A process used in nine out of ten natural gas wells in the United States, where millions of gallons of water, sand, and chemicals are pumped underground to break apart the slate rock and release gas: "The explosive growth of hydraulic fracking; especially, in areas where gas is often located closer to people’s homes and population centers has exposed some of the environmental risks associated with shale gas."

"Scientists and environmentalists are worried that the chemicals used in hydraulic fracturing may pose a threat either underground or when waste fluids are handled and sometimes spilled on the surface of the ground."

"Hydraulic frackings involve the injection of more than a million gallons of water, sand, and chemicals at high pressure down and across into the horizontally drilled wells as far as 10,000 feet below the surface of the earth."

"The pressurized mixtures used in hydraulic frackings cause the rock layer of shale to crack and these fissures are held open by the sand particles so the natural gas from the shale can flow up the well to the surface and into storage tanks from where it is taken for distribution and sold to users."