Hydraulic fracturing or fracking is a process in which a well is drilled and a steel pipe is inserted into the well bore with holes in the bottom and then a liquid under very high pressure, typically containing water, chemicals, and a proppant (usually sand), is inserted to overwhelm the natural pressure and fracture or crack rock underground to release gas or oil. During the stage of well completion known as “flowback,” the fracturing fluids, water, and gas come to the surface at a high velocity and volume including VOCs, methane, and air toxics. The flowback lasts from 3 to 10 days and creates substantial amounts of air contaminants. Also when the borehole turns 90° to go into the shale formations, in some areas the concentrations of radon are considerably higher than others. This produces radioactive borehole cuttings that are brought to the surface. These are often sent to landfills or fill areas where they can become the source of radioactive contamination.
The fracking process, which is currently producing a large amount of natural gas, has several additional potential environmental concerns. They are air quality issues, including the release of VOCs, including methane; other hazardous air pollutants; and greenhouse gases released into the ambient air from the wastewater, from spills, from the gas or oil being recovered, and from the chemicals being used in the fracking process. There is also a problem of airborne dust coming from construction sites and traffic.