Strategic Delineation at Per‐ and Polyfluoroalkyl Substance (PFAS)–Contaminated Sites: A Framework Combining Source Identification, Background Assessment, and Plume Migration Insights for Remedial Investigations

In recent years, many US entities, including the Department of Defense, have initiated hundreds of remedial investigations (RIs) at sites with per‐ and polyfluoroalkyl substance (PFAS) contamination. Although this work generally follows traditional guidance, considerable autonomy is given to the consultant conducting the RI, leading to variable methodologies and associated outcomes, all else equal. Thus, there is a need for a conceptual and systematic framework for conducting an RI for PFAS, especially considering growing knowledge related to the novelty of their fate and transport and ubiquity in the environment. To address this need, at least as it pertains to defining the nature and extent of contamination, we summarize various methods presented to date and recommend a standard of practice that balances trade‐offs between technical rigor and cost as a systematic guide for practitioners consistent with the state of the science.