Oil Spill Efforts Turn to Risky Dome Operation

Updated 12:52 a.m. ET

Workers eased a giant concrete-and-steel box into the Gulf of Mexico late Thursday, starting the long process of lowering the contraption over the blown-out oil well at the bottom of the sea in an untested bid to capture most of the gushing crude and avert a wider environmental disaster.

The 100-ton containment vessel is designed to collect as much as 85 percent of the oil spewing into the Gulf and funnel it up to a tanker. It could take several hours to lower it into place, after which a steel pipe will be installed between the top of the box and the tanker.

The 100-ton containment vessel is designed to collect as much as 85 percent of the oil spewing into the Gulf and funnel it up to a tanker. It could take several hours to lower it into place by crane, after which a steel pipe will be installed between the top of the box and the tanker. The whole structure could be operating by Sunday.

The technology has been used a few times in shallow waters, but never at such extreme depths - 5,000 feet down, where the water pressure is enough to crush a submarine.

Complete Coverage: Disaster in the Gulf

The box - which looks a lot like a peaked, 40-foot-high outhouse, especially on the inside, with its rough timber framing - must be accurately positioned over the well, or it could damage the leaking pipe and make the problem worse.

Other risks include ice clogs in the pipes - a problem that crews will try to prevent by continuously pumping in warm water and methanol - and the danger of explosion when separating the mix of oil, gas and water that is brought to the surface.

"I'm worried about every part, as you can imagine," said David Clarkson, BP vice president of engineering projects.

If the box works, a second one now being built may be used to deal with a second, smaller leak from the sea floor.

"Hopefully, it will work better than they expect," first mate Douglas Peake told The Associated Press aboard the ship that brought the box to the site. The AP is the only news organization on board the vessel.

The well blew open on April 20 when the Deepwater Horizon drilling platform exploded 50 miles out in the Gulf of Mexico, killing 11 workers. The well has been spewing an estimated 200,000 gallons a day in the nation's biggest oil spill since the Exxon Valdez disaster in Alaska in 1989.

Oil slicks stretched for miles off the Louisiana coast, where desperate efforts were under way to skim, corral and set the petroleum ablaze. People in Mississippi, Alabama and Florida watched in despair.

CBS News correspondent Mark Strassmann toured the slick by sea plane early Thursday and saw rolling ribbons of oil, some that looked a mile long, approaching the Chandeleurs. Down below, shrimp boats with absorbent booms looked mismatched against approaching slicks.

As the oil drifts toward shore, it changes over time, getting less toxic and more sticky. Eventually it becomes like tar, and clings to almost anything. Its stickiness becomes the big threat to wildlife and marshland, Strassman reports.

CBS News gave a bottle of spilled crude to Ed Overton, an oil spill expert at Louisiana State University. It was scooped from the slick on Tuesday.

Tests in Overton's lab confirmed that two weeks in the Gulf had diluted the oil's toxicity, but Overton said, "It looks like it's going to stick to everything."

On Thursday, oil reached several barrier islands off the Louisiana coast, many of them fragile animal habitats. Several birds were spotted diving into the oily, pinkish-brown water, and dead jellyfish washed up on the uninhabited islands.

"It's all over the place. We hope to get it cleaned up before it moves up the west side of the river," said Dustin Chauvin, a 20-year-old shrimp boat captain from Terrebonne Parish, La. "That's our whole fishing ground. That's our livelihood."

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An Associated Press reporter saw a pinkish oily substance washing up Thursday on the sands and into the marshland at this part of the Chandeleur barrier islands chain.

It was at least the second time the AP has confirmed oil coming ashore. Oil was seen washing up at the mouth of the Mississippi last week.

On New Harbor Island, birds are diving into the oily waters, but they didn't seem to be in any distress. It's nesting time for sea gulls and pelicans and the danger is they may be taking contaminated food or oil on feathers to their young.

There are also numerous dead jellyfish, including some that have washed up on the beach.

As BP burned off more oil, environmentalists worry all the unseen damage: the marine life that swims near the surface. BP has also fought the leak with more than 160,000 gallons of chemical dispersants. Molecules in the dispersants attach to the oil and break up its density. The oil droplets then sink to the ocean floor.

But dispersants include toxic chemicals - so toxic, critics say they do more harm than the oil itself, Strassmann reports.

The dropping of the box is just one of many strategies being pursued to stave off a widespread environmental disaster. BP is drilling sideways into the blown-out well in hopes of plugging it from the bottom. Also, oil company engineers are examining whether the leak could be shut off by sealing it from the top instead.

The technique, called a "top kill," would use a tube to shoot mud and concrete directly into the well's blowout preventer, BP spokesman Bill Salvin said. The process would take two to three weeks, compared with the two to three months needed to drill a relief well.

@katiecouric: Oil Spill's Impact on Gulf Coast Wildlife:

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During a visit to Biloxi, Miss., Homeland Security Secretary Janet Napolitano said of the containment vessel: "I hope it works. But we are still proceeding as if it won't. If it does, of course, that will be a major positive development."

"We are facing an evolving situation," she warned. "The possibility remains that the BP oil spill could turn into an unprecedented environmental disaster. The possibility remains that it will be somewhat less."

Meanwhile, a six-member board composed of representatives of the Coast Guard and the federal Minerals Management Service will begin investigating the accident next week.

And a federal judicial panel in Washington has been asked to consolidate at least 65 potential class-action lawsuits claiming economic damage from the spill. Commercial fishermen, business and resort owners, charter boat captains, even would-be vacationers have sued from Texas to Florida, seeking damages that could reach into the billions.

"It's just going to kill us. It's going to destroy us," said Dodie Vegas, who owns a motel and cabins in Grand Isle, La., and has seen 10 guests cancel.