NEW ORLEANS — BP officials on Monday announced another experimental plan to capture the crude oil that's gushing from a mangled well 5,000 feet below the surface of the Gulf of Mexico as Louisiana authorities prepared for the likely arrival of a massive oil slick along the state's marshy shoreline.
Workers filled sandbags, shrimp boats deployed anti-oil booms, and helicopters and dredges were put on alert for a land, air and sea assault ahead of an oil slick that will be difficult to clean up if it gets into the fragile marshes that make up Louisiana's coast.
"We haven't dealt with an oil spill, but we've dealt with enough hurricanes to be calm," said Brennan Matherne, a spokesman for Lafourche Parish, whose coast, where hundreds of sandbags were being filled Monday, lies about 60 miles southwest of New Orleans.
BP officials called their latest effort to stop the flooding oil a "top hat" and said engineers would try to place it over the main leaking pipe perhaps as early as Thursday. The oil captured inside then would be pumped to a barge on the surface.
The strategy is similar to BP's failed weekend effort to place a massive 78-ton steel and concrete cofferdam the size of a four-story house over the pipe, but the "top hat," just 4 feet in diameter and 5 feet tall, is the size of a shed.
BP officials said the small size should help avoid the formation of the slushlike hydrates that thwarted the earlier cofferdam effort by clogging its opening and making it too buoyant to form a watertight seal against the seafloor.
To make certain, the "top hat" will be warmed with hot water and injected with methanol, a solvent whose use under water required EPA approval.
"The rationale is there will be less seawater in the smaller dome, and therefore less likelihood of hydrate formation," BP Group CEO Tony Hayward said.
BP engineers plan to follow that effort with a so-called "junk shot," which foresees shooting shredded tires, golf balls and knotted rope into the well at high pressure to clog it and stop the flow. That effort won't be ready for two weeks, however.
Asked about the potential that the "junk shot'' will enlarge the leak, Hayward said, "The risk of that is very, very, very low. . . . That's one of the things we're clearly very focused on as we move forward: to make sure this intervention only has upside and no downside."
Hayward said that an international team of scientists, engineers and oil drilling experts from the government, private industry and academia was working round-the-clock at BP offices in Houston to find a solution.
However, he acknowledged that BP's response to the spill, from the use of tens of thousands of gallons of chemical dispersants and anti-oil booms to the cofferdam and top hat capping efforts, is unprecedented.
"There is an enormous amount of learning going on here because we are doing it for real for the first time," Hayward said.
Kent Wells, a BP senior vice president, compared the efforts to "trying to do heart surgery at 5,000 feet."
The only sure way to stop the leak — by intercepting it with a relief well — is still at least 75 days away. A second relief well is to be started in the next 10 days.
"Our initial shock has been taken over by our resolve to stop the leak, under the sea, on the sea, on the shoreline," said David Nagel, an executive vice president of BP America.
So far, cleanup and drilling the relief well have cost $350 million, a company fact sheet said.
Meanwhile, off the Louisiana coast, the slick was being watched with the attention usually reserved for an approaching hurricane.
Already, some of the richest fishing grounds in the gulf are off-limits, idling thousands of commercial fishermen. Shrimping boats that usually are combing the fertile waters for catch instead were loaded with booms, sent to string barriers along the fragile coastline.
Traces of oil have been found in offshore island ramparts such as Little Pass, authorities said, and the center point of the slick appears to be taking aim at the mouth of the Mississippi River, with the thickest part of the slick closing in on the west side.
Winds are expected to continue blowing out of the southeast for the next two days, nudging the spill farther north and west.
Coast Guard Rear Adm. Mary Landry said Monday that crews already were in place with booms and oil-absorbent material on Grand Isle, La., where landfall could happen in the coming days.
For Mississippi, the news was better. A Coast Guard flight found that the oil so far has avoided Mississippi's beaches and marshland.
U.S. Rep. Gene Taylor, D-Miss, said the disappointment that BP's efforts to cap the well had failed so far was eased by the fact his state wasn't facing an imminent threat.
"Nobody is happy about this," Taylor said. "But the bright spot in all this is that after another week, the oil is no closer to Mississippi. The islands looked beautiful, and if I'd had the day off, I would have loved to go swimming. . . . Hopefully, our Creator will continue to smile on us."
The slick's likely continued movement westward, however, was unwelcome news in Texas, where emergency management officials said it seemed almost inevitable that tar balls or a frothy substance resembling chocolate mousse would reach Texas gulf waters.
Officials with the Oil Spill Prevention and Response Program in the Texas General Land Office already are bracing for what they call a "tar ball event," possibly as soon as two to three weeks.
The continued leak and the size of the spill, however, mean that no one can rest easily, not even along the east coast of Florida, forecasters warned.
While the oil leak is 80 miles north of the gulf's powerful Loop Current, it's likely that the slick will shift direction over the next several weeks and could still be caught in the current that rings the gulf before it shoots down past the Florida Keys, where it joins the Gulf Stream, which rides along the East Coast of the United States.
"If the oil continues to leak, if we have a spill that goes on for a month, we're going to see oil going east and west and north and south," said Doug Helton, the incident operations coordinator for the National Oceanographic and Atmospheric Administration team that's tracking the spill's movement. "What it does will depend on winds and currents at that time."
(Washburn reports for The Charlotte Observer. Pender, of the (Biloxi, Miss.) Sun Herald, reported from Biloxi. Chang and Lebovich, of The Miami Herald, reported from Miami. Miami Herald reporters Amy Sherman in Miami and Mary Ellen Klas in Tallahassee, the Fort Worth Star-Telegram's Dave Montgomery in Austin, Texas, and McClatchy correspondent Maria Recio in Washington contributed to this article.)
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