Environmental Due Diligence

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Q&A from LightBox’s February 2023 PFAS Event: Phase II Scoping Strategies

LightBox Profile
LightBox Insights
April 18, 2023 7 mins

“Given the significant risk that can be associated with a PFAS BER, environmental professionals should educate themselves on these risks and discuss them with their clients.”  

In Part 1 of our PFAS Due Diligence Scoping webinar series on December 14, we focused on the technical and legal issues associated with adding PFAS to a Phase I ESA scope of work under ASTM E1527-21. In Part 2 on March 1st, we continued the discussion by turning our attention to action steps that can be taken if a Phase I ESA identifies a likely PFAS condition: Phase II scoping and investigation strategies. Our goal was to demystify PFAS and give EPs tips for how to handle this extremely complex topic given that policies and regulations are still taking shape. Moderated by LightBox’s Dianne Crocker, Alan Agadoni, SVP EDR Solutions, led a technical discussion with two leading PFAS experts: 

  • Jon Kitchen, a principal at Civil and Environmental Consultants, Inc. who recently completed an extensive database study of PFAS sites in New England; and 
  • Ned Witte, an attorney shareholder in the Environmental Strategies Practice Group of Godfrey & Kahn, a Milwaukee-based law firm. In late 2020, Witte, a nationally-recognized PFAS expert, was selected by the Biden-Harris Agency Review Team for the federal EPA as an outside PFAS consultant. 

After the moderated discussion, we received more questions than we had time to address. Below are responses to the outstanding questions raised by attendees during the live event: 


Are PFAS included as a Part of ASTM regulation? What is the purpose of doing it? When is it a must thing to include PFAS? 

“PFAS and other emerging contaminants are specifically excluded from the ASTM Standard (E1527-21), but the standard acknowledges that some non-environmental professionals may assume these to be hazardous substances and that emerging contaminants can be included as a non-scope consideration in states where they are regulated or if requested by the client.  Certain PFAS are currently proposed to be designated as hazardous substances under CERCLA, at which time they will be covered by the ASTM standard.   

The purpose of including PFAS at this time is to assess them as a Business Environmental Risk (BER) that may be very significant in some jurisdictions.  In fact, with pending regulation under CERCLA it is prudent to discuss the PFAS as a BER with your clients, regardless of what state you are working in.    

Including PFAS is a “must” when desired by your client.  To reiterate, given the significant risk that can be associated with a PFAS BER, we suggest environmental professionals educate themselves on these risks and discuss them with their clients.” 

This discussion is very much appreciated. I’m curious though how the points we’re considering are different from the question we already face during due diligence? Seems it’s the same scenarios, with the difference being the contaminant of concern. 

“Your comment rings true. In many ways, PFAS can be addressed the same as any other contaminant.  However, like other contaminants, there may be some subtleties in addressing PFAS.  The prospect (or rather a reality in some states) of standards being set at very low concentrations and the ubiquity of these compounds in the human environment and certain environmental media may make deciding when to investigate and how to interpret data obtained a bit tricky (especially as the professional and regulatory communities develop an understanding of how these compounds are to be regulated).”    

Technical PFAS Questions 

Does PFAS tend to float on the water table or sink? 

“Most often, PFAS are not going to exist as a “free product” or “non-aqueous phase liquid.”  As such, one would expect them to move like any other dissolved contaminant.  However, it is potentially a bit more complicated…  it has been documented that PFAS can form an “invisible sheen” of high concentrations due to unique positioning of the molecules at the air/water interface.  In simple terms, the PFAS molecules contain a hydrophilic head and hydrophobic tail and the molecules will position themselves at the air/water interface with their hydrophobic tails sticking out of the water.  Thus, resulting in a higher concentration of PFAS at the air/water interface.” 

Are you familiar with any studies or investigations that found that PFAS tend to disperse further out than solvents?  Different for various mediums (i.e., soil, groundwater, vapor)?   

“CEC conducted a literature study of regulated release sites in New England.  Based upon that review, there were very few groundwater plumes that had been fully or substantially delineated.  However, of the few that had, the plumes were very long… often extending until they reached a point of surface water discharge.  Both the theoretical PFAS fate and transport properties and this preliminary empirical data suggest that PFAS plumes, on average, will be longer than solvent plumes.  We are not aware of many studies regarding other media, but there are certainly individual case studies suggesting significant air transport around manufacturing facilities.”    

In case study #1, what is the driver for suspecting PFAS at the former fire station? 

“In this case study, we had a fire house with a floor drain leading to a dry well.  The presence of the conduit to the subsurface, along with the possibility of (incidental and non-specific) use of aqueous film-forming foam (AFFF) was the driver for conducting subsurface investigations.”   

Are we saying that if there is a firehouse with in XX distance of the Subject Property, we should recommend PFAS testing of wells? 

“We are aware of a number of instances where private wells in the vicinity of fire stations have been impacted and the fire station is viewed as a potential source.  This is an issue that will continue to develop over time.  The specifics on whether sampling should be recommended will vary based on hydrogeologic, client risk tolerance, regulatory setting, and many other factors.” 

Are there any effective remediation options for PFAS contamination in groundwater? 

“While outside the scope of these presentations, there are effective remedial options for PFAS.  These may include ex-situ options such as granular activated carbon (GAC), ion exchange resins, other absorptive media such as modified clays, foam fractionation, and reverse osmosis, among others.  Some in-situ options have been developed, but may be limited in application due to the typical scale of PFAS plumes.”   

Is the emphasis on groundwater in these case studies due to groundwater MCLs, or should a CSM look for each scenario to look at what might be the source?  For instance, in the former woolens/box making/plating case study property, could it also be an emissions site which may have nothing to do with GW flow direction? 

“A conceptual site model (CSM) is always recommended when evaluating potential release sites.” 

What are common analytical methods for groundwater — 1663, 537, other? 

“While EPA Methods 533 and 537 are limited to drinking water, many laboratories offer isotope dilution methods similar to these methods for other groundwater samples.  EPA Method 1633 is still a draft method, but it covers additional media.  Some labs are offering analyses based upon the draft Method 1633.  This is a limited list of the analysis methods available and a full review of analysis options is beyond the scope of this discussion, but in general, we suggest talking with your laboratory about methods, media to be sampled, detection limits, and target compound lists prior to conducting a sampling event.” 

What is considered a “low” concentration of PFAs? 

“There is no correct answer to this question.  It will depend upon the media, exposure pathways, and the regulatory environment.”   

What is the likelihood of soil PFAS impacts related to a fire training facility on an adjacent site?  It appears it typically migrates via groundwater. 

“This would require more information. For instance, is there a possibility of over-spray or stormwater runoff?”     

Are VECs a concern as related to PFAS?  Would soil gas surveys be required even in cases where the assessed property is on city/county water supply?  

“Generally speaking, vapor intrusion potential for the most common PFAS compounds has not been a focus.  However, volatile PFAS is an area of ongoing research.  Keep in mind that there are thousands of different PFAS compounds and, while they may share some similar properties, there properties are far from uniform.”   

How can we distinguish between different sources of PFAS on a client’s property?  Is there a forensics form of fingerprinting for PFAS? 

“Forensic fingerprinting can be accomplished for PFAS compounds.  Many companies and individuals have developed approaches to conducting fingerprinting by looking at relative percentages of various PFAS compounds, understanding the use different PFAS compounds, and understanding the potential for transformation of those compounds in the environment.”  

Are there set distances like in the vapor intrusion standard? 

“We are unaware of any “rules of thumb” for “safe” distances from various PFAS sources.  A variety of factors should be reviewed and professional judgement should be applied.”    

Does PFOS/PFAS travel further than other contaminants? or is it that the detection limits are so low that makes it appear to travel further? 

“All things being equal, many PFAS compounds will travel further than other contaminants of concern.  Low detection limits do play some role, but also the lack of degradation is extremely important.”  

Is the cost of PFAS cleanup significantly more expensive than current requirements? 

“Costs will vary significantly based upon regulatory framework, but assuming you are in a state where PFAS is regulated, the cost would be expected to be high relative to many other contaminants.”   


For the full replay of our March 1st LinkedInLive event, including more insights from our panelists on considerations for scoping out PFAS investigations, click here.  

To stay abreast of the latest developments and technical resources related to assessing PFAS risk, as well as links to past blogs and webinar replays, visit the LightBox PFAS Resource Center.  

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