A small flash fire burned and was extinguished about 13 minutes before the Chevron Richmond refinery 4 Crude Unit caught fire on Aug. 6, the company said.
Chevron's report also explained the white cloud that formed above the refinery around 6:28 p.m. "A significant amount of water was being applied on scene and considerable steam was created," the report says. "Because the white cloud did not ignite we have questions about its composition."
Chevron has its own experts who are working to determine the cause of the incident, so we should know more soon.
Meanwhile, here are some highlights from the report:
Chevron's timeline of events
After noticing a major surge in the leak release around 6:25 p.m. the order was given to shut down the unit. At 6:32 p.m. the fire ignited, and at 6:35 p.m., Chevron warned the community of a Level 3 alert. Support was called in from surrounding fire departments, and shelter-in-place orders were issued for neighboring communities. At 11:30 p.m., Contra Costa Health Services lifted the shelter-in-place order. However, Chevron does not state what happened between 6:22, when the small fire was extinguished, and 6:24 p.m.
Air quality is okay
Chevron monitored air samples in 19 downwind locations. These samples were checked for sulfur compounds and hydrocarbons, and were conclusively below the exposure levels set by California Environmental Health Agencies. Concentrations of hydrogen sulfide, sulfur dioxide, and carbon monoxide were also below detection limits. However, there was an evident spike in sulfur dioxide released from the fire.
As of Aug. 28, 21,200 claims have been filed
According to the report, hundreds of nearby residents flooded local emergency rooms after the fire sparked, but only three individuals were admitted to the hospital. Most cases were described as "minor." That said, Chevron "intends to compensate affected community members with valid claims."
Chevron will continue to provide updates as it investigates what caused the refinery fire.