A clogged pump line in the refinery and a communication breakdown between workers at the Chevron refinery in Richmond, CA, were the causes behind two separate releases of toxic gas into the region in December, company officials said.
In December, San Francisco residents reported a sulfuric, rotten egg stench wafting through the city for two days in a row last December.
After PG&E received numerous calls from San Francisco residents on December 28 and 29, air quality officials began investigating two separate incidents at the Chevron refinery.
The county’s chief environmental health and hazardous materials officer maintains neither report actually explains why high levels of hydrogen sulfide ended up measured near the facility.
The first malfunction started at 11:45pm December 27 when a line that empties a tank, also known as a “liquid knockout drum,” became clogged. The company did not disclosed what caused the clog.
The second incident, the result of a human error, occurred 16 hours later. A compressor that restarted after a maintenance shutdown began malfunctioning because it had nothing to compress. The compressor was then shut down again for more than three days.
Both incidents activated the refinery’s flaring system.
PG&E received 54 calls from San Francisco residents after the first incident, and 15 calls after the second. Most of the calls came from neighborhoods near the waterfront, including Bayview, the Marina, the Outer Sunset and Richmond, as well as SoMa.
Randy Sawyer, Contra Costa County’s chief environmental health and hazardous materials officer, said despite the reports, Chevron officials told his office they are still investigating what caused the company’s air monitors in Point Richmond to detect an “abnormally” high amount of hydrogen sulfide.
Contra Costa County officials are not the only ones investigating December’s stink. In January, District 2 Supervisor Mark Farrell called for a series of hearings with Chevron executives. The Bay Area Air Quality Management District is also conducting its own investigation.
In the meantime, Chevron’s reports said the company has asked contract workers to stick to company standards when installing devices at the refinery. The company also plans to look into possible upgrades to the Richmond refinery’s alarm systems.