Pittsburgh-based Consol Energy, the largest U.S. producer of coal from underground mines, will build an advanced wastewater treatment plant to treat wastewater from multiple mines in Appalachia as part of a settlement with the U.S. Dept. of Justice, the Environmental Protection Agency and the state of West Virginia. The federal complaint, filed concurrently with the settlement agreement, alleges that, in the past four years, Consol mines violated pollution discharge limits in their Clean Water Act permits hundreds of times. The settlement, announced on March 14, calls for Consol to pay a $5.5-million civil penalty for Clean Water Act violations at six mines in West Virginia and install $200 million in pollution controls to reduce discharges for mining wastewater. While admitting no liability, Consol has agreed to build and operate a wastewater treatment plant to serve as the centerpiece of its pollution controls, it says. The plant, near Mannington, W.Va., will use reverse-osmosis technology to remove high levels of chloride. When completed, the plant will be able to treat 3,500 gallons per minute of mining wastewater and eliminate more than 96 million lb of total dissolved solids, including more than 11 million lb of chloride.