Is eminent domain causing a health threat?

An oil company is willing to give some property for free to a city as long as the city doesn't use it to build houses. The company says that the land is polluted. The city is accepting the claim and will take the land. One question: will the oil company be liable for any future illnesses? If so, the city and developer don't have the right incentives to make the correct development decision. Of course, this wouldn't even be a problem if the Kelo case had never been decided the way it was by the Supreme Court.