Formatted Title
Passive In Situ PFAS Immobilization and Removal Using a Novel Funnel and Gate System
Background/Objectives
The migration of poly- and perfluoroalkyl substances (PFAS) in shallow groundwater emanating from aqueous film forming foam (AFFF) sources is a critical environmental challenge for the DoD and other stakeholders. While several promising novel approaches for destructive treatment of PFAS are currently under development through on-going research projects, continued testing and development is needed before field-scale application and validation of destructive in situ approaches can be considered. To address the pressing need of PFAS plume control at impacted sites, ex situ treatment technologies involving groundwater extraction coupled with granular activated carbon (GAC) and/or anion exchange resin (AER) are currently being employed, as passive and long-term in situ PFAS treatment approaches have yet to be demonstrated. This ESTCP-funded field-scale project will evaluate effective and long-term PFAS plume mitigation by installing a funnel and gate system that utilizes AER within the gate for PFAS immobilization and subsequent removal. The primary objective of this project is to demonstrate the long-term and cost-effective capture and removal of PFAS emanating from an AFFF source area using a passive funnel and gate approach.
Approach/Activities
The fundamental concepts supporting this field demonstration are (1) the utilization of a funnel and gate system to divert groundwater through a gate for treatment; (2) the use of AER for PFAS immobilization; and (3) the ability to remove and replace the AER from the gate. The approach is based on the well documented ability of AER to remove both long and short-chained perfluoroalkyl acids (PFAAs) in groundwater without frequent replacement of the resin. The design and construction of the gate will allow for removal and replacement of the AER, as required. To date, project activities have included site characterization, site-specific laboratory column testing, and funnel and gate design, with installation scheduled for the first quarter of 2024. Treatment performance will be conducted over a 2-year period using numerous wells installed upgradient, within, and downgradient of the gate.
Results/Lessons Learned
There are currently no cost-effective passive in situ options for the treatment of groundwater plumes containing PFAS. This technology is expected to provide the DoD and other stakeholders with a demonstrated in situ, passive, cost effective method to mitigate PFAS impacted groundwater in shallow overburden aquifers. There are many different PAB configurations possible for this technology, making it widely applicable at a variety of sites. The funnel and gate approach can be implemented in either high concentration source areas to reduce mass flux, or in larger dilute plumes to protect downgradient receptors and/or mitigate expansion of the plume. Site characterization, laboratory column testing results, funnel and gate design and installation for this project will be presented.