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WaterPlan 2050 - Mardi-Mangrove Link

The Mardi-Mangrove Link Project is a key element of WaterPlan 2050 which is the long term water supply stsnippet mangrovee creek damrategy for the Central Coast. It will help to secure the region’s town water supply over the next four decades by linking Wyong River and Ourimbah Creek to Mangrove Creek Dam, via Mardi Dam

The Project is an initiative of Gosford City and Wyong Shire Councils with Australian Government funding of $80.3 million from the Water Smart Australia Program.

It is the largest water infrastructure project undertaken on the Central Coast since the mid-1980s when Mangrove Creek Dam was built.

It involves building:

  • a 2.1 kilometre buried water pipeline from Wyong River to Mardi Dam through Mardi
  • a 19 kilometre buried pipeline from Mardi Dam to the existing Bunning Creek Tunnel at Mangrove Creek Dam, running through Yarramalong Valley
  • a new pump station at Mardi Dam
  • a new pump station beside Wyong River

The Central Coast community will benefit from the Mardi-Mangrove Link as it will help to boost dam storage levels, speed up drought recovery and help protect the region against future extended periods of below average rainfall.

Click on the links below to find out more about the Mardi-Mangrove Link Project.

Educational resources

A series of fact sheets have been prepared for community and educational use to provide more detailed information on key issues affecting the Mardi-Mangrove Link project. See more here.

For more information contact the Mardi-Mangrove Link Project Office in Anzac Avenue, Wyong, on (02) 4350 1682 or email This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Industry information

For construction industry information on the Mardi-Mangrove Link Project on the NSW Central Coast click here.

What progress has been made so far?

A Mardi-Mangrove Link Project Team has been established to deliver the Mardi-Mangrove Link Project. Since mid-2007 the focus has been on identifying a route for the pipelines and preparing concept and detailed designs.

This has involved extensive liaison with local landholders as well as comprehensive engineering, geotechnical and environmental investigations.surveyor

A route corridor has now been identified for the whole length of the pipeline route as it runs through Mardi and Yarramalong Valley. Part of the route lies within the Yarramalong Road reserve while the majority runs through private land.

Concept designs are also complete for all elements of the Project. Detailed designs are also complete.

A Review of Envrionmental Factors (REF) document has also been approved for the Project as part of the overall statutory approvals process. Tenders have also been invited from construction companies to build the Project. 

Route selection process

Selecting the pipeline route through Mardi and Yarramalong Valley was a major element of the Mardi-Mangrove Link Project . Where possible, the route selection process considered the following factors

  • local topography to avoid extreme changes in elevation country road
  • protected ecological and heritage features
  • potentially difficult pipe laying conditions (eg rock, thick vegetation, etc)
  • construction needs (eg sufficient space for equipment operation, pipe storage, backfill materials, etc)
  • potential road closures and impact on local traffic flows
  • access to the pipeline for future operation and maintenance work

An expert panel then used a multi-criteria analysis to assess five key criteria including:

  • Landowner impacts
  • Community impacts (including impacts on Yarramalong Road)
  • Environmental impacts (including heritage / cultural impacts)
  • Constructability
  • Comparative cost estimates

Each criteria was scored based on its impact (0 = no impact, 5 = high impact) and then each score was validated with a sensitivity analysis overall robustness. The lowest score determined the recommended route for each sector of the pipeline.

The pipeline route was subject to stringent reviews from an engineering, construction, design, environmental, geological and cost perspective. The route has now been locked in following approvals by both Gosford City and Wyong Shire Councils.

The Project Team has also worked with affected landholders to complete detailed engineering, environmental and geotechnical studies to confirm, mark and survey the exact alignment of the water pipeline.

These studies have helped the Project Team to confirm issues such as: 

  • ground conditions
  • presence of different types of vegetation
  • location of existing buildings & existing underground/overhead utilities
  • future ease of access

Each affected landholder has been able to walk the proposed route on their property to raise questions or point out features that might affect the alignment of the pipeline.

Protecting the Yarramalong Valley environment

green frogExtensive envrionmental planning and investigations have been undertaken for the Mardi-Mangrove Link Project to ensure activities do not have a significant impact on the Yarramalong Valley envrionment.

The pipeline route has been selected to avoid sensitive ecological areas and to avoid significant impact on threatened species and endangered ecological communities. Senior ecologists were also involved in the entire route marking process.

A number of safeguards and mitigation measures will also be implemented during construction of the pipeline and associated works. These include:

  • retention of large trees either side of the pipeline easements as close to the pipeline as possible to maintain a local resource of hollow-bearing trees used by local fauna
  • delineation of sensitive ecolological areas using temporary fencing or tape
  • on-site attendance of a fauna ecologist during vegetation clearing.

Detailed Project investigations have also identifited that the pipeline route corridor will not have a significant impact on local aquatic ecology. No fish passages will be blocked.

When areas in the Valley are disturbed during construction of the Mardi-Mangrove Link Project, revegetation will occur as quickly as possible to further minimise the overall impacts.

An Indigenous heritage study was also undertaken to check if any important cultural items exist in areas where the pipeline will be built. If any are found during construction they will be managed in accordance with relevant State Government requirements and the Aboriginal community.

Landholder liaison

Extensive landholder liaison has been undertaken by the Project Team, particularly with those who are directly affected by the pipeline route corridor.

Individual landholder input was a key part of the route selection process and ongoing liaison is occuring with many affected landholders. Community meetings, Open House events, one-on-one discussions, telephone and email discussions, and written correspondence have all formed part of that liaison process.

residents reading

The Project Team has provided affected landholders with comprehensive Landholder and Easement Packs which include a range of fact sheets and other information about the Project. The Packs help to explain land entry protocols, the easement acquistiion process, insurance and liabilties, compensation payments, construction issues and other related matters.

The Project Team will continue to liaise with affected landholders as the project progresses.

Gosford City and Wyong Shire Councils have a statutory right under the Water Management Act to access properties affected by the Project. Their preference, however, is to gain landholders' consent before accessing their land.

Easements for the pipeline route

A pipeline easement will be registered on each affected land title for Wyong Shire Council to construct, operate and maintain a buried water pipeline on that piece of land (except for where some above ground facilities may be required, such as valves and pipe-bridges).

Affected landholders will receive compensation for the pipeline easement under the NSW Land Acquisition (Just Terms Compensation) Act 1991. An accredited valuer engaged by Wyong Shire Council has visited each affected property to value and assess the compensation payable in accordance with the Act.

land corridorEasements will be subject to a number of usage restrictions once the pipeline is built and the land restored back to its original condition. These include landholders being unable to:

  • erect any buildings or structures on the easement
  • plant trees or carry out deep ripping or deep excavations
  • take onto the easement any vehicles or equipment that weighs more than the maximum legal load for such vehicles or equipment on NSW Roads

Subject to obtaining prior consent from Council, landholders can still:

  • construct a roadway, pavement, fence, billboard or cable
  • make other improvements on or under the easement
  • alter the existing grades and ground levels of the easement
  • plant orchards, small trees or shrubs, carry out other landscaping work

Landholders will continue to have access over the easement and can use the land for cultivation, cropping and grazing of livestock. They can also grow pasture, farm turf, control and eradicate weeds and top dress and pasture seed.

Crossing Wyong River

The pipeline route corridor for the project will need to cross Wyong River four times as it runs through the Yarramalong Valley.  sector 3

Three of these river crossings will be pipe-bridged (in Sector 3  and Sector 9  of the pipeline route) and one will be underbored (in Sector 8) to avoid a state-recognised Property Vegetation Plan. Each river crossing has been individually assessed to ensure minimal impact on the surrounding environment during construction.

Pipe-bridges are not formal access bridges but the pipe itself will 'bridge' between supports on each side of the river. The pipe-bridges will require foundation support piles which are set back from the edge of the watercourse.

Any bank stabilisation or restoration work needed along the river bank will be carried out within weeks of construction. Riparian zones will also be restored or rehabilitated after construction.

All river crossings have been subject to extensive NSW Government liaison. The work will also be conducted in accordance with conditions in the Review of Environmental Factors (REF) document.

Platypus management

Studies indicate that the pipeline crossings of Wyong River will have minimal impact on the local platypus population.platypus

Platypus are mobile, with multiple burrows along the river. Studies show that they acclimatise to noise and vibration or relocate to alternative burrows.

A platypus survey has been ocnducted to identify existing platypus habitats in areas where the new pipeline will cross Wyong River. A comprehensive platypus report has also been included in the Review of Environmental Factors (REF) document which relates to platypus habitats and platypus management around all river crossings along the pipeline route.

A Platypus Expert will continue to be engaged by the Project to manage and monitor the construction of the pipeline as it crosses Wyong River. This Expert will provide ongoing platypus management advice as required.

Statutory liaison and approvals

The Mardi-Mangrove Link Project is subject to extensive statutory input and approvals. The Project Team has been liaising with about 10 NSW Government agencies and has to meet a number of NSW Government legislation and regulations. These include:

  • the Water Management Act 2000
  • the Environmental Planning and Assessment Act 1979
  • the Land Acquisition (Just Terms Compensation) Act 1991.

Environmental approval for the Project has been determined under Part 5 of the Environmental Planning and Assessment Act 1979. This involved preparation of a Review of Environmental Factors (REF) document which identifies a series of detailed management plans which need to be implemented during and after construction.

The plans to be developed by the Project include:pen writing

  • Construction Environmental Management Plan
  • Vegetation & Habitat Management Plan
  • Rehabilitation Management Plan
  • Water Quality Monitoring Program
  • Soil & Water Management Plan
  • Construction Noise Management Plan
  • Traffic Management Plan
  • Waste Management Plan, and
  • Weed Management Plan

The REF was formally lodged with Wyong Shire Council on 30 June 2009 and was placed on public exhibition to invite written submissions for 28 days from 3-31 July 2009.

Seven written submissions were received in response to the REF and these were reviewed, along with the REF, by an independent consultant engaged by Wyong Shire Council to ensure all statutory and other requirements are fully met. A report was prepared for consideration by Wyong Shire Councillors and a decision to approve the REF was granted on 23 September 2009.

Further licences and approvals will be required from various State Government Agencies as the Mardi-Mangrove Link Project progresses.

The Project Team is also in regular liaison with the Federal Department of Environment, Water, Heritage and the Arts. It must also meet Federal Government legislation and regulations including:

  • the Environmental Protection and Biodiversity Conservation Act 1999
  • the Building and Construction Industry Improvement (Accreditation Scheme) Regulations 2005.

Traffic management

Traffic management will be a key construction issue for parts of the Mardi-Mangrove Link Project. Yarramalong Road will be impacted by construction vehicles, as well as pipe-laying in the road reserve and other related activities.

To help manage this issue and to keep traffic flowing as much as possible, a number of traffic management conditions will be included in the construction contract documents. A number of traffic management issues and mitigation measures are also referred to in the REF document.traffic management

A Traffic Management Plan will also be developed by the construction contractor with significant input from the Project Team and formal approval from the Wyong Shire Council Traffic Committee. It will seek to ensure that:

  • emergency vehicles and school buses are given priority access through the construction zone where required
  • all affected landholders are given ongoing access to their properties, including the use of temporary access arrangements where necessary.

The Traffic Management Plan will detail measures for effective traffic arrangements such as:

  • a comprehensive community information and awareness program before and during construction
  • signposting of access roads and extensive use of construction warning signs
  • use of appropriate traffic controls and warning signs for areas with potential safety risks.

Water licences upgrade applications

Wyong Shire Council has applied to the NSW Department of Water and Energy (DWE) to upgrade its two existing water licences on Wyong River. These upgrades will help to:

  • improve fish movements in the river
  • improve monitoring of water flows over Wweiryong River weir
  • optimise the volume of water extractions from Wyong River once the pipeline is built

The proposed upgrades will increase Council’s water pumping capacity from 125 million litres a day to a maximum of 320 million litres a day to service town water needs until 2050. This will help maximise water extraction opportunities during higher river flows, such as after heavy rains.

Council will not extract river water during very low flows (not until there are sufficient flows to operate the proposed new fishway) and only then will extraction be a proportion of the river flow at other times. This will help to restore Wyong River to more of its natural flow regime and will help to improve the river’s health.

A public exhibition of the upgrade applications has been undertaken and a Land Board Hearing was held in March/April 2009 for additional assessment. A formal determination on the upgrades is anticipated by DWE shortly.  

Project timeframes

The Mardi-Mangrove Link Project is the most significant water supply infrastructure project since the early-1980s when Mangrove Creek Dam was built. It will therefore take some time to carry out all the works necessary to meet community, government and construction requirements. construction

A general timeframe for the project currently includes:

  • Call expressions of interest - July 2009 (complete)
  • Call tenders for construction – October 2009 (complete)
  • Award construction contracts - December 2009
  • Start construction - early 2010
  • Complete construction & final commissioning – mid 2011