This project will create two different groundwater fate and transport models specific to per- and polyfluoroalkyl substances (PFAS) that leverage existing code, user interfaces, and the most recent PFAS fate and transport knowledge for effective remediation decision-making at PFAS-impacted sites. Through this, the project team aims to enhance the ability to accurately model remediation actions, forecast likely PFAS plume responses, and thereby determine the most suitable remediation strategies. The ultimate deliverables are two open-source PFAS remediation models: the spreadsheet-based "REMFluor" for simple to intermediate complexity sites and the more complex MODFLOW-USG-T Model Adapted to Model PFAS (USGT-PFAS).

Two New Proposed PFAS Models - REMFluor and USGT-PFAS

This project will integrate two core resources: 1) existing groundwater models and user interfaces previously developed by the project team, and 2) up-to-date PFAS fate and transport knowledge drawn from the latest scientific research and PFAS groundwater modeling experience.

The REMFluor model will be a user-friendly, free tool developed with a familiar Biodegradation of Chlorinated Solvents and Remediation Model for Chlorinated Solvents with Matrix Diffusion interface design. However, it will be customized to focus specifically on PFAS fate, transport, and remediation in saturated zones for sites of simple to intermediate complexity. In contrast, the USGT-PFAS is a robust MODFLOW-USG-Transport-based numerical model that will be customized for incorporating PFAS source loading data. The design will allow users to employ key SERDP & ESTCP tools like the University of Arizona's PFAS-LEACH suite of Tiered Models.

These tools will empower users with the ability to simulate PFAS plume responses to specific remediation options, facilitating informed decision-making for Feasibility Studies. The REMFluor and USGT-PFAS models' flexibility enables the application of the most suitable model based on an individual site’s complexity. At certain sites, these models could determine whether source remediation significantly impacts downgradient plume migration in the short to middle term (a few decades). These models could also provide the necessary performance and longevity data to compare permeable reactive barriers and pump-and-treat remedies at sites where some form of near-term plume control is needed. Finally, these models could potentially catalyze the adoption of retention-based monitored natural attenuation for smaller, low-risk sites. Overall, these PFAS models have the potential to revolutionize the remediation decision-making at PFAS-impacted sites, leading to significant financial savings and enhanced environmental stewardship that will bolster operational capabilities and warfighter preparedness. (Anticipated Project Completion - 2026)