Smarter PFAS Groundwater Transport Modeling

Smarter per- and polyfluoroalkyl substances (PFAS) groundwater transport modeling requires more than standard flow and transport assumptions; it demands tools designed for persistence, mobility, and complexity.  With the Groundwater Modeling System (GMS) 10.9, groundwater professionals can use MODFLOW-USG Transport to represent PFAS fate and migration with greater accuracy and confidence. Using GMS, a well-constructed PFAS transport model improves numerical stability, enhances credibility, and strengthens regulatory support.

Why PFAS Modeling Requires Advanced Transport Tools

PFAS compounds present unique challenges for groundwater transport modeling compared to traditional contaminants which GMS solves. They are typically:

• Persistent over long time scales

• Mobile within aquifer systems

• Influenced by complex flow paths and subsurface heterogeneity

Because of these characteristics, effective PFAS modeling requires unstructured grids, targeted refinement, and realistic representation of flow and transport pathways which are strengths of MODFLOW-USG Transport in GMS.

What’s New in GMS 10.9

GMS 10.9 expands MODFLOW-USG Transport modeling capabilities by adding PFAS interface options, allowing users to simulate contaminant movement within unstructured grids such as quadtree and nested meshes. This GMS release offers several key advantages:

• Integration with MODFLOW-USG Transport Flow Models

• PFAS transport simulations are directly linked to the MODFLOW-USG Transport groundwater flow solution, ensuring internally consistent flow and transport results.

• Support for Complex Geometry

• Unstructured grids support local refinement around source areas, pumping wells, and surface water boundaries where transport behavior is most sensitive.

• Improved Representation of Heterogeneity

•  Variable grid resolution allows improved representation of layered geology, thin aquitards, and preferential flow paths that strongly affect PFAS transport.

Typical PFAS Modeling Workflow in GMS

1. Develop and calibrate a MODFLOW-USG Transport groundwater flow model within GMS using a conceptual framework.

2. Activate MODFLOW-USG Transport and specify PFAS as the transported contaminant.

3. Define source terms, porosity, dispersivity, and key transport properties.

4. Simulate PFAS migration and analyze plume behavior using GMS visualization tools.

This workflow supports predictive scenario analysis, including plume forecasting, pumping impacts, and remediation effectiveness.

Turn PFAS Complexity into Defensible Results with GMS

The addition of PFAS transport modeling in GMS 10.9 marks a significant advancement for groundwater contamination studies. Leveraging MODFLOW-USG Transport’s unstructured grids allows for improved representation of complex geology and transport pathways. This integration enables modelers to represent contaminant migration more accurately in heterogeneous and complex systems, supporting confident technical and regulatory decisions.

Download GMS 10.9 to explore advanced PFAS transport modeling workflows and apply them to your next project.