Background
The Water Corporation holds licence L6640/1994/11 under Part V Division 3 of the Environmental Protection Act 1986 (EP Act) for the Gnarabup Wastewater Treatment Plant, located on Gas Bay Road, Gnarabup (the premises). The premises is licensed for the following activities:
- Category 54 Sewage facility: premises –
(a) on which sewage is treated (excluding septic tanks); or
(b) from which treated sewage is discharged onto land or into waters.
The licence authorises the Water Corporation to accept and treat up to 356 cubic metres of sewage at the premises per day and specifies conditions for its operation.
The Department of Water and Environmental Regulation (DWER) has responsibility under Part V Division 3 of the EP Act for granting works approvals and licensing or registration of prescribed premises.
DWER conducts environmental assessments in accordance with its Regulatory Framework and follows a risk-based approach to determining the outcome of applications. This process involves the identification of potential emissions sources, pathways, and receptors relevant to the proposed activities at a premises and an assessment of the risks of identified emissions, with consideration of the applicant’s proposed controls and separation distances to sensitive receptors.
On 21 May 2021, DWER granted an amendment to licence L6640/1994/11 to enhance the groundwater monitoring network including the replacement of two monitoring bores. In assessing the Water Corporation’s application, DWER undertook a review of groundwater and ocean shore water monitoring data near the premises. DWER’s findings are presented in the Amendment Report.
DWER’s review identified some uncertainties in the current understanding of groundwater and shore water quality. To address these gaps, DWER required the monitoring program to be enhanced by expanding the groundwater bore network and suite of analytes. DWER also required the Water Corporation to provide a more detailed assessment of environmental monitoring data within its annual environmental reports. These requirements have been incorporated into licence L6640/1994/11.
Part of DWER’s role is to monitor compliance using tools such as inspections, reviews, audits, community reports and complaints, and to review information provided or collected from other regulatory authorities. If offences are committed, DWER will take appropriate action in accordance with its Compliance and Enforcement Policy. The premises was last inspected by DWER on 24 October 2023, at which time the Water Corporation was found to be compliant with its licence conditions. The facility will be subject to an inspection in the 2025/26 inspection program.
What is happening now
Show moreThe Water Corporation has submitted three Annual Environmental Reports (AER) to DWER since the revised monitoring and reporting program was implemented, covering the 2021/2022, 2022/2023, and 2023/2024 reporting periods. DWER’s assessment of the three AER’s determined that:
- Groundwater and surface water monitoring results indicate that the concentrations of monitored analytes remain consistent across annual monitoring periods.
- There was no evidence of risk to human health or the coastal environment due to contaminants migrating from the premises via infiltrated treated or untreated wastewater to land or underlying groundwater
Microbial concentrations recorded in shore water samples at Gas Bay decreased in the 2022/2023 and 2023/2024 monitoring periods, compared to concentrations recorded in the 2021/2022 monitoring period, to below the Level of Reporting (LOR), indicating that sampled water quality has improved from a ‘Category B’ to a ‘Category A’ under the NHMRC Guidelines for Managing Risks in Recreational Water. This suggests good to very good water quality under that framework.
- Recreational water sampling results indicated that the water quality within Gas Bay is comparable to the water quality at Gnarabup beach and Gracetown beach.
In summary, results from the enhanced monitoring program indicate that it is unlikely that water quality in Gas Bay is being impacted from Gnarabup Wastewater Treatment Plant. The review of future AERs, together with data gathered during DWER’s compliance activities, will inform future regulatory decisions relating to the premises.
Future developments
Show moreDWER is aware that the community is concerned about the potential implications of the proposed Gnarabup Tourism Development – Resort and Beach Village on wastewater treatment capacity needed at Gnarabup Wastewater Treatment Plant. This development is currently under assessment by the Environmental Protection Authority (EPA). The EPA’s future assessment report to the Minister for Environment will be subject to a 21-day appeal period.
Should Water Corporation wish to make changes at the premises, such as constructing new infrastructure or increasing the daily wastewater treatment capacity, it will need to submit a works approval and/or a licence application to DWER for assessment under Part V of the EP Act.
Applications for any new licences, works approvals and major or contentious amendments will be advertised on DWER’s website . Any submissions made by the public during the advertising period will be duly considered by DWER when deciding the outcome of an application.
More information
Show moreThe department will update this page as new information comes to hand. If you have any questions related to the Gnarabup Wastewater Treatment Plant, please email info@dwer.wa.gov.au and quote L6640/1994/11.
Complaints can be made to DWER’s 24-hour Environment Watch Hotline on 1300 784 782 or you can submit a report online.
