Merimbula Sewage Treatment Plant Upgrade and Ocean Outfall Project
- Project typeWater and Sewer
- Project value$44 million
- Project scheduleIn Progress
Project summary
Merimbula Sewage Treatment Plant (STP) services Merimbula, Pambula and South Pambula.
Merimbula originally had an ocean outfall that extended beyond the surf zone. In the 1970s it was damaged by large seas and a temporary beach-face outfall was constructed. That temporary arrangement remains in place today.
Treated flows are currently managed through a combination of recycled water supply and effluent disposal, including discharge via the existing beach-face outfall and disposal via the dunal exfiltration ponds. These disposal pathways are no longer suitable to meet contemporary regulatory standards and community expectations.
Council is progressing a combined project to upgrade the STP and deliver a new deep ocean outfall. The project will improve treated effluent and recycled water quality and provide a reliable pathway for managing surplus effluent during wet weather periods when recycled water cannot be supplied and used.
What is happening now?
Council is progressing through the State Significant Infrastructure (SSI) assessment process, which involves detailed studies, agency review and opportunities for community input.
The STP upgrade and the deep ocean outfall form one integrated project. Some elements can progress within the existing STP site, while the outfall also requires additional land tenure and access steps. These include matters being managed in parallel with the planning process, such as unresolved Aboriginal Land Claims over parts of the Crown Land affected by the proposed outfall alignment. Council will align delivery timing to the completion of the relevant approvals and access arrangements.
Purpose - why is it needed?
The purpose of the Merimbula STP Upgrade and Ocean Outfall project is to deliver a safe, reliable and environmentally responsible wastewater system for the Merimbula–Pambula area. By upgrading treatment processes, replacing the outdated beach-face outfall and ending routine disposal to the dune exfiltration ponds, the project will:
- Protect sensitive coastal and wetland environments
- Safeguard public health and water quality
- Support population and economic growth
- Create a more resilient wastewater system for the future.
The current disposal arrangement includes nearshore discharge and disposal in sensitive dune environments. These arrangements are not suitable to meet contemporary standards and community expectations.
Recycled water supply will continue and expand where feasible, but recycled water demand varies seasonally and reduces during wet periods due to saturated ground conditions. At the same time, inflows to the STP can increase during wet weather. This mismatch means a reliable disposal pathway is required for surplus effluent during those periods.
What the project will deliver
Although this is one integrated project delivered through parallel approvals and access pathways, the project delivery is likely to be staggered, with the STP upgrade able to progress first.
Merimbula STP upgrade
The STP upgrade will:
- Upgrade treatment processes and operational controls to improve effluent and recycled water quality, including chemical dosing to support nutrient removal and ultraviolet (UV) disinfection
- Apply chlorination to recycled water only (effluent discharged via the ocean outfall will not be chlorinated)
- Continue supplying recycled water to Pambula Merimbula Golf Club and Oaklands for irrigation.
Deep ocean outfall
The outfall works will:
- Decommission the existing beach-face outfall
- Cease routine effluent disposal to the dunal exfiltration ponds
- Construct a new deep ocean outfall pipeline (approximately 3.5 km) with a submerged diffuser located about 2.7 km offshore at around 30 metres depth
- Install an upgraded ocean outfall pump station.
Funding
The project is funded by a combination of Council’s Sewer Fund and the NSW Government’s Safe and Secure Water Program contributing up to 25% of the total cost.
Community Strategic Plan (CSP)
This project aligns with the Bega Valley Shire Council Community Strategic Plan through:
- A.3 Ensure growth and change in our towns and villages enhances character that reflects local identity, improves liveability, and supports community needs.
- A.7 Ensure community safety and public health is planned for.
- C.1 Deliver and support integrated water management.
- C.2 Ensure land use planning and resource use supports sustainable growth whilst protecting the quality of the natural environment and our rural landscapes.
- D.1 Plan and provide for waste, water, sewerage and stormwater infrastructure and services that will meet current and future needs.
This project supports the implementation of Council’s adopted Delivery Plan as identified through the following Key Projects:
- Complete Bega and Merimbula Sewer Treatment Plant Upgrades
- Merimbula Ocean Outfall.
Terms
- Effluent – The liquid produced from the treatment of sewage and disposed to the environment
- Recycled Water - The liquid produced from the treatment of sewage and supplied to a user.
Questions & Answers
Why is the Merimbula STP being upgraded?
Merimbula STP was built more than 30 years ago. Parts of the system are no longer suitable to meet contemporary environmental standards and community expectations, and upgrades are required to ensure the STP continues to meet licence conditions and service future growth safely and reliably.
Why is the deep ocean outfall needed?
During wet periods, recycled water demand decreases due to saturated ground conditions, while inflows to the STP can increase. A disposal pathway is required for surplus effluent during those periods. A deep ocean outfall provides an offshore discharge point designed to support dilution and dispersion away from sensitive nearshore environments.
Where will the new outfall be located?
The pipeline will be installed underground onshore and extend about 3.5 km from the STP to a submerged diffuser located about 2.7 km offshore at about 30 metres depth.
Will there be visible infrastructure on the beach once it is built?
No. The outfall discharge point will be submerged offshore. Onshore works will be within the STP site and along the onshore alignment during construction. The existing beach-face outfall will be decommissioned.
How has the community been consulted?
Engagement has included community information sessions, stakeholder briefings, an agency and stakeholder focus group (2009), the Community Working Group established in 2017, and formal public exhibition of the EIS in 2021. Agency and community submissions were addressed through Council’s Response to Submissions in 2025.
How will the community be kept informed?
Updates will be shared through Council’s website, media releases and public notices as the project reaches key milestones. When public exhibition opens, you will be able to view the documents and lodge a submission through the NSW Planning Portal. Council will publish exhibition dates and links on this page when confirmed.
The public can also opt in to receive notifications of the project as it progresses through the SSI process via the NSW Planning Major Projects Portal
Merimbula Sewage Treatment Plant Upgrade and Ocean Outfall | Planning Portal - Department of Planning and Environment
What is the quality of the effluent going to the ocean outfall?
Effluent quality data for Merimbula STP (and other STPs) is available on Council’s website.
Why can't we reuse 100% of recycled water from the Merimbula STP?
Investigations have considered expanded recycled water schemes as well as STP upgrade and disposal options. Recycled water demand varies seasonally and reduces during wet periods due to saturated ground conditions. At the same time, inflows to the STP can increase due to wet weather infiltration and inflow, which can substantially increase the volume requiring treatment and disposal. While recycled water schemes will continue and be expanded where feasible, a reliable disposal option will always be required.
Are other recycled water schemes in place throughout the shire?
Yes. All of Council’s sewage treatment plants have recycled water schemes in place. The total amount of recycled water supplied fluctuates according to the weather.