Hydraulic fracturing, or fracking, extracts natural gas from underground shale by drilling vertically and then horizontally and injecting water, chemicals and proppants under high pressure into the well to release the trapped gas. According to the Energy Information Administration, US production of shale gas increased from 1,990,145 million cubic feet (mcf) in 2007 to 8,500,983 mcf in 2011 to make up 30% of natural gas production in the US. However, the so-called “fracking boom” has generated environmental issues as well, including questions about the impact on ground and surface water quality. Analytical instrumentation plays an important role in accessing the effect of fracking operations on water quality. However, in some cases, in order to properly apply analytical testing to these issues, new or modified analytical methods will be required. Two new efforts seek to further analytical method development for analyzing the effects of fracking on drinking water quality.

Analytical method development is part of the EPA’s “Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources.” Initiated last year, with the first draft scheduled for publication in 2014, the Study is charged with examining the possible impacts of fracking on drinking water resources.

The EPA Study will primarily focus on flowback water, produced water and fracking fluids. Flowback waters, as defined by the EPA, is the water mixture that returns to the surface after fracking, but before a well starts producing. Produced water is the water mixture that returns once the well starts producing. Flowback and produced waters are termed “hydraulic fluid wastewater.” The volume of hydraulic fluid wastewater can amount to 30%–70% of the original injection, which can total more than one million gallons.

Fracking fluids, which are injected into the well, consist primarily of water (90%) and sand (9.5%). The remainder consists of chemical components, including acids, biocides, corrosion inhibitors, friction reducers, gelling agents, scale inhibitors and surfactants. The mixture varies depending on a site’s geology, water chemistry and others factors. According to the EPA, each chemical additive makes up between 0.5% and 2% by volume of the fracking fluid. The exact formulations of fracking fluids are oftentimes unknown due to competitive concerns. Disclosure of fracking fluid constituents is becoming more common through industry efforts and state regulations. Fracking fluids are exempt from the federal Safe Drinking Water Act.

In addition, hydraulic fluid wastewater may also contain various naturally occurring substances, including formation fluids, such as sodium chloride and sodium bromide; trace elements, including mercury, lead and arsenic; naturally occurring radioactive material (NORM), including radium, thorium and uranium; and organic materials, such as organic acids, polycyclic aromatic hydrocarbons and volatile organic compounds. Such substances may also react with fracking fluid chemicals, leading to chemical transformation or degradation products, and the increased mobility of such substances.

The EPA Study encompasses 18 research projects. Analytical methods development will contribute to the Study in three areas of focus: chemical mixing and the accidental release of chemicals into surface and ground water; flowback and produced waters and their potential release into surface water, ground water and other drinking water resources; and wastewater treatment and waste disposal.

For research activities related to chemical mixing, the EPA intends to modify analytical methods for the detection of the chemical additives in fracking fluids. For research activities related to flowback and produced water, the EPA plans to develop or modify methods for the detection of naturally occurring substances released by fracking. Finally, for water treatment and disposal, the EPA intends to develop or modify analytical methods for the detection of hydraulic fracking wastewater constituents.

According to a February presentation, the EPA has compiled a list of 14 classes of chemicals for initial analytical method testing. The substances include those chemicals added to fracking fluids as well as naturally occurring substances mobilized as a result of fracking. Among the classes with a larger number of chemicals on the list are glycols, inorganics and radionucleotides.

For existing methods, the EPA plans to modify an analytical method if the method does not cover all of the chemicals within a class, lacks the required sensitivity, the extraction efficiency is too low or experiences matrix interference. Hydraulic fracturing water matrices contain high concentrations of total dissolved solids. If no base method is available, the EPA will develop a method. In a February presentation by the EPA, alkylphenols, and alcohols and amines were identified as having no base methods.

Examples of the EPA’s method modification and development efforts related to fracking are detailed in a December 2012 progress report on the Study. To address the inadequate sensitivity of EPA Method 8015b, which uses GC with flame ionization detection, for the detection and quantification of glycol and related compounds in fracking water matrixes, the EPA is verifying an LC/MS/MS method based on ASTM and EPA Solid Waste methods.

MS is also being used in the development of methods for measuring ethoxylated alcohols and disinfection by-products, according to the progress report. The EPA is developing a method for quantitating ethoxylated alcohols based on ASTM and US Geological Survey methods utilizing SPE and LC/MS/MS. The method is being modified in order to analyze all nonylphenol ethoxylate oligomers or alcohol ethoxylate oligomers. For the detection of disinfection by-products in fracking water matrices that could be excessive due to the interaction of bromide and chloride in hydraulic fluid wastewater with the chlorination process of wastewater plants, the EPA is modifying EPA Method 300.1 to replace the use of an electroconductivity detector with MS, enabling selective ion monitoring. The progress report also details method development efforts for radionucleotides and inorganic chemicals.

Working with the EPA on these efforts is the ASTM. This summer, the ASTM formed Subcommittee D19.09, a subcommittee under the jurisdiction of the organization’s International Committee D19 on Water. The new Subcommittee seeks to develop and propose standards for the analysis of contaminants in water impacted by fracking, including surface water, ground water and spring water, wastewaters, and flowback and produced water. The Subcommittee is also working with ASTM Subcommittee D18.26 on Hydraulic Fracturing, which was formed last year. According to Richard Jack, PhD, North American Environmental Marketing manager at Thermo Fisher Scientific and head of Subcommittee D19.09, the new subcommittee will work with other D19 subcommittees. “This way then we can learn from each other and put all our solutions together in one package.”

The Subcommittee is currently developing a proposed standard, WK40832, entitled “Test Method for Measurement of Dissolved Gases Methane, Ethane, Ethylene and Propane by Static Headspace Sampling and Flame Ionization Detection (GC/FID).” Currently, there is no validated method for measuring methane in ground water. “This method is based on Robert S. Kerr 175 RSK-175, however, this is a Standard Operating Procedure (SOP) and not a formal method,” said Dr. Jack. “An SOP testing procedure for dissolved gases has the potential to be up to interpretation.” Single lab validation is near completion, and the method should be published next year.

Asked what other contaminants the Subcommittee plans to address, Dr. Jack said that is still under development. “We plan to look at all methods, primarily for inorganic and radiological measurements, and evaluate their robustness in high saline matrices.” The extent of method development or modification required will vary. “Some will only require an update to the appendix; for others, we need to determine the scope of industry needs, thus we need more feedback on regulatory requirements—which are also in development.”

For the organic components of hydraulic fluid wastewater, the challenges to method development, cited by Dr. Jack, include “the evolving use of new organic compounds for fracturing that vary in concentration and type.” In addition, the presence of naturally occurring substances or substances present due to industrial events, such as agricultural runoff or old oil wells, further complicates the determination of fracking’s impact on water quality. “Obviously, the fracking solution is about 1% chemicals, right? And let’s suppose they frack, or there’s a spill, or a pipe breaks; well, that water is going to get diluted in the subsurface,” explained Dr. Jack. “So is it diluted—by the time it migrates through the subsurface—5,000, 6,000, 10,000 feet below the ground, moves three miles—it’s going to dilute how much? One to 10, one to 100, 1 to 1,000, 1 to 10,000? Nobody knows. So what’s the sensitivity that you need for a compound x?” He added, “[T]here is no single compound x and what is the sensitivity because there will be some sort of dilution. So what do you pick to determine impact?” One solution that is being discussed among researchers, but not yet by the ASTM, is a tiered testing approach, according to Dr. Jack.

The makeup of fracturing fluids continues to change with the introduction of more environmentally conscious formulas and the composition of more fracking fluids being made public. In addition, the number of studies investigating the impact of fracturing on water sources continues to increase. “As a standardization body, like ASTM, we’ve got to say, ‘Within this moving environment, we know we can test for those things that have been mobilized.’”