CTGM replacement - Brookfield Tunnel to Burmi Creek
We're planning to replace a 12-kilometre section of the Chichester Trunk Gravity Main (CTGM) between Brookfield Tunnel and Burmi Creek.
Project overview
We're planning to replace a 12-kilometre section of the Chichester Trunk Gravity Main (CTGM) between Brookfield Tunnel and Burmi Creek.
The CTGM is a critical part of our water network, supplying around 40 per cent of the Lower Hunter's drinking water. This section of the pipeline was originally built in 1923 and is showing signs of deterioration.
Replacing the pipeline will help us continue to deliver a safe, reliable and resilient water supply for our region by:
- reducing leaks and conserving drinking water
- improving safety for workers and the community
- reducing the risk of unplanned water supply interruptions
- strengthening the network for future generations.
What we're planning
As part of planning for the replacement pipeline, we investigated different route options and assessed potential environmental, community and construction impacts.
Two main alignments were considered:
- a route alongside the existing pipeline through Columbey National Park
- an alternative route that diverts south-west after Woerdens Road and follows an existing powerline easement for much of its length.
Following detailed investigations, the alternative alignment was selected as the preferred route (pictured below). This option reduces impacts on native vegetation, threatened species habitat and environmentally sensitive areas compared with a route through Columbey National Park.
Where the route diverts around Columbey National Park, south-west of Woerdens Road, the new pipeline will be installed underground, primarily within an existing powerline easement. This approach was informed by landowner feedback and helps minimise impacts on surrounding properties and the environment. At the northern and southern ends, the route crosses several private properties before reconnecting with the existing alignment.
The replacement pipeline will also be slightly larger than the existing pipeline, increasing from 900mm to 1050mm in diameter. This will improve network capacity and help support water security into the future.
The existing CTGM will be removed once the replacement CTGM is built and connected in to the network.
Resource library
The following Review of Environmental Factor (REF) documents and concept design plans for the CTGM were recently on public exhibition from Monday 7 September to Sunday 4 October 2026.
Some documents may not comply with accessibility requirements (WCAG) or may have a large file size (up to 50MB). If you are having trouble accessing information in these documents, display copies are also available at Hunter Water's head office in Honeysuckle. Please contact CTGM@hunterwater.com.au for assistance.
What happens next?
The proposed CTGM replacement was recently on public exhibition. We're currently reviewing the submissions received. Next steps:
- Community feedback will be reviewed and key themes summarised in an outcomes report.
- The REF will be finalised, taking community feedback into consideration.
- A determination will be made on the proposed project.
- The community will be informed of the outcome.
Subject to approvals, detailed design and construction planning will continue.
Frequently asked questions
What is the CTGM?
The Chichester Trunk Gravity Main (CTGM) is a major water pipeline that supplies around 40 per cent of the Lower Hunter's drinking water. It transports water from Chichester Dam to water treatment and distribution facilities across the region.
Why does the CTGM need to be replaced?
The remaining 12-kilometre section of the pipeline between Brookfield Tunnel and Burmi Creek was built in 1923 and is deteriorating. Replacing it will help maintain a safe, reliable and resilient water supply while reducing the risk of leaks, failures and unplanned interruptions.
What are the benefits of replacing this section of CTGM?
Replacing the CTGM between Brookfield Tunnel and Burmi Creek will:
- reduce leaks and conserve drinking water
- maintain a reliable water supply for the region
- improve safety for workers and the community
- replace ageing infrastructure with a more resilient pipeline
- help strengthen water security for the future.
What is a Review of Environmental Factors (REF)?
A Review of Environmental Factors (REF) is an environmental assessment that identifies and evaluates potential impacts of a proposed project before work begins.
The assessment considers matters such as biodiversity, heritage, traffic, noise, water quality and property impacts, and outlines measures to avoid, minimise or manage potential impacts.
How was the preferred route selected?
The route was selected following environmental, engineering and operational investigations. It was chosen because it reduces impacts on native vegetation, threatened species habitat and environmentally sensitive areas while also considering construction requirements.
When will construction start?
Subject to approvals, construction is expected to commence from 2029 and will be completed over several years.
Will my water supply be affected?
The replacement pipeline is being carefully planned to maintain a reliable water supply throughout construction. Once completed, the new pipeline will help reduce the risk of future supply interruptions.
Will construction create noise or traffic disruptions?
Some temporary impacts are expected during construction, including increased vehicle movements, noise and vibration near work areas. Management plans will be developed to minimise impacts and maintain safety for residents, businesses and road users.
Will private land be affected?
Some land acquisition and new easements will be required along sections of the route. We will continue working closely with affected landowners throughout the planning and delivery of the project and will seek to minimise disruption wherever possible.
How will environmental impacts be managed?
The project has been designed to reduce environmental impacts wherever possible. This includes avoiding significant clearing in and near Columbey National Park, using existing cleared corridors where practical, protecting waterways through specialised construction methods and rehabilitating disturbed areas after construction.
Other project materials
View previous project updates and information