Fracking sites drilling much shallower than previously thought, says Stanford study

"The nation's first survey of fracking well depths shows shallow fracking is more widespread than previously thought, occurring at 16 percent of publicly recorded sites in 27 states, posing a potential threat to underground sources of drinking water," says a study by Stanford University researchers published in the journal Environmental Science & Technology, Zahra Hirji reports for InsideClimate News. Researchers found that 7,000 of 44,000 wells reviewed were fracked less than one mile below the surface.

"Using well data from the website FracFocus spanning 2008-13, the researchers found well depths ranged nationwide from deeper than 3 miles to as shallow as 100 feet," Hirji writes. "Of the 27 states reviewed, 12 had recorded at least 50 shallow wells, defined as those drilled less than a mile deep. The three top states for shallow wells include Texas with 2,872 wells, Arkansas with 1,224 and California with 804." Reseachers said those estimates are probably low because of limited reporting to FracFocus. (Stanford graphic)

"Not all shallow wells pose the same threat to groundwater," Hirji wries. Researchers say "the 'riskiest' fracked wells are both shallow and use high levels of water—1 million gallons or more. Studies have shown that when these high-pressure wells fracture the bedrock, the cracks can extend as much as 2,000 feet upward. This provides an opportunity for the chemical-laced water used in fracking to migrate to the shallower depths of the water table. And the smaller the gap between drilling and surface water, the greater the chance of interaction." (Read more)