About 34,000 pounds of hydrogen sulfide leaked from a Richmond Chevron refinery flare stack two weeks ago, causing a rotten egg smell that blanketed parts of west Contra Costa County, according to newly released details from the oil company.
In a statement emailed to Richmondside on Thursday, Chevron spokesperson Caitlin Powell said that, in addition to the hydrogen sulfide, just over 1,600 pounds of ammonia was also released. The thousands of pounds of chemicals were released over a 42-hour period on Oct. 22.
“We understand the concern that Richmond residents raised about the odor reported October 22. Chevron has been cooperating with regulatory agencies and engaging with community members since the event,” Powell wrote. “We are committed to sharing information.”
A few days after the release, the Contra Costa County Hazardous Materials programs upgraded the incident from a Level 1 to Level 2 event, changing its classification to a “major chemical accident or release.”
The Bay Area Air District also issued Chevron a notice of violation for public nuisance.
Because of this upgraded classification, Chevron must now do a “root cause analysis,” which the company said is underway. The report is due within the next month.
Contra Costa County uses a four-tier community warning system. The potential health impacts to residents differ between the first two levels, with the main difference being that Level 1 has no public health impact and Level 2 may impact the health of “sensitive populations.” How the community is notified is also different. Level 2 alerts must be sent to all residents via a phone notification.
Sources with knowledge of the refinery’s response the night of Oct. 22 told Richmondside that it was “hours” before refinery operations realized that the refinery was the source of the odor.
In total, the Bay Area Air District received 226 complaints about the smell and said that hydrogen sulfide readings at a Chevron air monitor near Castro Street went from about 3.5 parts per billion (ppb) to nearly 500 ppb. The current standard set by the California Air Resources Board is 0.03 ppm for a one-hour average.
“We are committed to learning from this incident and strengthening safeguards against similar events in the future,” Powell wrote.
