In the chaotic aftermath of the explosion on the Deepwater Horizon oil rig, a poorly orchestrated effort to knock down the towering blaze may have inadvertently led to the sinking of the platform, according to interviews and documents obtained by the Center for Public Integrity and shared with ABC News.
As part of an ongoing government investigation, Coast Guard officials are trying to reconstruct the initial response to the rig explosion that unleashed one of the worst environmental disasters in U.S. history. One concern surrounds the use of briny seawater instead of fire-retardant foam to drench the rig. The Coast Guard confirmed that Capt. Hung M. Nguyen, who is heading the investigation, is examining whether the decision to spray salt water across the burning platform overwhelmed the ballasts that kept the rig afloat, changing its weight distribution and causing it to list, and then sink.
"The joint investigation is absolutely looking into that, and whether it contributed to the sinking," Capt. Ronald A. LaBrec, the Coast Guard's chief spokesman, told the Center.
By the time the rig sank, oil was already flowing through the dysfunctional blowout preventer a mile below, and the sinking did nothing to make a swift and effective response any easier. As the giant drilling platform sank to the bottom, the riser pipe that had been carrying oil from a mile below the surface ruptured, and the oil from the ruined well began to gush from the pipe.
Coast Guard officials have acknowledged there will likely be important lessons to be learned by studying the mistakes they made in the aftermath of the massive explosion on the night of April 20.
For instance, Coast Guard officials told the Center for Public Integrity that while the service is well-equipped to mount search and rescue operations on the water, it lacks the expertise to fight a fire aboard an oil rig and did not even have ships in the area equipped to combat the blaze after the BP-operated rig exploded. That left the task of knocking down the conflagration to a group of private boats that answered the initial distress call, and the Coast Guard has yet to determine whether either those boats or the rig operator had access to fire-retardant foam, the preferred substance for combating an oil-based fire.
The Coast Guard's official maritime rescue manual – updated just seven months before the BP accident – recommends Coast Guard personnel avoid participating in firefighting aboard a rig. Instead, the manual requires Coast Guard responders to set up an "Incident Command System" and assign an expert, such as a fire marshal, to lead the efforts to extinguish the blaze.
But on April 20, the Coast Guard had little success coordinating the actual response, according to testimony gathered by the Coast Guard's joint inquiry with the Interior Department.
Kevin Robb, a civilian Coast Guard search and rescue specialist who functioned as the first watch commander the night of the accident, said at a May 11th hearing that there was no attempt by the Coast Guard Command Center to designate a fire marshal to coordinate the firefighting activities.
"Did you, sir, make any efforts on that first night when you responded to the Command Center to identify a certified fire marshal to oversee the firefighting efforts?" Robb was asked.
"No, sir, I did not," he answered.
"Are you aware of anyone else at the Coast Guard Command Center that made such an effort?
"No, sir, not to my knowledge.
"Do you know, if at any point, over the next several days there was ever any designation of an authority, a governmental authority to oversee or coordinate the firefighting effort for this rig?" Robb was asked.
"No, sir, I don't," Robb replied.
In fact, Robb told the investigative panel there were no Coast Guard boats capable of fighting the massive rig fire after it broke out the might of April 20. Within hours of the firefighting beginning, the rig began listing and eventually sank midday on April 22, Coast Guard incident logs show.
"The assets that were responding to this particular incident that night were basically search and rescue response assets. They were not firefighting assets," Robb told the Coast Guard inquiry in May 11, according to a transcript reviewed by the Center.
The captain of the Damon Bankston, a large private boat that helped rescue the majority of the rig employees, said neither he nor anyone else he knew coordinated the firefighting.
"I think it was a general response," Capt. Alwin Landry testified. The Transocean rig master captain and the first mate also reported little coordination of the firefighting efforts by their employees, whom they described as focused on trying to safely abandon the burning rig.
As vessels began trying to battle the blaze, they directed streams of gulf water onto the rig to try and knock down the flames.
Mobile Offshore Drilling Units (MODUs) such as the Deepwater Horizon stay afloat using a series of buoyancy chambers – large spaces filled with air and water from the ocean. The more water, or ballast, in a chamber, the lower on the water the rig will sit. An operator on the rig can adjust the water level to alter the height of the rig. But if the chambers swell with too much water, the rig could sink dangerously close to the surface of the water.
LaBrec said none of the Coast Guard ships sent to the explosion were equipped to fight a rig fire -- they focused instead on search and rescue. He acknowledged that spraying salt water onto a burning rig may have affected the ballast. "In the end it may really depend on what agent is available and in this case it appears it was salt water only," he said.
"We have expertise in fighting a fire on board our vessels, but since fire fighting is not one of our missions, we do not train for rig fires and that has really been the responsibility of the rig owner and operator," LaBrec said.
The chaotic, uncoordinated firefighting left Nguyen to openly question whether it contributed to sinking the rig.
"So what we're looking at here is maybe if there's no coordination out there, no direction out there, we may be throwing water onto a disabled vessel that may lead to this sinking; is that correct? Is that the potential?" Nguyen asked Robb. "If the firefighting efforts are not coordinated and we're putting water onto a disabled vessel, there's the possibility that no coordinated action may result in the sinking of the vessel? Is that correct, any vessel?"
"That is exactly correct," Robb testified.
Experts agreed that salt water can affect the balance of a rig but they disagreed whether it would have mattered in the case of the Deepwater Horizon, since the explosion was so severe.
Dr. Benton Baugh, president of the oil engineering firm Radoil , said it is possible that the seals that protect the buoyancy chambers failed, and that the massive amounts of water being used to put out the fire found their way inside.
"I and others have speculated that the access to the buoyancy chambers was compromised, potentially by heat, and the fire boats simply flooded the buoyancy chambers and caused the rig to sink," he told the Center.
Dr. Paul Bommer, a 25 year vet of the oil industry and now a senior lecturer at the University of Texas at Austin, thinks the rig was doomed by the fire, regardless of uncoordinated firefighting attack.
"I do not believe anyone thought they could put the fire out with foam or water – it was too big and too hot," he said. "Without putting the fire out – which was impossible – there was no way to save this vessel."
His belief is that the fire "simply melted away enough of the structure and support systems" on the rig, causing the buoyancy system to fail.
John Solomon and Aaron Mehta are reporters with the Center for Public Integrity, a nonprofit investigative journalism organization.
Matthew Mosk of ABC News contributed to this report.