Geotextile research reveals hidden PFAS contamination risk 

Associate Professor Will Gates contributed to the paper, “Are Geotextiles Silent Contributors of Ultrashort Chain PFASs to the Environment”, which analysed per- and poly fluoroalkyl substances (PFAS) in geotextiles commonly used in geosynthetic composite lining systems for waste containment facilities.

At a glance

  • Research has revealed a hidden PFAS contamination risk in the geotextile lining systems used in landfills to stop waste seeping into soil and waterways.
  • Geotextiles contain the PFAS compound pentafluoropropionic acid (PFPrA) – usually considered a breakdown product of PFAS.
  • Next steps include research into improving PFAS containment with modern engineered lining systems.

Geotextile lining systems are essential components of composite lining systems in modern landfills to contain waste and leachates seeping into soil and waterways, but new research has revealed they may be part of the problem – instead, spreading potentially harmful ultra short-chain PFASs into the environment. 

PFASs, or per- and poly fluoroalkyl substances, are chemicals used in various textile manufacturing and fabric treatment applications for stain and water protection. They are also notorious as ingredients in fire-fighting foams.  

Although the full extent of the risks of PFAS to humans is unknown, the chemicals can remain in humans and the environment for years and as a precaution exposure should be minimised.  

In the paper, “Are Geotextiles Silent Contributors of Ultrashort Chain PFASs to the Environment”, researchers, including IFM’s Associate Professor Will Gates, analysed per- and poly fluoroalkyl substances (PFAS) in geotextiles commonly used in geosynthetic composite lining systems for waste containment facilities.

Geotextiles, like this, are commonly used in geosynthetic composite lining systems for waste containment facilities.

The research revealed that the geotextiles do contain the ultrashort chain PFAS compound pentafluoropropionic acid (PFPrA) – usually considered a breakdown product of other PFAS. Although smaller PFAS are considered less toxic and used in many consumer products, they also appear to disperse further and are present everywhere they have been looked for, according to Assoc. Prof. Gates. 

“This body of research has revealed the fact that materials used for mitigation may form part of the problem,” he said. 

“PFPrA was detected in 100% of all samples from polypropylene geotextiles and at least 70% of all polyester geotextiles at concentration that potentially pose environmental risks – from products used to contain contaminants themselves. 

“All geotextiles tested had been locally manufactured in Australia between 2020 and 2022 from imported virgin plastics. 

“These results lead to questions as to whether PFPrA is as much breakdown product as believed.” 

Why use geotextiles?

In landfill, geotextiles are used together with other materials and products to stabilise the subsoil and side slopes; serve as filters, root barriers and protective layers for critical components, such as leach collection pumps; and are an integral part of composite liners, for example, geosynthetic clay liners.   

“Normally geotextiles are used in conjunction with geomembranes, or high-density polyethylene sheets,” Assoc. Prof. Gates said.   

“To be fair, until recently composite lining systems have not been engineered to retain PFAS and currently there are limited economic alternatives for this purpose available.”  

He said that given the worldwide bans on production and use of PFASs in fire-fighting foams and the more recent listing of many PFAS as contaminants, there had been a shift from industry to manufacture and use shorter chain length PFAS. 

“The ultra short chain length PFAS have been considered to be less likely to bioaccumulate, have shorter half lives in biological systems and appear to be less toxic,” he said. 

“However, the recent explosion of research into the presence and quantification of all sorts of PFAS in various environments (natural and anthropic) and in various manufactured products has shown that they are everywhere. Basically, wherever one searches, one finds them.”  

Developing new infrastructure materials

Assoc. Prof. Gates, who specialises in sustainable and durable infrastructure materials, previously showed that  PFAS contaminated soil, after being remediated through a novel heat treatment process, could be used as fine aggregate for concrete and mortar.  

Now, he hopes to continue his research on improving PFAS containment with modern engineered lining systems.    

“This research was part of an ARC Linkage grant for the project ‘Designing the next generation of geosynthetic liner systems’ in which I was a co-Chief Investigator, along with colleagues at Monash University, University of Sydney and Queens University in Canada, as well as with Australian and international industry partners” he said. 

“Landfill lining systems are an important part of critical infrastructure.   

“The US Environmental Protection Agency has already lowered acceptable limits of PFAS compounds to near no-detection levels.    

“The EU has recently instigated legislation to eliminate the use of any PFAS in the manufacture of geomembranes, or high-density polyethylene products used in landfill lining.   

“I expect other jurisdictions will follow suit.”