New York (CNN) -- The Environmental Protection Agency will hold its final public hearings on hydraulic fracturing to access natural gas on Monday and Wednesday.

The controversial process of hydraulic fracturing, or "fracking," requires drillers to pump large amounts of water mixed with sand and chemicals into shale formation under high pressure to depths 8,000 feet or greater or even wells less than 1,000 feet, according to the EPA. This process fractures the shale around the well, which allows the natural gas to flow freely, according to the Pennsylvania Department of Environmental Protection.

Over the past few years, technological advances and increased profit margins have spurred increased use of hydraulic fracturing, according to the EPA.

The U.S. Department of Energy estimates shale gas will make up more than 20 percent of the nation's total natural gas supply by 2020.

With the expansion of fracturing, there are increased concerns about its potential effects on the underground water table, public health and the environment.

These concerns have prompted the EPA study of the potential problems with fracturing and public hearings to help decide how to conduct the study.

This week's hearings will take place in Binghamton, New York.

In July, public hearings were held in Fort Worth, Texas; Denver, Colorado; and Canonsburg, Pennsylvania, to help determine how the EPA will conduct the study.

The EPA plans to begin the actual study in January 2011 and release initial study results by late 2012, said Briskin.

Although hydraulic fracturing has been around for decades, it has never been done on such a massive scale so close to major population centers. Shale gas extraction has since spread to the Northeast and is occurring outside large population centers such as Philadelphia and New York City. Areas near Chicago, Illinois; Detroit, Michigan; and Cleveland, Ohio, could be next.

Currently, most natural gas is burned to produce electricity or heat and cool buildings. When burned, it emits about half the carbon dioxide as coal.

For this reason, most of the country's big environmental groups are cautiously supportive of increased shale gas development.

Up until now, the federal government has generally agreed with industry. The EPA, which has said fracturing is safe, has left regulating the process largely up to the states.

But this is little comfort to the people whose lives have been affected by the drilling. They are quick to say that the federal government has been too close to the industry for years. The 2005 Energy Act signed under the Bush administration did not subject fracturing to oversight under the Clean Water Act. That has only stoked their fears.

At the very least, they want EPA to regulate the practice, require the companies to disclose what chemicals they are injecting into the ground and require greater treatment of the fluids when they are returned to the surface.

CNN's Sarah Hoye and Steve Hargreaves contributed to this report.