Role

• Retained as a testifying expert by co-defendants in a PFAS class action.
• Provided independent scientific analysis and expert rebuttal.
• Worked with attorneys from several defense firms.

Scope

• Evaluated whether evidence supported claims that PFOS, PFOA, 6:2 FTS, and other PFAS emissions from a single source caused city-wide impacts to soil, indoor air, and drinking water, and whether uniform remedies were scientifically justified.
• Presented findings to counsel in weekly meetings.
• Prepared expert rebuttal report.

Process

• Conducted a forensic hydrogeologic analysis of an extensive discovery record, integrating environmental investigation reports, laboratory results, hydrogeologic data, historical operational records, deposition testimony, regulatory documents, and published technical literature. The analytical data included groundwater, soil, attic dust, water heater sediment, tap water, and public water supply samples.
• Analyses addressed source attribution, contaminant fate and transport, groundwater flow conditions, plume delineation, temporal concentration trends, sampling methods, exposure assumptions, and alternative PFAS sources.
• Developed independent conclusions about source attribution, contaminant fate and transport, and the extent of alleged impacts
• Evaluated whether the opposing expert’s methods and interpretations were consistent with the evidence, accepted scientific practices, and the limitations of the available data.
• Presented findings to counsel in weekly meetings, explaining how unsupported assumptions and methodological deficiencies in plantiff’s expert report affected the scientific basis for alleged impacts and proposed remedies across the class.
• This collaboration helped counsel understand the relevance of the findings to class-certification arguments.

Outcome

• Rebuttal identified dozens of technical flaws in the plaintiffs’ expert report, underscoring how arguments of a single contaminant source and commonality of impacts and remedies were not justified.
• Rebuttal report included concise explanations and focused illustrations, making the environmental data, unfamiliar scientific concepts, and scientific rationale of rebuttal arguments accessible to counsel and the court.
• Analysis, presentations, collaboration, and rebuttal report helped counsel achieve a very favorable settlement.