German Submarine U-864 - Rediscovery

Rediscovery

In March 2003, the Royal Norwegian Navy minesweeper KNM Tyr, alerted by local fishermen, found the wreck. An expedition to gather more detail by sonar mapping of the seafloor was mounted in October 2003. The wreck was in two major sections, fore and aft, with the center section missing, including the conning tower. Further analysis was performed with a remotely operated underwater vehicle (ROV) in August 2005, locating an additional 107 pieces of vessel debris in the area, likely parts of the exploded center section. The mercury, contained in 1,857 rusting steel bottles located down in the vessel's keel, was found to be leaking out and currently poses a severe environmental threat (see mercury poisoning and Minamata disease).

So far 4 kilograms (8.8 lb) per year of mercury is leaking out into the surrounding environment, resulting in high levels of contamination in cod, torsk and edible crab around the wreck. Boating and fishing near the wreck has been prohibited. Although attempts using robotic vehicles to dig into the half-buried keel were abandoned after the unstable wreck shifted, one of the steel bottles was recovered. Its original 5 millimetres (0.20 in) thick wall was found to have corroded badly, leaving in places a 1 millimetre (0.039 in) thickness of steel.

The delicate condition of the 2,400-ton wreck, the rusting mercury bottles, and the live torpedoes on board would make a lifting operation extremely dangerous, with significant potential for an environmental catastrophe. A three year study by the Norwegian Coastal Administration has recommended entombing the wreck in a 12 metres (39 ft) thickness of sand, with a reinforcing layer of gravel or concrete to prevent erosion. This is being proposed as a permanent solution to the problem, and the proposal notes that similar techniques have been successfully used around 30 times to contain mercury-contaminated sites over the past 20 years.

The proposal of entombing the wreck rather than removing it has been criticised by locals concerned about possible future leakage.

On 11 November 2008, the Norwegian Coastal Administration awarded the contract for the possible salvage of the U-864 submarine and its cargo of mercury to salvage company Mammoet Salvage BV. Mammoet, which was awarded the contract for the salvage of Russian nuclear submarine Kursk in 2001 had proposed a method of raising the U-864's wreck which would satisfy the environmental requirements, described as "a safe and innovative salvage solution". This was reported to be a safe, fully remotely-controlled operation which would raise the submarine and remove the source of pollution without the need for anyone working under water. On 29 January 2009, the Norwegian government approved the proposed method of raising the wreck, and the operation was scheduled to begin in 2010. The operation was estimated to cost 1 billion kroner (USD 153 million). However, the operation has been postponed after the government wanted additional studies done.