The owner of a Flint area chemical company pleaded guilty Thursday, January 14 to violating the Clean Water Act.

Robert Massey, owner of Oil Chem, Inc., was charged with directing employees to dump landfill leachate into the city of Flint’s sanitary sewer system, which eventually ends up in the Flint River. The violations occurred from 2007 – 2015 when nearly 48 million gallons of the substance was dumped into the sewers. While the company had a permit to dispose of certain materials, officials say the landfill leachate was not treated beforehand. Federal prosecutors also say Massey did not inform the city of Flint the leachate was being dumped into the sewers.

The company was taking truckloads of the substance from eight landfills. The leachate would be pumped into a holding tank during the day, then dumped into the sewer system at the end of the business day. One of the landfills had significant PCB contamination, according to prosecutors, which also ended up in the Flint River.

The facility is located downstream from the site where the city tapped the river for its water supply, meaning no harmful materials entered the supply from the dumping.

Massey faces up to three years in prison and potentially millions of dollars in fines. Fines could be between $5,000-50,000 per day the leachate was dumped. Sentencing takes place May 14.