Editor’s Note: For Scientific American’s complete coverage of the Costa Concordia disaster see links at the end of this story.

After more than two and a half years and $1 billion, the capsized cruise ship Costa Concordia is about to set sail again, although it won’t be under its own power. The move could not come too soon, because the risk that it will damage the environment is much higher now than when the ship originally crashed near the Tuscan island of Giglio in January 2012.

If all goes well, the crippled vessel, which was rotated to an upright position (parbuckled) in September, will be lifted to the surface in an even riskier operation sometime around the middle of July—likely the 14th because the salvors working on the operation are superstitious enough to avoid having the refloat in progress on the 13th.

So far, the biggest problem the uplift team has faced was detachment of a flotation caisson in April. These caissons are large metal boxes into which compressed air will be pumped to float the ship. Salvage crews repaired and remounted the escaped caisson and are now finishing installation of the remaining ones. The Concordia will have 30 caissons in all to carry out the refloat. Once the ship has been lifted, two of the caissons will have to be refitted to help keep the craft ship afloat while it is being towed 240 kilometers to Genoa, where it will be dismantled.

Lifting the ship more than 12 meters off the giant underwater platforms that have been supporting it since September will take three or four days, but raising it the first two meters will be the most dangerous part of the exercise. That’s when the hull could crack and spill out a toxic stew of chemicals, rotten food and debris trapped since the shipwreck that has been swilling around inside the sunken ship for more than two years. If the hull breaks apart, the ship would likely never be removable from Giglio in one piece and would have to be dismantled in situ.

Once the ship is floated two meters off the platforms, salvors will carry out crucial checks to make sure the ship has no hidden fissures or further structural damage. Then they will move it eastward some 30 meters to begin the full refloat. Franco Porcellacchia, project manager for Costa Cruises, told Scientific American that the ship will be then be lifted above the surface deck by deck, with salvage crews stopping after each new deck emerges to look for environmentally harmful substances as well as clean the debris so that it does not leak into the sea. Italy’s environmental ministry is “greatly concerned” that the wrecked ship will spew flotsam and contaminants all the way to Genoa. But the engineers working on the project and Costa Cruises (which is owned by American Carnival Cruises) have assured them that the pollution produced en route to Genoa will be “temporary and of little significance.”

The superficial debris that salvagers will remove before the vessel sets sail includes mattresses, suitcases and personal effects belonging to guests as well as fully stocked freezers (that could pop when the water pressure is eased) and entire restaurants with plates, utensils, tables and chairs. And even if the hull remains intact, bunker fuel left in the tanks and engines, along with other harmful chemicals such as cleaning supplies could also befoul the water if not removed promptly.

The risks posed by raising the ship are real but leaving the Costa Concordia in place is not an option because as the ship decays and saltwater and waves crash against it, the likelihood of pollution fouling the waters off Giglio rises. Salvors have told Scientific American that they cannot guarantee the ship would survive another winter intact. “It’s far more dangerous to the environment to leave it where it is than to tow it away,” said Franco Gabrielli, Italy’s Civil Protection chief, when he met with Giglio residents this week to explain the process. “It must go as soon as possible.”