State investigators say the Dubai Star oil spill occurred
when one of the ship's massive fuel tanks overfilled during an early morning refueling stop
and crew members failed to notice until oil had already seeped into the bay.
Officials initially suggested a faulty hose played a role in the Oct. 30 incident
that allowed between 400 and 800 gallons of bunker oil to reach six
miles of Alameda coastline, killing at least 37 birds.
Steve Sawyer, assistant counsel for the California Office of Spill Prevention,
the state agency conducting the state's investigation, said the focus is
on what caused the tank to overfill during the 6:45 a.m. "bunkering" operation -
when a barge filled with bunker oil saddled next to the Dubai Star to
refuel it for its journey to Mexico.
Sawyer said after the Dubai Star's port-side tank filled to capacity,
workers turned a valve to begin filling the starboard tank.
Unbeknown to workers on the refueling barge, operated by the Foss Maritime company,
or crew members on the Dubai Star, the port-side tank continued to take on bunker oil.
The overflow exceeded a containment tank on the Dubai Star
before it began flowing into the bay, Sawyer said.
The workers were stationed on the opposite side of the ship
and did not immediately notice that anything had gone afoul.
"By the time they saw it, it was too late," Sawyer said.
"It leaked out one side, and everybody was on the other side."
Sawyer said investigators were inspecting the valve
to learn if it contributed to the incident.
He was unsure whether a monitoring system on the Dubai
Star had failed to alert workers of the overfill.
Shipping experts say it is not uncommon for vessels of that size
to be equipped with such warning systems.
State regulations require that refueling barges
either pre-boom around the refueling area before the operation begins,
or keep 600 feet of boom on deck that's capable of being deployed within 30 minutes.
State officials said the vessel did not pre-boom but it did have the required materials aboard.
However, by the time workers realized there was a leak,
it was too late to contain by deploying the booms, said Sawyer.
He added that the Foss Maritime vessel and its workers did not appear to be negligent in the transfer.
Sam Sacco, a spokesman for Foss Maritime, which conducts about 20 bunkering operations in the bay each week,
said his company had been told that it was cleared
in the federal investigation by the Coast Guard investigators the day of spill.
"The fueling operation did not play a part in the spill," Sacco said.