The Northern California city of Richmond on Friday sued Chevron Corp, saying the company was willfully negligent in a massive refinery fire and a smoke cloud last year that sent thousands of people to hospitals. Richmond city officials filed the lawsuit in Contra Costa Superior Court seeking unspecified damages. Health workers, environmental and community groups planned to rally in Richmond on Saturday in advance of the one-year anniversary of the August 6 fire. The fire, which was started by a pipeline rupture, knocked out the refinery until April.