Chevron fire ignited by idling rig? Chevron workers barely escaped vapor cloud - more than 9,000 people sought treatment at ERs

Members of the Chemical Safety Board juggle photographs of the scene of the scene outside Chevron. Investigators from the federal Chemical Safety and Hazard Investigation Board discussed their early findings into the fire at the Chevron refinery in Richmond, Calif. Tuesday August 14, 2012. less Members of the Chemical Safety Board juggle photographs of the scene of the scene outside Chevron. Investigators from the federal Chemical Safety and Hazard Investigation Board discussed their early findings ... more Photo: Brant Ward, The Chronicle Photo: Brant Ward, The Chronicle Image 1 of / 12 Caption Close Chevron fire ignited by idling rig? 1 / 12 Back to Gallery

The Richmond refinery fire that sent more than 9,000 people to emergency rooms could have been touched off when a cloud of flammable vapor reached an idling and abandoned Chevron fire truck, investigators said Tuesday.

A company surveillance videotape that captured the two minutes before the blast showed that a dense vapor cloud fueled by the leak expanded to more than 200 feet wide and 200 feet high at the refinery's Crude Unit No. 4, surrounding as many as a dozen workers, who fled just in time.

"They were enveloped by a vapor cloud that later ignited when it found an ignition source," said Don Holmstrom, an investigator for the U.S. Chemical Safety Board, which is overseeing the fire investigation. The inquiry has involved 50 interviews and scrutiny of thousands of pages of documents.

Holmstrom noted that a possible source of ignition was the idling rig's diesel engine, but stressed that exactly what set off the cloud may never be known for certain.

Diesel engines have been tied to earlier refinery accidents, including the devastating 2005 explosion that killed 15 workers and injured scores of others at the BP refinery at Texas City, Texas. That accident occurred when an idling diesel pickup truck drew in flammable hydrocarbon vapors and exploded, hitting trailers full of workers.

Narrow escape

The source of the vapor plume at the Richmond refinery is believed to be an 8-inch pipe carrying super-heated hydrocarbons from the crude unit to be cooled and processed into fuel elsewhere in the facility. Repair crews were at the scene to assess what was assumed to be a minor leak in the pipe and narrowly escaped death in the Aug. 6 explosion and fire, investigators said.

Key lines of the investigation are the decision to leave the crude unit in service after the leak was discovered and the determination last fall that the 40-year-old, 8-inch pipe could be safely left in service even while a companion line was replaced because of corrosion, said Daniel Horowitz, managing director of the Chemical Safety Board.

The Chronicle reported Tuesday that Chevron considered but rejected replacing the 8-inch line last year and judged it safe for five more years. The company has said it is premature to comment on that decision, but investigators said the decision was a fateful one.

"This line was not replaced," Horowitz said. "We are very much interested in understanding the decision about why to keep this line in service - I'm sure that everybody wishes that decision might have turned out differently."

The inquiry has been hampered by limited access to the site. Investigators wearing respirators are not able to come closer than 10 feet from the ruptured pipe because of structural safety concerns. They have taken several photographs of the rupture site that show the cracked line that peeled open before the fire.

9,000 seek treatment

Earlier in the day, Contra Costa County health officials announced that more than 9,000 people have sought emergency room medical attention for breathing problems and other health issues that might be related to the fire.

While earlier reports indicated no one had been admitted to a hospital, officials said it now appears that two or three people were hospitalized, including a girl who was admitted to Children's Hospital Oakland after reporting her asthma was made worse by smoke.

Dr. Wendel Brunner, director of public health for Contra Costa County, said many people were sickened by particulate matter in the smoke - those levels are still being studied by regional air quality regulators.

Brunner's report to the county Board of Supervisors came as a local environmental advocacy group said that it had been invited to join an investigation of the fire.

The group, Communities for a Better Environment, said it will take part in an analysis required by overlapping industrial safety ordinances in Contra Costa County and the city of Richmond.

Greg Karras, a senior scientist with the group, said the county and city invited his group to participate in part to assure a "truly independent investigation."

His group will receive updates from local, state and federal agencies, he said, adding that an independent analyst also will be hired by Richmond, and compensated by Chevron, to review the findings.

One issue will be the extent of the pollution and fallout from the fire.

"Our bodies measured what the government's grossly inadequate air monitoring missed: The community is the real expert on what Chevron's crude unit fire did to us," Andrés Soto, a Richmond organizer for the group, said in a statement.

In the days after the fire, thousands of people complained of eye, nose and throat irritation as well as wheezing, headaches and nausea.

Exposure levels

The Bay Area Air Quality Management District initially said its testing found no toxic contaminants above the state's "reference exposure levels," meaning no adverse health effects would be anticipated.

But the agency later reported that one air sample showed an elevated level of acrolein, which can cause skin, eye and respiratory tract irritation. The agency said the amount of acrolein - though violating state standards - was within a range typically seen in the Bay Area.

Brunner and Randy Sawyer, the county's chief environmental health and hazardous materials officer, plan to give supervisors another update next week.

Sawyer said Tuesday that the county system that warns residents to stay indoors through automated telephone calls worked poorly, and that it was possible the vendor, CityWatch of Bloomington, Minn., would be replaced.

"It was not what we were expecting and not up to our standard," Sawyer said. "We're getting people who are saying they can do it much faster."

While the phone calls began right away, he said, the system took more than three hours to make 18,000 calls to people in a section of Richmond close to the refinery. The county believes the system should be able to make 30,000 calls in an hour, Sawyer said.

Calls to officials at CityWatch were not immediately returned.