Category Archives: Benicia Fire Department

Valero Benicia Refinery closes investigation of ‘Hydrogen Sulfide Saturday’ – but Benicians are still waiting for answers

[Note from BenIndy: Valero’s 30-day report on the February 24 hydrocarbon spill, which was categorized as a “Level-3” incident due to the potential threat to human health, raised yet more concerns about the refinery’s promptness and openness in notifying the City and its residents of hazardous events. If liquid hydrocarbon was detected on Tank 1738’s roof at 4:13am, why was the City not informed “immediately,” as required by its 2019 Cooperation Agreement with Valero? What does “immediately” even mean, in this context? Questions about Valero’s emergency management and dedication to safeguarding the community, particularly when considering the health risks posed by hydrogen sulfide exposure, certainly linger. Additionally, Valero’s tweaking of the spill’s reported volume – which could be 83 or 35 gallons, depending – spotlights why enhanced regulatory oversight and wide-spanning improvements to notification requirements should be an urgent priority of the refinery, its regulators, and of course the City of Benicia. Once again, we urge readers to check out to learn more about the City’s push for an Industrial Safety Ordinance from the perspective of its supporters.]

Valero Benicia Refinery releases cause of Feb. 24 incident, closes investigation

Valero’s Benicia Refinery. | Pat Toth-Smith.

Vallejo Times-Herald, by Lynzie Lowe, March 24, 2024

The Valero Benicia Refinery released its required 30-day report on Monday to provide additional details about the Feb. 24 releasing of a foul odor into the city of Benicia, and announced that the investigation has been officially closed.

The incident began on Friday, Feb. 23 when a gas turbine in the Benicia Refinery Fluid Catalytic Cracker Unit tripped, causing an emergency shutdown procedures and rerouting to “slop system” tanks to take place. During this process, Tank 1738 was turned off at approximately 4:13 a.m. Feb. 24 after it was discovered that there was some liquid hydrocarbon on the roof of that tank.

By 5:30 a.m. the next morning, the report noted that the Benicia Refinery Fence-line monitors detected Hydrogen Sulfide above background levels Southwest of the Refinery that was accompanied by the signature odor of H2S, which accounted for the rotten egg smell that was present throughout the city of Benicia at that time.

“Refinery Operations began investigating the source of the odor and identified hydrocarbon on the roof of Tank 1738 at approximately 4:13 a.m. (Feb. 24) as the source,” read the report. “… Cleanup efforts began at approximately 1 p.m. and refinery personnel continued to clean material off of the tank roof until the majority of the material had been removed and there was insufficient daylight to continue. At the time the work stopped, odors were no longer being detected beyond the refinery fence-line. Operations resumed the next morning to continue spot cleaning the residue on the tank roof and cleanup was completed on Monday, Feb. 26.”

Refinery officials said their initial report estimated that there was approximately 83 gallons of refined hydrocarbon material.

“However, based on visual accounts from the personnel overseeing the cleanup of the material, it was noted that the material on the roof was a very light sheen and the roof of the tank was still visible through the sheen, indicating it was a very thin layer of liquid hydrocarbon,” read the report. “Based on the information on the sheen thickness and the area of the roof that had material, the estimate was revised to be approximately 35 gallons of hydrocarbon material. The bulk of the material removed from the roof was rainwater.”

According to the report, an investigation team – composed of managers, engineers and hourly operators from the facility – was formed two days after the incident occurred to determine the root cause and recommend corrective actions for the Feb. 24 event.

“Data was gathered from multiple sources, including equipment monitoring trends and accounts from personnel involved in the incident,” read the report.

According to the report, the investigation identified that the floating roof on Tank 1738 had slightly tilted, and was most likely caused by vapors entering the tank.

“The investigation team looked at the various sources of slop material that were routed to the tank during the event to identify potential sources of lighter hydrocarbon materials to the tank,” read the report. “From those potential source streams, there was insufficient data for the team to identify which stream was the conclusive source of the vapors.”

The investigation team did, however, determined that the volume of material on the roof was likely not significant enough to cause offsite impacts, and therefore a vapor release from the tank was suspected to have occurred.

“The investigation team also considered the possibility of other sources as the cause of the odor, but evidence from refinery fixed H2S monitors and the wind direction during the event provided evidence that the tank was the source of the odor,” read the report.

Because the investigative team believed that light hydrocarbon materials vaporized in Tank 1738 causing the roof tilt and atmospheric substances to be released, the Refinery will schedule a meeting on or before Sept. 30 with the City of Benicia and Solano County Certified Unified Program Agency to develop engineering solution for the potential slop sources and options for monitoring and alarms, procedural options, or other means to reducing potential for vapor carry under to tankage and to implement engineering solutions.

Further actions on how to proceed with corrective action will be discussed and acted on at that time but the investigation into the incident has now been closed, according to Refinery officials.

Other reporting on this recent refinery incident:

Benicia Herald columnist Stephen Golub’s questions about Valero’s ‘Hydrogen Sulfide Saturday’

Benicia resident and author Stephen Golub.

By Stephen Golub, first appearing in the Benicia Herald on March 1, 2024


By the way, a big thanks to Benicia Fire Chief Josh Chadwick and our Fire Department for their efforts to alert Benicians about Saturday’s incident at the Valero Refinery, particularly since it resulted in the release of the dangerous neurotoxin Hydrogen Sulfide (H2S) into our air. While, as suggested below, the incident and the reporting more than ever demonstrate the need for an ISO, those efforts are nonetheless appreciated.

Thanks, too, to the Valero personnel who labored to clean up that mess, perhaps at risk to their own health. Of course, this does not let the Valero refinery or the corporation’s Texas headquarters off the hook for this dangerous event  – or for many other accidents and violations. But the workers who work to mitigate such harm merit praise. In fact, an ISO could benefit them as well as the rest of us.

So far, based on some very good reporting by Benicia Herald editor Galen Kusic and other sources, we have some initial knowledge about what happened. But dozens of questions remain.

For now, I’ll just address a few questions mainly raised by Kusic’s February 28 article and data shared by the Benicia Community Air Monitoring Program (BCAMP), a local non-profit that (as its website states) “has been established to monitor local air quality in real-time, operate a website, and provide education on health as related to air quality.” (For more information on BCAMP, here’s the group’s site:

  1. As Kusic’s article states, “It isn’t clear as to why alerts went out at 7:40 a.m. when H2S was discovered on Tank 1738 at 6:08 a.m. and H2S was detected in the air as early as 4:30 a.m.” In fact, as noted by BCAMP, Valero’s own monitoring system indicated alarming levels of H2S in the air as early as 4 a.m. And BCAMP data indicates a spike in H2S hours earlier than that.

So why the delay in alerting the public?

  1. What’s more, the current (and quite weak) City of Benicia – Valero Cooperation Agreement incorporates the requirement that the Benicia Fire Department must be notified immediately if there is a release or a threatened release of a hazardous substance that could harm people’s health. It certainly does not sound like Valero provided immediate notification – which to my simple mind, means as soon as possible.

Why was that the case?

  1. As stated in the Herald article, when asked about the delay, “Valero Benicia Refinery Director of Community Relations and Government Affairs Paul Adler responded, ‘In order to answer your first question, I suggest that you review the Public Information website along with that policy which defines the requirements of notifications.’”

I don’t know about you, but I’d prefer a straightforward answer to a straightforward inquiry about an urgent public health matter, rather than being shunted off to a website.

Why not provide that?

  1. Did the first information the Fire Department received about the incident come from the public reporting the “rotten eggs” odor of H2S in the air or from Valero? And if not Valero, why was that the case?

5.  BCAMP data reported an alarming spike in H2S in the air during the late afternoon on Saturday, supposedly after the worst of the incident had passed. Were we safe at that time?

I’ll note that I know one individual whose asthma was apparently greatly aggravated by this incident (though this is not a matter of medical certainty) and two others who reported feeling ill, all on the west side of town. Not scientific proof of danger, but not something to be ignored.

Again, these are just a few questions prompted by Valero’s release of H2S on Saturday. Coming on top of many Valero violations and other incidents, they point to the need for a far stronger way of protecting the safety and health of our kids, our seniors and our entire community. We can start by showing support for an ISO at the City Council meeting on March 5.

Other reporting on this recent refinery incident:

Benicia Herald on Valero Refinery spill of toxic Hydrogen Sulfide

[Note from BenIndy: The Benicia Herald  does not have an online edition but this Wednesday, February 28 article by Galen Kusic, editor, represents the best and most complete coverage of the Valero incident last weekend, including reactions from local representatives for Valero and our own elected officials. Supporting local journalism is crucial for ensuring communities are informed and facilitates transparency and accountability during important local events like this one. You can subscribe to the Herald by email at or by phone at 707-745-6838.]

Benicia Valero Refinery spill of hydrocarbon releases Hydrogen Sulfide; odor smelled throughout Benicia

Valero’s Benicia Refinery on January 25, 2024. | Galen Kusic.

By Galen Kusic, Editor, The Benicia Herald, February 28, 2024

On Sat. Feb. 24 at 7:40 a.m., the City of Benicia reported that Benicia Fire Department was working with the Benicia Valero Refinery “on mitigating an odor coming from the refinery.” The source, which was reported as “refined hydrocarbon” was actually Hydrogen Sulfide (H2S), a dangerous neurotoxin.

According to the mandatory 72-hour report provided by Valero Benicia Refinery, between 5:30 and 6 a.m., Benicia Dispatch informed Valero of three odor complaints, and the Refinery received two inquiries related to odors smelled in the community. Residents noticed the strong odor throughout Benicia ranging from neighborhoods near Southampton, First St. and the lower east side.

As stated in the report, refinery operations began investigating the source of the odor and identified hydrocarbon on the roof of Valero Refinery’s Tank 1738 at approximately 6:08 a.m. Valero activated the Emergency Operations Center (EOC) around 7:48 a.m. and cleanup efforts began at approximately 1 p.m. Prior to the event, refinery operations were following emergency shutdown procedures to safely posture a unit that included transferring material to Tank 1738. The bulk of the material on the roof of the tank, currently estimated to contain less than 83 gallons of refined hydrocarbon, was removed by Sat. evening.

Levels of H2S spiked between 5:30 and 8:30 a.m., with levels reaching a maximum five minute average around 400 ppb (parts per billion) and a maximum one hour average around 142 ppb, according to data from the refinery’s fenceline website at

“It was a very low level,” said Benicia Fire Chief Josh Chadwick. “Dangerous levels are at 50,000 ppb and we start to get concerned at 1,000 ppb.”

To put that in perspective, those numbers are more than twice the level Centers for Disease Control and Prevention lists as an acute Minimum Risk Level (MRL) of 70 ppb over an hour period. The Reference Exposure Level (REL) determined by California Office of Environmental Health Hazard Assessment (OEHHA) for H2S is 30 ppb over an hour period.

In the report it states, “A REL is an airborne concentration level of a chemical at or below which no adverse health effects are anticipated for a specified exposure duration. RELs are based on the most sensitive, relevant, adverse health effect reporting in the medical and toxicological literature and are designed to protect the most sensitive individuals in the population by the inclusion of margins of safety.”

Two separate flaring incidents at Valero were reported by Benicia Fire Department on Feb. 18 at 12:39 a.m. and Feb. 23 at 8:30 p.m. Ongoing intermittent flaring that exceeded the 500 lbs. Sulfur Dioxide (SO2) reporting threshold occurred as part of the unit shutdown. According to Valero, the flaring did not contribute to the community odors.

After detecting the odor, Valero provided communication to the City of Benicia and other appropriate agencies and cleanup efforts were initiated to abate the odor. The City of Benicia Fire Department responded as a member of the EOC and also conducted air quality testing using their portable air monitors at multiple points throughout the City. Refinery personnel continued to clean off the material also referred to as “slop” from the tank roof until there wasn’t enough daylight to continue.

The refinery continued to spot clean the remaining residue on the tank roof and expected to have that activity completed by Mon. evening. Samples are being taken of the containers that are holding the material removed from the roof to obtain a more accurate estimate on the amount of oil.

“The strong smell has dissipated,” said Chadwick. “There is currently no health hazard.”

An investigation is underway to determine how the hydrocarbon material got onto the tank. A summary of the investigation will be provided to the Fire Chief once it is completed. Chadwick estimates the investigation can take up to a month.

Valero Refinery is also required to submit a 30-Day Investigation Report with root cause analysis. The 30-Day report will be posted publicly when available. In addition, Solano County Environmental Health will work in conjunction with the City of Benicia to perform a full incident investigation report that will also be released publicly.

It isn’t clear as to why alerts went out at 7:40 a.m. when H2S was discovered on Tank 1738 at 6:08 a.m. and H2S was detected in the air as early as 4:30 a.m. When this question was posed to Valero Benicia Refinery Director of Community Relations and Government Affairs Paul Adler, he responded.

“In order to answer your first question, I suggest that you review the Public Information Bank website along with that policy which defines the requirements of notifications,” he said.

In the Valero Cooperation Agreement, it states that “immediate notification is required in all Level-1 through Level-3 incidents. This was categorized as a Level-3 incident, but nowhere in the agreement does it describe what actual time frame constitutes “immediate notification.”

While the City noted in an update on Sat. evening that the smell was dissipating, driving by the Valero Refinery at 1:30 p.m. on Mon. on I-680 the smell was still strong. According to the City, Solano County Public Health only recommended to shelter in place if the odor smell was too strong and/or if it was “aggravating.”

When asked about further updates on Sun., Mayor Steve Young responded, “I don’t sorry,” but noted that he was meeting with Chadwick and City Manager Mario Giuliani on Mon.

“Hopefully I will have more information then,” he said. Young did not respond for further comment by press time Tue.

There were no injuries associated with the event, and no reports of offsite injuries or property damage have been reported.

Other reporting on this recent refinery incident:

Weekend odor in Benicia caused by mechanical issue at refinery

[Note from BenIndy: You may be wondering why we’ve been slow to report on this incident at the Valero Benicia Refinery when usually we’d be all over it, and well ahead of the game at that. In this case there was a need elsewhere, in the form of helping the good folks in the Benicia Industrial Safety and Healthy Ordinance Working Group (BISHO) put a website together to generate more interest and community engagement in pursuit of Benicia adopting its own industrial safety ordinance. We regret the sparse coverage of this important incident at the Valero Benicia Refinery, but hope you understand that those of us keeping the BenIndy going are also active in service to delivering the brilliant, overarching goal of meaningful City and community oversight over heavy industry in Benicia. Please forgive this lapse in our coverage, and take a minute to review the website. If you are interested in these matters, please sign up using the contact forms on that website. Also, don’t forget to sign up for future incident alerts at]

Valero Benicia Refinery file photo. | Paul Chinn / SF Chron.

Vallejo Times-Herald, by Lynzie Lowe, February 26, 2024

The Valero Benicia Refinery informed the Benicia Fire Department on Friday of an unanticipated mechanical issue, which released refined hydrocarbons that caused a strong odor throughout the city of Benicia over the weekend.

When the unit went down, officials said it was necessary to immediately move the product inside into another tank.

“It was discovered that in the process of moving the product, some of it got on the lid of a tank and that was the source of the strong odor,” read a release issued by city officials on Saturday. “There is no specific name for the product; it is a mixture of refined hydrocarbons similar to a light oil. The chemical vapor in the air causing the odor is H2S, hydrogen sulfide. The odor has dissipated significantly in most parts of Benicia.”

Della Olm, Management Analyst and Benicia Fire Department Public Information Officer, said, as of Monday morning, the spill on the tank lid is almost cleaned up and is expected to be completely mitigated by the end of the day Monday or Tuesday morning.

City officials said the Benicia Fire Department has been in continuous communication with Solano County Public Health, who has recommended to only shelter in place if the odor smell was too strong and/or it was aggravating. The Benicia Fire Department staff were also activated at the Valero Emergency Operations Center over the weekend.

“The refinery is flaring intermittently due to the unit shut off on the evening of February 23,” according to a press release. “Intermittent flaring will continue for an undetermined period of time.”

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Other reporting on this recent refinery incident: