In 2018 Defence completed a detailed environmental site investigation incorporating RAAF Base Tindal and private land in the vicinity of the Base. The investigation identiﬁed that PFAS contamination had entered groundwater and migrated off-site towards the Katherine River. As a result of the contamination, restrictions in the use of ground and surface water were placed on impacted properties surrounding the Base. The Katherine town water supply was also impacted by the contamination. Two primary source areas were identiﬁed on the Base; the ﬁre training area (FTA); and the ﬁre station area (FSA).
ECT2 were contracted to install groundwater treatment systems at both the FTA and FSA source areas to assist Defence in managing PFAS contamination on the Base and the impacted surrounding properties. The remote location, climatic conditions and lack of waste disposal and treatment facilities for PFAS laden waste in the NT represented important considerations during the design of a solution that would not only ensure that the selected water treatment technology would reduce PFAS levels to health based guidance values (HBGV) established for drinking water, but to do so in way that would minimise waste generation.
Modular 12.6L/sec treatment systems were installed at the two source areas. Groundwater is extracted via wells, passes through pre-treatment media to remove ﬁne solids, volatile organic compounds (VOCs), semi-volatile organics (SVOCs) and total organic carbon. The pre-treated water then passes through ECT2’s proprietary SORBIXTM RePURE regenerable resin to remove PFAS compounds and ﬁnally through specialty SORBIX PURE resin which acts as a ﬁnal polish, targeting shorter chain PFAS compounds. Treated water is then directly reinjected into the aquifer via separate well networks at each location. A central SORBIX RePURE regeneration system services both the FTA and FSA systems.
The FTA and FSA treatment systems were commissioned in December 2018 and March 2019, respectively. The regeneration system has been operational since April 2019. The lead/lag conﬁguration, multiple electronic failsafe features and remote monitoring capabilities have helped the water treatment systems achieve an uptime of over 98% during 24/7 operation. By mid March 2020, the treatment systems had treated over 655 million litres of groundwater, and the regeneration system had completed four regenerations of SORBIX RePURE resin, which would have otherwise had to be sent off-site for further treatment and disposal. There have been no exceedances of the established treated water criteria.