Four “Musts” When Evaluating PFAS at Your Site
Author: Krystina Lincoln, GIT – Project Geologist
Deciding to begin a Site Investigation for Per- and polyfluoroalkyl substances (PFAS) can be a worrisome proposition for any property owner or facility manager. Frequently referred to as “forever chemicals”, PFAS compounds are man-made compounds found in many consumer products, manufacturing processes, and aqueous film forming foams (AFFF) for firefighting. These compounds have been widely used since the 1950s and, while their gradual (and ongoing) phaseout has been underway for the last few decades, their presence and impact is far reaching. Further information on the background of PFAS compounds can be found in this ITRC Fact Sheet. This guide provides four “musts” when evaluating PFAS at your site.
Conduct a “Deep Dive” Into Historical Site Use
As PFAS compounds can have many sources, a good starting point is to conduct a “deep dive” into historical uses at the site and surrounding area. State/municipal records should be reviewed early on, including available Sanborn maps, to identify any past manufacturers, including metal finishing, textiles, carpeting, leather, paper products, automotive, industrial surfactants, and more that existed on the site. Dry cleaners may have processed PFAS-containing clothing, as well as any manufacturer of consumer products that applied stain or water repellants. AFFF could have been deployed during training or emergency response at fire stations, airports, military bases, or even at the location of a past building fire or vehicle accident. If the presence of PFAS is suspected at the site, potentially impacted areas of the site should be contained and identified. For instance, was fire training conducted in the rear parking lot? Is there a leach field that received discharge from a floor drain on the production floor?
Carefully Consider Your Analytical Methods
Given the low required reporting limits and complex nature of PFAS analyses available, commit sufficient time to read the regulations and to fully understand the analytical methodologies. At this stage, a great deal of proactive communication and planning with the analytical laboratory as well as other project stakeholders is critical. There are currently two widely available EPA approved methods for the analysis of PFAS compounds in drinking water (Methods 533 and 537.1), along with a third recently finalized method intended for non-drinking water matrices (SW-846 Method 8327). As SW-846 Method 8327 was only finalized in June 2021, many labs still do not have their Method 8327 certifications, but offering a Method 537 “Modified” approach for non-drinking water matrices. It’s important understand that each analytical method offers different, but overlapping, lists of PFAS compounds, so care must be taken to comply with the methods accepted by each State regulatory agency.
Must Avoid Cross-Contamination Risks In the Field
When conducting a PFAS-focused investigation at your site, it’s critical that any PFAS reported in the samples accurately represents the concentrations in site soil, groundwater, and/or surface water. Cross-contamination introduced during sampling will produce inaccurate results. PFAS compounds have been detected in many common products used during an environmental investigation including new clothing, rain gear, some sunscreens, water-proof field notebooks, and Polytetrafluoroethylene (PTFE)-based materials. While great care must be taken to prevent cross-contamination when collecting traditional environmental samples, an additional level of caution needs to be utilized when sampling for PFAS due to the presence of PFAS in many everyday items. PFAS containers should be collected before any others in a sampling suite, to minimize cross contamination. Frequent changes of nitrile gloves are necessary when handling any down well equipment and sample containers. Any suspected PFAS containing products should be kept far from the sampling area, or off-site if possible.
Off-site PFAS Sources Must Be Considered
After the sample results come in, a valuable exercise is to carefully evaluate potential offsite sources – if PFAS are found at your site. While not always conclusive, individual PFAS sources generate a different “signature”, or balance, of PFAS compounds. For example, AFFF use can create a PFAS signature with significant Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS), and Perfluorohexanesulphonic acid (PFHxS), compared to other analyzed compounds. Even at the same AFFF impacted site, PFAS signatures may differ based on the “generation” of AFFF deployed in certain areas at the site. Older foams may contain higher relative amounts of PFOS when compared to PFOA. Metal plating facilities may generate PFOS heavy signatures. Signature evaluation may prove important when developing a conceptual site model in an industrialized area where multiple potential sources of PFAS are present. PFAS plumes can be longer than other contaminants like MtBE, BTEX, and chlorinated compounds, so the upgradient survey must keep this in mind.