County firefighters were called to the refinery, located at 1380 San Pablo Ave., at about 2:30 p.m. to help monitor a leak reported by refinery officials, a Contra Costa County Fire Protection District dispatcher said.
Hughes said the incident lasted for about half an hour. No injuries were reported and no community impact could be detected.
The company is required to report spills even when they do not pose a threat to public health.
