Protesters claim that a tract in the Carousel neighborhood is contaminated with high levels of methane and benzene because Shell used to operate an oil tank farm there.
They want the oil giant to clean it up. Brockovich told protesters to not give up.
"I've been doing this for 20 years, and the thing that can make the difference will be you. Unfortunately, this is a story that is playing itself out all over the United States. You are not alone," Brockovich said.
Shell media relations did not issue a response to the protest.
