[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 beniciacirculation@gmail.com or by phone at 707-745-6838.]

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

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 www.beniciarefineryairmonitors.org.

“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, Vallejo Times-Herald, February 27, 2024
• Valero Benicia Refinery incident causes ‘strong odor’ in city. | ABC10 Bay Area, February 24, 2024
• Benicia Fire Department announce an odor is coming from Valero Refinery | Vallejo Times-Herald, February 24, 2024
• Odor from Valero Refinery noticeable to residents in nearby Benicia | KTVU, February 24, 2024