Tackling PFAS “forever chemicals” in Greater Western Sydney
In recent years, the issue of per- and poly-fluoroalkyl substances (PFAS) has gathered significant attention due to its widespread environmental impact, particularly in regions with a history of firefighting activities. At the TestSafe facility in Londonderry, Greater Western Sydney, this concern became a pressing reality as runoff from historical fire training exercises led to contamination of stormwater retention dams. With an average PFAS concentration of 85 µg/L, action was a priority for the site owner and local community.
Understanding the forever chemicals
PFAS, often referred to as “forever chemicals,” are notorious for their persistence in the environment and potential health risks. At TestSafe, the site faced contamination not only from PFAS but also from co-contaminants such as humic and fulvic acids. Recognising the urgency, TestSafe engaged SciDev in 2018 to implement a comprehensive strategy for dewatering the contaminated dams, treating the water, and safely disposing of the sediment.
Innovative Water Treatment Solutions
To tackle the contamination effectively, SciDev designed a Temporary Water Treatment Plant (WTP) capable of treating up to 4.6 litres per second (73 gallons per minute). This facility used FlourofIX™ – a cutting-edge technology developed by SciDev that leads the world in PFAS treatment. It effectively removes the full profile of long-chain and short-chain molecules in PFAS. The WTP was engineered for quick mobilisation and demobilisation, allowing it to adapt to the evolving needs of the project. The WTP has been mobilised and commissioned six times over a seven-year period, treating a total of ~20 megalitres (5.3 million gallons) of contaminated water without a need to replace filtration media.
The WTP’s sophisticated design includes a primary reactor tank, a filter bank with twelve filter vessels, and a discharge tank. The filtration process incorporates multiple media types, including zeolite for the first clarification, Granular Activated Carbon (GAC) for adsorption, and two specialised ion exchange resins to ensure thorough treatment. This approach culminates in a final scrub using GAC, allowing for treated water to be safely discharged into the environment via drip irrigation. The discharge followed regulations from the NSW Environmental Protection Agency, under SciDev’s mobile environmental protection license.
Comprehensive Earthworks and Remediation
In addition to water treatment the site required significant earthworks. This included the transport and disposal of contaminated sediments from the retention dams.
The SciDev Team remediated two of the three contaminated dams, they were then capped and decommissioned using clean fill and Geosynthetic Clay Liners, followed by local grass seeding to restore the area.
The third dam was enhanced to triple its holding capacity from 209 kilolitres to 610 kilolitres (or 55k gallons to 161k gallons). To prevent any future leaching of contaminants, the dam was lined with high-density polyethylene liner ensuring robust protection for the surrounding ecosystem.
Successful Outcomes and Benefits
This project shows how targeted interventions can effectively manage PFAS contamination down to a post treatment level of <0.001ug/L. Through cutting-edge technology and strategic earthworks, this initiative not only remediates existing issues but also paves the way for a cleaner, safer environment.
The collaborative efforts between TestSafe and SciDev addressed the immediate environmental concerns and set a precedent for future PFAS treatment initiatives. The project highlights the importance of innovative, sustainable solutions in tackling complex environmental challenges, reaffirming the commitment to protecting our water resources for future generations.
