❓ A WA parliamentary question on notice addresses Alcoa's management of sewage treatment plants and PFAS treatment at its Huntly and Willowdale mines, focusing on approvals, monitoring, and potential environmental impacts within a drinking water source area.
AnsweredQoN 1101Legislative Council
QuestionView source ↗
(1) I refer to Table 3-2 on page 48 of Alcoa's Water Resources Management Plan for the Huntly and Willowdale Mines (WRMP) lodged with the EPA, together with Figures 3-15 and 3-16 of the WRMP that refer to Biomax Locations and Proposed Groundwater Monitoring Locations, noting that Biomax in Western Australia are a company that produces sewage treatment plants, and I ask? (2) are there any sewage treatment plants on either of the sites currently: (a) if yes to (2), can the Minister please provide details of their location? (3) under what approval/s is Alcoa permitted to treat and release wastewater for each site? (4) what conditions apply to these approval/s? (5) what are the monitoring and enforcement arrangements for the approval/s? (6) is the Minister aware of any instances of sewage treatment plants releasing partially treated sewage wastewater within a Priority 1 drinking water source area? (7) does the Huntly mine have an existing PFAS treatment unit at its Myara site: (a) if yes to (7), what approval is Alcoa permitted to treat PFAS under at this location; and (b) if yes to (7), what monitoring and compliance arrangements are in place to ensure the water released is safe?
AnswerView source ↗
Answered
24 February 2026
Responded by
Minister for the Environment
Response time
5 days
(1) – (2) Yes, based on the Water Resources Management Plan, there are 13 Biomax sewage treatment plants (BSTP) at the Huntly Minesite and eight BSTPs at the Willowdale Minesite. The locations of the BSTPs are depicted within the Water Resources Management Plan (WRMP), 7 February 2025 as being located in the following mining areas:
Mine
Mining Area
Number of BSTP
Huntly
Myara
5
McCoy
3
White Road
2
Huntly Central
1
Del Park
1
Hun19A (Near Pinjarra Refinery)
1
Willowdale
Larego
6
Arundel
2
(3) Approval is required for BSTPs under the Health Act 1911 and Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974 , administered by the Department of Health. The Shire of Murray and the Shire of Waroona may also require Alcoa to hold approvals for sewage treatment. The Department of Water and Environmental Regulation has sought latest information from Alcoa to identify the cumulative throughput of BSTP at Willowdale and Huntly to determine whether licensing provisions in Part V of the Environmental Protection Act 1986 apply.
(4) - (6) These questions should be referred to the Hon Meredith Hammat MLA, Minister for Health.
(7) Yes. A temporary PFAS treatment plant is located at the Myara mining hub, treating water with low levels of PFAS.
(7) (a) The temporary PFAS treatment plant allows Alcoa to remove detectable PFAS and be compliant with Licence L6210/1991/10 [I table a copy of the Licence.], including condition 4, which states the Licence Holder must treat contaminated or potentially contaminated wastewater prior to discharge. The licence does not authorise the discharge of PFAS.
(7) (b) The Licence requires wastewater monitoring (Licence L6210/1991/10). DWER undertakes regular compliance activities in accordance with its Compliance and Enforcement Policy.
Mine
Mining Area
Number of BSTP
Huntly
Myara
5
McCoy
3
White Road
2
Huntly Central
1
Del Park
1
Hun19A (Near Pinjarra Refinery)
1
Willowdale
Larego
6
Arundel
2
(3) Approval is required for BSTPs under the Health Act 1911 and Health (Treatment of Sewage and Disposal of Effluent and Liquid Waste) Regulations 1974 , administered by the Department of Health. The Shire of Murray and the Shire of Waroona may also require Alcoa to hold approvals for sewage treatment. The Department of Water and Environmental Regulation has sought latest information from Alcoa to identify the cumulative throughput of BSTP at Willowdale and Huntly to determine whether licensing provisions in Part V of the Environmental Protection Act 1986 apply.
(4) - (6) These questions should be referred to the Hon Meredith Hammat MLA, Minister for Health.
(7) Yes. A temporary PFAS treatment plant is located at the Myara mining hub, treating water with low levels of PFAS.
(7) (a) The temporary PFAS treatment plant allows Alcoa to remove detectable PFAS and be compliant with Licence L6210/1991/10 [I table a copy of the Licence.], including condition 4, which states the Licence Holder must treat contaminated or potentially contaminated wastewater prior to discharge. The licence does not authorise the discharge of PFAS.
(7) (b) The Licence requires wastewater monitoring (Licence L6210/1991/10). DWER undertakes regular compliance activities in accordance with its Compliance and Enforcement Policy.
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