A processing unit at the Phillips 66 refinery in Rodeo flared Monday night, producing a bright flame visible from some distance but causing no injuries, refinery officials said Tuesday.
The flare occurred when one of the refinery's processing units experienced a process interruption around 10:15 p.m., according to refinery officials.
There were no injuries and the refinery continues to operate, refinery officials said. An investigation will be conducted to determine what caused the flare. Flaring occurs when the refinery's safety systems vent and burn off excess gas.
"When there is material from the refining process that does need to be burned off, there's an environmentally approved manner in which we do it," Phillips 66 refinery spokesman Paul Adler said, noting that the county had issued only a Level 1 community warning for the incident, the lowest possible alert level.
Adler said the flare was still going Tuesday morning as the refinery continued to burn off excess material, but it was small and less visible in daylight.
Contra Costa Health Services officials said they have a team looking into the incident.