More than 60 years after the initial introduction of per- and polyfluoroalkyl substances (PFAS) to commercial and industrial manufacturing, this once innovative, complex family of more than 3,000 man-made fluorinated organic chemicals is now appearing as a pollutant in many public drinking water systems. For the better part of the 20th century, PFAS were used in products such as nonstick cookware, water and stain repellent clothing, as well as foam for fighting fires. What was not considered during its prevalent application was that certain derivatives of this chemical family are mobile, persistent, bioaccumulate, and consequently, do not break down in the environment.
As products containing PFAS made their way to landfills and fire suppressant foam turned to runoff, these chemicals did not decompose over time. In hindsight, it is no surprise that early environmental sampling and PFAS analysis identified this class of compounds in surface water, groundwater, sediment, and associated biota. With ubiquitous presence in many of our natural resources, it was inevitable that PFAS would also affect public drinking water supplies.
After discovering the ramifications of PFAS used in manufacturing, many companies voluntarily agreed to cease using these compounds in their products. Despite this effort to reduce PFAS introduction to the environment, many municipalities are left scrambling to identify the source of PFAS, remediate elevated concentrations if present, in their aquifers, and remove it from their public drinking water systems – all amidst a dynamic regulatory backdrop.
The United States Environmental Protection Agency (USEPA) has not yet established a maximum contaminant level (MCL) for PFAS compounds, however, in 2016 a Health Advisory level of 70 parts per trillion was established for drinking water. As the drinking water industry awaits a formal plan and regulations from the USEPA on best practices to manage and limit PFAS exposure, many states are developing independent standards. These state-specific regulations vary greatly in terms of both risk-based threshold and the individual PFAS concentrations, or sum of concentrations, upon which the MCLs are based.
Tracing the source of PFAS
When PFAS are detected in a municipality’s drinking water source, it is important to fully understand the system and assess potential sources and migration pathways for these compounds. This includes evaluating existing well logs and hydraulic models, reviewing operational information and drawing a bigger picture of where both municipal and industrial wastewater treatment inputs may be located. Local landfills and waste transfer stations must be analyzed, in addition to consideration of surface water hydraulics and prevailing groundwater gradients. Furthermore, it is important to identify sources of PFAS including industrial and manufacturing entities who historically used PFAS in production, and whether the local or neighboring fire departments used aqueous film-forming foam (AFFF) concentrates. Identifying the entry points of PFAS compounds into the environment may help mitigate and manage further impacts.
Remedial strategies to improve public water quality
Several options are available to public and private suppliers of water who face PFAS contamination. However, the unique chemical properties of PFAS frequently require innovative treatment approaches including proven unit processes that many water suppliers do not already employ. Examples of treatment processes capable of removing PFAS compounds from drinking water include granular activated carbon (GAC), ion-exchange (IX), and membrane filtration. In some instances, a combination of these processes may prove fiscally beneficial.
Presence of PFAS in any drinking water source must be addressed, and remedial strategies will come at a cost. Regardless of treatment approach, public water suppliers need to consider consequential expenditures to their capital and operational budgets, especially when considering the evolution of regulatory standards. With communities across the country encountering PFAS compounds in the water supply, Woodard & Curran has been a key resource in evaluating and developing public water system improvements, undertaking remedial efforts in the environment, and handling residual streams produced by both potable and wastewater treatment facilities.
