Gnarabup wastewater planning
Project goal:
We are undertaking wastewater planning for Gnarabup to ensure we can cater for future demand.
Status:
In planning
Delivery Date:
NA
What's happening?
Water Corporation are reviewing scheme planning for wastewater for Gnarabup to ensure we can cater for future demand. We are working with the State Government on evaluating potential options for the local wastewater scheme if the Margaret River Resort and Village at Gnarabup proceeds.
Wastewater from the community is currently treated at the Gnarabup Wastewater Treatment Plant (WWTP). Based on normal development and population forecasts, this plant can continue safely and effectively treating wastewater until 2030. Beyond then, a higher capacity scheme will be needed.
A decision to make changes to the operations of the wastewater scheme will be considered if there are any significant changes within the area causing an increase in wastewater volumes, such as approval of the resort development.
Due to the long lead times involved in wastewater planning, early survey work including flora and fauna and Aboriginal Heritage surveys were undertaken in November 2021 and January 2022. Feature and service locating survey work and geotechnical investigations will be completed during July to September 2024. This will assist us to thoroughly assess possible wastewater planning options.
What options are we assessing for the scheme?
The most viable options being assessed are:
- Upgrade the existing WWTP capacity
- Decommission the Gnarabup WWTP and construct wastewater pumping facilities and pipeline to convey wastewater from Gnarabup to the Margaret River Water Resource Recovery Facility (WRRF) for treatment.
Water Corporation is also assessing tankering from Gnarabup WWTP to Margaret River WRRF during the peak summer season when inflows are expected to exceed wastewater treatment capacity.
Flora, fauna and heritage survey findings
As part of the planning process, we completed flora, fauna and heritage surveys in November 2021 and January 2022 in and around Gnarabup.
No threatened or priority flora species or significant cultural heritage findings were recorded within the survey area. We did, however, identify some protected fauna species. The survey findings will allow us to plan any future work to avoid or limit disturbance to these species and the wider environment.
What are the next steps for planning?
We will complete a feature and service locating survey and geotechnical investigations and combine this information with our findings form the flora, fauna and heritage surveys. This will help to further refine scheme options and manage environmental constraints.
Environmental considerations, Heritage and Native Title rights, community feedback, treatment requirements, pumping facilities and pipeline requirements, and cost of treatment or pumping to customers are all considered when we are trying to decide on which option for a scheme.
Water Corporation are reviewing scheme planning for wastewater for Gnarabup to ensure we can cater for future demand. We are working with the State Government on evaluating potential options for the wastewater scheme.
We have received questions from the community surrounding this work. Here is additional information to answer some of your enquiries.
We plan wastewater treatment capacity upgrades based on the latest population forecast data* and operational lifespan. The current wastewater treatment plan (WWTP) is adequate until 2030 based on normal development activity within Gnarabup.
A decision to make changes to the operations of the wastewater scheme will be considered if there are any significant changes within the are causing an increase in wastewater volumes. The planning work we are completing is assessing the viability of options available if this is required. However, these timelines can be pushed back if wastewater volumes are below forecasts.
A project will only be activated once development is certain and funding requirements have been determined and therefore, a forecast delivery timeframe will be established.
*Historical Australian Bureau of Statistics data and location specific projection data is considered in establishing a forecast for a town. Potential tourist/visitor developments are also considered. Based on this information, residential growth in the area is expected to continue.
Gnarabup WWTP meets strict conditions under its environmental licence with Department of Water and Environmental Regulation (DWER).
We undertake thorough environmental monitoring to comply with all the conditions of our operating licence. This includes monitoring bores to review groundwater quality upstream and downstream of the plant and this data is reported to DWER annually. DWER has reviewed the site and approved its operation until 2023.
The treated wastewater is disposed of via infiltration beds. These are large ponds where treated wastewater is stored and either evaporated or infiltrated into the ground, similar to stormwater ponds.
Prevelly currently does not have reticulated sewerage and we have no plans to undertake infill sewerage in the area.
The 'infill sewerage program' was a State Government initiative to extend wastewater networks to areas where the presence of septic tanks posed a risk to public health, drinking water supplies and the environment. Under this program, more than 100,000 septic tanks in high-risk areas were decommissioned at a total cost of $1.2 billion.
All priority areas as determined by public health and environmental risk factors have been connected to wastewater schemes and there are no further infill sewerage projects.
Should landowners want a reticulated wastewater scheme, they could establish a contribution scheme whereby benefitted landowners could share the cost of providing the necessary infrastructure.
The proposed future options (WWTP upgrade and conveyances) are sized to cater for the potential additional flow from infill sewerage.
There are infrastructure headworks, connection costs and connection fees involved for customers wanting to connect to a wastewater scheme.
Kristy Lind - Community Engagement Specialist