Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7n. PFAS Source and Forensic Considerations

Formatted Title:

PFAS in Groundwater Forensics: Case Study Findings and Lessons Learned

Background/Objectives:

Five years ago, per- and polyfluoroalkyl substances (PFAS) source identification forensics was not possible. Little was known or proven on PFAS sources, degradation pathways, fate and transport, and manufacturing history. However, recently there has been headway on PFAS forensics and now there are best practices for evaluating sources and general timing of releases. This presentation will cover a case study and best practices that can be useful to address PFAS source claims with limited data.

The background for this case began when the insured received a request to investigate PFAS on the property after the state found PFAS in nearby private drinking water supply wells. In response to the state’s request, the insured initiated PFAS monitoring in groundwater at their property and tested the soil as well. The state also requested the local municipality to also monitor groundwater for PFAS from an inactive unlined landfill across an intermittent brook near the claimant’s property. The state wanted to understand what the source of PFAS to the private drinking water wells was for the purpose of assessing liability for costs associated with installing temporary point of entry treatment systems and future connections of the affected properties to the local municipal water supply.

The objective of this case study will present the findings using PFAS specific forensic tool with the limited analytical data provided and the lessons learned.

Approach/Activities:

Insurance coverage issues arising out of PFAS claims will spur questions by an insurer to justify coverage or deny a claim. The most common questions include:

How was the release discovered?
Did the PFAS release occur within the policy period?
What is the alleged source subject to the claim?
Are there any other potential sources of PFAS adjacent to the insured property and the private drinking water wells?

This presentation will look more closely at those four questions and best practices to consider for data evaluation and data gap analysis. The best practices involve best practices and several lines of evidence including but not limited to:

What to share with your consultant and what should not be shared to avoid unintentional bias
Age dating using timing of regulations such as import under the significant new use rule or other country or state rules, precursors and analytical data gaps.
Alleged suspected source versus the reality using graphical representations and data plot that identified multiple sources and comingling using carboxylate sulfonate ratios and other data representations.
Possible other sources and the justification to support possible other sources.

This will include education on the definition of a carboxylate functional group versus the definition of a sulfonate functional group in laymen terms and why these functional groups should be part of your PFAS vocabulary.

Results/Lessons Learned:

PFAS source forensics has evolved significantly in the last five years. With any forensics analysis there is no ‘silver bullet’; forensic tools must be used along with other supporting lines of evidence such as groundwater flow direction, velocity, and reviews of facility processing or raw material use records. Based on the data provided in this case study, there appears to be two separate sources of PFAS to the groundwater in the vicinity of the affected drinking water supply wells: the landfill and the insured property. However, the predominant contributor of total PFAS to groundwater is the unlined landfill. The dominant PFAS in from the landfill were carboxylates whereas the dominant PFAS on the insured property were sulfonates. The sulfonates in the insured property wells would have been discharged at least before 2002 in light of the SNUR restrictions in 2002 for PFOS. Additionally, the Safety Data Sheets of raw mateirals containing PFOS and precursors were dated before 2002. There is a possible third source, the transfer station. The transfer station may be an ongoing source to both the landfill, the claimant’s property and the private water supply wells but has not been evaluated.

Lessons Learned

There were several data gaps identified as part of this forensics study. Data gaps are a result of not involving subject matter experts in the planning of an investigation:

Groundwater flow directions are not understood as there was no common elevation datum and one monitoring event for all wells, it’s best practice to use national geodetic datum.
There were insufficient groundwater elevation monitoring events and no events for all wells within one day. Surface water elevations were not monitored during groundwater elevation monitoring. Stakeholders may not want to collaborate for liablity protection.
Insufficient vertical profiles and monitoring well locations. This was an initial investigation but the data was insufficient to support a claim.
Monitoring well design was not available for all the wells.
There was an additional potential source of PFAS that was not evaluated. An active ajacent transfer station northwest of the landfill, is a source of PFAS.
No other analyses were performed such as geochemistry, branched/ linear identification or TOC Assay so the overall recommendtion is additional investigation. However, data presented to date suggests the PFAS release is a condition that existed before the policy period.

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Katie Phelps