An internal report by Alyeska Pipeline Co. said the May 25 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 and published by The Anchorage Daily News.
The internal report was completed in June and shared with state and federal regulators in July but not shared with the public until early last month when a pipeline watchdog, Richard Fineberg, posted on the Web a redacted version that he obtained from state officials.
Alyeska says it has been unable to determine what caused the technical glitch that led to the spill. The June report said Alyeska was running a battery of fire-system tests when 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.
Alyeska has hired a global consulting firm to assess system-wide risks along the 33-year-old pipeline, from the North Slope to Valdez. It is also examining whether it has enough staffing and storage tank capacity at the pump stations.