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 covers thousands of square miles and 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. Its coast, where hundreds of sandbags were being filled Monday, is about 60 miles southwest of New Orleans.
BP officials called their latest effort to stop the flooding oil a "top hat" that engineers would try to place 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 78-ton steel and concrete cofferdam the size of a four-story house over the pipe and into the seafloor, but the "top hat," 4 feet in diameter and 5 feet long, is only 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 underwater required EPA approval.
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, BP Group CEO Tony 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."
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 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.