Series of human errors blamed for May jet fuel leak at Kadena
KADENA AIR BASE, Okinawa — A May leak in which up to 4,000 pounds of jet fuel seeped into soil surrounding a tank near the Kadena flight line was caused by a series of human errors, base officials said Thursday.
Initially, Kadena officials reported that about 2,300 pounds of JP8 fuel spilled from a storage tank on the northwest side of the runway May 25. The leak was not discovered until May 29.
An investigation revealed the leak continued through May 28 and dumped up to 4,000 pounds of fuel, Kadena spokeswoman Maj. Dani Johnson said Thursday.
The spill resulted from three human errors, she said.
Kelly P. Livingston, an environmental engineer with 718th Civil Engineer Squadron, explained how the spill occurred.
Kadena’s fuel tanks have two valves, one to pipe fuel out to aircraft and another to pipe excess fuel back into the tank, he said.
The first error was that valves on one tank, labeled Tank B, had been closed incorrectly in preparation for switching to a connected tank, Tank A, he said. That allowed shift workers to pump fuel from Tank B but blocked the return of excess fuel to it.
Tank A’s valves were opened for use by the oncoming shift, he said.
The second error involved a breakdown in communications during a shift changeover, Johnson said.
The new shift issued fuel from Tank B instead of switching to Tank A. The excess fuel was piped from the blocked return valve of Tank B into Tank A until finally fuel overflowed the venting system, Livingston said.
The final error involved the system that alerts personnel when a tank overfills, Johnson said. The system does not sound an alarm; an alert is signaled on a computer screen.
“But, at the time, there was no one specifically assigned to monitor the computer screen,” she said.
Because of that, though workers saw the alarm they didn’t respond, she said.
To prevent future spills, the investigation board recommended several measures that the base already has put in place, Johnson said.
Workers have been retrained on the proper tank procedures, shift changeovers now have a checklist and brief the incoming shift, and a new position was created with the sole purpose of monitoring the alarm system.
The spill site has been cleared of contaminated soil and covered with new soil and sod, and grass is already growing, Johnson said.
The more than 650 cubic meters of contaminated soil will be purified on base using a land-farming technique that takes six months to complete. The technique uses enzymes that encourage natural bacteria to remove contamination from the soil. Once cleaned, the soil will be used at different locations around base.