The historical use of aqueous film forming foam (AFFF) at RAAF Base Tindal in the Northern Territory (NT), resulted in per- and polyfluoroalkyl substances (PFAS) groundwater contamination of the Tindall aquifer, which is used to supply the NT Power and Water Corporation’s (PWC) Katherine Water Treatment Plant. The Katherine community relies predominantly on surface water from the Katherine River with groundwater used to meet peak demand requirements. The contamination of the groundwater potentially impacts the safety of the drinking water supply, which services approximately 10,000 people. To secure the Katherine community’s water, it was determined that a treatment solution was required for both the immediate and long term.
A quick and proven solution was required to provide the Katherine township with secure and safe drinking water. Defence agreed to provide a treatment system to meet the need. The speed at which the treatment system needed to be fabricated and deployed, the means of transporting the system to Australia, and the evolving needs of PWC represented significant challenges that required innovative solutions. ECT2, Defence and PWC formed a close partnership to finalise design, fabrication, transport, installation and commissioning of the treatment system within four months of PFAS being identified in the drinking water supply.
The emerging nature of PFAS resulted in community members and some regulators expressing concerns regarding the effectiveness of the water treatment system and whether the treatment process would simply solve the issue of low levels of PFAS in the water supply by concentrating PFAS on media which then had to stored due to limitations on disposal or destruction options, particularly in the NT. These concerns were managed though ongoing and close communication with all stakeholders and working with PWC, and Defence where relevant, to provide information to stakeholders, including the community, as well as opportunities to view the treatment system.
ECT2 designed a PFAS treatment system that includes pre-treatment filtration to remove solids and other fouling agents prior to PFAS removal by ECT2’s proprietary SORBIXTM resin. Manufacturing of the system took place in ECT2’s central fabrication shop in Maine where it was installed in international shipping containers for easier transportation from the United States to Australia. This approach also facilitated operational adjustments prior to shipment and translated to faster on-site readiness. Defence further accelerated the delivery schedule through air-freighting the system in an Antonov An-124 transport plane to Darwin, Australia, where it was then transported approximately 330 kilometres by road to Katherine.
The 12.6 litre-per-second water treatment system went online in late October 2017, and by early February 2021 almost 1.2 billion litres of water had been treated with no exceedances of the treatment criteria which is set at below the Australian Drinking Water Guidelines of 0.07µg/l for the sum of perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) and 0.56µg/l for perfluorooctanoic acid (PFOA). To meet long-term water supply requirements of the Katherine community, PWC have engaged ECT2 to design a treatment system with the capacity to process 10 megalitres of water per day with additional capacity to increase the volume, if necessary.