sort of accident from happening again. It has also instituted new procedures during shutdowns to make sure that some workers are in charge of looking at the entire system while their colleagues concentrate on the task at hand.
Also, after urging from U.S. Sen. Lisa Murkowski, R-Alaska, Alyeska is paying for a global consulting firm to assess systemwide risks along the 33-year-old pipeline, from the North Slope to Valdez.
Separately, the company is examining whether it has enough staffing and storage tank capacity at the pump stations, Egan said.
And, she said, the company is investigating a July whistleblower complaint alleging that an Alyeska worker falsified maintenance work records at the pump station, among other accusations.
In recent years, the company has been automating its pump stations as a way to cut its expenses. The project is near completion but has run years behind schedule and cost tens of millions of dollars more than expected.
Alyeska is owned by BP, Conoco Phillips, Exxon Mobil, Koch Industries and Chevron, the companies that also own the pipeline.
Alyeska's internal report listed six prior cases between 2007 and 2009 that showed a "trend of operational discipline deficiencies" similar to the May incident. Four of those cases, including a 2007 fire, happened at Pump Station 9.
The report says a major factor in the May accident was the "lack of situational awareness" of workers stationed at the pipeline's command center in Anchorage and at the pump station.
But the report noted that workers at both locations are facing new complexities in their jobs that they hadn't in the past.
All four of the pipeline's pump stations are configured in different ways while Alyeska transitions to an automated system.
"For automated stations, the interconnection and failure modes are complex and can be difficult to troubleshoot," the report said.
Also, workers at the pump stations have to handle more responsibilities.
"Currently, there are expectations for maintenance and response personnel to fill some of the roles historically performed by operations personnel. In the case of the (tank spill), one individual filled three roles," including pump station caretaker, maintenance technician and chief contact person for one of the tests scheduled during the May shutdown, the report said.