Systems analysis of the Ballarat and connected regions

A first ever systems analysis of the Ballarat region provides a reality check on assumptions underpinning proposed water grids for the state of Victoria. Essentially, it is proposed that a water grid supplies the towns in the Ballarat region by transfer of water from dryer irrigation areas and the water stressed Murray Darling River Basin. Detailed systems analysis of hydrology, water resources, irrigation and urban behaviors across multiple linked water districts provides a wealth of cautionary information about the need for systems analysis to truly understand linked water systems.

Hydrology and Water Resources

The Ballarat region chosen for this investigation includes 144 State Suburbs, 7 local government areas and significant river basins managed by 5 Catchment Management Authorities. Central Highlands Water provides urban water supplies to 15 water districts and reticulated sewerage services to 10 districts within the region. The region is also dependent on groundwater resources and bulk water allocations from the Moorabool, Campaspe, Goulburn, Loddon and Yarrowee River catchments. These shared regional water resources are also subject to management by Southern Rural Water, Goulburn Murray Water, Coliban Water and the Murray Darling Basin Authority.

This report focuses on the base case behaviour of the Ballarat and Maryborough water districts from the context of the performance of the entire region and whole of water cycle behaviours. A Systems Framework of the Ballarat region was developed  to allow understanding of whole of water cycle challenges and opportunities across the region.

A base case Systems Framework for the Ballarat region included ongoing interactions with stakeholders via a Strategy Development Team (SDT). The Strategy Development Team was guided by the Office of Living Victoria’s Chief Scientist in the collation of information, data and insights underpinning the analysis presented in this report. This process also included liaison with a broader group of collaborators including local Catchment Management Authorities, Local Government, land developers and environmental groups via formal workshops and various discussions.

The Systems Framework includes high population growth and climate change scenarios. The Systems Framework was built up from local scale land uses from across the region and includes whole of water cycle processes at local, suburb, town and regional scales. This structure captures the spatial, temporal and behavioural variations of the water cycle across the region.

Figure 2: Spatial distribution of annual average rainfall across Victoria

The framework was developed to a state where it can be reliably and robustly applied to detailed and targeted ‘what if’ analyses, including assessments of future water security under a range of climatic and population growth scenarios, and future management options. The spatial and temporal detail within the Systems Framework allowed understanding, reproduction and testing of the complex interactions between waterways, reservoirs, operations, water demands and water restrictions.

Figure 3: The Ballarat region is connected to a dryer irrigation districts and the Murray Darling Basin

The Key Insights from this investigation are summarised as follows:

1. Key drivers for water cycle management in the Ballarat region include a variable climate, population growth, interactions with surrounding regions, health and viability of river basin, flooding, water security and climate change.

2. The Systems Framework for analysis of the base case water cycle management scenarios for the Ballarat region is complete. The Framework can be reliably utilised to test scenarios and options for water cycle futures, to optimise the performance of water operations and to investigate policies for water allocations (including stormwater) and protecting waterways

3. Water Cycle management in the Ballarat region involves strong interaction with surrounding regions including dependence on bulk water allocations and impacts on waterways. These surrounding regions often experience lower rainfall depths and frequencies than the immediate Ballarat region.

4. There is a high level of spatial and temporal variation across the region for most of the parameters impacting on water cycle management. Analysis using monthly or annual average assumptions would not reliably capture these important variations and hence would limit the associated understanding of challenges and opportunities.

5. The region is subject to cyclic patterns of wet and dry conditions which drive strong variations in spatial weather conditions. As a consequence, there are stark differences in the resilience of river basin and water catchments across the region.

6. The characteristics of water uses throughout the region have changed dramatically over the last decade. A majority of buildings and households have already incorporated measures which deliver increased water efficiency.

7. The Systems Framework has successfully reproduced the water cycle behaviours over the last decade including water demands and the performance of reservoirs.

8. The Ballarat West bore field, local water efficiency measures and water restrictions had a significant impact on the water security of Ballarat during the last decade. Introduction of the connection to the Campaspe and Goulburn River via the Goldfields pipe and flooding rains ended the critical water shortages for Ballarat that were associated with drought.

9. A majority of reservoirs and extractions for water supply to the region are situated in the headwaters of river systems that are subject to highly variable flows and their location and functionality has significant impacts on downstream catchments and waterways.

10. Inclusion of the Goldfields pipe and the Ballarat West bore field has changed the operating behaviour of the water supply system for Ballarat.

11. The water supply systems in the region are highly sensitive to a range of assumptions and display strong variations in responses to operating rules. This understanding has been unlocked by the detail in the Systems Framework. There is substantial opportunity to optimise water cycle systems using the Framework.

12. Regional storages that provide bulk allocations are subject to highly variable irrigation and evaporation demands that can impact on the availability of water allocations.

13. The predictions of future average water demands for Ballarat and Maryborough are consistent with the published Water Supply Demand Strategies. However, the detail in the Framework has produced an improved understanding of substantial variability in the magnitude of future demands and associated uncertainty.

14. The Ballarat district is not expected to experience unacceptable levels of water restrictions within the planning horizon to 2051. This trigger for augmentation of the water supply is later than previously reported. However, there is a probability of requirement for higher allocations from ground and surface water within the planning horizon.

15. The linked spatial and temporal detail that is incorporated in the time based analysis in the Systems Framework is substantially different to static methods of estimating “yields” from systems using average inputs at a coarser temporal scale. 
16. Figure 4: Verification of the Systems Framework to water levels in Lake Eppalock 

16. Waterways throughout the region are impacted by extractions for water supply, population growth, urban stormwater runoff, rainwater and stormwater harvesting, wastewater discharges and climate change. The future of regional waterways includes potential increased impacts on waterway health and higher flood risks. The Systems Framework can guide the development of necessary policies for management of waterways and aquifers from the perspective of the entire water cycle.

17. It is an important insight that the waterways throughout the region are subject to cumulative impacts including loads of contaminants, flood risks from high flows and diminishing fresh water flows. Whilst indicators for water quality (as indicated by concentrations of contaminants), peak flows (flooding) and average flows or flow regimes (waterway health) may be acceptable at a location in a catchment (especially in the headwaters), the resultant downstream cumulative impacts may not be acceptable.

18. There are a considerable number of properties that are subject to flood risks and there may be opportunities to manage water supply storages in the upper catchment to also mitigate some of the flood risks.

19. The West Moorabool River is currently highly stressed due to low flows and this situation is expected to worsen into the future. There is a need to decrease extractions for water supply from the river.

20. The Yarrowee River is likely to experience substantial increases in stream flows by 2051 that are generated by increased inflows of effluent from wastewater treatment and flows in river are expected to be dominated by effluent from the Ballarat South wastewater treatment plant. Substantial increases in nutrient loads are likely that may impact on the health of the waterway. These impacts can be mitigated by reducing extractions of fresh water from the Yarrowee catchment and reducing discharge of wastewater to the river.
21. Burrumbeet Creek may experience greater peak flows with associated increased flood risks. These flows are likely to be decreased by the climate change scenarios. The creek will be subject to moderate increases in nutrient loads because discharges of effluent from the Ballarat North wastewater treatment plant are diminished by reuse of treated wastewater.

22. Bet Bet Creek in the Maryborough district may be subject to increased peak flows and associated flood risks by 2051.

23. This investigation has revealed some interesting paradoxes including an understanding that replacement of agricultural land uses with urban development results in the decreased loads of nutrients in waterways. However this waterway health impact is countered by increased nutrient loads from wastewater discharges and increased frequent flows in waterways.

24. Urban areas in Ballarat and Maryborough generated greater stormwater runoff than water demands during the last decade. A combination of urban stormwater runoff and wastewater discharges to existing treatment plants generated water volumes that were at least twice the volume of water demands.

25. By 2051, the Ballarat district will be highly dependent on bulk water supplies from external sources whilst discharging volumes of urban stormwater runoff and wastewater that are three times the volume of water demands. There is an opportunity to utilise local water sources to minimise impacts on surrounding communities and ecosystems.

26. By 2051, water supply to Maryborough will be highly dependent on the surface water extracted from the headwaters of McCallum and Stoney Creeks with back up from bulk water allocations and ground water, whilst discharging volumes of urban stormwater runoff and wastewater that are six times the volumes of water demands. There an opportunity to utilise local water sources to minimise impacts on surrounding communities and ecosystems.

Figure 5: Validation of the Systems Framework to water levels in the Warranga Irrigation Basin near Golburn River Weir

Figure 6: Water demands and resources within the Ballarat Water District

Systems analysis report for the Ballarat region: Systems Analysis

Economic Analysis of Option for the Region

This report has focused on the economic behaviour of the Ballarat water district in the context of the performance of the entire region for Business as Usual (BAU), for Scenarios that may challenge the future performance of the System (such as Climate Change and High population Growth) and Options for future management (including building, precinct and regional scale strategies). A Systems Framework of the Ballarat region was developed as part of the Living Ballarat Project to assist in understanding the whole of water cycle challenges and opportunities across the region.

This investigation does not seek to define the best or preferred strategy for the Ballarat region. The purpose of this report is to provide insights into the behaviour of the water cycle system throughout the Ballarat region and the likely economic response of the regional system to different Scenarios and Options.

The Dynamic Economic Framework utilised in this analysis is a linked component of the Systems Framework that combines all available costs for the whole water cycle across the region to produce a range of economic futures. The economic analysis of the entire system (Systems Economics) utilised in this investigation is based on cash flows of costs throughout the water cycle system.

Whilst the Economic Framework allows rapid assessment of almost all inputs, this report has presented the results for the inputs provided in Section 2 using a real discount rate of 5%. The results presented in this report should be considered in conjunction with the previous reports, namely “Systems analysis of water cycle systems – analysis of base case scenarios for the Ballarat region” and “Summary of the performance of options and key insights”.

The framework has been developed to a state where it can be reliably and robustly applied to detailed and targeted ‘what if’ analyses, including assessments of future water security and economics under a range of climatic and population growth scenarios, and future alternative strategies. The spatial and temporal detail within the Systems Framework allowed understanding, reproduction and testing of the complex interactions between waterways, reservoirs, operations, water demands, water restrictions and financial impacts.

Figure 7: Validation of the Systems Framework to total operating costs for the Ballarat Water District 2002 – 2012

This report includes hind casting of the economic analysis across the historical period from 2002 to 2012 that includes known financial information about the costs of the water and wastewater systems in the region. This process was used to verify and calibrate the inputs to and processes within the economic framework. In general, the hind casting process was able to verify the efficacy of the systems economics as highlighted by Figure 2. This version of the report also includes a sensitivity analysis that responds to workshops held by the Victorian government and tests the most significant drivers of economic behaviour revealed by this investigation. Finally, this report is accompanied by supporting web-enabled software that allows the reader to further investigate the investment processes for water cycle management in the Ballarat region.

Figure 8: Verification of total costs predicted by the Systems Framework  2002 – 2012

Key Insights from this investigation are:

1. The whole of System finances and economics of the Living Ballarat region are highly sensitive to variation in physical and financial parameters throughout the scales (temporal and spatial) within and external to the regional. Only a small proportion of regional costs are fixed or invariant from a systems economic perspective. This insight is consistent with classic economic knowledge that all costs are variable in the long run.

2. The systems analysis has produced a richness of results and information that are available for additional analysis. Only a fraction of the information and results are presented in this report.

3. The analysis using the economic framework has utilised real data from Central Highlands Water, City of Ballarat and a wide range of published reports by the National Water Commission, The Essential Services Commission and others.

4. Analysis of the entire water cycle, including linked or dependent regional systems, counting all costs and use of a planning horizon that is consistent with the behaviour of infrastructure reveals the highly sensitive and variable nature of the System’s economics.

5. There is substantial value within the Ballarat Options that indicate that the project can provide outstanding value to the State of Victoria. The most significant future economic costs are to society for declining waterway values and flooding, and the water authority for water supply and wastewater management.

6. The Ballarat water district is challenged by a range of potential Scenarios. Changes to operating rules, reliance on regional bulk water sources, increases in regional irrigation demands, climate change and high population growth has substantial economic impacts on the Ballarat water district.

7. The Systems Economics Frameworks utilised in this investigation are based on input output economics (cash flows), whole of system costs and whole of water cycle costs. The analysis is not based on revaluations of deteriorating infrastructure. This analysis is different to the assumptions in economic or financial analysis used to satisfy various regulatory assessments.

8. A fully dynamic economic model is now available for Ballarat that can allow gaming of Options or Scenarios in seconds. This capability should allow unprecedented value for testing assumptions and a wide range of perceptions in a workshop forum.

9. Importantly, a Systems Economics framework has been created for Ballarat that allows testing of the majority of “contentious inputs” from the most objective perspective possible (does not reply on assumptions or professional opinion) – this is a first for the water industry and it is recommended that the Victorian government utilise this powerful capability to understand the potential of the region.

10. Local or building scale strategies improve the overall viability of the water cycle in the region by reductions in water demands, wastewater discharges, stormwater runoff, pollutant loads to waterways and reliance on bulk water source resulting in diminished impacts on waterways. This creates reduced costs for water supply, wastewater and stormwater management with increased costs to citizens for building scale solutions.

11. Precinct scale strategies such as wastewater reuse and stormwater harvesting improve the overall viability of the water cycle in the region. The wastewater reuse strategy produces moderate benefits that are derived from reduced water demands and wastewater discharges with associated diminished impacts on waterways.

12. However, the most significant benefits are derived from the stormwater harvesting for potable use (perhaps via managed aquifer storage processes) and for the multiple scale integrated water cycle management (IWCM) strategy.

13. This analysis has incorporated all available financial data and economic information in a whole of systems economic framework. Certainty about the analysis can be further improved by inclusion of additional information and knowledge about inputs and processes. For example, the valuation of nitrogen sourced from Melbourne Water dominates the costs of pollution.

14. A significant proportion of the economic benefits revealed from this investigation are derived by smoothing the investment cycle for regional infrastructure by use of local and precinct strategies that impact as smaller increments of costs.

15. Some of the economic benefits derived from the systems analysis are dependent on understanding and acceptance of the improved and synergistic performance created by various local and precinct scale strategies.

The Scenarios used to test the performance of the Ballarat water district are summarised in Table E1 and an overview of the performance of Scenarios is provided in Table E2.

Table E1: Overview of Scenarios

Table E2: Impact of Scenarios on performance of the water cycle in the Ballarat Water District

16. The majority of future costs of water cycle management accrue to the Water Authority and to Society as defined by impacts on waterways and flood risks. The costs of providing reticulated water and sewerage services, flood risks and impacts on waterways are the dominant economics costs for the Ballarat Water District. The total net present costs of water cycle management to 2051 for the BAU option is $4,108 m. Jurisdictional NPCs for all scenarios are presented in Table E3.

Table E3: Jurisdictional NPCs for all scenarios

17. Only using groundwater resources for drought relief results in a requirement to augment water security infrastructure and an overall 3.6% ($146 m) increase in costs that accrue to the water authority.

18. A greater reliance on external water supplies from the Goulburn, Campaspe and Loddon catchments by not extracting water supply to meet urban water demands from the Moorabool and Yarrowee Catchments generates an overall 3.7% ($153 m) increase in costs that accrue to the water authority.

19. A greater reliance on external water supplies from the Goulburn, Campaspe and Loddon catchments by not extracting water supply to meet urban water demands from the Moorabool and Yarrowee Catchments with 100% increases in regional irrigation demands generates a 3.7% ($148 m) increase in costs that accrue to the water authority.

20. The impact of high emissions climate change generates an overall 8.6% ($351 m) increase in costs that accrue to the water authority, developers and society. Reductions in costs to local government are generated by reduced costs for managing stormwater quality and the diminished costs to Society are created by reduced pollutant loads.

21. Accelerated population growth with 2051 population achieved in 2041 creates an overall 19.2% ($790 m) increase in costs that accrue to all jurisdictions with a higher proportion of costs impacting on local government, developers and society. These increases in costs are driven by a requirement for additional resources and infrastructure to service a higher population, and greater impacts on waterways created by additional urban growth.

22. A combination of accelerated population growth and high emissions climate change generates a 19.5% ($803 m) increase in costs that accrue to all jurisdictions with a higher proportion of costs impacting on local government, the water authority and society. These increases in costs are driven by a requirement for additional resources and infrastructure to service a higher population, greater impacts on waterways created by additional urban growth and reduced availability of water resources.

23. A sensitivity analysis revealed that changes in costs of rainwater harvesting and water efficient appliances displayed a similar impact on all of the Scenarios. Increases in costs to operate water and wastewater services generated greater impacts on the Scenarios with greater dependence on bulk water sources with limited local use of groundwater resources. Reductions in the costs of pollutants discharging to waterways provided that greatest reductions in costs for the high growth Scenarios.

The details of the alternative Options are summarised in Table E4 and an overview of the performance of the Options are provided in Table E5.  The jurisdictional distribution of NPCs for each Option is presented in Table E6.

Table E4: Summary of the Alternative Options

Table E5: Impact of Options on performance of the water cycle in the Ballarat Water District

Table E6: Jurisdictional NPCs for all options

24. Inclusion of building scale strategies for water efficiency and rainwater harvesting for all new and renovated buildings generates an overall 11.1% ($458 m) reduction in costs that accrue to local government, the water authority, developers and society. Local government and society are proportionally higher beneficiaries and citizens experience higher costs to create these benefits. These decreases in costs are driven by a reduced requirement for water resources and infrastructure, and reduced impacts on waterways.

25. Inclusion of building scale strategies for water efficiency, rainwater harvesting and street scale stormwater management for all new and renovated buildings creates an overall 16.1% ($661 m) reduction in costs that accrue to local government, the water authority, developers and society. Local government and society are proportionally higher beneficiaries and citizens experience higher costs to create these benefits. These decreases in costs are driven by a reduced requirement for water resources and infrastructure, and reduced impacts on waterways.

26. An Integrated Water Cycle Management (IWCM) strategy that includes reuse of wastewater, rainwater harvesting and water efficient buildings provides an overall 36.9% ($1,515 m) reduction in costs that accrue to local government, the water authority, developers and society. Local government and society are proportionally higher beneficiaries and citizens experience higher costs to create these benefits. These decreases in costs are driven by a reduced requirement for water resources and infrastructure, and reduced impacts on waterways.

27. Stormwater harvested from regional stormwater management storages in new urban areas and treated to potable standards for injection into water distribution infrastructure generates an overall 21.2% ($870 m) reduction in costs that accrue to local government, the water authority, developers and society. The Water Authority and society are proportionally higher beneficiaries and citizens experience slightly higher costs to create these benefits. These decreases in costs are driven by a reduced requirement for water resources and infrastructure, and reduced impacts on waterways.

28. Wastewater Reuse using existing or modular treatment plants and distribution via a third pipe network for toilet, outdoor and open space uses at all new buildings provided an overall 17.1% ($701 m) reduction in costs that accrue to local government, the water authority, developers and society. The Water Authority and society are proportionally higher beneficiaries with citizens and developers experiencing slightly higher costs to create these benefits. These decreases in costs are driven by a reduced requirement for water resources and infrastructure, and reduced impacts on waterways.

29. An investigation into the sensitivity of the Options to changes in costs demonstrated that the relative value of Options were mostly insensitive to the selected changes in costs. The IWCM, SWH and WWR Options show consistent high value for the Ballarat region. However, a substantial reduction in the costs of pollutants discharging to waterways creates a significant change in the viability and economic ranking of the BC2, IWCM and WWR Options.

30. Reductions in pollutants loads discharging to waterways via stormwater runoff and wastewater discharges is a significant contributor to the value of the IWCM Option that includes wastewater reuse and rainwater harvesting, to the WWR Options that includes wastewater reuse and to the BC2 Option that includes streetscape stormwater management measures.

Economic report: Ballarat Economics

Key Findings and Recommendations

Key Findings

1. This study has adopted unique spatially and temporally explicit methods of systems analysis to establish that alternative water cycle management embedded within existing centralised water cycle networks can offer technically, commercially and environmentally viable strategies.
2. A stakeholder, review and hindcasting process was utilised to obtain data and information that allowed enhancement of an existing systems model.
3. The integrated systems model was used to support an evidence based policy process.
4. The enhanced systems model successfully reproduced the behaviour of regional storages, water demands and wastewater discharges. The spatial robustness of the systems model was verified for generation of water demands and wastewater discharges throughout Greater Melbourne. Costs and greenhouse gas emissions in the systems model were also successfully verified against all available data.
5. The systems model provided similar or more conservative results for the impacts of expected climate change than estimates provided by CSIRO and IPCC.
6. More than 40 discrete combinations of Options and Scenarios were tested that provided a rich data set for understanding the future challenges and opportunities for Greater Melbourne’s water cycle.
7. The existing system (BAU) is critically dependent on (or sensitive to) variations in climate and population.
8. The expected increases and accumulation of wastewater and stormwater in water cycle networks are significant challenges for Greater Melbourne to 2050.
9. This investigation has found that up to three additional augmentations of the regional water supply system are required for BAU to 2050 in response to potential climate change.
10. The building scale Options (BASIX and BASIX1) substantially mitigate the challenges of variable population and climate.
11. The precinct scale Options (ULT and ULT1) almost eliminate the challenges of variable population and climate.
12. Alternative Options can generate substantial reductions in water demand, wastewater discharges and stormwater runoff.
13. Alternative Options can provide significant reductions in the cost of providing water and wastewater services that include reduced transfer costs of providing water and sewage services.
14. The full costs (and benefits) of projects for water cycle management are not currently considered. This is likely to create bias in decision making processes towards augmentation using large scale infrastructure.
15. The variances and inconsistencies in data highlighted in this investigation indicate that it has been previously difficult to develop accurate spatial understanding of the performance of Greater Melbourne’s water cycle. Thus it is unlikely that the actual costs of providing services to discrete spatial locations throughout Greater Melbourne have been considered.
16. One of the most significant outcomes of the MAC process was the large number of individuals who demonstrated significant good will and willingness to generate change across the sector.

Key Recommendations

1. Implement “whole of Melbourne” minimum objectives for water cycle management that include minimum annual reductions in demand for mains water, wastewater discharges and stormwater runoff of 80%, 50% and 30% respectively. These objectives should be combined with spatially relevant building scale targets that include minimum annual reductions in demands for mains water, wastewater discharges and stormwater runoff of 50%, 30% and 20% respectively.
2. Minimise the total distances involved in the transfer of water and wastewater throughout Greater Melbourne in water cycle planning and design of infrastructure.
3. Eliminate “lumpy” expenditure for large scale centralised infrastructure wherever possible. There is significant value in avoiding investment in large scale infrastructure by utilising timely investment in smaller scale local infrastructure as required.
4. Water cycle planning and associated decision making should be derived from the integrated systems analysis methods utilised for this investigation to provide better understanding of the spatial variance and complexity of the water cycle throughout Greater Melbourne.
5. Implement design guidelines that are underpinned by the latest knowledge, understanding and integrated systems processes. The new guidelines must consider the impacts of multiple water sources, water efficiency and local variability on the design of infrastructure.
6. Implement a high quality monitoring and data management system for the entire Greater Melbourne water, sewage and stormwater networks. This system should be implemented and managed independently and in partnership with all water authorities to ensure consistency. The “whole of Melbourne” monitoring and information management systems should also include observations of stormwater runoff volumes and quality.
7. Implement a competitive process for management of water resources throughout Greater Melbourne. An essential element of this process is the structural seperation of planning, approval and operational processes involved in delivering water cycle services. At a minimum this will involve assigning water cycle planning and approval functions to an independent authority.
8. Provide open, transparent, and freely accessible information about the performance of water cycle systems throughout Greater Melbourne to all stakeholders and the community. This information should be managed by an independent authority and be available in a common location and format.

Introduction

The purpose of this investigation was to provide systems analysis of the water cycle for Greater Melbourne and advice in support of the Ministerial Advisory Council (MAC). This process aimed to generate discussion and deeper understanding of the detailed transactions that drive water cycle management throughout the region.

This alternative view was used as a basis for the implementation of the Living Melbourne, Living Victoria policy and this report supports the recommendations in the MAC’s final Stage II report.

The Ministerial Advisory Council (MAC) commissioned Dr Peter Coombes and Bonacci Water to provide “Modelling in support of the Living Victoria Ministerial Advisory Council work program” using the Greater Melbourne Systems Model utilised during Stage I of the MAC process. This process involved a range of key objectives including:

• Assist in deepening the understanding of the MAC about the Stage I model and outputs.
• Validate and strengthen the model and outputs for the MAC.
• Provide continuing support for investigations and policy processes undertaken by the MAC.

An integrated systems approach was employed by this study to analyse the performance of integrated water cycle management Options throughout the Greater Melbourne region. Options were determined to generate understanding of the response of the water cycle systems within Greater Melbourne to alternative strategies and to subsequently inform decision making for water policy.

This unique analysis was dependent on detailed local inputs throughout the system, such as demographic profiles and human behaviour, and linked systems that accounts for water supply, sewage, stormwater and environmental considerations. The systems analysis was built on local scale (the people) inputs (a “bottom up” process) rather than traditional analysis of metropolitan water resources that commences with regional scale assumptions (a “top down” process).

This project has utilised the powerful framework for detailed systems analysis of the Melbourne region that has been developed over a long period of continuous investigation. Three decades of research, two separate investigations (the previous investigation commenced in 2006) and a year of dedicated analysis have enabled a robust analysis.

Options and Scenarios

Options

Four alternative options were examined for water cycle management within Greater Melbourne. The performance of each Option was compared to the performance of the Business as Usual (BAU) Option.

The purpose of establishing Options was to facilitate testing of the physical, technical and commercial performance of the system without the influence of opinions, perceptions and agenda. Defining a base case (Business as Usual) and alternative Options enable the testing, comparison and understanding of the behaviour of the Greater Melbourne system. This study did not seek to pick an endpoint or to provide a detailed design of the Options. It provides useful insight into systems behaviour that can inform decision making.

These Options were established to test, compare and contrast a range of alternative future states. Note that each Option is also subjected to a range of naturally variable climate scenarios. The alternative Options are described in Table E1.

Scenarios

Scenarios describe the potential changes in qualitative drivers that may influence the behaviour of the system. These qualitative drivers create behaviours that may be experienced by any Option. The consequent plausible alternative futures test the viability of the Options. The Scenarios applied to each of the Options for water cycle management throughout Greater Melbourne examined in this study are summarised in Table E2.

Methodology

This study employed an integrated systems approach to analysing the performance of alternative water cycle management Options for Greater Melbourne. Options were determined to generate understanding of the response of the water cycle systems throughout Greater Melbourne to alternative strategies.

This unique analysis is dependent on detailed inputs, such as demographic profiles, and linked systems that accounts for water supply, sewage, stormwater and environmental considerations.

The systems analysis was constructed from the basic elements (the lot scale inputs) that drive system behaviours and account for first principles transactions within the system to allow simulation of spatial performance of the system. Biophysical systems in the region were constructed using three basic components:

• Sources –  Regional and local water sources, catchments and waterways
• Flux – transport and treatment of water, sewage and stormwater throughout the region
• Sinks – Stormwater runoff and wastewater disposal to waterways

The analysis is anchored by a regional framework of key trunk infrastructure, demand nodes, discharge points, waterways and regional sources of water in the systems model.

Major water distribution, stormwater, sewage, demographic, climate and topographic zones are combined in this framework. This process compiles inputs from a wide range of commonly utilised analysis tools, including for local water demands and water balances and hydrology. Key inputs to this framework include:

• Demographic data from the Australia Bureau of Statistics and State Government departments including the Department of Planning and Community Development (DPCD)
• Climate data from the Bureau of Meteorology (BOM) and streamflow data from the Victorian Data Warehouse and MWC.
• Water and sewage flows sourced from MWC, CWW, SEW and YVW.
• Local and cluster scale inputs simulated in the PURRS model at 6 minute timesteps using long climate records sourced from the BOM.
• Urban areas and LGAs analysed using a range of models including PURRS and MUSIC.  These smaller scale systems are also analysed in more detailed WATHNET models.
• The biophysical and scale transition model compiles inputs from PURRS into zones based on statistical local areas and calibrates to observed data from water and sewage catchments.
• The Wathnet model was used to collate and simulate all inputs across the entire region

This framework incorporates the movement of water throughout the region and connectivity to the water supply headworks system. Similarly, this framework includes the movement of sewage throughout the region and connectivity with discharge points or reuse systems.

Details of the analysis, extractions from the data and modelling process have been provided throughout this report to assist with understanding the systems processes used in this study.

Household water consumption for the period 2005 to 2006 was selected in this study as representing base water consumption for the region during a period relatively free of water restrictions. These water demands were then modified by a range of processes including adoption of water efficient appliances in some houses, connection to wastewater reuse systems and changes in demographics. The economic analysis was based on the 2009/10 financial period.

Results

Most parameters relevant to water cycle management are subject to significant spatial variation throughout Greater Melbourne. These include climate, water demands, wastewater generation, stormwater runoff, socio-economic and demographic profiles, and the cost of providing water and wastewater services.

The water cycle for Melbourne cannot be described by homogenous parameters based on a single location or even regional averages. Similarly, this study has shown that the existing performance of the Greater Melbourne system or its response to policy changes cannot be based on single parameters or solutions. In particular, the existing system (BAU) is critically dependent on (or sensitive to) variations in climate and population.

The expected increases and accumulation of wastewater and stormwater in water cycle networks are significant challenges for Greater Melbourne. This investigation has found that up to three additional augmentations of the regional water supply system may be required. A summary of requirements for augmentation are presented in Table E3.

Table E3 demonstrate that alternative Options for water cycle management provide significant improvements in the security of Greater Melbourne’s water supply and that the climate change and population growth is likely to have a significant impact of security of water supplies.

The ULT Option that includes multiple sources of water and efficient use of water eliminate requirement to augment regional water supply.

It is noteworthy that the high emissions (HE) and low emissions (LE) generate requirement for additional regional water sources for all Options expect the ULT Option. In addition, the BAU Option includes up to three augmentations and requires continuous operation of desalination plants which the alternative Options require use of desalination when total water storage in regional dams are drawn down below 65%.  In addition, the alternative Options BASIX, ULT and ULT1 eliminate the requirement for additional water supplies. The results of this study are summarised in Table E4.

Impact of rainwater and stormwater harvesting on the water cycle

Table E4 reveals the key findings of this study that include:

• Population growth is a key driver of future water demands, wastewater generation and stormwater discharges. The costs of incorrectly predicting population growth has critical implications for the State of Victoria.
• Future variations in climate regimes will create substantial variations in water demands and availability of water. Higher temperatures drive greater water demands and this concurrently reduces rainfall and streamflow (that drives centralised supply).
• The debate as to whether future urban growth should occur as Greenfield or Infill development does not appear to be significant. These Options do not have significantly different impacts on the system.
• A change in the structure of the Victorian economy could have a significant impact on water demands, security of water supplies and the spatial response of the system.
• Mistaken predictions of water cycle impacts and associated requirement for large scale infrastructure may result in stranded assets – large infrastructure without the demand to pay for it.
• Alternative Options consistently deliver significant reductions in water demands, wastewater generation and stormwater discharges:
  • The ULT Option generates the greatest reductions in water cycle impacts in comparison to BAU.
  • The other alternative Options generate significant (but diminished when compared to ULT) reductions in demands on the water cycle for Greater Melbourne.
  • Alternative Options also deliver the greatest resilience and flexibility when subject to future variability:
    • The ULT Option delivers the greatest resilience and flexibility in comparison to BAU due to the use of multiple water sources in combination with water efficiency.
    • The other alternative Options also generate significant (but diminished when compared to ULT) resilience and flexibility.
    • Water efficient gardens and public open space are an important component of overall water efficiency for Greater Melbourne. This initiative delivers tangible benefits including reduced water demands and avoids augmentation of infrastructure. Water efficient gardens should form part of future water policies.
    • The omission of stormwater harvesting for injection into the mains system for potable use from the ULT Option “leaves significant value on the table”. This lost value includes the ability to affect substantial reduction in mains potable demands, improved water security and reduced requirement of regional augmentation.
    • Perceived problems that originate from concerns about institutional and governance issues need to be challenged and overcome.  Failure to resolve these issues stand in the way of substantial benefits to society.
    • Alternative Options generate significant economic and financial benefits. The ULT Option generates the most significant reductions in costs and the other alternatives generate significant (but slightly reduced) benefits, including:
      • Reduce the cumulative total costs of the system by up to $30 B over 40 years
      • This equates to 1% to 2% of State’s total expenditure every year to 2050 or 65% of Victoria’s 2011-12 budgeted expenditure.
      • This value is equivalent to 30 hospitals or 60 new prisons or 10 new Freeways or 6 Regional Rail Links
    • Total water cycle management costs vary significantly in response to different futures. Substantial reductions in total costs are generated by the low growth and economic structural change Scenarios. In contrast, the high growth and climate change Scenarios produce considerable increases in total costs.
    • The ULT Option generates the greatest resilience to variations in costs resulting from alternative future states and the other alternative Options generate diminished but still significant resilience.
    • The alternative Options generate a range of additional financial, social and environmental benefits, including:
      • Up to a 20% (8,246 tonnes) decrease in nitrogen loads entering waterways
      • Significant reduction in the costs of stormwater infrastructure (up to a 13% decrease), the flooding (up to a 17% decrease) and management of nutrients (up to a 17% decrease)
      • Up to a 30% (34,171 kT) reduction in cumulative GHG emissions. This result challenges the perception that alternative Options consume more energy than BAU. It also highlights the importance of holistic and integrated systems analysis

This study used detailed systems analysis to compare the spatial capacity and potential spatial performance for each Option.  These are defined as follows:

• Capacity: the definition of the potential of each Option at each building or household or precinct throughout Greater Melbourne
• Performance: the definition of the behaviour of each Option within the planning horizon that is modified by population growth, renovation rates, demographic processes and the legacy of existing infrastructure and policies

The study found that buildings and households across Melbourne have the capacity to achieve significant reductions in water demand, wastewater discharges and stormwater runoff. The use of a spatially explicit modelling framework in this study was able to show that this capacity varies across Melbourne. All Options provide reasonably consistent capacity outcomes that result in substantial reductions in water demands, wastewater discharge and stormwater runoff for all locations across Greater Melbourne.

The spatial variation in performance of Options is driven by a multitude of factors including rainfall, proportion of residential and non-residential buildings, the age of suburbs, the condition of existing infrastructure and the distance to and from water supply sources and wastewater treatment facilities:

• The ULT Option achieves consistently greater capacity and higher performance for all measured indicators for all of Greater Melbourne.
• Other alternative Options generate significant (but slightly diminished) capacity and performance for Greater Melbourne.

Conclusions

The Options considered in this study provide the following key outcomes:

• the existing system (BAU) is critically dependent on (or sensitive to) variations in climate and population.
• The building scale Options (referred to in this study as BASIX and BASIX1) substantially mitigate the challenges of variable population and climate
• The precinct scale Options (referred to in this study as ULT and ULT1) almost eliminate the challenges of variable population and climate
• The alternative Options generate reductions in
  • water demand, wastewater generation and stormwater runoff
  • the cost of providing water and wastewater services, and
  • the transfer costs of providing water and sewage services

Verification of the Systems Framework using sequences of predicted and observed total dam storage

Summary

Two significant and related issues confronted the managers of the Hill End water and sewage scheme: the potential for water shortages and the surcharge of untreated sewage to the environment. These concerns are particularly relevant during peak tourist periods. Urban Water Cycle Solutions was commissioned by the NSW Department of National Parks and Wildlife Services to evaluate the efficacy of the water and sewerage scheme that services the town of Hill End. The report reviewed and collated existing information provided by DNPWS into a synopsis that identifies main issues and important gaps in knowledge.  The overall objectives of the investigation was to achieve optimum operation of the water and sewerage schemes such that a reliable and safe water supply is provided, wastewater discharges to the environment are minimised and sustainable funding of the schemes. An equally significant goal is to create ecologically sustainable approach to the management of the water and sewerage schemes.

Introduction

The township of Hill End was established during the 1880s due to the discovery of gold in the area and in 1967 part of the town known as the historical village of Hill End was proclaimed as a historical site. Hillend is located about 70 km northwest of Bathurst and 69 km south of Mudgee.

Water supply and sewerage disposal schemes were constructed by the Department of National Parks and Wildlife Services (DNPWS) prior to the proclamation of the village of Hill End as a historical site. The DNPWS own and manage the historical village of Hill End including the water and sewerage schemes. The surrounding areas are managed by Evans Shire Council.

The majority of permanently occupied tenements within the historical village of Hill End are connected to reticulated water and sewerage systems. All of the dwellings are also connected to rainwater tanks and septic tanks. Houses outside of the historical village of Hill End rely on rainwater tanks for water supply and septic tanks for wastewater management.

Outstanding heritage values exist in the historical village of Hill End including a museum, historical buildings, old mine sites, camping grounds, a hotel and bed and breakfast accommodation that serve to attract a large volume of visitors to the area during school holidays and weekends.

Rainfall at Hill End is recorded using daily readings from an accumulating rain gauge located at the visitors’ centre. During the period 1988 to 2002 the average, maximum and minimum rainfall depth recorded was 804 mm, 1248 mm and 500 mm respectively. Even in the driest years the town has sufficient rainfall to ensure that drinking and cooking demand is adequately supplied by rainwater tanks in most circumstances.

Population and water demands

Water supply data from the reticulated network provided by the NSW government was used to establish that 84 people currently occupy 37 dwellings in the historical village of Hill End. This population includes 55 permanent residents occupying 23 dwellings and 29 occasional residents that occupy 14 dwellings. About 14,015 people also visited the town and signed the visitors’ book in 2002. It is also noted that 26 people attend the school during week days in the school terms. Note that DPWS (2000) estimated that 60 students attend the school.

Historical records from 1996 revealed that 58 residents occupied 31 dwellings in the historical village of Hill End and the town received about 16,000 visitors. The population included 39 permanent residents that occupied 22 dwellings and 19 occasional residents occupy 9 dwellings. The population of the historical village of Hill End has grown by 45% since 1996 and the population of locality of Hill End has increased by 20% since 1991.

                       Visitors to Hill End from 1997 to 2003

Water use

The majority of dwellings and commercial premises located in the historical village of Hill End have water meters installed. Results from meter readings indicated that water use of dwellings in the historical village was 6.362 ML/annum during the period 1997 – 2002 and metered water use in the village was 3.688 ML/annum in the period 1981 – 1996. There has been a 42% growth in metered water use since 1996.

In 2002 the average water use in dwellings with permanent residents was 214.5 kL/annum, the average water use in dwellings with occasional residents was 90.2 kL/annum and the average water use in the Hotel was 573.6 kL/annum. Note that not all water meters are operational and water use is not regularly recorded.

This study motivated the installation of water meters during September 2002 to buildings that are subject to water use from the visitor population to Hill End. These locations are not subject to rates assessments therefore water demand had not previously been recorded. A full network of water meters was also utilised to locate leaks or unaccounted for water in the Village.

The total annual reticulated water demand for Hill End in 2002 can be estimated to be 7,173 kL. Note that the water reticulation system has been found to be leaking in several locations. Thus the total water demand will be greater than the total of annual readings.

Estimate water use for the town of Hill End

 The majority of dwellings in the town of Hill End use rainwater tanks to supply drinking and cooking water demand which is about 5% of total household water demand. Rainwater tanks are also used to supply outdoor water demand. Analysis of the rainfall records for Hill End (daily records measured at the Visitors’ Centre (1988 – 2003) show that rainwater tanks could be used to successfully partially supply other water uses with backup from the reticulated bore water supply as required.

Site inspections at Hill End have established that single flush toilets with a flush volume of 13 litres are installed in most residences and commercial premises. It was noted that the use of water conservation measures such as 6/3 litre dual flush toilets will substantially reduce water demand in Hill End. The replacement of all the 13 litre flush toilet cisterns with 6/3 flush cisterns will reduce water demand for toilet flushing by up to 60%.

The Water Supply Scheme

The NSW Government was licensed to extract up to 40 ML/annum from the aquifer under Hill End for water supply purposes. This water is sourced from four ground water bores located within the town of Hill End. Some of these bores have collapsed due to ground movement that has resulted from past mining activities.

A majority of reticulated water supply to Hill End was drawn from a recommissioned ground water bore located near Clarke Street. No details of the capacity of this bore were provided. However local staff reported that the pump has the capacity to supply ground water at a rate of about 0.8 L/s.  In addition the NSW government explained that during periods of low rainfall ground water levels are lowered resulting in reduced flow rates available from bores.

The chlorination of the water supply before distribution to large storages that have significant residence times is not optimum and will result in the need to re-chlorinate the stored water on a regular basis. This can produce water with high chlorine content that has unacceptable quality. Local staff reported that it is indeed necessary to re-chlorinate water on a regular basis. It is highlighted that most residents of Hill End use water from rainwater tanks for drinking and cooking.

The water supply from the Germantown tanks should pass through a filter to remove organics and then chlorinated prior to distribution to Hill End. This would involve reconfiguration of the distribution arrangements at the Germantown tanks and moving the chlorination apparatus from the bore pump to the Germantown tanks. Moving the filtration and disinfection process to after the Germantown storages will allow the storages to act as facilitators of natural flocculation and settlement processes that will remove significant amounts of organics prior to treatment thereby improving water quality.

Water is also transferred via a pump to a storage tank with a capacity of 3 kL in the Glendora Camping Ground that is used to supply water to the camping ground. A 135 kL storage tank near the visitors centre and two 90 kL tanks near High Street are also supplied via the High Street booster pump. The visitors centre, toilet block, workshop and nearby dwellings are supplied with water from the storage tank at the visitors centre. An active ground water bore is located near the Visitors’ Centre but no information is available about water use from this bore. A water meter should be installed on this bore and water extractions should be recorded at 9 am each day.

The Sewerage Disposal Scheme

The locality of Hill End has two different sewerage disposal schemes that service the town of Hill End and Glendora Camping Ground. In both schemes sewage is captured in on-site septic tanks that discharge effluent via small diameter pipes to evaporation ponds. This type of sewage management systems is known as a septic tank effluent disposal scheme (STEDS).

Effluent from septic tanks in the town scheme gravitates via pipes to an underground storage tank that has a capacity of 10 kL near Clarke Street. Two submersible grinder pumps with capacities of 1.28 L/s and 1.09 L/s are located in the storage tank. The smaller pump is used as a backup for the larger pump. Effluent is transferred from the storage via the pump and a 50 mm diameter PVC rising main to the Kitty’s Flat oxidation and evaporation ponds.

The two oxidation ponds have surface areas of 1,460 m² and 1,196 m² respectively and the three evaporation ponds with surface areas of 1,958 m², 3,097 m² and 4,600 m² respectively. A small portable pump was used to transfer effluent from the first oxidation pond to the second oxidation pond. This results in limited utilisation of the evaporation ponds for treatment of the sewage effluent. A gravity transfer system using valves and small pipes should be installed to allow efficient transfer of effluent to the evaporation ponds.

The ponds have the capacity to treat about 25 ML of effluent per annum and the DNPWS also have a license from the EPA to discharge effluent from the ponds to the environment. Note that the actual volume of sewage requiring treatment is about 5 ML per annum. Provided that effluent can be efficiently transferred from the oxidation ponds to the evaporation ponds and large volumes of stormwater do not enter the sewerage system, the sewage treatment system is adequate for two reasons:

1. The annual sewage volume has been over-estimated by a considerable amount (actual volume: 5 ML/annum, volume used in previous design: about 25 ML).
2. The volume of sewerage discharges in traditional systems during wet weather can be up to 15 times normal dry weather sewage discharges due to stormwater infiltrating into the sewerage system. However the use of septic tanks and small diameter pipes (STEDS) to manage sewage eliminates the infiltration of stormwater into the sewage system during wet weather. Thus traditional sewage design assumptions will significantly over-estimate the volume of sewage discharges in Hill End.

A number of manholes have been placed in the sewage reticulation system that runs along Clarke Street. Whilst the use of manholes is advisable at bends and junctions to allow removal of blockages the use of manholes also allows stormwater into the sewerage system resulting in surcharges of sewage to the environment. A number of additional manholes have been placed at intervals in straight sections of the sewerage reticulation system (especially in Clarke Street) and the tops of these manholes are below ground level. Thus the risk of sewage surcharges was greatly increased. Indeed the imperviousness of the Hill End sewerage scheme to stormwater infiltration is compromised by the presence of the manholes. Note that the NSW Government reported that the Clarke Street bore had been previously closed down due to faecal contamination of the water. It is most likely that the faecal contamination resulted from sewage surcharges.

The majority of manholes in straight sections of the sewerage reticulation system are redundant. It is recommended that pipe sections with inspection points be placed in those manholes to provide a sealed connection through the manholes. The remaining manholes that are placed on bends or at the intersections of sewerage pipes in the lower reaches of the sewerage system should be sealed with an appropriate sealant to avoid ingress of stormwater into the sewerage system.

Three houses in Germantown do not have adequate sewer management facilities. It is proposed to convey effluent from the existing septic tank at Rose Cottage in a gravity reticulation system with small diameter (50 mm) pipes towards the Village Camping Ground. A septic tank with a capacity of 3 kL will be placed in the grounds of Miller’s Cottage to collect sewage from Miller’s Cottage and the adjoining cottage. Effluent from the new septic tank will be collected in the new gravity reticulation system that falls towards the Village camping ground. It was also recommended that 6/3 litre dual flush toilets be installed at both houses to reduce water demands and sewage discharges.

The proposed Germantown sewerage scheme

Two significant and related issues confronted the managers of the Hill End water and sewage scheme: the potential for water shortages and the surcharge of untreated sewage to the environment. These concerns are particularly relevant during peak tourist periods. The availability of the ground water resource is unknown but will be variable and the performance of the Kitty’s Flat sewage facility will also vary in accordance with climatic conditions. Both issues can be addressed by use of water efficient appliances, elimination of water leaks, and reuse of effluent for toilet flushing and irrigation purposes within the town of Hill End.

It was proposed to use treated effluent to flush toilets in the Village Camping Ground and for toilet flushing in all nearby buildings subject to high tourist visitations. It is also proposed to use the treated effluent to irrigate the commons and the Village Camping Ground. The annual water demand for toilet flushing at the Village camping ground is about 114 kL with a peak daily water demand for toilet flushing of about 4 kL. In addition the annual water demand for irrigation of the commons and the camping ground will be dependent on the area subject to irrigation but it will be reasonable to assume that about 400 kL per annum will be used for irrigation. Thus the proposed scheme will, at a minimum, reduce annual water demand by about 114 kL and reduce annual sewage discharges by about 514 kL. A schematic of the treated wastewater reuse scheme is shown below.

Schematic of the proposed Village treated wastewater reuse scheme

 The Glendora Camping Ground has a separate sewerage system that services the amenities block. Wastewater from the amenities block discharges to a large septic tank that overflows via a gravity reticulation system to an oxidation pond and an evaporation pond. The average sewerage discharge from the amenities block is 141 L/day and the peak daily sewerage discharge is 3.2 kL/day. The average and peak water demands at the amenities block are similar.

The ponds are located in the upper reaches of a water supply catchment and the ponds have small surface areas that provide limited opportunity for oxidation and evaporation. As a result the ponds remain full and during rainfall events are likely to overflow.

The important issue to be resolved at the Glendora Camping Ground is to ensure that the ponds do not overflow into the water supply catchment. This was achieved by intercepting the effluent discharging from the septic tank for treatment and reuse in toilets at the amenities block and for irrigation of the grounds. The ponds would remain in the system as a backup to store excess effluent for short durations during peak periods and the treated wastewater irrigation system can be optimally employed to ensure that effluent levels in the ponds is kept to a minimum. A schematic of the wastewater treatment strategy is shown below.

 The proposed Glendora wastewater treatment scheme

Conclusions

A number of solutions were proposed for the improvement of the water and sewage systems at Hill End including a conventional wastewater disposal and treatment system, removal of all septic tanks, removal of rainwater tanks and total reliance on an improved reticulated groundwater system. However the town’s limited budget for new infrastructure excluded many of the proposed conventional solutions. The list of feasible solutions included the integrated water cycle management (IWCM) solution were:

• Install water efficient toilets
• Install rainwater tanks for toilet flushing at the hotel and public toilets
• Install water filtration and disinfection at water distribution tanks
• Make sewage manholes impervious to stormwater inflows
• Connect all properties to the common effluent scheme (STEDS)
• Establish an effluent reuse scheme
• Only discharge excess effluent that is treated to high quality to waterways
• Install water meters and implement a program of daily observations to refine management strategies
• Eliminate leakage from the water distribution system

Summary

The purpose of this investigation was to provide an alternative view of the potential for water cycle management throughout the Greater Sydney region and the role of Sydney Water Corporation (SWC). This study employed an integrated systems approach to analysing the performance of integrated water cycle management Options throughout the Greater Sydney region. The Options were determined to generate understanding of the response of the water cycle systems throughout Greater Sydney to alternative strategies.

This unique analysis is dependent on detailed local inputs throughout the system, such as demographic profiles and human behaviour, and linked systems that accounts for water supply, sewerage, stormwater and environmental considerations. A parallel investigation was also undertaken by a highly experienced and skilled group of industry leaders which were our Though Leadership Group. This Group provided analysis and commentary about all aspects of SWC and the Greater Sydney region from multiple perspectives, input to the systems analysis, review and interpretation of systems outcomes, and input to the final report.

This project has utilised the powerful framework for detailed systems analysis of the Sydney region that has been developed over a long period of continuous investigation. The unique systems analysis and the Thought Leadership process have generated a considerable volume of information and capability for additional analysis of the Greater Sydney region. It was only possible to present some of the outcomes of a very detailed analysis in this report.

Introduction

Cities constantly change. This continuum of change is influenced by demographic, economic, political, environmental, cultural, and social factors – evolution of a city will vary depending on dominant influences at the time.

The nature, scale and location of water cycle (water, wastewater and stormwater) services have evolved with the metropolis. However, the current approach to water services is largely unchanged from the services established in the late 1800’s and early 1900’s. The future reliability of centralised urban water systems is uncertain. SWC faces the challenge of remaining a global leader in provision of water services to an evolving city in a sector transitioning to a new paradigm of provision of water services.

Dr Peter Coombes and Bonacci Water were engaged by SWC to provide an Alternative Water Strategy for the Greater Sydney region.

SWC was seeking an alternative vision of the future of Sydney and the requirement for water cycle services.  This project defined an alternative vision and outlines a roadmap to realise this vision. SWC was seeking a transparent and robust choice of alternative futures that will allow prudent response to an evolving Greater Sydney region. A strategy was provided to manage both imminent and future changes to provision of water services, management of infrastructure, regulation, policy and political challenges.

The extent of the urban footprint for Greater Sydney (NSW Department of Planning)

This report has gathered independent ideas and transformed them into a plan for integrated water cycle services across the Greater Sydney region.  Importantly, this project and report has not sought to reconfirm SWC’s existing ideas.  Rather it seeks to provide alternative views and strategies that should be considered.

The report does not represent a final destination.  It is a starting point in the transition to a new paradigm for provision of water cycle services.

Background

Sydney has been shaped by the availability of reliable supplies of potable water. The site of the colonial settlement of Sydney was chosen for its proximity to the best known freshwater spring – the Tank Stream.  Wastewater was collected in water closets or discharged either into cess pits or open sewers.  Waterways quickly became overloaded by waste. Sydney is currently serviced by a complex network of pipes, pumps, treatment plants, dams and a desalination plant.

Much of this infrastructure is aging, and services provided by some of those assets are diminished.  Recent water supply shortages further exacerbate the problem because it is difficult to efficiently use water with traditional approach to provision of infrastructure.  Across Australia, the performance of water infrastructure has been rated as only adequate to poor and it is known there has been considerable underinvestment in water infrastructure of many billions of dollars. SWC confronts many challenges in the near to medium term. These challenges relate to the ongoing ownership and operation of aging infrastructure, and the provision of new services for a growing Greater Sydney region.

The origins of alternative water services can be traced back to the phrase ‘Water Sensitive Urban Design’ (WSUD). The broadest definition of WSUD represents significant changes in the strategies for planning and design of settlements that includes all aspects of water cycle management. The recent drought and the omission of water cycle management strategies from WSUD has led to more holistic philosophies known as Integrated Water Cycle Management (IWCM) that often include WSUD strategies as components for stormwater management. IWCM strategies consider the availability of all water resources as well as reducing water demand by encouraging the use of water efficient appliances and practices. IWCM strategies combine best practice stormwater management with reductions in mains water use and reduced sewage loads to improve the security and sustainability of regional water supplies.

The influence of IWCM is becoming increasingly evident in the Australian landscape and there have been some excellent examples of IWCM applied to challenges of providing water services in the Australian water sector. Five illustrative case studies were provided to demonstrate IWCM strategies that have been investigated, implemented or applied.

Objectives

High level guiding objectives and desired outcomes for the Greater Sydney area were developed in partnership with the Thought Leadership Group. These objectives are also focused on the institutions that influence the future of Greater Sydney with a focus on the importance of water cycle management in the system.

SWC identified a number of key objectives for their Alternative Water Strategy. Each of the overarching objectives state the Alternative Water Strategy should be based on the principles of decentralisation, more sustainable provision of water services, greater integration across water services, and a clear evolution from current thinking and practices.

To enable definition and testing of an alternative water strategy, these overarching objectives were translated into a series of specific principles or targets across the full scope of integrated water service provision.  These objectives are consistent with an IWCM strategy and included minimising mains water demands, discharge of sewage, carbon footprints and costs of the development whilst protecting the environment.

Options and Scenarios

Options enable testing of the physical, technical and commercial performance of the system. Defining a base case (Business as Usual) and an alternative (Ultimate) option enabled the testing, comparison and understanding of the behaviour of the Greater Sydney system.

Scenarios (unlike forecasting) do not seek to predict the future. Scenarios are used to describe the expected time based transitions in the qualitative drivers that also influence the behaviour of the system.  These qualitative drivers create phases of behaviours that will be experienced by any Option. The consequent plausible alternative futures can sensitise our perceptions of reality as it unfolds and provides intellectual “wind tunnels” in which business strategy Options can be tested.

The following options have been established as part of the investigation:

• Option 0: Base Case – Business as Usual. The base case and represents the existing approach of centralised water, wastewater and stormwater management in Greater Sydney. This Option in includes the BASIX policy.
• Option 0.1: BAU with Climate Change. This variation of Option 0 incorporates the impact of a high emissions climate change scenario to understand the resilience of water cycle management to climate change.
• Option 1: Alternative Option (Ultimate). All new developments and redevelopments will form part of precinct scale IWCM strategies. All new buildings would implement sustainable (water, energy and design) building practices, equivalent to Green Star 6 appliances, local rainwater and stormwater harvesting and reuse of wastewater.
• Option 1.1: Ultimate with climate change. This variation of Option 1 incorporates the impact of a high emissions climate change scenario to understand the resilience of water cycle management climate change.

Three alternative scenarios were established:

1. Status Quo – continue with current practice.  SWC does the best they can with current strategies, knowledge and capability.  This scenario is consistent with the BAU Option.
2. Middle Ground – Take advantage of some opportunities but miss out other significant opportunities.  This scenario is a variable combination of the BAU and ULT Options.
3. Aspiration – The only sensible thing to do.  World leader, best practice, innovation and greatest political benefit.  This scenario is consistent with the ULT Option.

Methodology

This study employed an integrated systems approach to analysing the performance of integrated water cycle management Options for Greater Sydney.  The Options were determined to generate understanding of the response of the water cycle systems throughout Greater Sydney to alternative strategies.  This unique analysis is dependent on detailed inputs, such as demographic profiles, and linked systems that accounts for water supply, sewerage, stormwater and environmental considerations.  This section outlines the key assumptions and methods used in this analysis.

Change in cumulative nitrogen loads in stormwater runoff generated by IWCM solutions

Change in greenhouse gas emissions generated by the IWCM solution

In addition, a parallel investigation was undertaken by a highly experienced and skilled group of industry leaders which were our Thought Leadership Group.  This Group provided analysis of all aspects of the SWC and the Greater Sydney region from multiple perspectives, input to the systems analysis, review and interpretation of systems outcomes, and input to the final report.

Conclusions

• It is clear that the considerable ongoing growth of Greater Sydney presents a range of substantial challenges to traditional planning and servicing paradigms.
• This challenging growth also presents compelling opportunities to change the approach to planning and providing water services for the region
• It is likely Sydney will not evolve as a uniform spatial or temporal process.
• This creates considerable uncertainty for the provision of traditional centralised strategies for management of water and sewage.
• The areas likely to experience the greatest growth also currently have the lowest household incomes which will present considerable long term challenges to managing the social structure of the metropolis.
• The increasing movement and accumulation of water, wastewater and stormwater throughout expanding or aging networks of infrastructure is the greatest challenge facing SWC.
• The increasing age and declining capacity and condition of assets is expected to escalate the cost of managing the assets.
• Incremental extension, renewal and amplification or the infrastructure networks to meet these challenges is likely to generate significant diseconomies of scale.
• Water cycle networks throughout Greater Sydney are reliant on significant amounts of energy to transfer water and sewage to locations where gravity can be utilised for distribution or disposal.
• Significant spatial variation exists throughout the Greater Sydney region that cannot be described by the averages and generalisations commonly employed in the water industry.
• Global responses of the Greater Sydney system are driven by a range of decentralised behaviours.
• There is a need for greater understanding of the regimes of water use behaviours throughout the region.
• Regional water security does not equate to spatial water security throughout the region.
• Areas of Sydney with the least water security also have the greatest concentration of rainfall.
• Decentralised systems are not necessarily “stand alone” systems. They represent a smaller system within a larger system that may have infrequent and dimished dependance on the existing system.
• Decentralised IWCM solutions provide a lower cost and greater community value approach to ensuring water security throughout Sydney.
• This study has established that alternative water cycle management is technically, commercially, socially and environmentally viable strategy.
• A holistic decision making framework for provision of services and investment decisions is required to recognise the value of alternatives.
• There must be a transition to an investment economics methodology to drive decisions that focus on operational efficiency.

Change in economic benefits generated by IWCM solutions

Key achievements

The Systems Framework has been used provide water cycle systems performance, strategic and policy advice to the Board of Sydney Water Corporation and the Living Victoria Ministerial Advisory Council. Previously, the Systems Framework was been used to provide analysis of the Lower Hunter, New South Wales Central Coast, the Pimpama Coomera Water Futures project in Queensland, the South East Queensland water supply and water supply system for Perth. A wide range of smaller scale projects have also been investigated using the Systems Framework including the Doncaster Hill, Egate and East Werribee precincts in Melbourne, Hill End, Fern Bay and the Eurobodalla strategies in New South Wales; Ridges and Buderim Escape developments in Queensland, and the Gidgegannup township in Western Australia. The Systems Framework has also been used to motivate and investigate state wide water strategies such as the New South Wales BASIX policy. This involved a systems analysis of the Greater Sydney region and then analysis of twelve water supply districts throughout New South Wales.

Overview

The Systems Framework is substantially different to traditional analysis of water resources in many key areas. The process includes detailed forensic analysis of a wide range of biophysical parameters throughout Greater Melbourne. The Framework is an integrated systems model that has been updated and enhanced for use incorporating the latest results from ongoing independent research into analysis of water cycle systems.^[1] These systems models subdivide a region or city into hierarchies of distributed linked zones that represent opportunities, constraints and feedback loops across multiple scales. Long sequences of spatial climate data were combined with local water use and demographic information across the entire region. Daily time steps are employed to increase the depth of analysis. This process maintains the long term climatic correlation between urban and water supply catchments. This ensures that urban water demands are temporally and spatially consistent with the rainfall and stream flows in water supply catchments. The Systems Framework is substantially different to the current practice of separate derivations of water demands and yields from water resources that utilise monthly or annual assumptions. Importantly, this analysis combines the entire water cycle including water demands, wastewater discharges, stormwater runoff, waterways, energy and the environment at multiple locations throughout a region or city in a single integrated system. This unique process provides a powerful numerical framework that allows understanding of trade-offs, costs and benefits of current and alternative strategies across the entire water cycle. The Systems Framework includes a dynamic financial and economic investment framework. In addition, the Systems Framework includes climate dependent behavioural models of water demands that also respond to a range of socio-economic and demographic drivers. Rather than using average water demands for households with average responses to alternative strategies, the Systems Framework evaluates the temporal and spatial performance of alternatives throughout the system. Analysis using the Systems Framework has also recently completed a similar analysis for Greater Sydney that was subject to comprehensive peer review and feedback.[2] The quasi parallel processes of refining the first principles systems analysis for the water cycles in Greater Sydney and Greater Melbourne has also contributed and enriched the processes underpinning the Systems Framework. The first investigation of alternative water strategies in Melbourne for the Department of Sustainability and Environment (DSE) by Dr. Peter Coombes commenced in 2006.[3] This project combined data from DSE, DPCD and water authorities with a series of workshops to refine the Systems Framework for Greater Melbourne. This process was further underpinned and complemented by analysis of integrated water cycle management (IWCM) Options for new growth areas in the Geelong region.[4] This project included comprehensive engagement with the development industry and local government resulting in further development of the demographic, socioeconomic and economic processes in the systems methodologies. This process was enhanced by interaction with real development issues on a large scale. These activities led to an invitation and subsequent submission to the Victorian Parliament’s Environment and Natural Resources Committee. The submission involved further refinement of the systems analysis to extract more detailed understanding of water resources available within Greater Melbourne and barriers to alternative business models that can facilitate the use of these resources. Methodologies for Systems Framework were extended for the analysis of a wide range of major projects including the Werribee Employment Precinct [5], Doncaster Hill [6] and Egate. This knowledge assisted with the development of alternative water policy for Greater Melbourne and was combined in the provision of systems analysis and advice for the Living Victoria Ministerial Advisory Council. The process involved a cycle of feedback with the MAC and a range of stakeholders.

Overview of the Systems Framework

This section provides an essential overview of the historical development of the Systems Framework and a range of existing key inputs. It is important construct the systems analysis from the basic elements (the local scale inputs) that drive system behaviours. It is also critical to understand and account for first principles transactions within the system to allow simulation of spatial and temporal performance of the system. This allows simulation of the response of the system to perturbations such as analysis of Options and Scenarios. Biophysical systems in a region are constructed using three basic components: Sources –  Regional and local water sources, catchments and waterways Flux – transport and treatment of water, sewage and stormwater throughout the region Sinks – Stormwater runoff and wastewater disposal to waterways The fundamental construct of this novel approach is outlined in the following Figure.

The framework for analysis of the Systems Framework was compiled from the lot scale to regional scale as presented in the Figure below.

This Figure shows the foundation principle used as the basis of the Systems Framework, namely that the overall system is driven upwards by demands at the lot scale (including water, sewage, stormwater and environmental demands or discharges).  Further, it shows that these demands require both movement of water (fluxes) from a range of sources and disposal of water (such as sewage and stormwater) to a range of sinks. An overview of the methods used to implement this upwards focussed analysis framework is presented in the following Figure.

The above Figures highlight the elements that were incorporated at different scales in the Systems Framework. This includes water use and demographics at the local scale, distribution infrastructure and information at the sub-regional or local government scale (the middle scale), and regional behaviours or infrastructure such as water extractions from and discharges of sewage to wastewater treatment plants. This process can be described as analysis of systems within systems across multiple scales. Our unique biophysical and scale transition framework links the dynamics of the systems with inputs across scales and time. The analysis is anchored by a regional framework of key trunk infrastructure, demand nodes, discharge points, waterways and regional sources of water in a network model. Major water distribution, stormwater, sewage, demographic, climate and topographic zones are combined in this part of the framework. This process compiles inputs from a wide range of commonly utilised analysis tools, including for local water demands and water balances and hydrology.  Key simulation inputs to this framework include:

• Demographic data from the Australia Bureau of Statistics and State Government departments
• Climate data from the Bureau of Meteorology and streamflow data from the state government and water utilities.
• Water and sewage flows sourced from water utilities.
• Local and cluster scale inputs simulated using the PURRS model at 6 minute timesteps using long climate records.
• Urban areas and local government areas analysed using a range of water balance and quality models. These smaller scale systems are also analysed in more detailed network models.
• The biophysical and scale transition model compiles inputs from local water balances into the zones based on statistical local areas and calibrates to observed data from water, stormwater and sewage catchments.
• The network model was used to collate and simulate all inputs across the entire region
• The Dynamic Economic Framework compiles all systems outputs and simulates the cascading financial transactions throughout the entire system.

This framework incorporates the movement of water throughout the region and connectivity to the water supply headworks system. Similarly, the framework includes the movement of sewage throughout the region and connectivity with discharge points or reuse systems. It includes stormwater catchments, conveyance systems and urban streams. Importantly, the framework shown in the above Figures is driven by long sequences of spatially and temporally consistent input data that captures the spatial and temporal variation in climate (rainfall, temperature and frequency of rainfall), demographics, water demands and water management strategies across any region. This ensures that the impact of the considerable spatial and temporal variation and connectivity across a region is robustly incorporated in the framework leading to accurate understanding of internal and external augmentation requirements. Clearly a region does not respond “on average” and this process captures the dynamics of feedback loops from sources to sinks throughout the region. This is a contrast to traditional analysis that assumes that the system response is top down in response to spatial or temporal averages. For example, this framework provides comprehensive systems understanding of the dynamics of sewage discharges, including interaction with stormwater systems, to sewage treatment plants and the impact of reusing treated effluent from the contributing sewage catchments. It promotes an understanding of the changes in sewage flows, demands for recycled water and requirement for reuse infrastructure throughout the region with the consequent changes in distribution of water from external sources (such as desalination and the north south pipeline throughout the Greater Melbourne region). This allows understanding of the changed energy profiles, the extent of reuse required and the operating costs of any strategy. In addition, this connectivity allows understanding of the regional water security and resilience to climate change provided by an alternative Options – a proportion of a city’s water security will be provided by internal sources. Wherever possible the analysis incorporates first principles information and sequences of inputs rather than averages.  Smaller scale inputs to the regional framework involve more detailed analysis of residential, commercial, industrial and agricultural areas. This analysis includes the dynamic inputs of local infrastructure and building form to the regional framework. Details of the analysis, extractions from the data and modelling process have been provided throughout this Section to assist with understanding the processes used in the Systems Framework. Household water consumption was selected in this study as representing base water use behaviours for a region during a period relatively free of water restrictions. These water demands were then modified by a range of processes including adoption of water efficient appliances in some houses, connection to wastewater reuse systems and changes in demographics.