This is an archived article that was published on sltrib.com in 2012, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Chevron Corp. had a process unit upset at its Salt Lake City oil refinery earlier this week after a backhoe hit a flare header and forced an area of the plant to evacuate, according to state regulators.

Chevron notified federal and state regulators of the upset at the 49,000-barrel-a-day refinery over concerns the incident may have resulted in the release of hydrogen sulfide, Sean Comey, a company spokesman said.

"There was no release of H2S due to the upset, all personnel are accounted for and safe, and refinery operations continue," said Comey, based at the company's headquarters in San Ramon, California.

A backhoe knocked the flare header off a pipe rack at the refinery at about 9:15 a.m. on Tuesday, according to a notice filed with the Utah Department of Environmental Quality.

"There are no off-site impacts, but the area inside the plant has been evacuated," Chevron said in the filing.

Flare headers are part of a refinery's gas processing equipment that is designed to prevent the system from being over-pressurized.