Costa Concordia: Salvaging a shipwreck

The following script is from "Costa Concordia" which aired on Dec. 16, 2012, and was rebroadcast on Sept. 1, 2013. Lesley Stahl is the correspondent. Rich Bonin and Sabina Castelfranco, producers.

Ever since the wreck of the Costa Concordia a year and a half ago, the huge Italian luxury liner has been sitting, semi-submerged, off the coast of Tuscany, looking like a big, beached whale.

It's the largest passenger ship ever capsized, easily surpassing the Titanic. And, as we first reported last year, removing the ship has turned out to be the most complicated, the most expensive, the most daunting and the riskiest salvage operation ever.

The Costa Concordia is a rusting carcass, sitting precariously on two underwater mountain peaks. The swimming pools and jacuzzis where passengers sunbathed and sipped cocktails, now empty and askew. A clock remains frozen in time, marking the hour and minute when the ship lost power.

And below, ghostly vestiges of the ship's contents litter the ocean floor in what the Italian authorities have designated an official crime scene. Thirty people died; two are still missing.

Nick Sloane: Welcome on board.

Lesley Stahl: Thank you.

Nick Sloane from South Africa is the senior salvage master. He took us out to the wreck site.

Lesley Stahl: How big is that ship?

Nick Sloane: She's huge and what you see at the moment is only 35 percent of her. So 65 percent underneath is like an iceberg underneath there.

Now the plan is to roll the 60,000-ton ship in one piece onto an underwater platform, raise it and then float it away so it can be cut up for scrap.

Lesley Stahl: So, you're planning to rotate a ship that weighs 60,000 tons.

Nick Sloane: Yeah.

Lesley Stahl: So, let me see. You're going to-- this is the ship. You have to do it like--

Nick Sloane: We'll roll it upright--

Lesley Stahl: --the whole thing together at once, creaking.

Nick Sloane: All the way along the three football fields long.

Lesley Stahl: Three football fields long?

Nick Sloane: Yeah. And we're going to rotate it all at the same time.

It sounds like an experiment in defying the laws of physics. The actual work is being shared by Nick Sloane's Titan Salvage, an American wreck removal company, and Micoperi, an Italian engineering firm. Sergio Girotto is the company's project director - in charge of re-floating a 60,000-ton ship filled with seawater.

Lesley Stahl: So, you have to create much more buoyancy than even the original weight of the ship, because of all the water?

Sergio Girotto: Absolutely. Absolutely.

A team of engineers came up with something ingenious: to in effect, weld a new ship onto the shipwreck. It starts here with the construction of towering steel boxes called "sponsons".

They're gigantic: the largest ones weigh 500 tons each and stand 11 stories high - and they'll be outfitted with hoses and sophisticated air pumps to create buoyancy.

Here's what's supposed to happen: one by one, nine of them will be welded across the exposed side of the ship.

Sergio Girotto: They will be joined together like a big Lego, outside in the open.

Lesley Stahl: And they have to be precisely welded, correct?

Sergio Girotto: The space from one sponson to the other, it is less than two inches. So they must be fabricated with a very strict tolerance.

This row of hydraulic pulleys will tighten a string of 36 cables attached to the sponsons, slowly rolling the ship upright.

Then other steel boxes will be welded to the other side of the vessel and eventually, the hollow, air-filled sponsons will act like waterwings so the Costa Concordia can be floated and towed away.

Lesley Stahl: Has this ever been done before?

Sergio Girotto: No, no.

Lesley Stahl: This is brand new?

Sergio Girotto: The-- brand new technology, brand new methodology. To lift a vessel in this way, it is the first time ever.

And no one's 100 percent sure lifting a vessel this gigantic in one piece is going to work. It's the biggest passenger ship ever wrecked -- twice the size of the Titanic. Before the accident, it was a 15-story floating palace -- big enough to house a small town of 4,000 people. As this promotional video shows, it had 1,500 luxury cabins, 18 restaurants and bars, four swimming pools, five jacuzzis, and a casino. The accident occurred in January of last year -- ominously on the night of Friday the 13th. Nervous passengers crowded together as water gushed in. Sailing too close to shore, the ship had struck a huge boulder hidden just beneath the surface.

Lesley Stahl: As you can see that it just tore the pipes apart.

Nick Sloane: Yeah the momentum of a large ship like this hitting that rock. She had no chance. Not at all.

Lesley Stahl: Almost like a shark eating the belly of a whale or something, it just ate into that.

Nick Sloane: Yeah, it was a big rock, about 96 tons.

The wreck's an eyesore right off the beaches of tiny Giglio Island that has been overrun by an armada of support vessels and an army of welders, crane operators and marine engineers. Because of the angle of the ship, the workers have to take a four-day course in mountain climbing. Here they're working on the strong cables that are keeping the ship in place.

Much of the work is being done underwater by specially-trained salvage divers - 111 in all.

Ebano who's from Brazil is being geared up and safety checked by other divers on his team.

Nick Sloane: He's got communication for talking. He's got the air. He's got back-up air. He's got a camera and a light.

Everyone who goes in has a support team of at least five up on deck. Once suited up, Ebano is lowered down in a cage.

The day we were there the divers were ratcheting, tightening - measuring those massive steel cables that run under and around the ship to tie it down so it doesn't slide of the mountain peaks and sink.

It's an exacting and dangerous job. So teammates stand by on deck in case of an emergency and a dive supervisor monitors and directs the action.

[Duane Morsner: Do you want to move back on your - on your camera and give us a wide shot of exactly what's going on down there.]

Duane "Monster" Morsner oversees a dive team.

Lesley Stahl: So you're just watching everything he does, listening to him?

Duane Morsner: And explaining to him exactly where to go because sometimes when you go past 30 meters you can get narcosis and it sort of affects your-- your thinking. And obviously if he's in trouble, I can see what the problems are, and help him out and check his depth, that sort of thing.

There's a salvage divers' camaraderie. They live in close quarters in floating barracks next to the ship. And while they come from eight different countries - speaking different languages - they're like soldiers in combat. They have each others' back.

[Duane Morsner: Move towards the bow of the Costa Concordia, please.]

Though these divers are in the water round the clock, each one can stay under no longer than 45 minutes at a time. They have five minutes to get from a depth of 40-feet into a decompression chamber. When a diver surfaces, it's a race to strip off his gear and get into the chamber.

The divers and everyone else work round the clock -- seven days and nights a week -- in a race against time. They have to remove the ship before storms like this one last winter break it apart.

Nick Sloane: Every storm weakens the structure. And there will be a certain point where the structure and she will just say, "I've had enough."

Lesley Stahl: So is that what has you worried the most, the weather?

Nick Sloane: Yeah, yeah. When you have bad weather, you don't sleep.

Neither do the insurance companies that are footing the bill.

Lesley Stahl: So how much is this operation costing?

Nick Sloane: Well, basically it's going to be around about 400 million, plus or minus, and that's a lot of money.

Lesley Stahl: Did your company ever consider proposing just blowing it up? Cause I know a lot of salvage operations - they just dynamite--

Nick Sloane: Yeah, some places in the world, that would be a solution. In this scenario, I don't think it would ever be allowed.

Lesley Stahl: Is the reason because this is such a tourist area?

Nick Sloane: Oh, the environment is the number one priority.

Lesley Stahl: Number one.

That's because the ship settled in a nationally-protected marine park and coral reef that's home to dolphins, exotic fish, these huge rare mussels and more than 700 other botanical and animal species.

[Lesley Stahl: Sergio.

Sergio Girotto: Hi, Lesley.]

Sergio Girotto took us to one of six shipyards in Italy that have been pressed into action. At this one, north of Venice, they're building this huge steel platform.

It's one of six platforms that'll be lowered into the water, its legs anchored into the hard granite sea floor. When the ship is rolled upright, it will roll onto them.

Lesley Stahl: So the ship is over there? And what, it's going to roll--

Sergio Girotto: Yeah, it's going to rotate and rotate slowly to rest on this platform -- exactly the same area where we are standing.

The platforms are necessary to keep the 60,000-ton ship from sliding off its mountain peaks, down into the abyss. But getting the platforms to the wreck site is an operation in and of itself.

Sergio Girotto: And we make the tour of Italy.

They will be floated by barge from the shipyard to the shipwreck, off Giglio Island.

Lesley Stahl: Around the heel, around the toe, and up to Giglio.

Sergio Girotto: Up to Giglio. It is a long trip.

Lesley Stahl: How long?

Sergio Girotto: It's going to take 15 days. I tell you, it is a gigantic project. If you simply think of the quantity of steel is three times the weight of the Tour Eiffel.

Lesley Stahl: Of the Eiffel Tower?

Sergio Girotto: Exactly. Three times the weight of the tower.

Out at the wreck site, they're lowering giant pipes that are used to drill holes in the seabed for the legs of those massive platforms.

Lesley Stahl: So these are these big pipes that you're putting down...

To protect the environment, the drill bit will be enclosed in the pipe in order to contain any debris from the digging.

Lesley Stahl: Wow, look how huge!

Nick Sloane: As you can see, this is about eight feet.

Eight feet is the diameter of the legs of those platforms. And the holes for the legs have to line up almost perfectly.

Lesley Stahl: When you put the platforms down, what's your margin of error?

Nick Sloane: The error that we can allow is less than six inches between them. So if we are more than six inches out, the platforms aren't going to fit.

Lesley Stahl: Has there ever been a salvage project this big?

Nick Sloane: No. This is, with the complexities and the amount of engineering - the scale of the equipment that we're bringing in, the size of the teams, this is by far the largest that's ever been done.

Lesley Stahl: In the history of salvage?

Nick Sloane: In the history of salvage.

Lesley Stahl: Let's talk about the day that you are going to rotate the ship onto the platforms. If something's not going right, can you stop it?

Nick Sloane: No, you can't stop it. You have one chance.

Lesley Stahl: One chance?

Nick Sloane: Once you start, you have to finish.

Lesley Stahl: We've spoken to engineers, marine engineers. They think you have a 50/50 chance.

Nick Sloane: No, it's more than 50/50 for sure.

Lesley Stahl: It is?

Nick Sloane: Basically, we've got a large engineering team. We have over 200 engineering documents and everything proves that it can be done. So--

Lesley Stahl: On a computer?

Nick Sloane: Yeah, we-- on a computer. Some parts of the ship will collapse internally. It's gonna be very noisy. There's going to be a lot of creaking, groaning, steel snapping. But we-- she'll come upright.

Lesley Stahl: Steel snapping?

Nick Sloane: Yeah.

Lesley Stahl: That doesn't sound good.

Nick Sloane: Yeah, well, there'll be smaller bits of steel. But the larger structure will take it.

Lesley Stahl: Is there a plan B?

Nick Sloane: We have plan B and C. But we don't want to get there.

"There" is cutting up the ship in place, which would be an environmental catastrophe. They'll put Plan A into effect later this month, when they attempt to raise the ship -- under the watchful eyes of the insurance companies, the Italian authorities and camera crews from around the world.

Should they succeed, the Costa Concordia will then be towed to a dry dock and cut up for scrap. There's so much ship, that process will take two years. And, now, the price tag is approaching $900 million.