An EQT Corp. subcontractor accidentally drilled into an abandoned coal mine in Southwest Pennsylvania, causing mine wastewater to empty into the Monongahela River. Keystone Clearwater Solutions LLC was drilling for a pipeline on January 28 to carry river water to EQT's drilling site in Forward Township, about 20 miles south of Pittsburgh, when it breached the mine causing the wastewater to leak into a tributary. While the incident was isolated, the Monongahela is one of three major rivers that run through the city. EQT hired another contractor to cleanup and the spill has mostly been contained. The Pennsylvania Department of Environmental Protection said the incident was not expected to cause problems for public drinking water supplies. Gas extraction has increasingly intersected with abandoned and operational mines in the state.