Fracking is the process of blasting water at high pressure into shale rock to release oil or gas held within it.

BBC: US oil production 'to jump by a quarter by 2014'

Grassed areas along the road were reinstated using aqua seeding, a process by which grass seed is sprayed using high-pressure pumps.

BBC: Months of road resurfacing work on A22 ends

Fracking is a controversial process that involves pumping water and chemicals into shale rock at high pressure to extract gas.

BBC: Cuadrilla bids to resume Westby and Banks fracking

About 25, 000 wells a year are being fracked, a process in which water, chemicals and sand are injected at high pressure underground to release trapped natural gas.

NPR: Report: Flaws In EPA Drilling Pollution Data

Fracking is a drilling process that frees gas from deep rock deposits by injecting wells with chemical-laced water at high pressure.

WSJ: Record: Libous ended stake in firm eyeing fracking