Advances in Remediation: Recharge Redux

Congratulations to Charles J. Newell, PhD, PE, BCEE, and Kenneth L. "Neth" Walker, Jr., PE, PG, co-authors of the recently published paper...

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Congratulations to Charles J. Newell, PhD, PE, BCEE, and Kenneth L. “Neth” Walker, Jr., PE, PG, co-authors of the recently published paper “Advances in Remediation: Recharge Redux” in Groundwater Monitoring & Remediation!

Alongside co-authors Craig Divine, Matthew Spurlin, Timothy Blount, Prashanth Khambhammettu, and Marc Killingstad, they explore the critical role groundwater recharge plays in contaminant fate and transport, with particular attention to PFAS.

The article highlights why recharge deserves closer attention in conceptual site models (CSMs) and discusses practical data and tools to help environmental professionals better understand contaminant movement and make informed site assessment and remediation decisions.

Grab a cup of coffee and dig into the research!

Read the publication: https://doi.org/10.1111/gwmr.70090

Implementation and Evaluation of Fully 3D Richards’ Equation in MODFLOW 6

Sebastián Vázquez-Gasty is the lead author of a new paper in Groundwater titled “Implementation and Evaluation of Fully 3D Richards’ Equation in MODFLOW 6,”...

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Sebastián Vázquez-Gasty is the lead author of a new paper in Groundwater titled “Implementation and Evaluation of Fully 3D Richards’ Equation in MODFLOW 6,” alongside GSI’s Sorab Panday, Christian Langevin of S.S. Papadopulos & Associates, and Tirthankar Roy of the University of Nebraska-Lincoln.

The paper introduces a fully three-dimensional Richards’ equation solver integrated into MODFLOW 6, enabling researchers and groundwater professionals to more accurately simulate water movement through saturated and unsaturated soils, including capillary effects and lateral moisture flow.

Using three benchmark tests against established groundwater modeling software, the researchers demonstrated strong agreement in simulated moisture and pressure responses, along with computational efficiency and numerical stability. This advancement offers new capabilities for studying groundwater recharge, vadose-zone processes, and complex subsurface flow conditions.

Congratulations to Sebastián and his co-authors on this publication and their contributions to advancing groundwater modeling capabilities!

Read the paper and access the research implementation and benchmark files here: https://www.gsienv.com/software/modflow-6-richards/modflow6-richards/

Use of Colloidal Gas Aphrons to Remove Per- and Polyfluoroalkyl Substances from Reverse Osmosis Concentrate

Congratulations to Jessica Alanis, Poonam R. Kulkarni, PE, Nicholas W. Johnson, PhD, PE, Hassan Javed, PhD, Victoria Ng, and Charles J. Newell, PhD, PE, BCEE, and their co-authors (Alexandra Farnell, John...

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Congratulations to Jessica Alanis, Poonam R. Kulkarni, PE, Nicholas W. Johnson, PhD, PE, Hassan Javed, PhD, Victoria Ng, and Charles J. Newell, PhD, PE, BCEE, and their co-authors (Alexandra Farnell, John A. Connor) on the publication “Use of Colloidal Gas Aphrons to Remove Per- and Polyfluoroalkyl Substances from Reverse Osmosis Concentrate” in Environmental Engineering Science.

The GSI team co-authored the article with the Los Angeles County Sanitation Districts (LACSD) (Eric D. Nelson, Bruce Mansell, Patricia Hsia, Mojtaba Farrokh Shad), and the University of Houston (Zanina Ilieva, and Hanadi S. Rifai).

The study evaluates colloidal gas aphrons (CGAs) as a treatment approach for removing PFAS from highly saline reverse osmosis concentrate. The researchers examined treatment performance under different operating conditions, and the results demonstrated removal of up to 97% of long-chain PFAS mass and 75% of short-chain PFAS.

The findings provide additional insight into the potential use of CGAs for managing PFAS concentrates through reverse osmosis treatment.

Read the article: https://journals.sagepub.com/doi/abs/10.1177/15579018261488656

Congratulations to all the authors!

Navigating California’s Waste Discharge Requirements for Wineries

California wineries are facing common compliance challenges under the Statewide General WDR, from monitoring requirements and water softener brine separation to pond...

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California wineries are facing common compliance challenges under the Statewide General WDR, from monitoring requirements and water softener brine separation to pond standards and compliance schedules.

In the new North Bay Business Journal article, “Navigating California’s Waste Discharge Requirements for Wineries,” Mehran Ebrahimi, PE, and co-author Donald Sobelman of Farella Braun + Martel take a closer look at these challenges and share practical considerations for wineries working toward compliance.

Read the article: https://www.pressdemocrat.com/2026/09/11/navigating-californias-waste-discharge-requirements-for-wineries/

Texas Stormwater General Permit Update

Is your facility ready for the 2026 Texas Stormwater General Permit renewal? The current MSGP expires on August 14, 2026. Facilities covered...

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Is your facility ready for the 2026 Texas Stormwater General Permit renewal?

The current MSGP expires on August 14, 2026. Facilities covered under the 2021 permit must update their Stormwater Pollution Prevention Plans and submit the revised Notice of Intent by November 14, 2026, to maintain coverage.

GSI’s review of the 2026 MSGP update identified several important administrative, reporting, and monitoring changes. These include expanded benchmark testing for multiple subsectors, quarterly benchmark monitoring during the first three years of coverage, additional monitoring for facilities discharging to impaired waters, and proposed reductions to several benchmark values.

Facilities should complete and implement all required SWPPP updates and submit the NOI before the November 14 renewal deadline to maintain coverage.

Gaurav Tripathi, PE, CESCP, Rajiv Y. Patel, PE, and Wynne Casteel, PG, can help facilities understand the updated requirements and prepare for the 2026 renewal. If you have questions about the new permit requirements or need assistance updating your SWPPP, GSI is here to help.

TPDES MSGP Renewal_GSI Environmental Inc

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