Cassilis Sewer Treatment Plant

Project typeConstruction of Sewer System
Project value$9.7 Million
Project scheduleNot available
Contractor nameNot available
Completion Date31 December 2028

Last updated: 11 February 2026

The Cassilis Sewer Treatment Plant Project will deliver long-overdue modern sewer infrastructure to the village of Cassilis, improving public health, environmental outcomes, and paving the way for more resilient services into the future.

This project responds to the critical need for a centralised sewage system in Cassilis, where ageing and often failing on-site septic systems have posed ongoing challenges. Once complete, the new system will serve residential properties, key community facilities and commercial sites, including those that support major local events like the Cassilis Rodeo and Campdraft.

Backed by the NSW Government’s Regional Water and Waste Water Backlog Program, the new sewer scheme includes a reticulated collection system, a purpose-built pump station, and a multi-stage sewage treatment plant with an effluent reuse system for pasture irrigation on Council-owned land.

Environmental safeguards have been embedded in every stage of the design, from pond-based treatment with extended detention times to a land-based irrigation system that avoids discharge to local waterways.

The project represents a major infrastructure investment in the future of Cassilis, enhancing liveability, supporting environmental protection, and enabling long-term sustainability for the local community.

February 2026 Update

The Cassilis Sewer Project continues to move forward, with steady progress across planning, design, consultation, and approvals. A Project Control Group remains in place to provide governance and oversight, with the most recent meeting held on 4 February 2026.

A Community Information Session was held in Cassilis on 9 December 2025, attended by Council senior staff and Cr Pat Ryan. The session focused on the proposed pump station location, visual amenity, project timing, costs, and future capacity. An updated design approach for the pump station, including improved landscaping and removal of fencing, was generally supported by those in attendance.

Consultation with affected property owners is underway following a decision to create easements over all properties containing sewer infrastructure. Council is taking a proactive approach to secure voluntary agreements wherever possible, supported by independent valuations and a draft voluntary acquisition deed prepared by legal advisors.

Survey work has identified some fencing and boundary discrepancies across affected properties. These will be addressed on a case by case basis to minimise impacts on landowners and avoid unnecessary compulsory processes.

Design work and value engineering are continuing, with sewer reticulation works now close to being construction ready. It is proposed to tender the reticulation package first, while further design and approvals continue for other components of the project. Additional investigations are also underway to confirm power requirements and reduce construction risk associated with soil conditions.

Over the next few months, Council will continue landowner engagement, finalise designs, progress approvals, and prepare for tendering of key construction works.

View the full February ISC Agenda, including detailed information on the Cassilis Sewer Project (pages 45–49):
ISC Agenda February 2026

December 2025 Update

Planning and approvals for the Cassilis Sewer Project continue to progress, with governance, design refinement, and consultation now well underway.

Key updates include:
• A Project Control Group has been established to oversee delivery and risk management
• Property owner consultation has commenced regarding sewer easements, with early feedback generally supportive
• Surveyors, valuers, and legal professionals have been engaged to begin the easement process
• Early discussions with the EPA confirmed no direct approval is required, with input to continue through the DCCEEW process
• Design value engineering is progressing, with potential savings expected to offset anticipated cost pressures for house connections
• Project timing remains unchanged, with tendering anticipated from late February 2026 and construction targeted to commence in June 2026

Over the coming months, Council will continue community consultation, finalise detailed design, progress easement agreements, and prepare tender documentation.

View the full ISC Agenda, including detailed information on the Cassilis Sewer Project (pages 51–54):
ISC Agenda December 2025

Frequently Asked Questions

What stage is the project at?

A detailed design for the sewage system was developed by Cardno in 2021. Since funding was secured, the design is under review and approvals being sought prior to going to market for construction.
What part of Cassilis is included?

A site catchment map is shown below shows the part of town included in the scope (red outline). At this point in time, Thompsons Road is not included in the scope. This may be altered pending available funds.
How is the project funded?

This project is funded by the Legacy Infrastructure Fund - Central West Orana Renewable Energy Zone (REZ) Community and Employment Benefit Program, with an overall funding of $9.7M. The Project includes all infrastructure and the connection of all households and businesses to the system. Including decommissioning of old DSMS tanks
What is the timetable?

Work is expected to start onsite in the second half of 2026 and is forecast to be completed by the end of 2028.
Will there be work on my land?

Work will be required on each Lot that is to be connected to the system. New pipework will be installed from the current inlet of the septic system on site, to the nominated connection point on the sewer main.
The design of the reticulated sewer collection system utilises public land wherever possible, such as the road reserve and laneways. In order to keep the system simple, using gravity as far as possible, some infrastructure will be required to be on private lands.
Arrangements will be made with each affected landowner, with an easement to be created where required. Works will typically involve underground pipework, with inspection and service access holes at changes in direction. The treatment plant will be located on Council owned land off Cassilis Road.
What will it cost me? (Connection provided, rates altered on completion)

Council will connect each house/business to the new sewerage reticulation system up to a suitable location. Each connection will be designed and reviewed by Council and landholder prior to installation. For gravity sewer, Council will maintain up to sewer shaft. For pump out pressure sewers (Scott Street, north of Buccleugh St intersection) Council will maintain up to boundary kit.
The project will fund all infrastructure and connection works. There is no installation costs for the property owner. Property owners will be charged maintenance through the sewer rates for each property. This is determined in the fees and charges.
What if I don't want to participate?

The system requires all connections to operate efficiently. Connecting at a later date will come at a cost due to the works then being considered private.
What will be construction disruptions?

Council will undertake consultation with each property owner when works are required on their land. Council and the contractor will aim to minimise disruptions.
What happens if I have a structure (e.g. shed) that runs along my property boundary where the sewer line is going?

At this point in time, the design has not identified going under sheds / property structures. As part of the design review, the site will be walked to ensure this is the case. Should it happen, it will be assessed on a case by case basis and we will look to minimise disruptions and return the surface back as close as possible to it's pre construction condition.
What happens with my old septic tank?

All existing septic tanks will be decommissioned, material removed and be cleaned out. A hole will be placed in the bottom of the tank and the lid modified to standard and filled with soil. Note: the tank will not be removed.
What happens during a flood?

Infiltration will be minimal as the new system is sufficiently scaled for minor flood events and will operate as normal.
During major flood events, the system may be inundated and diluted.
Will there be a smell from the plant?

Response: Odour has been considered part of the detailed design report and can be found here.