Last Updated January 31, 2012
When the massive cruise ship Costa Concordia came to rest in shallow waters near the island of Giglio, Italy the citizens of the picturesque community acted quickly along with the Italian Coast Guard to rescue the 3,200 Passengers and 1,000 workers on board.
Survivors were whisked into the warm houses and public buildings so quickly that many were unaccounted for throughout that terrible night.
These passengers came to see the spectacular natural and man-made scenery along the coast of Italy and her islands. Sightseeing vessels of all sizes ply these sapphire blue waters throughout the year without incident. While far from pollution free, these excursions produce few problems in comparison to the economic benefits they provide to the region.
One of the draws for visitors is the possibility to see marine mammals including whales in their natural habitat. The marine sanctuary where these animals live is the largest in Europe. On the mainland just to the northeast of the sanctuary is Italy's Natural Park of Maremma whose rustic shoreline gives tourists a glimpse of the coast as it was before modern development.
It is not only the tourists who love these places; the local people are zealous caretakers of these natural wonders.
This is why it was not surprising that once the majority of the passengers were safe attention turned to minimizing the risks of pollution.
Costa Concordia's Fuel
Heavy fuel oil that powers a ship's prime movers is the first thing that comes to mind when someone mentions pollution from a wrecked passenger ship. Costa Concordia was at an early stage of her voyage when she hit Le Scole Reef so her tanks were full of fuel.
Contrast this with the wreck of a bulk carrier full of crude oil and the Costa Concordia's estimated one million gallons of fuel seems small.
But in fact a tiny bucket of fuel oil can easily cover several hundred square meters with a rainbow of oily sheen. This may not impact larger animals directly but their food sources can be devastated by a spill.
Absorbent booms catch some of the seepage that escapes from the submerged portions of the ship but oil driven by currents or tidal action can carry it outside of the controlled area.
The solution is to remove the fuel from the ship before weather and structural weakening combine and cause the full contents of the tanks to enter the sea.
This is a salvage process known as lightering. It is a complex and dangerous procedure in the best of conditions. The Costa Concordia's position on the brink of an underwater cliff makes everything more difficult.
To lighter this ship it will be necessary to hot tap the areas that contain the fuel and pump the oil and seawater mixture into a holding vessel. The act of hot tapping is essentially adding several valves at strategic locations to capture the fuel from the tank without having access to engineered openings where fuel is normally delivered.
Ships rarely need to have fuel removed from their tanks so this functionality is not built into the design. With the vessel laying on her starboard side the job becomes even more difficult.
Because the buoyancy of the vessel will change when fuel is removed and that increased buoyancy will cause the wreck to shift, seawater must be pumped in to replace the fuel. Salvors carrying out the process will need to be well aware of changing sea conditions since hot tapping requires workers to enter the wreck.
Another aspect of the salvage operation is plugging the 50 meter (165 foot) long gash in the starboard side below the waterline. To do this the ragged portions need to be cut away and new, temporary plates need to be welded to the hull.
Once the lightering and hull repairs are done the next step is to re-float the vessel. A combination of large pumps and chains with links the length of a man's forearm will work to increase buoyancy while pulling the ship into an upright position. Anchors buried in the seabed or shore will strain under the load. One salvage operator, who is not involved with the effort, estimates the required pulling force to be near 6,000 tons.
Other Pollution from the Costa Concordia
A cruise ship the size of Costa Concordia is a small floating city. There are many possible scenarios for pollution from the many systems and provisions on board even though most cruise operators have adopted a green cruising strategy.
Secondary fuels for equipment and cooking are much the same threat as the heavy oil for the prime movers. The relatively small amounts will be difficult to remove because of inaccessibility. Designers plan for significant amounts of heel to avoid spills but as the Costa Concordia lies on her side it is certain some secondary fuel stores have spilled.
Chemicals used throughout the ship are hazards to the marine food chain in the area. Treatments for swimming pools, cleaners used throughout the ship, refrigerants and coolants, and a variety of electronics will add to the disaster if the ship breaks apart and spills her contents into the sea.
Grey water and sewage are possible pollution sources as well; the one point of hope in this situation is that holding tanks were mostly empty since the trip was at an early stage. We do not know if the officers who remained on the bridge after the collision emptied starboard ballast and waste tanks overboard to try and right the ship as she made her attempt to reach the shallow waters near the coast of Giglio.
Salvage of the Costa Concordia Wreck
Salvors of the vessel estimate it may take as long as one year to remove it from the place where it now rests. This is assuming the ability to re-float the vessel. Seasonal winds and strong wave action are hallmarks of spring on the western Italian coast.
A shift into deeper water directly adjacent to the ship, or the destruction of the ship by wind and waves will end any hopes of removing her and her contents intact.
If the ship loses structural stability the only practical way to remove it is too saw through the structure and contents with an abrasive-covered steel cable and remove the ship in sections. This is a worst case situation since everything still inside will spill into the sea.
While the ship's owners are liable for damages, much of the responsibility falls on the salvage operation. As the current law stands salvors become responsible for damages if any part of the precarious operation fails and pollution results. In 2010 salvage associations continued their attempts to change the law so salvage operators would have less financial responsibility if daring efforts to avoid pollution failed.