BP Tests New Oil Containment Cap

Oil giant BP hoped Tuesday to finally stem the catastrophic flow of toxic crude in the Gulf of Mexico as it tested a new tighter-fitting cap attached to the gushing well.

The test, according to BP, will last from six to 48 hours "or more depending on the measurements that are observed," said Admiral Thad Allen, a former Coast Guard chief who is leading the government's response to the crisis.

Robotic submarines earlier pierced the near darkness 1.6 kilometers (1 mile) down on the sea floor with special lights and relayed live pictures of the operation that could mark the beginning of the end of the 13-week disaster.

SEE ALSO: New Cap Could Seal Well as Relief Drilling Continues

With the "Top Hat 10" attached to the leaking pipe, engineers aim next to close valves on the gigantic 82-ton system and start taking readings as its pressure sensors bear the full brunt of the massive gusher.

"It is expected, although cannot be assured, that no oil will be released to the ocean for the duration of the test," BP said, adding however that that would not indicate whether the flow had permanently stopped.

If the pressure readings are high enough, BP officials have suggested the valves will be kept shut, effectively sealing the well.

But if they are too low, that would indicate a leak somewhere in the casing of the well, which extends four kilometers (2.5 miles) below the sea floor.

"We need to make sure that the flow can't come around the well bore rather than through the well bore," BP's chief operating officer Doug Suttles said.

Allen stressed that "significant progress has been made on the capping stack installation" ahead of the test process.

"The measurements that will be taken during this test will provide valuable information about the condition of the well below the sea level and help determine whether or not it is possible to shut the well for a period of time, such as during a hurricane or bad weather, between now and when the relief wells are complete," he added.

BP sought to temper expectations, saying in a statement that such a cap had never before been deployed at such depths and its "ability to contain the oil and gas cannot be assured."

Here are the most recent figures on the Gulf of Mexico oil cleanup, provided by the U.S. Joint Information Center and BP (in some cases estimated and rounded).

• 553: Miles of Gulf shoreline contaminated by oil. That would be 313 miles in Louisiana, 99 miles in Mississippi, 66 miles in Alabama, and 75 miles in Florida.


• 81,181: Square miles of the Gulf of Mexico federal waters that have been closed to fishing -- about one-third of the total.


• $3.5 billion: Amount BP says it has so far spent some so far on the spill response, including containment, relief well drilling, grants to Gulf states, Gulf cleanup, and compensation claim payouts.


• 6,850: Total number of vessels assisting in containment and cleanup efforts, including skimmers, tugs, barges, and recovery vessels.


• 580: Number of oil skimmers deployed to protect the Gulf coastline.


• 46: Number of oil skimmers operating in the vicinity of the well.


• 117: Number of aircraft in use, helping to track moving oil and assist ships below.


• 330: Number of controlled burns that have been carried out to remove oil from the ocean surface.


• 1,525: Number of National Guard troops from Gulf Coast states active in the response effort.


• 17,500: Number of National Guard troops authorized by the Obama administration to be deployed in response to the crisis.


• 46,000: Number of personnel currently working to protect and clean up the Gulf shoreline and wildlife.


• 3.12 million: Feet of containment boom deployed to contain the spill. An additional 816,000 feet of containment boom is ready for use.


• 6.16 million: Feet of sorbent boom deployed to contain the spill. An additional 2.32 million feet of sorbent boom is ready for use.


• 31 million: Gallons of oil-water mix that have been recovered.


• 10.34 million: Gallons of oil that have been burned off.


• 1.79 million: Gallons of dispersant that have been applied in Gulf, both on the surface and underwater. An additional 454,000 gallons are ready for use.


• 17: Number of separate staging areas where officials are conducting cleanup operations.