MODFLOW-USG Software Update 2.6.0

GSI has released Version 2.6.0 of USG-Transport (USGT), our advanced groundwater modeling tool for structured and unstructured grids. This latest update includes...

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GSI has released Version 2.6.0 of USG-Transport (USGT), our advanced groundwater modeling tool for structured and unstructured grids. This latest update includes expanded capabilities, bug fixes, and documentation updates that support more flexible modeling and improved accuracy.

What’s new in Version 2.6.0?

• DRT: Now supports multiple return flow cells per drain cell, allowing more uniform water distribution across recharge zones or agricultural fields
• BCT: Added Variable Solubility option to account for spatial variability in solubility parameters
• New documentation provides guidance for simulating evapotranspiration in variably saturated soils using the EVT or ETS packages

The update also includes example datasets and a ReadMe file outlining the changes.

USGT supports a wide range of groundwater and solute transport processes, including:

• PFAS and heat transport in vadose and saturated zones
• Connected linear networks (CLNs) for modeling wells, streams, wetlands, and infrastructure
• Saturated and unsaturated flow using the 3-D Richards Equation
• Dual porosity and multicomponent transport with chain decay
• Borehole Heat Exchangers (BHEs)
• Density-dependent flow and transport
• Advanced recharge and extraction options through the QRT and DRT packages
• PHREEQC integration available as a separate executable
• Support for GUIs, PEST utilities, and particle tracking

Access the update and supporting documentation at:
https://www.gsienv.com/product/modflow-usg/

You can also find the PFAS-focused version at:
https://www.gsienv.com/software/modflow-usg/usgt-pfas/

USGT continues to evolve to meet the needs of environmental professionals solving complex groundwater challenges.

Charles J. Newell and David T. Adamson: "A Long Way to Go: Challenges and Strategies for Managing PFAS in Groundwater" explores national-scale PFAS remediation strategies.

A Long Way to Go: Challenges and Strategies for Managing PFAS in Groundwater

A new publication in "Remediation" features contributions from GSI’s Charles J. Newell and David T. Adamson: "A Long Way to Go: Challenges...

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A new publication in “Remediation” features contributions from GSI’s Charles J. Newell and David T. Adamson: “A Long Way to Go: Challenges and Strategies for Managing PFAS in Groundwater.”

Co-authored with Paul B. Hatzinger (APTIM) and John S. Cook, this open access article explores national-scale PFAS remediation strategies by comparing pump-and-treat systems within situ permeable sorptive barriers across more than 10,000 hypothetical contaminated sites in the U.S.

The analysis finds that containment-focused approaches at a greater number of sites may offer more effective and cost-efficient risk reduction than intensive cleanups at fewer locations. The authors propose a phased national strategy: near-term containment and exposure prevention, followed by targeted mass removal as in situ destructive technologies evolve.

Read the open access article about challenges and strategies for managing PFAS in groundwater: https://onlinelibrary.wiley.com/doi/full/10.1002/rem.70028

This article was developed in support of a wider tech transfer-focused project led by Dr. Hatzinger and funded by PFAS-Related R&D Efforts, SERDP-ESTCP

regulatory criteria to perfluoropolyethers

A critical review of the application of polymer of low concern and regulatory criteria to perfluoropolyethers

GSI’s Hassan Javed and Graham K. Ansell, together with co-authors Frank Adamsky, Marco Malvasi, Paige K. Mulvaney, Pier Antonio Guarda, Robert H....

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GSI’s Hassan Javed and Graham K. Ansell, together with co-authors Frank Adamsky, Marco Malvasi, Paige K. Mulvaney, Pier Antonio Guarda, Robert H. Moffett, Simone Genna, Steve Johnston and Xian Liang, have published a study titled “A Critical Review of the Application of Polymer of Low Concern and Regulatory Criteria to Perfluoropolyethers” in Journal of Fluorine Chemistry.

The paper examines perfluoropolyethers (PFPEs), a class of polymeric PFAS widely used as lubricants in aerospace, healthcare, automotive, and other sectors, and evaluates them against Polymers of Low Concern (PLC) criteria. The study finds that PFPEs, owing to their high stability, negligible bioaccumulation, and distinct physicochemical characteristics, pose minimal risk to human health and the environment. The authors emphasize that PFPEs should be evaluated as a separate class for regulatory purposes, distinct from non-polymeric PFAS.

Read the full article about regulatory criteria to perfluoropolyethers here: https://www.sciencedirect.com/science/article/abs/pii/S0022113925000715

aqueous film-forming foam (AFFF)

Characteristics of aqueous film forming foam (AFFF) sites impacted with per- and polyfluoroalkyl substances (PFAS): A 37-site study

We’re proud to share a new publication in "Water Research": "Characteristics of aqueous film forming foam (AFFF) sites impacted with per- and...

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We’re proud to share a new publication in “Water Research”: “Characteristics of aqueous film forming foam (AFFF) sites impacted with per- and polyfluoroalkyl substances (PFAS): A 37-site study.”

Co-authored by Poonam Kulkarni, PE, Abigail Cartwright, PE, David T. Adamson, PhD, PE, John Cook, EIT, and Charles J. Newell, PhD, PE, BCEE of GSI, along with Nicolette E. Andrzejczyk and Arun Gavaskar, this article provides insight into PFAS concentration patterns in soil and groundwater at AFFF source zones across the U.S.

Key findings include:
• PFOS and PFOA are the primary contributors in soil, while groundwater concentrations show broader variability
• Maximum PFAS concentrations typically occur in the top one meter of soil
• Median inferred plume lengths for the seven PFAAs range from 220–800 meters
• PFOS, PFOA, and PFHxS contribute 99% of the estimated groundwater exceedance magnitude

Read the full paper about Aqueous Film Forming Foam (AFFF) sites impacted with per- and polyfluoroalkyl substances (PFAS) here: https://www.sciencedirect.com/science/article/abs/pii/S0043135425010310

PFAS analytical methods – A practical guide

We’re proud to share a new publication by GSI’s Graham K. Ansell, PhD and Hassan Javed, PhD titled "PFAS Analytical Methods – A Practical Guide," available...

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We’re proud to share a new publication by GSI’s Graham K. Ansell, PhD and Hassan Javed, PhD titled “PFAS Analytical Methods – A Practical Guide,” available in the “Journal of Fluorine Chemistry.”

As PFAS science advances, so does the need for accurate and reliable analytical methods. This article offers a practitioner-focused overview of current PFAS methods, from EPA’s promulgated methods to screening methods, highlighting the strengths, limitations, and key considerations of each.

Whether you’re experienced in PFAS analytical methods or just starting to explore the challenges of PFAS analyses, this guide is a valuable resource for informed decision-making.

Read the full article here: https://www.sciencedirect.com/science/article/abs/pii/S0022113925000569

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