State environmental officials have halted disposal of manufactured gas plant waste at a central Illinois landfill where they're also banning PCBs.

The Illinois Environmental Protection Agency informed the owners of the Clinton Landfill of the action in a letter Thursday.

The agency earlier this week said it was modifying a permit to prohibit disposal of polychlorinated biphenyls because local landfill approval in 2002 didn't include the chemical.

The landfill is located above the Mahomet aquifer, which provides water to 750,000 people in about a dozen counties. Many towns worried PCBs could contaminate the aquifer.

But they also worried about manufactured gas plant waste, a byproduct of producing gas from coal.

Normal Mayor Chris Koos praised Gov. Pat Quinn for moving quickly on their additional concerns.