CLEVELAND, Ohio - The former owner of Hardrock Excavating LLC, in Youngstown, pleads guilty to discharging brine and oilfield waste into a tributary of the Mahoning River.

When 63-year-old Ben Lupo of Poland was initially charged in 2013 with violating the Clean Water Act he pleaded not guilty.

But now, Lupo has changed his plea to guilty, admitting that as the former owner of Hardrock Excavating LLC, he instructed employee Michael Guesman to discharge brine and oilfield waste into a sewer, and that waste ultimately made its way in to a tributary of the Mahoning River.

Brad Beeson is a Special Assistant U.S. Attorney in Cleveland who says the discharge of the waste lead to a massive clean-up effort. "The United States got involved in this because there was a pollutant that this discharge made it into a water of the United States," Beeson said.

It's estimated that dumping of the brine and drilling mud could have occurred at least 20 times between November of 2012 and January 31st of 2013, and Lupo could ultimately pay fines of $50,000 for each discharge, or up to $250,000.

The company, Hardrock Excavating LLC, itself, has also been separately charged in the criminal case. "The company today didn't plead guilty, and we're still in negotiations with the company, and we'll see where it leads," Beeson said.

The intent of this prosecution is to send a message to those who don't follow the rules.

Lupo will be back in court June 16th at 10:00 a.m. for sentencing. He's already agreed to pay more than $3-million dollars in clean-up costs according to the U.S. Attorney's Office, and could be sentenced up to three years in prison.