Residents in Richmond were alarmed Sunday night at the sight of flames shooting into the sky at the Chevron oil refinery.
Social media lit up with reports of a fire, but Chevron said it was "normal" flaring that occurs during the refining process. Witnesses said the latest flare lasted from before sundown until about 10pm and sent a plume of smoke into the air.
Chevron spokeswoman Leah Casey said the flare was a result of an "upset" in one of the hydrocracking process units.
Casey said the flare was not part of scheduled maintenance and came in response to a build up of pressure within the hydroprocessing unit.
"There was initial flaring, then a pause for a while. It looked pretty severe because of the timing, the smoke against the sunset," she said. "Although it looked alarming, our air quality monitoring systems showed emission levels within the safe range."
Richmond Hills resident Matt Renner said he saw flames shooting in the sky and saw a big, black cloud of smoke blowing in his direction.
"It's not supposed to happen. They're not supposed to just burn off chemicals and polllute the sky," he said. "It felt like the world was ending. The refinery is blowing up, the Warriors lost."
"Although the sight of the flare may cause concern, we want to assure our neighbors that occasional flaring is an important part of keeping the refinery running safely," the statement said. "Flares are a safety device used in refineries to relieve pressure during the refining processes and help keep our equipment and plants operating safely."
The hydroprocessing unit removes impurities like sulfur and nitrogen and heavy metals. It also uses catalysts breaks down larger hydrocarbon molecules into fuels for gas tanks, diesel engines and jets.
California refineries are required to report hazardous materials emissions to the governor's Office of Emergency Services where preliminary information is recorded in a database.
One report filed Sunday said hydrocarbons were being released into the atmosphere but promised that the situation would stabilize soon. Another report, filed more than 3 hours later, described a release of black smoke and reported a flare caused by the depressurized hydroprocessing unit.
The Contra Costa Co. Health Department's hazardous materials division has asked Chevron to file a report within 72 hours because the incident was visible from off-site.
The refinery must file another report on the cause of the flare within 90 days to the Bay Area Air Quantity Management District, which could find a violation of air quality rules and impose fines for the incident.
The oil giant encouraged concerned residents to visit www.fenceline.org/richmond to view real-time air quality data and call 510-242-2127 for any odor concerns.
— AMAZON WATCH (@AmazonWatch) June 20, 2016
— Andy Donohue (@add) June 20, 2016
— Jeremy Miller (@JeremyJ_Miller) June 20, 2016
Watching a fire at the Chevron Richmond Refinery from my house pic.twitter.com/mVnp7N7A8i
— Emma Fern Colner (@meemameemameema) June 20, 2016
— Josephine M. (@Honigdachschen) June 20, 2016