CLEVELAND, Ohio - The final defendant has been convicted of a federal crime for dumping tens of thousands of gallons of drilling waste that lead to a $3 million dollar environmental cleanup of the Mahoning River and its tributaries.

Three men were convicted earlier of violating the Federal Clean Water Act, but the latest guilty plea comes not from a person, but a company.

Hardrock Excavating pleaded guilty to one count of making an unpermitted discharge into a U.S. waterway.

In U.S. District Court on Thursday, Judge Donald Nugent signed off on a plea agreement that is not being made available for public view.

The court docket says Hardrock has been ordered to make a community service payment in the amount of $25,000 that will be split between Friends of the Mahoning River and Midwest Environmental Enforcement Association.

The company was also fined $75,000.00.

Ben Lupo of Poland, who formerly operated Hardrock is serving a 28 month sentence for ordering two former employees on as many as 31 separate occasions, to dump oil and gas well waste into a storm sewer on Salt Springs Road in Youngstown.

Lupo agreed to pay more than $3-million dollars in clean-up costs.

The two employees were also convicted for their part in the crime.