Post got in touch with Brockovich when she realized her dream house stood on top what had been a Shell oil reservoir. Shell says it sold the land to a developer in the 1960s who promised to clean it up, but Post and other homeowners in the community say no one, not Shell or the developer, warned them about the tanks.
Post and many of her neighbors claim the buried oil is now bubbling up in their backyards emitting the chemical benzene. While Shell says they are conducting an environmental investigation and so far the levels of benzene do not present an "imminent health or safety risk to the residents," they have warned the community not to disturb the soil. Neighbors are now keeping their children and pets from digging in the yards.
But Brockovich said the benzene and petroleum products have leaked into the groundwater aquifer.
"I believe that we have a huge problem with the water in America," Brockovich said. "We don't want to make that connection that these chemicals, at varying levels, in our water supplies, over time, is, in fact, related to our disease process. And it concerns me greatly."
Another hotspot on the Brockovich map is Duncan, Okla. Residents contacted her about a contaminant called percholrate that had seeped into their wells. The source? A Halliburton plants that cleaned missile casings during the Cold War. Halliburton told "Nightline" in a statement that they have taken responsibility for the problem and are working with the community to clean it up.
"There's a very fundamental basic value system that I think America was built upon and that's mutual respect, honor, integrity and concern for our environment and the right to clean water," Brockovich said. "And we have moved away from it."