A temporary power outage at the Phillips 66 refinery on the Nipomo Mesa caused a flaring incident Tuesday morning, which was spotted by some local residents.
Company spokesman Dennis Nuss said the loss of power happened about 9:30 a.m. and resulted in an unscheduled shutdown of the refinery.
"As a result, fuel gas was directed to the refinery's flare, resulting in visible flaring," he wrote in an email.
Phillips 66 employees monitored air quality off-site and have not reported any impacts, he said.
The company is required to notify regulatory agencies including the San Luis Obispo County Air Pollution Control District, California Office of Emergency Services, the National Response Center, the Cal Fire station on the Mesa and the county's environmental health department.
PG&E spokesman Blair Jones said Tuesday the outage lasted about two minutes and affected spots of customers from Shell Beach to Nipomo.
The cause is under investigation, Jones said.
The Nipomo Mesa refinery also had a flaring incident in May as a result of a power outage. In that incident, the outage lasted about 90 minutes and caused an unscheduled shutdown of the facility, which also sent fuel gas to the refinery's flare.
No other customers were affected in that outage. The cause was due to an equipment failure near a substation, Jones said Wednesday.