Removal method of Costa Concordia

The removal plan of costa concordia  ( the wreck of the ship, which measures 952 feet in length and weighs more than 114,000 tons) could be divided in six subsequent phases:

Stabilisation

The first phase involves the anchoring and stabilisation of the wreck to prevent any slipping or sinking along the steep seabed. This will make it possible to work safely even in bad weather.

Stabilisation is performed using an anchoring system made up of four submarine anchor blocks fixed to the sea bottom between the center of the wreck and the coast.

At the beginning of November, the Consortium announced the completion of the wreck stabilisation. Later, 12 retaining turrets will be installed for use during the parbuckling of the wreck. 

Strandjacks (individually controlled by computers) mounted on the tops of the turrets are attached to chains (two per turret or a total of 24 chains) that pass under the hull and are fixed to the port side of the wreck. This holdback system will be used for balancing purposes during the rotation and parbuckling of the wreck.

 

2nd Stage :- Installation of submarine supports and portside caissons

Second stage involves the preparation of the false bottom on which the wreck will rest after rotation.

The preparation of the false bottom is divided into two separate phases.

Firstly grout bags will be positioned and filled with cement to occupy the empty space between the two spurs of rock (one in the stern area and the other in the bow of the hull) on which the wreck is resting and create a stable base for the hull. After divers have positioned the bags, a special ecofriendly cement prepared on a barge will be injected into them. The grout bags have eyelets for easy removal during clean-up operations. Recently, the Pioneer support vessel was positioned on the shore side of the wreck. This provides a logistics and operating base for the production, preparation and positioning of the false sea bottom, made up of removable grout bags.

After positioning the grout bags, three large platforms and three smaller ones will be fixed in place. The piles will be inserted into the granite ground by drilling a 2 m hole, using a closed circuit system so that no waste is dispersed in the sea. Currently, work has also already begun on sea bottom drilling to prepare foundations for the 6 undersea platforms on which the wreck will rest after rotation into a vertical position. This highly delicate and difficult operation is being performed by UK company Frugo Seacore, a world leader in offshore drilling operations.  After preparing the false bottom, the Micoperi 30 crane will be used to install 15 refloating sponsons on the left side of the wreck. These caissons are welded onto the wreck 

Parbuckling 

the parbuckling or rotation will take about a couple of days, as the movement has to be extremely delicate and constantly monitored. The parbuckling will be performed using strand jacks which will be tightening several cables attached to the top of the caissons and to the platforms, which will be pulled seawards, while the cables attached to the starboard turrets will be used for balancing.

This is a very delicate phase, during which the forces involved have to be offset carefully to rotate the wreck without deforming the hull. 

Installation of caissons on starboard side

then other 15 refloating sponsons will be attached to the starboard side of the wreck. These caissons will be used during the subsequent re-floating stage

Re-floating

At this point the hull is resting on the false bottom at a depth of about 30 m. A pneumatic system will be used to empty the water gradually from the caissons on both sides of the wreck, giving the sufficient shove to push it upwards. On completion of the emptying process, a section of about 18 m will remain submerged.

While it was reiterated that in such a unique, complex, dynamic and articulated technical and engineering project, it would be both misleading and unrealistic to fix a precise date for the conclusion of work, in part because it is reasonable to imagine that there may be suspensions of work due to bad weather and sea conditions or other unforeseeable situations, the latest timing based on the progress of work on the project envisages that the wreck will be removed by the summer of 2014.

RESOURCES

At the present time, at Giglio’s yard, about 500 workers (representing 21 nationalities), engineers and divers are active at the site day and night, seven days a week, together with about 30 diverse vessels.

The efforts being made and investments in resources and materials are also demonstrated by an increase of about USD 100 million on the initial cost forecast, for a total estimated budget of over 500 million Euro.

ECOSYSTEM SAFEGUARD

The plan to re-float the hull in one piece gives top priority to minimising environmental impact, sea and land, to protecting Isola del Giglio’s tourism and economy and to ensuring the safest possible working conditions.

Environmental protection will have top priority throughout this monumental salvage operation, the likes of which has never been attempted before anywhere in the world. Once removal is complete, the sea bottom will be cleaned and marine flora replanted.

The main objective in this phase was to characterise the marine environment closest to the Concordia wreck and the whole East coast of Giglio, in consideration of the salvage works. The survey addressed all components of the marine environment (chemical and physical characteristics of the water column, plankton and benthonic communities, Posidonia meadows, underwater noise and marine mammals, etc.). This data was integrated into a detailed map of benthic communities and represent the baseline for future monitoring and evaluation of the potential impact of salvage operations. This information also allows to determine the best areas for operations and to mitigate salvage works.

DEFUELING

Right after the incident, Costa acted immediately to prevent the potential environmental impact by establishing a protection perimeter around the ship using booms, and on Saturday 14th January, 2012, engaged international experts Smit Salvage, who developed an action plan in close cooperation with the authorities.In order to remove the oil from the ship, Costa Crociere hired the world’s leading salvage company Smit Salvage BV, which worked in collaboration with the Italian firm Tito Neri srl.

The operations began on February 12 and were completed successfully. Costa Crociere made a multi-million euros investment to extract all the oil from the ship, with the primary focus on removing the oil from the ship as quickly and cleanly as possible. Fuel removal was carried out by a total of 20 marine vessels (platforms, tugs, transport ships, crane barges, tankers, oil spill response vessels, etc.) and a team of 100 experts from a number of different countries. Defueling operations were completed in 31 days, within the 5 weeks that were originally planned. The removal of about 2,100 tons of oil from 17 tanks of the ship was completed on March, 24th. Operations have been performed using a system of pumps and valves. Basically, “hot tap” valves were attached to the side of the ship, a hole was drilled into the tank and a pipeline was attached.

This enabled the oil to be heated and pumped out while sea water was pumped in so as to maintain the ship’s stability. Minimal physiological amounts of fuel cannot be pumped out from the bulkheads of the tanks; but they are in such small quantities as to pose no significant environmental risk.

CARETAKING

“Care taking” has been carried out cleaning substantial quantities of debris from the wreck from the seabed and the area around the hull. Also in this case Costa Crociere has contracted Smit Salvage BV, in partnership with Tito Neri srl. Eight marine vessels (oil spill response vessels, crane barges and transport ships) have been deployed as well as containers, cranes and rubber dinghies and a team of 42 experts.

Methodology in Snapshot