Huge dome probes ocean depths to cap US oil leak

Workers lowered a huge dome over an oil leak gushing from a sunken rig deep in the Gulf of Mexico early Saturday, as energy giant BP battled the slick lapping ashore on protected islands off the US coast.

Updated: May 08, 2010, 20:00 PM IST

New Orleans: Workers lowered a huge dome over an oil leak gushing from a sunken rig deep in the Gulf of Mexico early Saturday, as energy giant BP battled the slick lapping ashore on protected islands off the US coast.

The complex, unprecedented operation to drop the 100-ton (90-tonne) chamber some 5,000 feet (1,500 meters) below the surface to cap the leak from the fallen rig was expected to be completed later on Saturday.

The dome was hovering just above the sea floor as the area was being prepared for it by robotic submarines, said officials with the Unified Command.

After the dome is adjusted to the ocean floor, engineers plan to hook a pipeline to it and pump the oil it collects into a waiting barge.

If it works as designed, engineers say the dome should collect about 85 percent of the oil spewing daily from the well.

"This is a very large device and needs to be very precisely placed," BP spokesman Doug Suttles told reporters after the dome began its descent late Thursday, adding engineers would "swing it over and they had to precisely lower it over the top of the leak point."

"Over the weekend, we expect to connect that dome to the drill ship Enterprise and hopefully beginning of next week, we`ll begin to start to evacuate the oil from the seabed up to the surface."

Coast Guard Rear Admiral Mary Landry said the operation was going to take a few days and might not succeed. "This is not the final solution," he added.

The leak is hemorrhaging some 200,000 gallons of oil a day into the Gulf of Mexico from the sunken Deepwater Horizon rig that exploded on April 20, killing 11 workers.

The delicate procedure is seen as the best hope to stave off the biggest US environmental disaster since the 1989 Exxon Valdez spill in Alaska, but officials remain cautious about whether it will work.

"This has never been done in 5,000 feet of water. It`s a technology first. It works in three (hundred) to 400 feet of water. But the pressures and temperatures are very different here," BP`s chief executive officer Tony Hayward warned on CNN.

"We cannot be confident that it will work."

Oil sheen from the massive crude spill began washing ashore on the Chandeleur Islands, some 60 miles (100 kilometers) off Louisiana, forcing US officials Friday to close a wildlife refuge there to minimize disturbance to nesting sea birds and to allow clean-up work.

The Breton National Wildlife Refuge refuge, home to endangered species of brown pelican, least tern and piping plover, is one of the oldest in the country and spreads across almost 7,000 acres (2,800 hectares).

The National Oceanic and Atmospheric Administration (NOAA) meanwhile extended the area closed to commercial and recreational fishing to 4.5 percent of Gulf waters, saying the fishing ban would remain in place until May 17.

News of the sheen reaching Louisiana`s outlying shores raised new fears for the fragile ecosystem of its wetlands and shores -- home to vital spawning grounds for fish, shrimp and crabs as well as a major migratory stop for rare birds.

BP meanwhile sprayed dispersants over the slick to break it up, and was deploying thousands of booms to try to contain the spreading oil.

US officials said the chemicals produced a similar effect to dishwashing liquid.

"It`s really designed to break down the oil," said Bob Perciasepe, deputy administrator of the Environmental Protection Agency (EPA).

"It does not make the oil disappear but it makes it into smaller and smaller particles that makes easier over the long haul to be biodegradable instead of big... really, oily globs."

Louisiana Governor Bobby Jindal meanwhile called for more booms to be deployed along the Louisiana coast, telling reporters that "it`ll be so much harder to clean up this oil if it gets into the marshes."

Political fallout over the spill also grew as a key US senator warned action on legislation to fight climate change was now "impossible" due to fierce new opposition to offshore drilling in the wake of the disaster.

"I believe it would be wise to pause the process and reassess where we stand," Republican Senator Lindsey Graham said.

A spokesman for the US Minerals Management Service said 30 deep-water rigs in the Gulf had meanwhile been inspected since the Horizon explosion and the agency has found no cause for concern.

Bureau Report