What are PFAS?
Produced by industrial/commercial facilities and present in consumer goods, PFAS (per- and polyfluoroalkyl substances) is a group of synthetic chemicals used in products that resist oil and water, control temperature, and prevent degradation of materials. Examples include non-stick cookware, pizza boxes and other paper-based food containers, stain-resistant fabrics and carpets, fire-resistant clothing and upholstery fabrics, rain gear, personal care products, detergents, and firefighting foams.
Although there are hundreds of PFAS compounds, PFOA and PFOS are the two that are the most studied and most prevalent. Dubbed “forever chemicals,” PFAS compounds possess chemical bonds that make them difficult to break down and allow them to bioaccumulate in living organisms. Some PFAS are highly soluble, making them relatively mobile in surface and ground waters, and their persistence in soils allows them to leach into drinking water aquifers.
Where are they located?
Currently, PFAS producers include airports/military installations and industrial/manufacturing sites. PFAS-containing firefighting foam is commonly used/stored at facilities where highly combustible materials, such as jet fuel, are used/stored and at airports and military installations where firefighting and fire training activities are performed.Industrial/manufacturing sites where PFAS are produced/used emit PFAS from air stacks, which can impact nearby soil and surface water bodies. At these sites, PFAS can also be present in the wastewater discharge.
Other sources of PFAS being investigated include wastewater treatment plants and landfills. Wastewater treatment plants (WWTPs) accept large quantities of wastewater from PFAS-producing industrial facilities and leachate (which may contain PFAS) from landfills. Treated water may contain residual PFAS which could impact local groundwater aquifers.
Landfills are the final destination for non-recyclable materials from WWTPs and waste from household, commercial, and industrial sources. These waste materials may leach PFAS into the soil or groundwater. PFAS can also be present in landfill leachate that, paradoxically, is often sent to wastewater treatment plants for treatment and disposal. To compound the problem, some landfill liners/membranes also contain PFAS.
It should be noted that landfills and WWTPs are not producers of PFAS per se, they are PFAS receivers and have limited authority to regulate PFAS sources entering their systems.
How are PFAS regulated?
Currently, the U.S. Environmental Protection Agency (EPA) has published a drinking water advisory level for PFAS (PFOA and PFOS combined) of 70 parts per trillion (ppt), but unlike a maximum contaminant level (MCL), the advisory level is not enforceable. However, public water systems with detections of PFAS above the advisory level are advised to notify their state drinking water agency.
Many states are taking steps to regulate these chemicals. CERCLA has listed PFAS as a compound group of concern, and California regulatory agencies such as DTSC, SWRCB, CARB, and OEHHA have taken steps towards regulating these compounds, which project proponents should be prepared to address.
- The California State Water Resources Control Board, in particular, has instituted a three-phase investigative approach for drinking water wells surrounding: (1) landfills and airports; (2) manufacturing facilities, refineries, and non-airport firefighting areas; and (3) water/wastewater treatment plants to which PFAS are known to have been discharged. Phase 1 of the investigation is underway; sampling work plans have been approved for many facilities and sampling has begun at some sites.
- In August 2019, OEHHA published Notification Level (NL) recommendations for PFOA and PFOS in drinking water. Based on the OEHHA recommendations, the California Division of Drinking Water (DDW) established NLs of 6.5 ppt for PFOS and 5.1 ppt for PFOA that are enforceable for drinking water suppliers. In February 2020, the DDW updated the drinking water response levels (RLs) for PFOA and PFOS to 10 ppt and 40 ppt, respectively.
- In October 2019, the California State Water Resources Control Board issued an order to chrome plating facilities requiring them to submit documents that confirm or refute their use of PFAS-containing fume suppressants.
- Starting in January 2020, Assembly Bill (AB) 756 requires that all California public water systems test for PFAS and notify the public of the results. In addition, there are very specific notification requirements including timeframes, language/terminology, and overall presentation format.
Why does this matter?
Due to the ubiquity of PFAS, new regulations have the potential to affect a multitude of activities, including those by the automotive, aerospace, construction, electronics, and water industries. The conventional water treatment processes that remove toxins and micro-organisms from raw drinking water are relatively ineffective in eliminating PFAS from finished water, which could pose an issue for public water supplies and wastewater treatment facilities, as well as for various users of groundwater.
For public water supply clients, the public notification processes will become more complicated as the regulations expand. AB 756 (effective January 1, 2020) has very specific testing and notification requirements. For drinking water suppliers, the very low RLs and updated DDW response levels may require taking wells offline.
As an emerging contaminant, PFAS regulation may also affect projects involving Phase I Environmental Site Assessments (ESA), as well as sites that have already been granted regulatory closure. The American Society of Testing Materials (ASTM) is working on revisions to the industry guidance documents for Phase I ESAs, to address PFAS. Since PFAS are so prevalent in the environment, this change in the ASTM Standard for Phase I ESAs could trigger additional investigations for many properties. Since PFAS are an emerging contaminant, and thus not previously considered or analyzed, sites that received regulatory closure may be required to initiate new investigations to evaluate PFAS impacts.
How can Dudek help?
Individual PFAS compounds differ in their physical and chemical properties, as well as behavior, so even minor differences in environmental properties (e.g., soil moisture, clay content, and organic matter) can have a substantial effect on their mobility. Because of this, addressing them as a single contaminant group can result in overlooking the most efficient approach to intercepting or treating the most mobile and/or toxic compounds. Rather, care should be taken to isolate specific PFAS that are present on a site-specific basis in order to reduce the number of target compounds or compound groups monitored at every sampling point. Additionally, knowing which of the PFAS compounds are likely to be the most mobile in a specific area (e.g., aquifers, surface waters, sediments, soils) is essential to selecting the most cost-effective methods for addressing the problem. This considered approach saves time and money in the interception, removal, or treatment (in-situ) of the contaminants.
Dudek environmental engineers, geochemists and hydrogeologists are able to determine which PFAS compounds present the greatest threat in a particular environment by combining knowledge of individual compound properties with specific characteristics of the soil or water in which they are found. For two projects, Dudek geochemist Donn Marrin assessed the probable sources of PFAS in groundwater on the basis of ambient water chemistry and aquifer characteristics, as well as the co-occurrence of PFAS with other contaminants and distinctive components of the natural waters.
As a result, the investigation and/or remediation efforts targeted the sources and environmental pathways that most likely contributed to the contamination. In addition, the assessment identified which PFAS compounds would continue to be transported in groundwater farther from the source(s) if no action were taken. This provided the client and regulators a basis upon which to select among the various options for follow-up investigations.
What are the next steps?
As formal regulations continue to take shape, planning and preparation will allow project proponents to thoughtfully navigate the interception, removal, or treatment of PFAS, rather than respond from a reactionary position.
Dudek staff continue to closely track the regulatory status of designated and emerging PFAS; sampling protocols; the most effective remediation technologies; laboratory technologies, methods, and pricing; and the risks associated with PFAS contamination.
For more information, contact Senior Hydrogeologist, Susie Smith, PG.