Police were notified around 12:05 a.m. of a possible burglary in progress at the yard, located at 210 Corona Road, Sgt. Andrew Urton said.
Officers stopped a vehicle seen leaving the area and found property stolen from the PG&E yard and burglary tools inside, Urton said.
Scott Franklin, 48, and Megan Figueroa, 31, both of Petaluma, were arrested for burglary, possession of stolen property, conspiracy and possession of burglary tools, Urton said.
Figueroa also was arrested for a violation of probation.