Hydraulic fracturing, commonly referred to as fracking, is conducted at shale formation locations throughout the United States to increase production of natural gas. The fracking process requires a large amount of water (flowback, production, and drilling) thereby producing wastewater that must be either disposed of, stored, or treated. Due to the constituents contained in the wastewater, treatment poses problems for water resource recovery facilities (WRRFs). Several considerations and preparations should be made by a WRRF prior to accepting such wastewater.
Nontypical wastewater pollutants
The largest concern for WRRFs is typically the high salinity of fracking wastewater, measured in total dissolved solids (TDS). In addition, fracking wastewater can contain high levels of fluid additives, metals, and naturally occurring radioactive materials. The constituents are often at levels not typically found in WRRF influent.
Fracking wastewater quality can vary significantly, depending on pretreatment, if any. It is also important to know the volume, frequency, and delivery method of the material. A clearer picture of these constituents and characteristics can be obtained by enrolling the fracking operation in an industrial influent management program. Through such a program, the WRRF should be able to control the receipt of fracking water by setting pretreatment quality specifications.
Regulations for fracking wastewater
States and the U.S. Environmental Protection Agency (EPA) share responsibility for regulating treatment and disposal of wastewater from shale-gas extraction under National Pollutant Discharge Elimination System (NPDES). In October 2011, EPA announced a schedule to develop categorical effluent standards for wastewater discharges produced by natural gas extraction from underground coal-bed and shale formations. EPA will publish the Final 2014 Effluent Guidelines Program Plan after incorporating feedback gathered during the public comment period, which ended November 2014.
Several states have developed or will be developing their own rules for the acceptance of fracking water at WRRFs (see http://www2.epa.gov/hydraulicfracturing). Some state regulators are also imposing new regulations on WRRF discharges to protect aquatic organisms and drinking water purveyors from excess concentrations of effluent constituents such as TDS in receiving waterbodies.
Each WRRF should discuss current NPDES requirements and other regulations for accepting water from fracking operations with its state regulatory agency and EPA before accepting fracking wastewater to ensure that the latest regulatory requirements (such as permitting, additional monitoring, and effluent discharge limits) are identified. Also, it is best to engage the regulatory community as soon as possible in an open discussion of the current and planned regulatory requirements for fracking wastewater treatment at a WRRF.
Confirm WRRF’s ability to treat wastewater
Once a WRRF understands potential influent constituents and what is needed to achieve consistent compliance with its NPDES permit, the WRRF should carefully review its ability to continue optimal operations with additional loading. The WRRF should review control processes and understand the potential impact of fracking wastewater on the facility, and in particular, the stability of operations in light of projected salt levels and concentration variability. Also to be considered are potential changes on the biosolids quality due to constituents that are removed from the liquid stream.
More resources available
In summary, prior to accepting fracking water at a WRRF, four steps should be followed:
- Determine the fracking wastewater constituents, volume, frequency, and proposed delivery method.
- Determine the type of pretreatment the fracking water has undergone.
- Discuss NPDES requirements and other regulations with the state regulatory agency and EPA.
- Consider the effects on both final effluent quality and biosolids.
For more information, download the fact sheet Considerations for Accepting Fracking Wastewater at Water Resource Recovery Facilities, which discusses in further detail each of the four steps listed above, definitions, and quantitative data as well as references and links to more information.
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By the WEF Fracking Task Force, as edited by Elizabeth Conway. Elizabeth is the Committee Coordinator at the Water Environment Federation (Alexandria, Va.). The full fracking paper created by the Task Force is found here. Elizabeth can be reached at email@example.com.