HOUSTON (Reuters) - Chevron Corp's
The shutdown triggered flaring at the refinery, according to the notice filed with U.S. National Response Center.
Refineries most often carry out planned shutdowns of refinery units to perform seasonal maintenance ahead of the summer driving season.
The Richmond refinery is fourth San Francisco-area refinery currently performing a planned overhaul.
(Reporting by Erwin Seba; Editing by Marguerita Choy)