Now, as rescue efforts continue, people are flocking to gas stations to fill up. But officials say there is no need for alarm. Motiva’s plant in Port Arthur, the nation’s largest refinery, shut down on Wednesday. And on the same day,Colonial Pipelinetemporarilyshut down its major pipeline. Refineries along the state’s coastmake up 15 percentof America’s total oil refining capacity, according to NBC Dallas Fort-Worth.