The plan to remove the massive wreck of Costa Concordia, which lies half submerged off the Italian island of Giglio after capsizing in January, was revealed Friday in Rome. At least 30 people died after the ship ran aground.
In an unprecedented effort, American-owned Titan Salvage is working with Italian firm Micoperi, and will use pulling machines connected to a custom-built subsea platform to hoist the hull upright in one piece. The firms won the right to perform the work during a months-long bidding process.
The first step is stabilizing the ship to prevent further slippage down the sloped sea bed on which it rests. That is expected to take about a year, Costa said in a statement. This will be achieved by attaching "tieback chains" from the submerged part of the ship -- starboard side, closest to shore -- to a structure built nearby.
After Concordia is stabilized, the subsea platform will be built along the port side -- the non-submerged side -- and huge caissons, in essence steel boxes, will be welded to the exposed side of the ship. The caissons will be filled with water. "This gives the ship extra buoyancy," explained Mark Hoddinott, general manager of the International Salvage Union. "Caissons have the effect of making the ship wider, and the water will add mass, which improves the 'turning moment' to bring it upright."
Pulling machines will then be connected to the subsea platform, and two cranes fixed to the platform will pull Concordia upright -- facilitated by the water-filled caissons. The ship will still be flooded, so it won't float; instead it will rest on the platform. When the ship is upright, caissons will be welded to the starboard side of the hull. The caissons on both sides will then be de-ballasted -- after treating and purifying the water to protect the marine environment -- and filled with air.
"This strategy has been used on a smaller scale by both the US and Royal Navy," added Hoddinott. "But no one has removed a ship of this size." Concordia is 950 feet long and weighs 44,612 metric tons (or nearly 100 million pounds), according to Titan-Micoperi.
Once upright, the wreck will be towed to an Italian port and dealt with in accordance with the requirements of Italian authorities. Gianni Onorato, Costa Crociere S.p.A. president, told Cruise Critic in early May that the ship will ultimately be scrapped.
No details on the cost of the project have been officially released, but a Costa spokesman told CNN that the figure could exceed $300 million.
According to today's statement from Costa, the "one piece" approach -- rather than slicing the ship up and barging it off bit by bit -- will "minimize environmental impact, protect Giglio's economy and tourism industry, and maximize safety." After the ship is removed, the sea bottom will be cleaned and marine flora replanted.
While the project is ongoing, the operation base will be located on the mainland near Piombino, where equipment and materials will be stored. This will mitigate impact on the island's port activities and leave Giglio's hotels open for tourists during the peak summer season.
Salvage plan for wrecked Costa Concordia unveiled in Rome - Travel on NBCNews.com