Mardi to Warnervale Pipeline

The Mardi to Warnervale Pipeline (M2WP) is a drinking water pipeline that runs from the existing Mardi Water Treatment Plant through to Sparks Road at Warnervale. The pipeline is nine kilometres long and 1000 millimetres in diameter.  

The pipeline tunnel runs north from the Mardi Treatment Plant, under Deep Creek to Collies Lane, before turning east to cross below the M1 Motorway and then along Mardi Road. The pipeline tunnel  then turns north again, running beneath Wyong River, Alison Road and Porters Creek and continues north to wrap around the edge of the Watanobbi Estate. The final section of the pipeline tunnel runs at a significant depth below the wetlands before continuing north along the proposed ‘Link Road’ to connect with the existing water mains at the intersection of Sparks Road and Albert Warner Drive.

Numerous planning studies have confirmed the pipeline is an integral piece of water supply infrastructure for the northern region of the Central Coast. The pipeline was identified to deliver two key functions:

1. Service growth in Central Coast Councils northern areas which include the State Government identified Northern Growth Corridor and the ‘Warnervale Town Centre’ Strategic Centre.
2. Improve drought security via increased bulk water transfers between the Central Coast and Hunter – up to 30 megalitres a day (12 Olympic swimming pools).

The M2WP provides the higher operating pressure required to service elevated areas and emerging low pressure areas within the northern water supply network (including Warnervale Town Centre) allowing reduced reliance on booster pump stations and increasing the efficiency of the water supply system.

The pipeline also provides opportunities for the Hunter and Central Coast regions to further work together on options to build drought resilience. 

The Hunter and the Central Coast have very different water supply systems. This allows each system to help the other in different circumstances.

In general terms, Central Coast Council has slightly better storage but Hunter Water has a better ability to capture water.

During periods of drought, the most drought-affected region will receive water from the system that is less drought-affected. As the water levels of both systems decrease less water is transferred and if both systems are equally drought-affected then water transfers stop.

Council continuously considered the environment throughout the planning and design stages of the M2WP and took a range of actions to minimise environmental impact.

Extensive environmental investigations were undertaken which have added to Council’s existing understanding of the local environment obtained from previous infrastructure developments such as the Mardi to Mangrove Link Water Project.

This information allowed the project team to select the most appropriate methods for constructing the pipeline whilst minimising environmental impacts. These methods included tunnelling the pipe significantly below the more sensitive environmental areas such as the Coastal SEPP Wetland north of Watanobbi and the sensitive riparian areas of Wyong River and Porters Creek. 

Extensive environmental investigations and surveys were undertaken as part of the projects planning phase. Multiple ecological surveys and impact assessments of the pipeline corridor were completed to ensure minimal impact on the environment. As a result of the surveys undertaken, further investigations and detailed management plans were completed to ensure the protection of the Wyong cryptic flora species and the Watanobbi flying-fox colony.

Other surveys and impact assessments included aboriginal heritage, noise and vibration, and soil and hydrology. All assessments were incorporated into the Project’s Review of Environmental Factors (REF).

A number of different trenchless methods were used to construct the pipeline.

Micro Tunneling was utilised for the M1 motorway and Deep Creek Crossings. Micro tunneling is a digging technique to construct small tunnels or in the case of our project used to install casing and pipe.

Reinstatement works have been completed by experienced and qualified horticulturists who were responsible for revegetating any disturbed areas. 

Before construction began a dilapidation survey was completed. This process involved capturing a detailed photographic record of land condition prior to construction. These records provided valuable information to allow the project team to restore the land to its former condition and in many cases to a better condition due to the reduction of weed species.

The majority of the land within the pipeline easement is Council owned and is contained within Council open space areas and roadways. The remaining land that was used is privately owned small rural allotments within the Mardi area. The project team contacted owners of impacted land in the Mardi area during the planning phase of the project and continued to work closely with property owners.

The project was funded by a combination of accumulated revenue and developer charges within Council’s water supply fund.

The pipe is 1000mm in diameter with the exception of a small section of pipe at Nikko Road which is 375mm.

There will be no noise generated from the pipeline. The pumps used to transport the water through the pipe are existing units located at the Mardi Water Treatment Plant. The flow velocity does not cause any noise or vibration.

Periodic inspections and maintenance of the pipeline valves will be required as per standard Council maintenance of its assets. 

This varies dependent on location, however the closest the pipeline’s centreline is to a property boundary is 5m.