The Netherlands-based marine salvage firm Mammoet Salvage B.V., has been awarded the contract for handling a 63-year-old U-boat wreck site on the Norwegian coast. The German type IX submarine U-864, which was sunk on Feb. 9, 1945, by the British submarine HMS Venturer, was carrying more than 65 tons of metallic mercury in 1,857 steel bottles.
Norwegian authorities found the two-part wreck in 2003, roughly two nautical miles west of the island of Fedje. The bow and stern sections lie near each other at a depth of almost 500 feet. Monitoring of the site has revealed highly toxic mercury leaking from the corroding wreck, making its proper disposal urgent before a large area of the sea floor is contaminated.
Given the potential for environmental disaster, the Norwegian Coastal Administration has decided on two possible solutions to the threat of mercury contamination:
• leaving the wreck in situ and encasing it with twin layers of sand and gravel
• or raising the wreck and bringing it ashore where the mercury can be remediated.
According to Mammoet spokesman Johan Pastoor, the Norwegian government will choose one of the methods soon. “Probably before the end of this year,” Pastoor said.
Should Norwegian authorities choose to raise the wreck, Mammoet, the salvage company that successfully raised the Russian nuclear submarine Kursk in 2001, plans to use an innovative lifting technique. A ship equipped with a set of lifting arms would be positioned over the wreck. The lifting arms would be lowered to the wreck site along with a large steel tray. The arms would pick up the stern section of the wreck, which contains the mercury, and place the wreck into the tray. The arms and tray would then be lifted to the surface. A semi-submersible ship would take the tray onto its deck and transport it to a site on shore. A multi-wheel dolly would roll the tray off the deck of the ship to a concrete building where the mercury would be safely removed.
What makes the salvage particularly tricky are the 22 unexploded torpedoes at the wreck site, some in the bow section, some in the stern. Because of the danger from these still potent weapons, the salvage will be directed from the surface. “We will do it by remote control,” Pastoor said. “Nobody will be in the water. No divers will be used.”
At the time of its sinking, U-864 was just beginning a long journey from Nazi Germany to Jakarta, Indonesia, then under the control of Imperial Japan. As part of Operation Caesar, the U-boat was delivering materials, parts and plans to Germany’s Axis ally. In addition to the mercury aboard, the sub also reportedly carried Me-262 jet engine parts, detailed plans for manufacturing the combat jets as well as German and Japanese scientists and engineers.