Culburra Sewage Treatment Plant (STP) Upgrade

The Culburra STP upgrade will improve treatment efficiency and reliability by replacing the inlet screen and grit system, upgrading the aeration system, and enhancing the electrical and control systems to support new infrastructure.

Culburra sewage treatment plant aerial image

Project StatusConstruction
Where 9 Strathstone Street, Culburra Beach 2540
Project value$3 million
Estimated completion date31 July 2026
Last reviewed 31 August 2026

The latest

Council has engaged a specialist contractor to progress the next stage of the Culburra Sewage Treatment Plant upgrade. The contractor is scheduled to commence after the January school holiday period to minimise disruption.

About the project

The Culburra Beach Sewage Treatment Plant (STP) services the coastal townships of Culburra Beach, Orient Point, and Greenwell Point in the Shoalhaven region of New South Wales (NSW). Like many coastal communities, these townships experience a significant influx of holidaymakers and day visitors during peak holiday periods—particularly between Boxing Day and Australia Day—resulting in sudden and substantial increases in sewage loads.

The current STP was completed in 1982 with a nominal design capacity of 10,500 residents. Council identified opportunities to improve capacity and efficiency by upgrading existing infrastructure and treatment processes. Enhancements to the inlet works and aeration tanks will help safeguard against peak population increases and ensure reliable performance.

The upgrade project involves major improvements to enhance treatment efficiency and reliability, including:

Replacement of the existing inlet screen and grit removal system.
Upgrades to the aeration system for improved biological treatment.
Electrical and control system enhancements to support new infrastructure.
Equipment replacements.

Background

The key objectives of the project are:

Increased reliability
Supporting regional growth
Increased safeguards

Progress

January 2026

Engagement with the construction contractor has commenced with contracts being awarded.

May 2026

Works at the Culburra STP are progressing well, with the Contractor having successfully emptied the bioreactor in preparation for the installation of the new diffuser system. This milestone allows the aeration upgrades to proceed as planned.

At the inlet works, the Contractor has completed the removal of the existing screen and grit removal equipment, clearing the way for the next phase of the upgrade. Installation of the new inlet screening and grit removal equipment has now commenced, with works advancing towards commissioning.

Image showing workers washing down bioreactor tank

Workers washing down the bioreactor tank.

Culburra sewage treatment plant clean bioreactor tank

Clean bioreactor ready for installation of new diffusers.

Culburra sewage treatment plant contractor removing rubber from diffusers for recycling

Contractor removing rubber from diffusers before recycling the metal.

Grit removal vortex.

Culburra sewage treatment plant mechanical inlet screen

Mechanical screen at inlet works.

August 2026

Inlet Works

The upgrade of the mechanical components at Culburra STP has now been completed, with the new equipment successfully installed and operational. The upgraded system has significantly improved screening performance and grit removal efficiency, resulting in higher quality effluent being delivered to the next stage of the treatment process.

Image: Grit removal machine

Bioreactor 2

During June, Council's contractors completed the replacement of the diffuser system in Bioreactor 2. The upgraded system is operating as designed and has already demonstrated improvements in treatment performance and process efficiency.

Image of sewerage treatment diffuser system

Image: Bubble testing for bioreactor 2

Bioreactor 1

In August, works commenced on Bioreactor 1, including dewatering, desludging, cleaning, and replacement of the diffuser grid system. Installation of new pipework and diffusers is currently underway, with testing and commissioning scheduled following completion of these works.

Image showing sludge removal in sewerage bioreactor tank

Image: Sludge removal in bioreactor tank

Image: Bioreactor tank cleaning

The opportunity to completely empty the bioreactor as part of these upgrade works, an activity that occurs infrequently, has also enabled Shoalhaven Water Operations to undertake critical maintenance on existing infrastructure within the tank. This includes inspection and maintenance of the decanter system and internal pipework, helping to improve the reliability and ongoing performance of the asset.