Idling engine may have set off BP explosion
Witnesses claim the driver tried to turn off the truck during vapor vent
The truck may have provided the spark for the explosion that killed 15 workers, although investigators with the U.S. Chemical Safety and Hazard Investigation Board say they are not ruling out other possibilities.
"Witnesses saw vapor in the area of the truck and observed the engine begin to rev up or race," said Investigation Manager Bill Hoyle in a statement. "This behavior by a diesel engine indicates the presence of a flammable atmosphere entering the air intake."
Investigators were expected to get into the blast site on Thursday, but were held up for several reasons.
Occupational Safety & Health Administration officials said the delay was initially caused by a morning review of the data from a leaking benzene tank that had been covered over by foam the night before.
Later, entry onto the site was prevented by last-minute negotiations over how evidence would be gathered and preserved.
By the end of the day, the so-called Evidence Preservation Protocol was signed by the three parties, BP, CSB and OSHA.
Under the agreement, an independent third party will photograph and videotape all entries into the blast site, oversee the tagging and collection of evidence, and ensure a secure location.
All the parties will have a chance to identify and request items to be retained and tagged. Access to the evidence will be controlled by CSB, OSHA and BP.
Investigators for attorneys representing injured and deceased workers will not be allowed to follow OSHA onto the site, as they had originally hoped, and will only be able to view the site after that agency's investigation.
"We did not want a lot of people entering in the safety area," an OSHA official said. "We want to do our walk-through first. More importantly, we didn't want evidence disturbed."
That same OSHA official confirmed Thursday that EPA investigators were at the plant, but it had not been classified a crime scene.
John McEldowney, an attorney representing some of the plaintiffs, said their hired experts have undergone training to enter the site if permitted and were standing by on Thursday.
"We are trying to be as unobtrusive as possible but still try and have someone there to observe the scene," McEldowney said.
Investigators have not been able to enter the blast site since they arrived on the scene late last week. BP and OSHA made a joint decision to prohibit access to the blast site on Thursday and Friday of last week because a safety assessment of the site had not been completed, according to BP officials. There were concerns about asbestos, tripping hazards, falling debris, the stability of structures and passageways and the possibility of other combustibles.
On Friday, contractors working for EPA detected benzene in the air at the plant, providing another reason for keeping people far from the site. It was determined a tank near the blast site was damaged and leaking.
BP started to make repairs to contain the leak on Tuesday and by Wednesday night had put down a layer of foam on top of the damaged tank.
BP officials said they are conducting their own investigation focusing on many of the same issues as OSHA and CSB, including the maintenance and restart of the isomerization unit and placement of temporary offices near the site.
BP America Group Vice President John Mogford said in a statement the company expects to complete the fact-finding phase next week, after which it will turn over copies of all the data to the government agencies.
Chronicle reporters Kevin Moran and Mary Flood contributed to this story.
tom.fowler@chron.com dina.cappiello@chron.com terri.langford@chron.com
Witnesses say a truck was idling near the scene of an explosion at a Texas refinery which killed 15 and injured over 100 others on March 23, according to U.S. Chemical Safety and Hazard Investigation Manager Bill Hoyle.

"Witnesses saw vapor in the area of the truck and observed the engine begin to rev up and race," Hoyle's statement said. "This behavior by a diesel engine indicates the presence of a flammable atmosphere entering the air intake. A driver reported trying to shut off the engine but was unable to do so." Hoyle's statement continued, "There are multiple possible sources of ignition in an operating refinery unit and we have made no determination about the ignition source at this time."

The investigation has been delayed by BP and Occupational Safety & Health Administration officials, who are trying to preserve evidence at the site for their investigation. They are also concerned about further injuries from hazards left over from the explosion, such as falling debris and unstable structures. The Environment Protection Agency also detected benzene in the atmosphere over the plant, which was treated with a layer of foam.

BP has retained control of the plant since the March 23 accident. Police arrived quickly the day of the explosion, but left after the initial emergency was over.

"Our officers could respond over there, but they don't have a clue," Texas City police Sgt. Curtis Pope told the ''Houston Chronicle''. "The fact is they have chemical and equipment hazards. We don't know the chemicals."