Sewerage upgrades to hit Eurobodalla budget
At the September Council Meeting it was revealed that Council is facing a $62 million bill for upgrading the Tomakin Sewerage Treatment Plant (STP), $12 million for diversion works from Batemans Bay to Tomakin and $5million to optimise the Batemans Bay facility.
With the Batemans Bay facility at capacity, the Tomakin STP has been taking the excess waste.
Report to council said :
“The northern sewerage system is currently experiencing capacity constraints. The Batemans Bay and Tomakin Sewerage Treatment Plants (STPs) are operating near or beyond maximum capacity, routinely exceeding their practical treatment limits, limiting the system’s ability to accommodate additional wastewater flows.
Forecast population growth across the Batemans Bay catchments, combined with climate‑driven increases in peak wet weather flows, means that the existing sewerage system configuration can no longer reliably service current and future loads.
These issues cannot be addressed through operational optimisation alone. Tomakin STP has insufficient capacity to reliably treat current and future peak season loads arising from population growth within the existing catchment.
Analysis of plant data demonstrates significant seasonal variability in influent flows, driven primarily by holiday occupancy during Christmas and Easter periods. Average dry weather flows during these periods already approach the practical treatment limits of the plant.
The Batemans Bay STP is experiencing operational strain as wastewater loads are near maximum capacity, with dry weather inflows during peak seasons exceeding design limits despite recent plant upgrades. This issue is intensified during wet weather events, causing excessive infiltration that forces the diversion of untreated wastewater into emergency storage and can lead to unauthorised discharges.
To address these challenges, Council’s long-term strategy, as defined in its approved Integrated Water Cycle Management Strategy (IWCMS) 2022, is based on cross-catchment load sharing along with the augmentation of the existing plants at Tomakin and Batemans Bay.
Land availability restrictions at Batemans Bay STP mean the options for increasing capacity at that plant are very limited.
The strategy relies on three integrated pillars:
1. Augmenting and upgrading the Tomakin STP to increase regional capacity. This is the main enabling project with an estimated cost of $62 million and subject of this business case.
2. Diverting sewerage loads from Batemans Bay STP into the upgraded Tomakin plant, with diversion works occurring concurrently to align with the Tomakin upgrade. Estimated cost $12 million.
3. Completing the Batemans Bay Stage 3 upgrade project, optimising the plant’s operational capacity by 2040, depending on growth. Estimated cost $5 million. The augmentation of Tomakin STP is the optimal regional approach. It maximises existing asset utility, using existing council land and improves water recycling options.
This project will divert significant sewer loads from the Batemans Bay catchment and restore critical operational headroom to Batemans Bay STP, safely absorbing future growth trends and futureproofing both facilities for the long term. The Tomakin STP Upgrade is required to support growth, maintain environmental compliance and meet the longterm wastewater management needs across the northern region of Eurobodalla.
Without this investment, Council faces increasing risk of environmental non-compliance, constraints on housing growth, increasing operational costs and reduced resilience during peak tourism and wet weather events.
The upgrade will unlock regional growth, protect waterways and beaches, improve service reliability and provide capacity for future generations.”
It was CARRIED that
1. That Council notes that augmentation of the northern region sewerage system is required to address existing capacity constraints, accommodate future population growth and maintain regulatory compliance.
2. That Council notes the Tomakin Sewage Treatment Plant augmentation is the key enabling project within Council’s adopted regional wastewater strategy, supporting future load diversion from Batemans Bay and optimisation of both treatment plants.
3. That Council acknowledges the necessity of this project.
4. That Council approves progression of the Tomakin Sewerage Treatment Plant Augmentation Project to the next phase, including completion of detailed design, preparation of tender documentation and obtaining the necessary statutory approvals.
5. That Council receives a further report following completion of the detailed design and tender process, including updated project costs and a recommendation regarding construction contract procurement.
(Councillor Schutz/Councillor Winslade)