A second release of hydrocarbon at the Valero refinery in Benicia Thursday night was a deliberate "safety mechanism" because of high temperature readings in a furnace, Valero spokeswoman Susan Fisher-Jones said this morning.
The steam cloud containing hydrocarbons was released at 8:50 p.m. and an "all clear" was sounded at 9:22 p.m., Fisher-Jones said.
The release was in the same area as a hydrocarbon release at 10:10 a.m. Thursday but the two releases are unrelated, Fisher-Jones said. The cause of the high temperature readings in the furnace is under investigation, she said.
Two employees and four contract workers in the vicinity of the morning release suffered minor injuries and three other contract workers in another area of the refinery reported throat irritation, Fisher-Jones said this morning.
No injuries were reported in the second release, she said.
The morning incident was due to a leak in a unit that creates a product that eventually is made into charcoal briquettes, Fisher-Jones said.
The product, known as "petroleum coke," mixed with steam to create a dark cloud, she said.
Neither release had any impact on the community, Fisher-Jones said.
Benicia Fire Department Battalion Chief and Fire Marshal Ray Iverson said the second release drew a two-alarm response from the fire department.
A "miscommunication" also activated sirens as part of the Community Alert Network that informs residents of a release at the refinery and advises them to tune in to local radio and television stations for news about the release, Iverson said.
There was no shelter-in-place order in Benicia for either incident but the fire department was flooded with 911 calls Thursday night, Iverson said.
The fire department and city officials are re-evaluating whether that is the best way to notify the public of hydrocarbon releases at the refinery, Iverson said.
Another option is a reverse dialing system to inform residents by phone, he said.