(CNN) -- The refining company Motiva has notified officials that an estimated 300,000 gallons of diesel spilled at its facility in Sewaren, New Jersey, when Superstorm Sandy pushed through, a U.S. Coast Guard spokesman said.
Russell Tibbets of the Coast Guard told CNN on Wednesday the incident occurred when one tank ruptured. Most of the diesel was contained by a backup containment unit, he said.
Earlier Wednesday, Shell, which owns part of Motiva, said at least two diesel storage tanks were damaged at Motiva's Sewaren terminal. It said the amount of the spill was unknown, but there were no further incidents. Sewaren is across from Staten Island.
"Previously deployed booms are continuing to skim released product in the Woodbridge Creek adjacent to the site," Shell said in a statement.
The Coast Guard is providing oversight of Motiva's cleanup, which includes the placement of containment booms, according to Tibbets. Vacuum trucks and about 100 workers will assist in the effort.
The Coast Guard, Motiva and state officials will work to verify the spill amount, Tibbets said.
Shell said terminals in New Jersey and New York had flooding because of the storm surge, as well as loss of power.
Diesel tank ruptures
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