Gnarabup Wastewater Treatment Plant

The Gnarabup Wastewater Treatment Plant is located on Gas Bay Road, Gnarabup.
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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 the operation of the premises. 

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 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 sources, pathways and receptors relevant to the proposed activities at a premises and an assessment of the risks of emissions, with consideration of the applicant’s proposed controls and separation distances to sensitive receptors.

Part of DWER’s role is to monitor compliance using tools such as inspections, reviews, audits, community reports and complaints, and information 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 18 February 2020. Inspectors found that the Water Corporation were compliant with their licence conditions, however, the two groundwater sampling bores were found to be dry and could not be sampled. 

What is happening now

On 14 December 2020, the Water Corporation applied for an amendment to licence L6640/1994/11 to change the groundwater monitoring network for the premises including the replacement of the two dry monitoring bores. In assessing the Water Corporation’s application, DWER completed a review of recent groundwater and ocean shore water monitoring data from the premises and its local surrounds. 

DWER granted the licence amendment on 21 May 2021. The findings of the monitoring data review and the outcome of DWER’s assessment are presented in the Amendment Report here.

DWER’s monitoring data review identified some uncertainties in the current understanding of groundwater and shore water quality within the vicinity of the premises. To address these gaps, DWER revised and updated the monitoring program by expanding the groundwater bore network and adding parameters to the analytical suites for groundwater and ocean shore water samples. DWER also revised the annual reporting conditions to require the Water Corporation to provide a more detailed assessment and interpretation of environmental monitoring data within annual environmental reports. 

DWER considers that the revised monitoring and reporting program is suitable for assessing potential impacts from current operations at the premises. The monitoring and reporting changes implemented within the licence amendment will improve the environmental dataset available. As more data is collected and reported, DWER will be able to refine its understanding of potential risks to receptors from activities at the premises and assess the ongoing suitability of the environmental monitoring and reporting program.

The information obtained from the revised monitoring program, together with data gathered during DWER’s compliance activities, will inform future regulatory decisions relating to the premises. 

Future developments

DWER is aware that the community and other stakeholders are concerned about the implications of the proposed scheme amendment to rezone an area on Lots 501, 502 and 504 Reef Drive and Lot 503 Seagrass Place from ‘Future Development’ to ‘Tourism’, on the Gnarabup Wastewater Treatment Plant. 

Should Water Corporation wish to make changes to the premises, such as constructing new infrastructure or increasing the daily treatment capacity, they will need to submit a works approval and/or licence application to DWER for assessment under Part V of the EP Act. 

Applications for new licences, works approvals and major or contentious amendments are advertised on DWER’s website here. Comments made by the public during the advertising period are considered by DWER when deciding the outcome of an application.   

More information

The 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 and quote L6640/1994/11.

Complaints can be made to DWER’s 24-hour Pollution Watch Hotline on 1300 784 782 or you can submit a report online.