Stuarts Point Sewerage Scheme

Geotechnical investigations at the site of the sewage treatment plant and dunal discharge site east of the Macleay Arm were completed. 

Geotechnical investigations at the site of the sewage treatment plant and dunal discharge site commenced. This was behind schedule due to Council waiting on permissions from other government agencies to begin the work.

Stuarts Point collection network masterplan capacities and flows - input into the sewage treatment plant design phase.

September 2021

A Stuarts Point collection network Master Plan design was completed including a concept design. The report was prepared by PSS P/L for internal use as a guide for detailed design and use in construction tenders.

Proposed environment protection licence concentration limits were agreed with the NSW Environment Protection Authority.

NSW Department of Planning and Environment - Water granted collection and treatment options assessment section 60 endorsements.

The key driver for the Stuarts Point Sewerage Scheme is addressing the issues with existing treatment systems in use in the villages. Council is focused on providing the most sustainable sewerage service to benefit and meet the needs of the whole community.

The modern wastewater management system resulting from this project will have numerous benefits for the entire area, including a positive environmental impact by reducing onsite system leakage and eliminating odour and water quality issues.

All the properties in Stuarts Point, Grassy Head and Fishermans Reach presently rely on onsite sewage management systems to treat and dispose of effluent. The majority of residences are served by septic tanks provided with absorption trenches or pump-out systems.

Many homes in the area are about 40 years old and their sewerage systems do not comply with modern standards for treatment quality and disposal area conditions. These systems risk groundwater contamination and associated public health impacts via overflow events and ineffective treatment.

Construction of a sewerage scheme means these properties will avoid significant costs in the future to bring their individual systems up to compliant standards.

While development is not the driving force behind the delivery of this scheme, it will provide opportunity for growth in the area, and there is land surrounding Stuarts Point already zoned for potential residential subdivision.

It is also anticipated that the sewerage scheme will improve property values in the area, based on increased land value, development potential and improved social benefits. The sewerage scheme will also help the area cater for visitor populations in caravan parks and allow for additional property development. The scheme is also anticipated to improve estuary health for oyster growers in the area.

Various options for methods of discharging the treated effluent were thoroughly assessed. Council has worked closely with the NSW Environment Protection Authority and NSW Department of Planning, Industry and Environment in this regard.

Dunal discharge was selected as the endorsed option of treated effluent discharge, similar to that in place at South West Rocks. Other options were considered, including subsoil irrigation to the west of the Sewage Treatment Plant site; however they were not suitable due to the ground conditions at Stuarts Point, particularly during periods of wet weather.

Modelling has been undertaken to ensure there is no impact on the environment in the area where the discharge will take place.

Use of treated effluent discharge as a water source for irrigation can still be pursued and is an ongoing consideration.

The Stuarts Point Sewerage Scheme had to be designed to ensure a sustainable and complete sewerage service that would benefit and meet the needs of the whole community into the future under any circumstances.

As such, the system design needs to allow for the full quantity of treated effluent to be disposed of in the dune area, as there will be periods where irrigation is not required, such as following wet weather. The capacity to dispose of the full quantity in the dunes does not make it compulsory.

The option of irrigation of safe, treated effluent from the scheme may exist and this idea will be further considered as the project is developed.

Like many coastal communities in NSW, the Stuarts Point, Grassy Head and Fishermans Reach communities rely on ground infiltration, where the water on the surface seeps into the soil, to manage stormwater.

Stuarts Point, Grassy Head and Fishermans Reach are all low-lying areas. This means the water table levels, which essentially reflect the height of water saturation in the ground, are hugely significant in the efficiency of stormwater management. A high water table level prevents the water from being absorbed into the ground.

The recent floods revealed unexpected groundwater issues, with water table levels well above those seen in the past 20 years, which in turn resulted in inundation of low-lying properties.

Kerb and guttering works may be an option for stormwater drainage improvement; however many properties sit lower than the roads. As one could imagine, this has the potential to worsen stormwater impacts in such locations.

Further investigations into the recent events are being carried out. These will allow Council to better understand stormwater upgrade needs and evolve a more informed maintenance plan of key drains in the area. These investigations will need to take into account both the impacts from heavy rainfall and associated flash flooding, as well as the complications of rising water table events.

A shire-wide goal is to improve stormwater drainage management. Council will consider the needs of these villages in the context of other locations across the shire that also experience stormwater and flooding issues.

The good news is that the high water table levels will not impact the proposed pressure sewer scheme. Tanks will be appropriately sealed to mitigate any such impacts and this process will be operated and maintained by Council.