PANAMA CITY, Fla. — Authorities battling the massive oil spill off the Gulf Coast planned to ignite part of the slick on Wednesday, the second such burn since oil started spewing into the water two weeks ago.
The effort to remove oil from the surface cames as oil giant BP said it had stopped one of three leaks at the deep-water well.
Overnight, BP installed a valve to the end of the broken drill pipe. Although it is not reducing the amount of oil flowing from BP's sunken rig, it will allow the company to focus efforts on attacking the two remaining leaks, said Coast Guard Petty Officer David Mosley.
"This is definitely a step toward the shut off or containment of the leak,'' Mosley said.
A large underwater box -- called a coffer dam -- was also en route to the site of the wrecked rig. Workers plan to place the box over one of the two remaining leaks.
While BP works to stop the leaks, calm waters Wednesday allowed authorities to continue their work with skimmers and chemical dispersants. There was also the controlled burn -- where workers surround large patches of oil with hundreds of feet of boom and ignite it.
Meanwhile, volunteers are still descending on the Gulf Coast region to help with expected cleanup operations.
The calm winds and mild seas that kept the 2-week-old oil spill relatively intact could push the slick toward the Florida Panhandle on Thursday.
Authorities have gotten unconfirmed reports of oil coming to the shoreline in a few spots in Mississippi and Louisiana.
"We have rapid response teams ready to deploy,'' Coast Guard Petty Officer Connie Terrell said from a joint information center. "So far we've not actually seen the oil on the shore.''
One unconfirmed report came from the Chandeleur Islands off the Louisiana coast. Journalists flying over the area on Monday reported patches of oil visible within the islands. Small patches of what appeared to be rust-colored oil also were spotted in the channel between Cat Island and Ship Island, 11 miles south of Gulfport, Miss.
A reporter who visited the barrier islands south of Gulfport reported that they appeared relatively unscathed Wednesday. Oil mixed with dispersant covered the water about 33 miles off Gulfport, where two fishermen carried a reporter on a trip to investgate the spill's impact.
The material looked like a flourescent orange highway winding along a portion of the islands' west side near the southern tip. Samples scooped up from the water beaded into very small, clear gelatinous droplets on one of the men's hand.
Thin brown partched of oil could be found within the fluorescent stream, but island marshes and sand appeared clean. Pelicans nested behind booms placed around one spit of marsh.
Seas were flat, the sky sunny. "Im relieved," said one the men, Bill Seeman. I have to say, there appears to be little permanent damage, which is encouraging.
Weather models suggested that the bulk of the slick won't make landfall before the end of the week, officials said.
``Let me phrase it this way,'' Alabama Gov. Bob Riley said after flying over the slick Tuesday. ``It is a great thing that we have a few more days to make sure we get all of the booms and barricades in place.''
In Washington, Pentagon officials have authorized the use of National Guard troops to assist. As many as 6,000 in Louisiana can be mobilized; 3,000 in Alabama; 2,500 in Florida and 6,000 in Mississippi.
Meanwhile, British Petroleum kept working 5,000 feet beneath the sea to stop the well's hemorrhage of an estimated 210,000 gallons a day.
BP said work had begun on a relief well to intercept the leaking well about 13,000 feet below the seabed and permanently seal it. However, the process could take three months, the company said.
BP Group Chief Executive Tony Hayward said the company was betting on the underwater box to cover one of the leaks and allow the oil to be pumped safely to the surface.
Asked about the outlook for that operation on Tuesday, Hayward said, ``No one can answer that with any finality.'' The operation has never been attempted in 5,000 feet of water, he said in Washington. ``This is all firsts.''
Amid growing criticism of BP's response to the spill, which began when the well exploded on April 20, setting off an enormous fire that sank the Deepwater Horizon drilling rig two days later, BP also announced that it would award four $25 million block grants to Mississippi, Florida, Alabama and Louisiana to help pay for the clean up.
``That will just be the tip of the iceberg if they can't cap that well,'' said Florida emergency management chief Dave Halstead.
Along parts of the coastline potentially endangered by the oil spill, some emergency managers were taking their own approaches.
In Walton County, emergency managers had devised a plan to load barges with hay, and shoot the hay into the water before oil reaches any of the county's 26-miles of beach.
"Everything has dealt with cleaning up once it's on the beach,'' said Sheriff Michael A. Adkinson, in charge of the county's emergency response. "That's an unacceptable solution for us. Tourism is the economic engine for our area.''
In Washington, Senate Majority Leader Harry Reid gave the growing effort to raise oil company liability limits dramatically an important boost Wednesday, saying, "I would support that.''
Some Democrats are pushing a plan that would increase the liability cap, now $75 million, to $10 billion. After a Tuesday briefing by administration officials on the spill, many lawmakers were skeptical about how much BP would pay for the costs of the cleanup.
(Recio reported from Washington, Lee of the Sun Herald in Biloxi, Miss., from Gulfport, and Miami Herald reporters Goodman and Lebovich reported from Pensacola and Miami, respectively.) Contributing to this report were Lesley Clark in Washington, Audra Burch in Panama City, Fla., Kevin Yamamura of the Sacramento Bee in Sacramento, and Miami Herald reporters Jim Wyss in Miami and Mary Ellen Klas in Tallahassee.)