It's been closed for more than four years.
Now, Century Aluminum has been ordered by the EPA to clean up a portion of its Ravenswood plant.
The problem actually goes back to when Kaiser Aluminum operated the plant from 1958 to 1989.
The U.S. Environmental Protection Agency says Century has to submit a plan to clean up the site, which was used for the storage of hazardous material waste from aluminum production.
The agency says that has resulted in groundwater contamination.
This comes as century has been in discussions to re-open the Jackson County facility.
"It wouldn't be a problem from a drinking water standpoint, as long as no one is digging any wells," says Spokeswoman Donna Heron of the EPA's region three office in Philadelphia, "and any existing wells on the property are not used for consumption."
Heron says the industrial part of the plant is not affected by the contamination.
Century Spokesman Mike Dildine says the company is reviewing the EPA order, and plans to comply with it.