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Inspection deferral draws objection Industry watchdog asks Alaska DEC to reconsider its approval of two-year delay for internal exam of huge Alyeska oil storage tank Wesley Loy For Petroleum News
An oil industry watchdog group is objecting to a state-approved deferral of a storage tank inspection at Alaska’s Valdez oil terminal.
The enormous tank is one of several used to store Alaska North Slope crude prior to loading aboard tankers.
Tank 5 was coming due for a summer internal inspection and cleaning, but terminal operator Alyeska Pipeline Service Co. on Feb. 1 obtained permission to delay the procedure for two years until 2014. The waiver came from the state Department of Environmental Conservation.
On Feb. 9, Mark Swanson, executive director of the Prince William Sound Regional Citizens’ Advisory Council, asked DEC to reconsider its decision.
Corrosion concerns raised “Routine internal tank inspections are critical oil spill prevention measures that are in place and necessary to protect the Prince William Sound environment,” Swanson’s letter said.
A council press release said Tank 5 is over 30 years old and can hold more than 20 million gallons of crude.
The tank was last drained, cleaned and inspected internally in 2001, the release said, noting significant corrosion was found in the tank floor.
Inspections provide a chance to remove sediment that can block fire suppression systems installed on tank bottoms, the council said.
The council’s main objection to the two-year inspection deferral concerns corrosion on the roof of Tank 5. Corrosion has eaten away considerably at some of the roof plates, the council said.
“The integrity of Tank 5’s roof is important for the proper function and safety of the vapor recovery system and to handle heavy Valdez snow loads,” Swanson wrote to DEC.
Swanson also questioned the accuracy of Alyeska’s measurements of roof plate thickness.
Alyeska’s request In an Oct. 20, 2011, letter to DEC requesting the two-year inspection deferral, Alyeska engineering director Brian Tuminello wrote: “The basis for this waiver stems from upgrades to the corrosion control and integrity monitoring systems on this tank.”
Beyond this, the letter didn’t state a reason why Alyeska wanted to delay the tank inspection until 2014.
Alyeska spokeswoman Michelle Egan told Petroleum News the company was aware of the points the citizens’ council had raised, but had “worked this issue directly with our regulator.”
The DEC waiver process “requires a rigorous evaluation of corrosion and leak detection data,” and Alyeska supplied such data to the agency, said background notes Egan provided.
Alyeska has installed two types of preventative systems on Tank 5 — corrosion control by cathodic protection, and leak detection.
“Only one is required by law,” the notes said.
Alyeska also installed a new steel floor and coating in Tank 5 at the time of its 2001 internal inspection.
DEC’s approval DEC said its engineering and spill prevention staff reviewed Alyeska data “to evaluate whether an equivalent level of protection would be provided by the technologies in place” at the Valdez terminal and on Tank 5 to support deferring the inspection.
The department said it granted the waiver based on the presence of leak detection, corrosion control and overfill protection technologies, plus inspection histories and a calculation of corrosion rates.
DEC’s Feb. 1 letter to Alyeska said it must take the tank out of service by July 1, 2014, and must complete the internal inspection and any necessary repairs before using the tank again.
But the citizens’ council recommended that DEC require a strict 10-year internal inspection regime due to Tank 5’s size and age, and its location in both an earthquake zone and “critically sensitive habitat.”
The council also is objecting to an inspection delay for another tank at the Alyeska terminal — Tank 10.
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