Citizen oversight group opposes oil-tank inspection delay at Valdez tanker terminal
The Prince William Sound Regional Citizens' Advisory Council is calling on the Alaska Department of Environmental Conservation to reconsider its decision to allow Alyeska Pipeline Service Co. to postpone for two years a scheduled internal cleaning and inspection of one of the giant oil-storage tanks at its Valdez tanker terminal.
"Routine tank inspections are critical oil spill prevention measures that are in place and necessary to protect the Prince William Sound environment," wrote the council's executive director, Mark Swanson, in a Feb. 9 letter to the agency.
The tank, known as Tank No. 5, is over 30 years old and can hold more than 20 million gallons of North Slope crude oil. Tank inspections are required to check for corrosion and mechanical fatigue, and to provide an opportunity to clean out sediment that builds up in tank bottoms, sometimes covering and blocking the fire-suppression systems installed on the bottoms.
Tank 5 was last drained, cleaned, and internally inspected in 2001. A new floor was installed after that inspection turned up significant corrosion of the original floor.
The tank was scheduled for another such internal cleaning and inspection this summer to check for corrosion of the 2001 floor and to examine the condition of the tank's walls, roof, and fire-suppression system.
However, in October 2011, Alyeska asked the state for permission to put off the inspection until 2014 . The Department of Environmental Conservation granted the request in a February 1 letter to the company, conditioned on Alyeska providing additional documentation on the operation of the tank.
The council's objections to the inspection delay focus primarily on corrosion of the tank roof. When the tank was inspected in 2001, measurements showed some of its roof plates were already so corroded as to be thinner than the 0.25-inch minimum envisioned in Alyeska's original design. When the tank was installed in the mid-1970s, its roof plates were 0.375 inches thick, meaning corrosion had eaten away more a third of the metal in some places by the time of the 2001 inspection.
Moreover, the council pointed out, a subsequent study commissioned by Alyeska had recommended a minimum roof thickness of 0.268 inches—rather than the original 0.25 inches—in some areas to accommodate Valdez snow loads.
In addition, Alyeska's figures suggested corrosion would be continuing to thin the plates at the rate of about .006 inches a year, indicating a further metal loss of up to 0.07 inches by 2014. That could leave the roof as thin as 0.18 inches in spots.
The council's concerns about the condition of the tank's roof were heightened by a problematic external inspection of Tank 5 that Alyeska conducted in 2007 with ultrasound technology. The less-expensive external inspections are required five years after each internal inspection as in interim check on the tank's condition.
The council letter identified at least two problems with the 2007 inspection. One was that, in some cases, it showed the roof plates to have inexplicably become thicker, rather than thinner, since 2001. Additionally, the council noted, Alyeska never established that the technician who conducted the 2007 inspection was properly certified to do so under standards established by the American Petroleum Institute.
Alyeska's application for a postponement of the Tank 5 internal inspection scheduled for this year did not address the 2007 external inspection, or the questions about how it was conducted and the results it produced.
"Due to the size and age of Tank 5, and its location in a critically sensitive habitat and Zone 4 earthquake area," Swanson wrote in the council's Feb. 9 letter, "a minimum inspection regime of 10 year internal inspections and 5 year external inspections is recommended, with more frequent inspections if warranted."
Besides going to the Department of Environmental Conservation, the council's letter also went to Alyeska and to the federal Bureau of Land Management, which shares jurisdiction over the terminal with the state.
Attached to this news release in PDF form are:
• Alyeska's Oct. 20, 2010, request for the inspection delay
• The state's Feb. 1, 2012, permission for the inspection delay
• The council's Feb. 9, 2012, request for reconsideration of the delay.
The same materials, along with two consultant reports the council relied on in developing its position, are available at the following link:
Alyeska is also seeking a delay of at least two years for an internal inspection of Tank 10, which, as in the case of Tank 5, was scheduled for this summer. The council has also objected to that request. Materials relating to that request and the council's objections are available at the following link:
The Prince William Sound Regional Citizens' Advisory Council, with offices in Anchorage and Valdez, is an independent non-profit corporation whose mission is to promote environmentally safe operation of the Valdez Marine Terminal and the oil tankers that use it. The council's work is guided by the Oil Pollution Act of 1990, and its contract with Alyeska Pipeline Service Company. The council's 19 member organizations are communities in the region affected by the 1989 Exxon Valdez oil spill, as well as aquaculture, commercial fishing, environmental, Native, recreation, and tourism groups.
Posted: February 16, 2012