US releases report on oil at sea as Deepwater Horizon declared largest accidental spill ever

US Coast Guard

Publish date: August 3, 2010

Written by: Charles Digges

NEW YORK – US Federal officials yesterday announced that the Deepwater Horizon oil spill has released 4.9 million barrels (208.8 million gallons) of oil from April 20 until it was effectively capped in mid July, making it the worst accidental oil spill in history, administration officials said.

But, in a somewhat tarnished silver lining, the federal government released figures on Wednesday, indicating that three-quarters of the oil from the Deepwater Horizon leak has already evaporated, dispersed, been captured or otherwise eliminated — and that much of the rest is so diluted that it does not seem to pose much additional risk of harm.

The National Oceanic and Atmospheric Administration (NOAA), the lead author of the report, however, has been under scrutiny sine the early days of the spill for downplaying spill rates and denying other spill related side effects, such as the formation of enormous undersea plumes of oil and dispersant.

The government report finds that about 26 percent of the oil released from BP’s runaway well is still in the water or onshore in a form that could, in principle, cause new problems. But most is light sheen at the ocean surface or in a dispersed form below the surface, and federal scientists believe that it is breaking down rapidly in both places.

White House energy adviser Carol Browner told ABC News that, “The scientists are telling us about 25 percent (of the oil) was not captured or evaporated or taken care of by mother nature,” said Browner on ABC news Wednesday morning. Browner called the government report “encouraging,” but added that more cleanup was necessary.

The report “is an initial assessment by our scientists in the government and outside the government. We think it’s important to make this available to the public. That’s what we’ll be doing today,” she said.

‘Static Kill’
On Tuesday, BP began pumping drilling mud into the well in an attempt to seal it for good in its “static kill” effort. BP announced later it had been a success.

Since the flow of oil was stopped with a cap on July 15 with another large dome, people on the Gulf Coast have been wondering if they should be bracing for another failure of BP’s numerous effort to cap the well — a huge underwater glob of oil emerging to damage more shorelines, for instance.

The government panel tasked with measuring the flow rate from the well released the new data Monday night. The panel suggests that the well released 62,000 barrels (2.6 million gallons) of oil a day initially, but that it eventually slowed to 52,000 barrels a day by June. The Gulf oil spill now officially outpaces the 3.3 million barrels released in the 1979 Ixtoc spill, which occurred in a different part of the Gulf of Mexico.  

The release of oil in the aftermath of the 1991 Iraq war may have resulted in more than 4 million barrels being released into the Persian Gulf, but, officially, that is classified as a war event, not an accident.

Early estimates completely inaccurate
But the new estimate also raises more questions about early downplaying of the flow rate by BP and its effect on the government’s response to the spill.

“The Obama administration had absolutely no answers on how to deal with this, and so they [said], ‘Let’s just keep BP in charge,'” Tyson Slocum, a policy expert at the non-partisan Public Citizen, a government watchdog group, told the Christian Science Monitor. “That did come to the detriment of … having early scientific analysis of the flow rate(…) which could have helped to better inform the government’s response.”

The estimate of how much oil is still at sea was partly made possible by the containment cap placed over the well last month, which has allowed scientists to gauge well pressure. The findings show that the flow rate was about 12 times greater than the initial estimate by BP and the Coast Guard.

BP says it didn’t block early studies of flow

BP has defended the early estimates, saying it had no accurate way to measure the flow before it placed the containment cap on the well.

But some scientists have complained that, early on, BP attempted to block efforts to get better, more high-resolution images of the leaks that would have helped in calculating the flow. Slocum suggests that this could be a result of BP’s “internal confidence” that it would be able to control the gusher quickly and limit its per-barrel liability.

The spill estimates went from an estimate of zero spillage on the day after the sinking of the Deepwater Horizon on April 20 to 1,000 barrels a day. That estimate was raised to 5,000 barrels a day, partially under pressure from the government.

Once the BP live feed came online in May, the estimate was raised to 12,000 to 19,000 barrels a day. By June, government scientists pegged it at between 20,000 to 40,000 barrels, and a few weeks later that estimate rose to between 35,000 to 60,000 barrels a day.

Still at sea over ecological damage

As for the oil that is still at sea, NOAA head Jane Lubchenco told reporters that, “There’s absolutely no evidence that there’s any significant concentration of oil that’s out there that we haven’t accounted for.”

She emphasized, however, that the government remained concerned about the ecological damage that has already occurred and the potential for more, and said it would continue monitoring the gulf.

Among the biggest unanswered questions, she said, is how much damage the oil has done to the eggs and larvae of organisms like fish, crabs and shrimp. That may not become clear for a year or longer, as new generations of those creatures come to maturity, Lubchenco said, according to the New York Times.

“I think we don’t know yet the full impact of this spill on the ecosystem or the people of the gulf,” Lubchenco said.

NOAA played down early spill rates

NOAA initially played down the size of the spill and the Obama administration was ultimately forced to appoint a scientific panel that came up with far higher estimates of the flow rate from the well. Whether the new report will withstand critical scrutiny is uncertain; advocacy groups and most outside scientists had not learned of it on Tuesday, the New York Times Reported.

NOAA came under fire in May for denying the existence of huge underwater plumes of oil and dispersant mixture that were discovered by independent Mississippi State university studies. When Lubchenco released her scathing contradiction, NOAA had two study vessels on the water in the Gulf, one in dry dock and another far west of the spill toward Texas.

Later studies by NOAA confirmed the existence of the plumes.

Wildlife toll not as bad as expected: report

Thousands of birds and other animals are known to have been damaged or killed by the spill, a relatively modest toll given the scale of some other oil disasters that killed millions of animals. But these estimates are also questionable as many marine biology institutes have likely downplayed how much dead sea life they were dealing with in exchange for large study grants and laboratory equipment supplied by BP.

Efforts are still under way in Louisiana, Mississippi, Alabama and Florida to clean up more than 600 miles of oiled shoreline. The government and BP collected 35,818 tons of oily debris from shorelines through Sunday.

It remains to be seen whether subtle, long-lasting environmental damage from the spill will be found, as has been the case after other large oil spills.

As the scientists who authored the report released today did their calculations, they were able to rely on direct measurements of the fate of some of the oil that spewed from the broken well. For example, BP and its contractors succeeded in capturing about 17 percent of it with various containment mechanisms, the report says.

The outcome for much of the oil could not be directly measured, but had to be estimated using protocols that were scrutinized by scientists inside and outside the government, Lubchenco told the Times.

The report calculates, for example, that about 25 percent of the chemicals in the oil evaporated at the surface or dissolved into seawater in the same way that sugar dissolves in tea. The government appears to have settled on a conservative number for that estimate, with the scientific literature saying that as much as 40 percent of the oil from a spill can disappear in this way.

The aggressive response mounted by BP and the government — the largest in history, ultimately involving more than 5,000 vessels — also played a role in getting rid of the oil, the report says. Fully 5 percent of the oil was burned at the surface, it estimates, while 3 percent was skimmed and 8 percent was broken up into tiny droplets using chemical dispersants. Another 16 percent dispersed naturally as the oil shot out of the well at high speed, the report, which has been released to the media, says.

All told, the report calculates that about 74 percent of the oil has been effectively dealt with by capture, burning, skimming, evaporation, dissolution or dispersion. Much of the dissolved and dispersed oil can be expected to break down in the environment, though federal scientists are still working to establish the precise rate at which that is happening.