Washington, DC — A new federal study finds wastewater from natural gas hydrofracturing has higher levels of contaminants the deeper in the storage tank the samples are taken. These findings may be a key to preventing environmental damage from disposal of huge volumes of post-fracking water produced in the boom to exploit shale gas, according to Public Employees for Environmental Responsibility (PEER).
Released November 16, 2011, the study by the U.S. Forest Service researchers is entitled “Chloride Concentration Gradients in Tank-Stored Hydraulic Fracturing Fluids Following Flowback.” It analyzes 11,000 gallons of fracking fluids that flowed back to the surface and were stored in two 18-foot tall tanks after drilling in the Fernow Experimental Forest within West Virginia’s Monongahela National Forest.
The key finding is that samples taken near the surface below the top scum are far less contaminated than samples taken deeper in the tank. Increasingly higher levels of the tracked chemical, chloride (Cl), are found the deeper samples are drawn. These differences are also visible to the naked eye:
“Differences in the physical appearance of the shallow (4- and 8-foot) and deeper (12- and 16-foot) samples also suggested the overall chemistry of these samples was quite different.”
This research also highlights limitations of current approaches to lessen environmental damage from disposal of these fracking flowback fluids, including –
- Typical test kit sampling greatly underestimates chemical concentrations;
- Shallow samples could allow operators to circumvent contamination limits on land disposal of these waste fluids; and
- Surprisingly high chloride concentrations remained even after “the primary source of Cl … the hydrochloric acid in fracking fluids … had been recovered separately…”
“Not all fracking fluids are created equal, meaning that a one-size-fits-all approach will not protect human health or the environment,” stated PEER Executive Director Jeff Ruch, whose organization has been urging the Forest Service to apply basic safeguards on shale gas extraction. “There are great uncertainties about fracking fluids injected into shale formations but the fluids returning to the surface are little understood, as well.”
This summer, another Forest Service study found land disposal of this fracking wastewater quickly wiped out all ground plants, killed more than half of the trees and caused radical changes in soil chemistry.
“Fracking flowback is a forgotten waste stream that may come back to haunt us,” Ruch concluded.