Review of maintenance records finds improvements needed for oil storage tank

Oil spill unlikely as long as planned repairs are not delayed further

Photo of Tank 8, which is one of the large crude oil storage tanks at the terminal. This tank is 63 feet tall, 250 feet in diameter, and can hold up to 21,420,000 gallons of crude oil.
Tank 8, seen here being cleaned in preparation for an internal inspection, is one of the large crude oil storage tanks at the terminal. This tank is 63 feet tall, 250 feet in diameter, and can hold up to 21,420,000 gallons of crude oil. Photo by Austin Love.

Last year, COVID-19 delayed planned repairs to one of the large crude oil storage tanks at the Valdez Marine Terminal. Alyeska rescheduled those repairs for 2023. A recent Council study found that, as long as these repairs are not delayed any longer than 2023, a spill is unlikely.

Taku Engineering, an engineering firm with expertise in tank and piping inspections, assessing and controlling corrosion, and cathodic protection conducted the tank inspection review for the Council. Taku’s engineers analyzed Alyeska’s documentation of inspections and maintenance for Tank 8 located within the East Tank Farm at the Valdez Marine Terminal.

2019 inspection raised concerns

After some concerning findings during a 2019 inspection of the inside of Tank 8, Alyeska planned to replace the tank floor and cathodic protection system. The repairs were scheduled for 2020. However, the COVID-19 pandemic delayed those major repairs. The Alaska Department of Environmental Conservation extended the deadline for completion to 2023. The tank will then be removed from service and repairs made.

Council conducted study to minimize risk of oil spills

Taku’s report concluded that the immediate risk of a leak from Tank 8 between now and 2023 is low. The engineers made several recommendations that would help ensure that a spill remains unlikely. They found that an unmaintained seal around the perimeter of the tank allowed rain and snow melt to migrate and accumulate under the tank’s floor. Under certain circumstances, this could lead to damage. Taku recommended that Alyeska maintain the seal so water cannot cause these problems.

Taku also found that some of the cathodic protection system testing data was inadequate. That data is used to ensure that the system is operating effectively, safeguarding the tank’s floor from corrosion.

Report

Details are available in the final report: 

 

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