A problem at Valero’s Benicia, CA, refinery suddenly worsened last weekend, leading to a release of petroleum coke dust that prompted fire officials to urge those with respiratory problems to stay indoors.
The incident led to a partial shutdown at the facility and brought state workplace regulators, the region’s local air quality district and Solano County health officials out to investigate why this occurred.
The releases of elevated levels of particulate matter led residents to complain of breathing problems and prompted Benicia’s mayor to call on Valero to pay the city back for its work dealing with the emergency.
Mayor Elizabeth Patterson said in a KQED report she’s gotten a flood of phone calls and emails from residents wanting to know why it took so long for Valero to suspend refinery operations.
California’s Division of Occupational Safety and Health began a probe into Valero March 25, the day after the company began the gradual shutdown of a significant portion of the refinery, said agency spokesman Frank Polizzi.
Cal/OSHA becomes the latest government agency to look into the breakdown of a key piece of equipment inside the refinery that went down two weeks ago. The Bay Area Air Quality Management District and Solano County officials have launched probes as well.
On March 11, the facility’s flue gas scrubber began malfunctioning. That meant the facility’s smokestacks began emitting a sooty plume of petroleum coke dust — minute carbon particles that are a byproduct of the oil refining process.
The initial problem prompted the Bay Area Air Quality Management District to issue eight notices of violation against Valero.
The air district and Solano County health officials said during the following days the flue gas scrubber had been fixed and the coke dust releases were intermittent and gradually coming to an end.
But the black smoke returned on Saturday. On Sunday, fire officials detected high levels of fine particulate matter, known as PM10, around the refinery and issued a health advisory urging people with respiratory issues to stay indoors.
“What we were seeing was dark gray, almost black smoke coming from the flue gas scrubber unit,” Benicia Fire Chief Josh Chadwick said Monday.
The EPA has said that once inhaled, petroleum coke dust can affect the heart and lungs and cause serious health effects.
It’s unclear why the flue gas scrubber began malfunctioning again.
Terry Schmidtbauer, Solano County’s assistant director of resource management, said his department’s investigation is focused on the scrubber unit, other refinery components that interact with the device and if refinery workers made a mistake in operating the unit.
It’s also uncertain how long it will take to shut down the affected parts of the refinery and how long that closure will last.