Overview
Alcoa of Australia Limited (Alcoa) holds licence L6465/1989/10 under Part V, Division 3 of the Environmental Protection Act 1986 (EP Act) for bauxite mining at the Willowdale Mine in Waroona.
On 20 February 2024, the Department of Water and Environmental Regulation (the department) approved Alcoa’s application to construct and operate a per- and polyfluoroalkyl substances (PFAS) wastewater treatment plant at the Willowdale Mine, through an amendment to licence L6465/1989/10. PFAS are a group of chemicals used in some types of fire suppression foams. The PFAS contamination at the Willowdale mine was identified in soils and stormwater sumps in the Orion and Arundel mining areas, attributed to the historical use of PFAS-containing firefighting foams to supress fires at the mine site. Alcoa advises it has ceased using foams containing PFAS at Willowdale mine.
The licence amendment gives Alcoa approval to discharge water that has been treated to ‘ultra trace’ levels of PFAS to McKnoes Brook. The PFAS treatment plant and discharge point will be located within the Willowdale active mining area and outside priority drinking water catchment areas. PFAS-containing wastewater will be trucked to the treatment plant from where it is currently stored in sumps in the Samson Brook drinking water catchment.
This licence amendment allows Alcoa to reduce the volume of PFAS contaminated water stored in the drinking water catchment areas, supporting a better environmental outcome.
Treatment of PFAS to ‘ultra trace’ detection levels is a conservative approach, as these are lower than national guideline values for freshwater ecosystems. The department has undertaken a comprehensive risk assessment and found that the discharge will not result in harm to public health or the environment due to the high level of treatment provided by the plant. Only water that meets the required concentrations, as demonstrated through testing, will be discharged to McKnoes Brook. Any water that does not meet the required standards will be returned for re-treatment.
The department considered all submissions received after the amendment application was advertised for public consultation and referred to direct interested parties in July 2023 in its risk assessment. A summary of submissions is outlined in Appendix 2 of the department's Amendment Report.
The amended licence together with the department's risk assessment can be found on the Licences and works approvals available for public appeal webpage.
What is happening now?
Any person who disagrees with the amendment of the licence may lodge an appeal with the Minister for Environment (through the Office of the Appeals Convenor) within 21 days of the amendment.
Investigations
In February 2023, the department received and responded to a complaint alleging that Alcoa had constructed and operated a pipeline and related infrastructure for the transport and storage of wastewater impacted by PFAS at the Willowdale mine without authorisation.
Two Prevention Notices have been issued to Alcoa relating to the unauthorised construction and operation of the PFAS wastewater pipeline and infrastructure and the ongoing management of PFAS impacted wastewater at the Willowdale mine. Alcoa has complied with the requirements of the Prevention Notices issued to date.
This matter is under investigation.
More information
The department will update this page as new information comes to hand.
For any questions related to the licence, please email info@dwer.wa.gov.au and quote 'L6465'.
For appeal enquiries, please contact the Office of the Appeals Convenor on (08) 6364 7990 or by email to admin@appealsconvenor.wa.gov.au.
