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Planning our water future

The portfolios

The portfolios
The portfolios at a glance

A number of portfolios have been developed based on combinations of shortlisted demand and supply options. Each portfolio is aligned with one of four strategies:

  • Climate independent (staged versus upfront capacity)
  • Surface water / traditional sources
  • Enhanced storage and water sharing with Hunter Water Corporation
  • Traditional transitioning to climate independent

Each portfolio is made up of the following:

  • Actions to supply additional drinking water – you tell us how much you like each of the five portfolios
  • A drought management plan – this is based on your preferred level of water supply in a long and severe drought
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Portfolio 1

Portfolio 1
Climate independent (staged desalination capacity)

 

This portfolio includes:

  • Water conservation
  • Recycled water (for non-drinking purposes)
  • Purified recycled water and/or environmental flow substitution
    • 6 megalitres per day
  • Desalination
    • 20 megalitres per day production capacity.
    • The desalination plant operating triggers (on/off) would be set to manage time in restrictions and water security risks.
    • The operating triggers can then be increased as demand continues to grow to manage time in restrictions and water security risks.

 

Environmental impacts

  • Low/medium impacts on natural biodiversity
  • High energy use, however, we have included offsets for greenhouse gas emissions for desalination to manage this impact.
  • Less treated wastewater released to ocean outfall

 

Social impacts

  • Purified recycled water for drinking is a new technology for the Central Coast, and the community will likely have an interest in the process and its reliability, and safety
  • Low cultural and heritage impacts
  • There will be some temporary disruption for local residents during construction of pipelines and treatment plants

 

Reliability and system resilience

  • Desalination, environmental flow substitution and purified recycled water:
    • do not rely on rainfall which increases the reliability of our supply system
    • improves the diversity of our water sources and the resilience of our system
    • are adaptable to be upgraded over time and provide flexibility to respond to a long and severe drought if required

 

Cost

  • The estimated average incremental cost for this portfolio is $2.30 per kilolitre. This is the total cost of the portfolio on a kilolitre basis across a 40 year period.
  • This includes both upfront costs to build and ongoing costs to operate the new assets across the 40 year period.

 

Drought management plan

  • As this portfolio uses the same technology as the emergency drought supply it means we can respond to a long and severe drought simply by bringing forward the construction of the next stage of the desalination plant. This means that the requirements of the drought management plan (if triggered) will be lower if this portfolio is implemented, compared to other portfolios
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Portfolio 2

Portfolio 2
Climate independent (upfront capacity)

 

This portfolio is the same as portfolio 1 with one slight difference - the desalination plant will provide 30 megalitres of water per day, instead of 20 megalitres of water per day. The benefit of this approach is that the water supply scheme would also be capable of meeting the majority of demand if a severe and prolonged drought were to occur. A higher capital cost would also occur when the plant was first constructed. 

This portfolio includes:

  • Water conservation
  • Recycled water (for non-drinking purposes)
  • Purified recycled water and/or environmental flow substitution
    • 6 megalitres per day
  • Desalination
    • 30 megalitres per day production capacity.
    • The desalination plant operating triggers (on/off) would be set to manage time in restrictions and water security risks.
    • The operating triggers can then be increased as demand continues to grow to manage time in restrictions and water security risks.

 

Environmental impacts

  • Low/medium impacts on natural biodiversity
  • High energy use, however, we have included offsets for greenhouse gas emissions for desalination to manage this impact.
  • Less treated wastewater released to ocean outfall

 

Social impacts

  • Purified recycled water for drinking is a new technology for the Central Coast, and the community will likely have an interest in the process and its reliability, and safety
  • Low cultural and heritage impacts
  • There will be some temporary disruption for local residents during construction of pipelines and treatment plants

 

Reliability and system resilience

  • Desalination, environmental flow substitution and purified recycled water:
    • do not rely on rainfall which increases the reliability of our supply system
    • improves the diversity of our water sources and the resilience of our system
    • are adaptable to be upgraded over time and provide flexibility to respond to a long and severe drought if required

 

Cost

  • The estimated average incremental cost for this portfolio is $2.30 per kilolitre. This is the total cost of the portfolio on a kilolitre basis across a 40 year period.
  • This includes both upfront costs to build and ongoing costs to operate the new assets across the 40 year period.

 

Drought management plan

  • As this portfolio uses the same technology as the emergency drought supply it means we can respond to a long and severe drought simply by bringing forward the construction of the next stage of the desalination plant. This means that the requirements of the drought management plan (if triggered) will be lower if this portfolio is implemented, compared to other portfolios
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Portfolio 3

Portfolio 3
Surface water (traditional sources)

 

This portfolio includes:

  • Water conservation
  • Recycled water (for non-drinking purposes)
  • Groundwater
  • Rainwater tank scheme
  • Dam enlargement:
    • Enlarge Mangrove Creek Dam by 80 gigalitres of storage
  • Water transfers
    • Transferring water from Mangrove Creek Weir to Mangrove Creek Dam

 

Environmental impacts

  • Impacts on terrestrial and aquatic biodiversity in and around dam and transfer pipeline
  • Medium energy use and associated greenhouse gas emissions
  • Reduced urban stormwater runoff due to utilisation of rainwater tanks
  • Additional studies required to confirm impacts on ground dependent ecosystems and aquifer health

 

Social impacts

  • Some temporary disruption for local residents during construction of dam and pipeline
  • Potential Indigenous and European cultural heritage impacts in the dam and pipeline areas based on preliminary investigations to date
  • Acquisition of easements may be required for pipe sections on privately owned property
  • Operation and maintenance cost of rainwater tanks transferred to customers

 

Reliability or system resilience

  • An enlarged dam increases the time to deplete our storages in droughts which improves the robustness of our supply system
  • Dams and transfer pipeline relies on rainfall and will not ensure ongoing supply of water in a long and severe drought
  • The lead time for dam raising is around 10 years including approvals and construction
  • Decentralised rainwater tanks have reliability risks for ongoing maintenance required by the owners
  • Additional studies required to confirm the long term sustainable yield of the groundwater systems

 

Cost

  • The estimated average incremental cost for this portfolio is $3.30 per kilolitre*. This is the total cost of the portfolio on a kilolitre basis across a 40 year period.
  • This includes both upfront costs to build and ongoing costs to operate the new assets across the 40 year period.
  • *Existing uncertainty exists for biodiversity offset costs associated with raising Mangrove Creek Dam. These costs are currently excluded from the $3.30 per kilolitre and will likely be significant.

 

Drought management plan

  • As the options within this portfolio are generally climate dependent (e.g. a dam relies on rainfall for it to fill up), this portfolio offers no added benefit to our drought management plan, which means in a prolonged and extreme drought we will still have a large drought management gap to fill (additional investments in a 20-30ML/day desalination plant would be required).
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Portfolio 4

Portfolio 4
Enhanced water sharing with Hunter Water Corporation

 

This portfolio includes:

  • Water conservation
  • Water sharing between regions
    • Increase water sharing capacity with Hunter Water Corporation (up to 60 megalitres per day)
  • Dam enlargements
    • Enlarge Mangrove Creek Dam by 80 gigalitres of storage
  • Recycled water (for non-drinking purposes)

 

Environmental impacts

  • Impacts on terrestrial and aquatic biodiversity in and around dam area
  • Medium energy use and associated greenhouse gas emissions (unless they are offset)

 

Social impacts

  • Potential Indigenous and European cultural heritage impacts in the dam area based on preliminary investigations to date
  • Some temporary disruption for local residents during construction of pipelines

 

Reliability and system resilience

  • Recycled water does not rely on rainfall which increases the reliability of our supply system
  • Water sharing with Hunter Water Corporation and recycled water improve the diversity of our water sources and the resilience of our system

 

Cost

  • The estimated average incremental cost for this portfolio is $3.40 per kilolitre*. This is the total cost of the portfolio on a kilolitre basis across a 40 year period.
  • Opportunities exist for cost sharing with Hunter Water Corporation due to joint benefits that would reduce costs.
  • This includes both upfront costs to build and ongoing costs to operate the new assets across the 40 year period.
  • *Existing uncertainty exists for biodiversity offset costs associated with raising Mangrove Creek Dam. These costs are currently excluded from the $3.40 per kilolitre and will likely be significant.

 

Drought management plan

  • As the options within this portfolio are generally climate dependent (e.g. a dam relies on rainfall for it to fill up), this portfolio offers no added benefit to our drought management plan (in the event of overlapping drought in Hunter and Central Coast), which means in a prolonged and extreme drought we will still have a large drought management gap to fill with additional investments in desalination.
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Portfolio 5

Portfolio 5
Traditional transitioning to climate independent

 

This portfolio includes:

  • Water conservation
  • Groundwater
  • Recycled water (for non-drinking purposes)
  • Dam enlargement
    • Enlarge Mangrove Creek Dam by 40 gigalitres of storage
  • Purified recycled water and or environmental flow substitution 
    • 6 megalitres of water per day
  • Desalination
    • 20 megalitres per day production capacity.
    • The desalination plant operating triggers (on/off) would be set to manage time in restrictions and water security risks.
    • The operating triggers can then be increased as demand continues to grow to manage time in restrictions and water security risks.

 

Environmental impacts

  • Additional studies required to confirm impacts on ground dependent ecosystems and aquifer health
  • Less treated wastewater released to ocean outfall
  • Impacts on terrestrial and aquatic biodiversity in and around dam and transfer pipeline
  • High energy use, however, we have included offsets for greenhouse gas emissions for desalination to manage this impact.

 

Social impacts

  • Some temporary disruption for local residents during construction of dam
  • Potential Indigenous and European cultural heritage impacts in the dam inundation area based on preliminary investigations to date
  • Some temporary disruption for local residents during construction of pipelines and treatment plants

 

Reliability or system resilience

  • Desalination, environmental flow substitution, purified recycled water, and recycled water for non-drinking purposes do not rely on rainfall - which increases the reliability and resilience of our system
  • Desalination is adaptable to be upgraded over time. It also provides flexibility to respond to a long and severe drought by bringing forward the construction of the desalination plant (if required)

 

Cost

  • The estimated average incremental cost for this portfolio is $2.00 per kilolitre*. This is the total cost of the portfolio on a kilolitre basis across a 40 year period.
  • This includes both upfront costs to build and ongoing costs to operate the new assets across the 40 year period.
  • *Existing uncertainty exists for biodiversity offset costs associated with raising Mangrove Creek Dam. These costs are currently excluded from the $2.00 per kilolitre and will likely be significant.

 

Drought management plan

  • Towards the end of the planning horizon (2051) this portfolio introduces the same technology as the emergency drought supply which means we could respond to a long and severe drought simply by bringing forward the construction of the next stage of the desalination plant. This means that the requirements of the drought management plan (if triggered) will be lower if this portfolio is implemented, compared to other portfolios.
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Planning our water future

Planning our water future

 It is important that we continue to plan for the Central Coast’s future water needs.

As the Central Coast grows, so does the demand for water. However, our current infrastructure can only supply us with a limited amount of water, so we need to address ways to grow our supply, to meet our future demand levels.

Central Coast Future Water Projections

The plan

There have been significant changes in environmental factors, water infrastructure, the operating environment and knowledge in the 13 years since we last planned for our region’s long-term water security. Those changes, combined with a steadily growing Central Coast community, and the current review of the Lower Hunter Water Security Plan by our neighbouring region, mean it is important to review our long-term water plans.

Together we’ll develop a plan that will secure the Coast’s water supply for future generations. This will be called the Central Coast Integrated Water Resource Plan. This will help our collaborative work with Hunter Water and the Department of Planning Industry and Environment to make sure both the Central Coast and Lower Hunter regions have water strategies that can work side by side.

Where are we now?

Over the past few months, we have worked with our community to understand their values around water and their views on the different water supply and demand options we're considering, and the portfolios we have grouped them in, as part of the Integrated Water Resource Plan. 

All the feedback we’ve received from the community will be considered alongside other ongoing investigations, modelling and analysis.

Now we're in the process of drafting the plan, which will be published for final community feedback in late 2021. 

After public exhibition, the plan will be finalised and provided to the NSW Department of Industry and Environment for approval. 

 

Community engagement

Understanding our community’s values and preferences is a vital part of our long-term planning.

We’ve used forums and online engagement to find out what the community values about water and what they think about different supply and demand options we’re considering:

All the feedback we’ve received from the community, as well as the outcomes of the investigations and analysis, enabled us to compare the options and develop a number of ‘portfolios’ – or groups of options, as no single option will suffice in isolation – to assess against future uncertainties, to inform our decision making and plan for our water future.

We then asked our community, through another set of forums and online engagement, for their support level of each of these five portfolios to help us refine them for further analysis:

The results of this community engagement process will be uploaded to this project page once they have been assessed.

Community feedback will be considered alongside other ongoing investigations, modelling and analysis. The portfolios will become a key component of the revised IWRP, which we’re aiming to release by the end of this year.

In late 2021 a draft of the Integrated Water Resource Plan will be published for final community feedback.

After public exhibition, the plan will be finalised and provided to the NSW Department of Industry and Environment for approval. 

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Who's listening
Name
Charles Leung, Project Manager
Name
Woolcott Research (forum inquiries only)

Will you be consulting with the community on this project?

Understanding our community’s values and preferences is a vital part of our long-term planning.

We’ve used forums and online engagement to find out what the community values about water and what they think about different supply and demand options we’re considering. 

We have also undertaken complex, robust investigations and analysis to ensure that we understand the environmental and social aspects, technical feasibility and costs of the option types.

Through forums held with a representative selection of our community, we’ve learned that water quality is their most important consideration when it comes to our water supply. In line with this, all options we’re considering as part of the IWRP review would meet strict water quality requirements.

The community has also told us reliability of water supply is important, closely followed by environmental sustainability and affordability. Our community wants us to be planning for the future now, to reduce the risk of needing to resort to emergency drought response measures in the future.

We’ve also heard that water conservation and recycled water (for non-drinking purposes) are their most preferred options. In line with this, we have included water conservation and recycled water for non-drinking in all portfolios.

The community also showed strong support for the option of stormwater harvesting, however this option has not been included in our portfolios as it will be investigated separately - specifically, how to integrate stormwater harvesting as part of new developments, irrigate new open spaces, and other non-potable uses. Additionally, we will revisit and investigate the effectiveness of existing stormwater schemes that were installed during the millennium drought; how they are operating, how effective they are, and how we can optimise them.

All the feedback we’ve received from the community, as well as the outcomes of the investigations and analysis, have enabled us to compare the options and develop a number of ‘portfolios’ or groups of options, to assess against future uncertainties, to inform our decision making and plan for our water future.

Community feedback will be considered alongside other ongoing investigations, modelling and analysis. The portfolios will become a key component of the revised IWRP, which we’re aiming to release by the end of this year.

In late 2021 a draft of the Integrated Water Resource Plan will be published for final community feedback.

This plan will be the culmination of community engagement, liaison with key government agencies and industry, and expert technical studies and recommendations.

After public exhibition, the plan will be finalised and provided to the NSW Department of Industry and Environment for approval.

Is Council going to build another dam?

The construction of a new dam was one of the many shortlisted options that Council investigated. 

However, a feasibility assessment identified that the construction of a new dam would face high and environmental challenges – significantly higher than the equivalent (or greater) capacity that can be provided by the option of raising Mangrove Creek Dam.

Is Council still building a desalination plant at Toukley?

Council is seeking to modify the existing planning approval for the possible construction of a drought response desalination plant adjacent to Toukley Sewage Treatment Plant (STP).

This is our insurance policy in case of unprecedented drought conditions. In order to do this, Council will need to engage with the community and undertake a series of studies including intake location, water quality, marine monitoring, marine hazard, ecology impact assessment and updating EIS documentation.

For more information on this, please visit the project page.

Will the long-term options increase my water bill?

The Independent Pricing and Regulatory Tribunal (IPART) determines Central Coast Council’s water revenues and prices during periodic reviews. 

Council’s next pricing submission is due for lodgement with IPART in September 2021 and will determine what prices Council can charge for these services from 1 July 2022 until 30 June 2026.

During March 2021, a survey was available to the community, asking for their feedback on water, sewer and stormwater prices. This feedback will feed directly into our next submission to IPART. 

Council's final submission will outline proposed service levels and prices for water, sewer and stormwater.

Current prices will not change until a new determination is made. Any changes made as a result of the new determination will come into effect from 1 July 2022.

Any impact to customer prices would be determined by IPART if and when projects proceed. 

The 'whole of life cost' of various options will be assessed as part of the Integrated Water Resource Plan. This will ensure that the infrastructure required to provide drought security and meet long-term demand for water are cost effective. Funding and cost sharing models for the preferred portfolios will be explored after the completion of the plan.

For more information on our water, sewer and stormwater submission to IPART, please visit the project page.

What is our plan to maintain water security during a severe drought? 

Our water supply system performs well in average conditions, but it is vulnerable to drought -it can't supply enough water to meet minimum customer demands in a long and severe drought (longer than any local drought in our lifetimes). The community has previously told us that this is not acceptable.

Our storages have relatively large capacities but require the assistance of our transfer pumps and pipelines to harvest the water from our rivers, as the dam storages’ natural catchment areas are relatively small. 

In a very long and severe drought (longer than any local drought in our lifetimes) that causes our water storage to fully deplete, our drought plan aims to provide an ongoing (or enduring) water supply equivalent to 100-125 litres per person, per day, for residential customers. Supply to non-residential customers will also be reduced. For comparison, our residential customers were able to restrict their usage to approximately 160 litres per person per day during the peak of the millennium drought, and our water wise target is 150 litres per person per day.

While the chance of actually needing to reduce our water usage to 100-125 litres per person per day is fairly small, the chance of needing to commence procurement of an emergency drought supply (e.g. a desalination plant) is much higher due to the time it takes to design and construct (approximately three years). Council would also rely on other sources including groundwater and surface water schemes to provide additional supply.

Council has been developing a project to implement drought response infrastructure in the form of a desalination plant on the Coast for many years. Studies since 2005 have supported the construction of a desalination plant and associated infrastructure adjacent to the existing Toukley Sewage Treatment Plant. This is our insurance policy in case of unprecedented drought conditions and our surface water storages decline to critically low levels.

Is Mangrove Creek Dam going to be expanded in the future?

Raising Mangrove Creek Dam is one of many shortlisted options being investigated under the Integrated Water Resource Plan. The plan seeks to review all feasible and effective options to address the Central Coast supply and demand balance.

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