State workplace regulators launched an investigation Monday into a malfunction at Chevron’s Richmond refinery over the weekend that led to the evacuation of a crew doing maintenance work at the facility.
A Chevron spokeswoman said one of the refinery’s process units experienced a problem Saturday morning.
“As part of the refinery’s safety protocol non-operational workers were temporarily evacuated and agencies were notified,” Chevron’s Amy Mosley said.
The plant was later deemed safe and the workers returned, Mosley said.
The company has not responded to questions about the specifics of Saturday’s problem, but in a brief filing with the Governor’s Office of Emergency Services, the company said that a system that controls the release of gas “was overwhelmed” because of an “upstream plant upset.”
Chevron’s report to the state said that “non-critical workers” were evacuated. It says that the incident may have led to the release of at least 500 pounds of sulfur dioxide, a pollutant that can cause respiratory problems.
The workers who had to leave the facility were contractors performing maintenance work, according to Randy Sawyer, Contra Costa County’s chief environmental health and hazardous materials officer.
Sawyer said the contractors were doing work on the unit that malfunctioned. He said one of the workers experienced some sort of medical problem a couple hours after the initial episode and that the problem “seems to be unrelated” to the refinery incident.
Two elected officials who represent the area of the refinery, Richmond Mayor Tom Butt and Contra Costa County Supervisor John Gioia, said they were not told about the incident.
“I’m surprised I was not made aware of this,” Gioia said in an email Monday.
Despite the fact that no refinery workers were seriously injured, California’s Division of Occupational Safety and Health has launched a probe into the incident, according to agency spokesman Frank Polizzi.
In the last two years Chevron’s Richmond refinery has experienced a spike in incidents in which the facility is forced to burn off excess gases because of operating problems.
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