Crews have removed more than 450,000 gallons of oil from a World War II-era shipwreck off the coast of Long Island.

That amounts to 99 percent of the recoverable oil aboard the British tanker Coimbra, which was sunk by a G7e torpedo from a German U-boat 77 years ago. Of the ship's 46-member crew, only 10 survived — six of whom were wounded — after being rescued from rafts and a lifeboat in the rough seas by American destroyers, according to its casualty narrative on www.uboat.net. The vessel had been carrying an estimated 2.7 million gallons of oil, but much of it burned after the torpedo hit.

The small amount of remaining oil aboard the tanker does not present a significant environmental risk, officials said, even though oil sheens might still be observed occasionally.

"The amount remaining in the vessel is very small and any sheening poses minimal risk to the local environment and no risk to the shoreline," Steve Lehmann, senior scientific coordinator at the National Oceanic and Atmospheric Administration, said in a prepared statement.

Any further potential environmental impact will be monitored by NOAA and the Coast Guard.

The oil recovery process started on May 11 and involved more than 100 government, industry and environmental specialists. The Coast Guard and the New York State Department of Environmental Conservation oversaw the project.

The Coast Guard contracted with Florida-based salvage company Resolve Marine Group to assess the wreck to determine the amount of oil on board the Coimbra, and then remove and dispose of it. Complicating the efforts was the Coimbra's position; it is broken into three parts and rests on its starboard side in 185-feet-deep water.

Crews used specialized equipment, including remote-operated underwater vehicles, and deep-sea divers, to carry out the oil recovery effort, which cost about $12.8 million. The money came from the Oil Spill Liability Trust Fund, established under a 1990 law to be used for federal responses to oil spills. A total of $18.6 million was allocated for the project, and unused money will be diverted back to the fund.

Both lubricant oil and heavy fuel oil were found on board. A closed-circuit heated water system had to be put together to remove the heavy fuel oil, given its thick consistency and because the shipwreck is in 40-degree water. Oil pumping operations are expected to be complete by this weekend. The oil is being disposed of at a permitted facility for oil disposal and processing in New York.

The wreck will remain in place and continue to serve as one of New York's artificial reefs, "which serve as an economic driver for the region's diving and fishing industries," said Basil Seggos, commissioner of New York's environmental conservation department.

Mariners are encouraged to call the National Response Center at (800) 424-8802 if they see any oil pollution in the area.

j.bergman@theday.com