Concerns that fluids from hydraulic fracturing, or “fracking,” are contaminating drinking water abound. Now, scientists are bringing to light another angle that adds to the controversy.
A new study, appearing in the ACS journal Environmental Science & Technology, has found that discharge of fracking wastewaters to rivers, even after passage through wastewater treatment plants, could be putting the drinking water supplies of downstream cities at risk.
Fracking involves high-pressure injection of millions of gallons of water mixed with sand and chemicals to crack geological formations and tap previously unreachable oil and gas reserves. The resulting wastewater is highly radioactive and contains high levels of heavy metals and salts called halides (bromide, chloride and iodide). The disposal of fracking wastewater poses a major challenge for oil and gas companies that use the technique.
One approach to dealing with this wastewater is to treat it in municipal or commercial treatment plants and then and then release it into rivers and other surface waters. However, these plants don’t do a good job at removing halides, and there is increasing concern among scientists that halide-contaminated surface water subsequently treated for drinking purposes could lead to the formation of toxic compounds called disinfection byproducts (DBP’s).
It is well established that chlorine and chloramine used to disinfect water can react with organic matter to form compounds such as trihalomethanes and haloacetic acids. These byproducts – some of which are regulated by the Environmental Protection Agency – have been linked with a range of health risks including cancer and disorders of the nervous system. But in the presence of halides such as bromide and iodide, the disinfectants can create byproducts that are even more toxic than their chlorinated analogs.
Given that high concentrations of these halides remain in fracking fluids even after they’ve been through wastewater treatment, it is possible that the disposal of these fluids into surface waters could introduce toxic byproducts into drinking water. In the new study, Drs. William A. Mitch, Avner Vengosh and colleagues set out to see if that was indeed the case.
Toxic byproducts formed even at lowest concentration of wastewater
The researchers obtained two samples of wastewater from hydraulic fracturing operations in the Marcellus Shale in Pennsylvania. To simulate the chemical composition of what a drinking water plant might take in, they diluted the wastewater with water from rivers downstream of the shale operations to get samples containing 0.01 to 0.1% wastewater by volume. Then, the researchers treated the samples with chlorine, chloramine, or ozone, just like at a drinking water plant.
Using mass spectrometry (an analytical chemistry technique used to measure the masses and relative concentrations of atoms and molecules), the researchers then measured levels of a range of disinfection byproducts and compared them with levels in treated river water without any fracking waste.
The team found that chlorinated samples containing as little as 0.01% wastewater had concentrations of trihalomethanes and haloacetonitriles that were higher than those in treated, unaltered river water. Samples containing 0.1% wastewater had 70 to 140% higher levels of trihalomethanes, and concentrations of some of those compounds exceeded EPA limits. In ozone-treated water samples, levels of bromate, a potential carcinogen, were also above regulatory limits.
What’s more, the analysis also demonstrated that even the lowest concentrations of fracking wastewater (0.01% wastewater by volume) led to increases in levels of brominated and iodinated disinfection byproducts, which are significantly more toxic than their chlorinated analogs.
Based on their findings, the researchers recommend either that fracking wastewater should not be discharged at all into surface waters or that future water treatment include specific halide-removal techniques. “The results suggest that total elimination of fracking wastewater discharge and/or installation of halide-specific removal techniques in centralized brine treatment facilities may be a better strategy to mitigate impacts on downstream drinking water treatment plants than altering disinfection strategies,” the team writes.
The findings also indicate the need for “comprehensive monitoring plans beyond the common regulated DBP’s” in areas of shale gas development to reduce the threat posed by DBP’s in drinking water utilities, the researchers say.
Dirty drilling
Fears about possible water contamination have fed resistance to fracking in communities around the country. And these fears are clearly not unfounded: In 2010, the Pittsburgh Water & Sewer Authority measured a significant increase in trihalomethanes in drinking water. The agency traced the problem to elevated bromide levels in the source water, which is thought to have come from industrial wastewater treatment plants handling fracking waste.
As a result, the Pennsylvania Department of Environmental Protection has started to discourage fracking operations from sending their wastewater to municipal treatment plants in the state. However, some of that wastewater has been diverted to Ohio for underground injection instead — a disposal method that raises concerns about induced earthquakes.
The fracking industry itself is fraught with contention. They’ve long been criticized for their secrecy — most notably, for their persistent refusal to publicly disclose the chemicals that are used in fracking — and a growing list of scandals hints at much deeper problems within the industry. Among the most troubling practices is the industry’s pattern of imposing harsh restrictions or simply blocking scientists from accessing their work sites for research purposes.
Drilling companies are also widely known to require people who settle damage lawsuits to sign non-disclosure agreements, preventing them from discussing the health effects of fracking. In one highly publicized case, a lifelong gag order was imposed on two children who were parties to a legal case that accused one gas company of unsafe fracking operations that caused them to fall sick. Even doctors must sign confidentiality agreements if they want to access information about the chemicals used in fracking for diagnostic purposes; they are barred from discussing the information with anyone, even patients.
Most recently, the fracking industry took center stage in two bombshell reports revealing startling lapses in their compliance with regulatory and safety standards.
One of the reports, released by the Washington, D.C.-based Environmental Integrity Project, found that several U.S. oil and gas companies have been unlawfully using diesel fuel in hundreds of fracking operations, and then doctoring official records to conceal violations of the federal Safe Drinking Water Act.
Diesel fuel contains a high concentration of toxic compounds that are known to cause cancer, neurological effects, and/or organ damage, even in very small doses. In fracking, diesel helps to keep shale formations from absorbing all the fluids used to crack open the rock or clay. But because the chemicals found in diesel are highly mobile in water, they pose a particularly high threat as a potent groundwater contaminant.
In the second report, a team of Stanford University scientists found that many U.S. energy companies are fracking for oil and gas at far shallower depths than widely believed, sometimes through underground sources of drinking water. While the fracking industry has long held that it does not hydraulically fracture into underground sources of drinking water — claiming that it’s unnecessary because oil and gas deposits sit far deeper than aquifers — the report delivered irrefutable evidence of fracking into drinking water sources.
Public health experts and environmentalists have long voiced concerns about the potential health-related effects of fracking, with more than 90 medical and public health professionals, and 25 professional organizations, co-authoring a statement urging lawmakers to delay approval of further fracking operations until additional research on the human impacts is carried out. And as further research continues to uncover more and more health risks associated with fracking, the time will come that we must ask ourselves the question, “What price are we willing to pay?”