The Missouri Public Service Commission has signed off on Ameren Missouri's plan to build a coal ash landfill at its power plant in Franklin County.
The five member commission unanimously granted the utility company’s request for a Certificate of Convenience and Necessity on Wednesday. That certificate gives Ameren the ability to expand the area of its Labadie power plant to build the new landfill.
The PSC took three months to review the testimony it received both for and against the application.
Opponents of Ameren's plans have argued that building a landfill in the floodplain of the Missouri River ― and in an area prone to earthquakes ― could end up contaminating drinking water.
But PSC Chairman Robert Kenney said the commission took those concerns into account.
"We felt that the evidence demonstrated that Ameren had designed the utility waste landfill and was undertaking all the necessary precautions to ensure that it was going to be safe and protective of public health," Kenney said.
Ameren has said the new landfill is designed to prevent contamination by storing the ash as a dry, concrete-like substance rather than as wet sludge. They also contend that the landfill would have a liner to keep the ash from contacting groundwater.
The company has also said that storing the ash next to its power plant would be much less expensive than transporting it elsewhere, reducing the future cost to its electricity customers.
Final approval for Ameren to begin construction now rests in the hands of the Missouri Department of Natural Resources. The agency officially has until January 5 to decide whether or not to grant Ameren’s construction permit, but there is nothing to prevent the agency from moving more quickly.
The Labadie Environmental Organization and others had appealed to the Franklin County Board of Zoning Adjustment to try to revoke Ameren's county-level landfill zoning permit. They lost that appeal last week, but intend to try again in state circuit court.
The group has a second lawsuit already awaiting a state appellate court’s decision. That one is contesting the Franklin County Commission's decision to amend the county's zoning regulations to allow landfills.
Follow Véronique LaCapra on Twitter: @KWMUScience