Michael Guesman, an employee at Hardrock Excavating in Youngstown, Ohio, pleaded guilty yesterday to an unpermitted discharge of pollutants under the Environmental Protection Agency's Clean Water Act. Guesman said that his boss, owner Benedict Lupo, ordered him to dump tens of thousands of gallons of fracking waste into the Mahoning River on at least twenty-four separate occasions.

Hydraulic fracturing, or fracking, is the process of injecting millions of gallons of chemically treated water at a high pressure into the ground in order to create tiny fractures -- often less than a single millimeter -- through which underground gas resources can migrate. That water, however, must be removed before the resources can move into them, and the EPA has strict rules governing how that toxic byproduct is disposed.

Guesman admitted to running a hose from a 20,000-gallon storage tank full of liquid fracking waste to a storm drain, then draining the combination of saltwater brine and a toxic oil-based drilling slurry from the tank directly into drain. The dumps occurred between November 1, 2012 and January 31, 2013, and they always happened at night and when Guesman was the only employee still at the facility.

According to Guesman, Lupo had also ordered him to lie to law enforcement officers about the number of times he disposed of the waste and the amount of waste that was disposed each time.

The Ohio Department of Natural Resources learned of the illegal disposal via an anonymous tip from someone within the Hardrock Excavating. Lupo, its owner, has also been charged with violating the Clean Water Act, and faces up to three years in prison and a $250,000 fine. It is not known whether testifying against his former employer is a condition of Guesman's plea.

In the wake of the January discovery, Hardrock Excavating lost its permits for brine injection wells, and Lupo was ordered to stop operations at three other companies that he owns. A single injection well owned by one of those companies, D&L Energy, was deemed responsible for eleven earthquakes in the Youngstown area between 2011 and 2012.

A CBS News report on the Youngstown earthquakes is below: