The city of Richmond, Calif. juts into the San Francisco Bay like the head of a rhinoceros looking west across the water, toward San Quentin State Prison and the tony towns north of the Golden Gate. It’s a low, industrial town, and 2,900 acres of it is an oil refinery. Chevron is Richmond’s biggest employer, and through taxes contributes about a quarter of the city’s total budget. Chevron is also Richmond’s eternal nemesis. Industrial accidents are an ongoing issue.