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Dear Editor and Readers,
This letter concerns the effect of PFAS-type chemicals(1) to the lifespan of polyethylene geomembranes and the potential for a reduction in lifespan from PFAS exposure. While there is great benefit from academic journals and publications, there is, on occasion, benefit to be had from industrial experience that is not academic in nature, but rather the result of real-world outcomes and experiences. Geosynthetics Magazine has a long history of support to the geosynthetics industry, and I hope to add to that here.
Clearly there is a human (and animal) health hazard that has been identified from exposure to PFAS-type chemicals. Activities, debate, and discussions are underway to calculate potentially acceptable contamination levels and how isolation and remediation should be undertaken. While the evaluation of these exposures is ongoing, humans have begun the efforts to contain and isolate PFAS contamination. One of the expected, and reasonable, methodologies for this is the isolation of PFAS contaminated materials in a landfill, dedicated storage facilities, or other civil construction that provides containment with a geosynthetic barrier. Past successes would suggest composite barrier systems are the most effective systems, particularly for meeting goals of parts per trillion exposure and containment levels.
The nearly universal materials for barrier containment are polyethylene-based geomembranes (perhaps in this case, multi-layer materials with Ethylene-Vinyl-Alcohol components) used with composite materials. Several suppliers offer composite materials with PFAS containment capabilities to provide the composite performance with geomembranes. The issue at hand is what effect the PFAS materials might have on the performance and lifespan of the geomembranes. While from an academic perspective this may be a “new question” there is significant industrial history suggesting that exposure to PFAS-type chemicals (heavily or completely fluorinated carbon chains) should not significantly alter the expectations for geomembrane performance.
The author has first-hand experience with this topic.
During the period 1994 to 2000, polyethylene geomembranes manufactured at the (then GSE) Hardy Street manufacturing facility in Houston, Texas, utilized small amounts of fluoropolymers as processing aids for geomembrane manufacture. These were present in the parts per million level. Tens, if not hundreds of million square meters of these geomembranes were manufactured, installed, and placed into barrier service, in every type of application. In fact, this material was used in several of the academic studies characterizing and estimating polyethylene geomembrane lifespan. There was, and remains, no apparent long-term damage or harm to the performance and lifespan of these materials from exposure to these types of chemicals.
There are simply too many chemicals to complete a direct examination of every combination; this extends to “PFAS.” However, a proven chemist’s principal is that materials with similar structure and composition behave similarly. The staff at Queen’s University(2) has done excellent work determining permeability coefficients for some PFAS varieties in polyethylene geomembranes. It is my opinion, based on my personal history and my knowledge of polyethylene geomembrane manufacture and use, that these materials, especially in combination with a PFAS absorbing geocomposite provide the best possibility for successful containment.
Our industry has identified many other factors, and best practices, to implement in providing effective containment. My recommendation is to focus on those issues. I do not view a reduction in the lifespan of geomembranes due to PFAS exposure as a serious concern.
With regards,
Boyd Ramsey
Boyd Ramsey Consulting LLC
Email: Boyd@Boydramseyconsulting.com
Web: www.boydramseyconsulting.com
Phone: 281-797-6183
1) Buck, R.C., (2001), “Perfluoroalkyl and Polyfluoroalkyl Substances in the Environment: Terminology, Classification, and Origins”, Integrated Environmental Assessment and Management — Volume 7, Number 4—pp. 513–541.
2) DiBattista, V., Rowe. R.K., Patch, D. and Weber, K. (2020) PFOA and PFOS Diffusion through Geomembranes at Multiple Temperatures, Waste Management – and others.