DRAFT TOTAL WATERMARK – CITY AS A CATCHMENTENVIRONMENT COMMITTEE REPORT Agenda Item 5.4 8 July 08 DRAFT TOTAL WATERMARK – CITY AS A CATCHMENT Division Sustainability and Regulatory

E N V I R O N M E N T C O M M I T T E E R E P O R T Agenda Item 5.4 8 July 08

DRAFT TOTAL WATERMARK – CITY AS A CATCHMENT

Division Sustainability and Regulatory Services

Presenter David Mayes, Manager, Strategic Planning and Sustainability

Purpose

1. To provide the Environment Committee the draft of the Total Watermark - City as a Catchment strategy (at Attachment 1) and to seek endorsement for the draft to be released for consultation.

Recommendation from Management

2. That the Environment Committee:

2.1. endorse the release of the draft Total Watermark - City as a Catchment for public consultation; and

2.2. note the proposed consultation process.

Background

3. The City of Melbourne has been implementing a progressive sustainable water management program since 2002. This includes a range of initiatives around water saving, and stormwater, wastewater and groundwater management. This work has been guided by Council’s current water policy Total Watermark April 2004.

4. Total Watermark - City as a Catchment has evolved from the work of the City of Melbourne’s Sustainable Water Use Reference Group chaired by Cr Fraser Brindley. This reference group has senior membership from Melbourne Water, City West Water, South East Water, Plumbing Industry Commission, Department of Sustainability and Environment, Monash University, University of Melbourne and Edaw Consulting.

5. Total Watermark - City as a Catchment will update the conceptual framework of Total Watermark as Council’s overarching sustainable water management policy. This update integrates water saving, stormwater management, wastewater and groundwater. The primary tool for implementing sustainable water management on the ground is known as water sensitive urban design (WSUD).

6. Using the city-as-a-catchment concept, new sustainable water management targets have been developed for Council and the municipality. These targets include the stormwater quality targets, which were endorsed by the Environment Committee on 6 May 2008.

7. Total Watermark - City as a Catchment philosophies and targets will be incorporated into the City of Melbourne’s future water action plans for parks, streetscapes and drainage infrastructure.

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Key Issues

8. The City of Melbourne is applying a ‘city as a catchment’ model to the municipality so that it moves towards a comprehensively managed, single urban water system. This includes rainfall on roads, roofs, footpaths, parks, waterways, evaporation and the reticulated supply to optimise the use of water and improve stormwater quality.

9. This model identifies the natural and reticulated water flows and the pollutants being carried with these flows; how to optimise the use of water resources; new opportunities to source water with greater emphasis on stormwater harvesting for re-use and improved runoff quality. A diagram outlining this is at Attachment 2.

Relation to Council Policy

10. Total Watermark - City as a Catchment will update the conceptual framework of Total Watermark April 2004 as Council’s overarching sustainable water management policy.

11. Total Watermark - City as a Catchment is consistent with City Plan 2010 and key elements of the draft strategy are currently included as “The City as a Catchment” in the Eco City goal of the consultation draft of the Future Melbourne plan.

12. This report is one of three environmental policies that are currently being finalised, the other two are: and Climate Change Adaptation Strategy, which focuses on the management of climate change risks; and Zero Net Emission Update 2008, which focuses on reducing climate change emissions within the municipality.

Consultation

13. The proposed public consultation will commence early July 2008 and finish early August 2008. This will allow the finalised report to be presented for consideration at the September Environment Committee meeting. The scope of the consultation includes:

13.1. directly seeking comments from internal and external stakeholders. A full list of external stakeholders is at Attachment 3;

13.2. making the draft available through the City of Melbourne website and Frontline;

13.3. a notice seeking public comment/submission will be published in Melbourne News, the Green Leaflet (electronic), Melbourne Weekly, and the Leader Newspaper; and

13.4. key elements of the draft strategy are currently included as “The City as a Catchment” in the Eco City goal of the consultation draft Future Melbourne.

Government Relations

14. State Government has been involved in and very supportive of the City of Melbourne’s leadership and initiative in developing Total Watermark - City as a Catchment.

Finance

15. Total Watermark - City as a Catchment is a new approach and will inform planning and priority setting of future capital works. Estimations of the annual costs of implementing the WSUD infrastructure measures of the policy are between $616,000 - $770,000 per year. This cost is almost all covered by Melbourne Water until 2009, with continued budget support from Melbourne Water for the three years following. This cost was reported to the Environment Committee’s 6 May 2008 meeting.

16. There are no direct financial implications arising from the recommendations in this report.

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Attachments: 1. Draft of Total Watermark – City as a Catchment 2. Diagram 3. List of external stakeholders

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Legal

17. No direct legal issues arise from the recommendation made in the report.

Sustainability

18. The proposal has a significant positive impact on sustainability by providing for:

18.1. greater water saving across the municipality;

18.2. greater water quality works across the municipality;

18.3. climate adaptation and greenhouse management of water issues; and

18.4. improved biodiversity and habitat implications.

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Attachment 1 Agenda Item 5.4

Environment Committee 8 July 2008

Total Watermark – City as a Catchment Draft for Comment

Table of contents 1. Introduction ................................................................................................................3 2. Background ................................................................................................................4 3. The basis for city as a catchment .............................................................................6 4. Framework for A Water sensitive city: A Strategy for Resilience.........................8

4.1 Access to a diversity of water sources .........................................................................9 4.2 Provision of ecosystem services for the built and natural environment ......................11 4.3 Community Engagement for sustainability .................................................................11

5. City of Melbourne: a water sensitive city ...............................................................12 5.1 Water balance for the City of Melbourne ....................................................................13 5.2 Pollutant budget for the City of melbourne .................................................................17 5.3 Water cycle management targets for the City of Melbourne.......................................18 Water Saving Targets........................................................................................................18 Alternative Water Use Targets ..........................................................................................19 Stormwater Quality Improvement Targets .........................................................................20 Wastewater Reduction Targets .........................................................................................21 Groundwater......................................................................................................................21 General..............................................................................................................................21

6. Current Status of Sustainable Urban Water Management Practices ...................22 6.1 Linking water quality and water conservation.............................................................23

7. Developing a Strategy for Resilience .....................................................................24 7.1 Implementation hierarchy ...........................................................................................24 7.2 Achieving 2020 interim targets across the municipality ..............................................26

References ..............................................................................................................................27 Appendix 1 ..............................................................................................................................28 stormwater pollutant load data .............................................................................................28 Appendix 2 ..............................................................................................................................29 Source of information to calculate water balance and pollutant loads .............................29 Appendix 3 ..............................................................................................................................30 Detailed spreadsheet of current WSUD project benefits ....................................................30

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Appendix 4 ..............................................................................................................................31 Example of future WSUD projects required to attain 2020 targets ....................................31 Attachment 1...........................................................................................................................32 Example Implementation Plan city as a catchment - parks ...............................................32

7.3 Framework for conserving potable water across parks and gardens .........................35 7.3.1 ..............................................................................................Policy context 35 7.3.2 ................................................Water conservation target for parks and gardens 35 7.3.3 ............................................................................................... Model set up 36 7.3.4 .............................................. Treatment requirements for harvested stormwater 36 7.3.5 ......................................................................................... Diversion options 37 7.4 Case study – Kings Domain .......................................................................................38 7.4.1 ................................................................................Harvesting opportunities 39 7.4.2 ................................................................................... Storage requirements 39 7.5 Case study – Fawkner Park .......................................................................................44 7.5.1 ................................................................................Harvesting opportunities 44 7.5.2 ................................................................................... Storage requirements 45 7.6 Case study – Yarra Park ............................................................................................49 7.6.1 ................................................................................Harvesting opportunities 50 7.6.2 ................................................................................... Storage requirements 50 7.7 Case study – Fitzroy Gardens....................................................................................54 7.7.1 ................................................................................Harvesting opportunities 54 7.7.2 ................................................................................... Storage requirements 55 7.8 Case study – Flagstaff Gardens.................................................................................59 7.8.1 ................................................................................Harvesting opportunities 60 7.8.2 ................................................................................... Storage requirements 60 7.9 Case study – Treasury Gardens ................................................................................64 7.9.1 ................................................................................Harvesting opportunities 65 7.9.2 ................................................................................... Storage requirements 66 7.10 Case study – Alexandra Gardens ..............................................................................68 7.10.1...............................................................................Harvesting opportunities 69 7.10.2.................................................................................. Storage requirements 70 7.11 Case study – Victoria Parade.....................................................................................73 7.11.1...............................................................................Harvesting opportunities 73 7.11.2.................................................................................. Storage requirements 73

This report has been developed based on a report issued to council titled ‘City as a Catchment: A Strategy for Adaptation, Report prepared for the City of Melbourne, by EDAW’s Ecological Engineering Practice Area

.

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C i t y a s a C a t c h m e n t 3

1 1. INTRODUCTION

Total Water Management in the City of Melbourne

Total water cycle management has been practiced by City of Melbourne since 2002 supported by the adoption of the Total Watermark policy in 2004 and the Water Sensitive Urban Design (WSUD) Guidelines in 2005.

Total Watermark is currently being revised by setting it within a city as a catchment philosophy. Public feedback on this report will help to determine Council’s progression of the Total Watermark policy.

This report deals specifically with the concept of introducing the city as a catchment approach to the City of Melbourne. Viewing the city as a catchment enables water management decisions to be understood in terms of the overall contribution to achieving water management targets across a municipality.

What is ‘city as a catchment’?

City as a catchment is a fundamental principle of a water sensitive city. It recognises the important role of the natural catchment but works primarily with the artificial city catchment (including its roads, roofs, impermeable surfaces) to minimise mains water consumption, minimise wastewater generation and reduce the impact of stormwater discharges on receiving waters.

The city as a catchment approach minimises importing potable water, and exporting of wastewater, from and to areas outside of the boundaries of the city, and instead optimises the use of water resources within a city.

Demand management practices and harvesting alternative water supplies is crucial to achieving more sustainable water management practices.

Understanding the quantity and location of water flowing through the municipality, and the pollutants being carried with these flows helps local government to initiate and assess sustainable water management projects. Sites across the city can be categorised as a ‘source' (eg: sites that can harvest stormwater such as a road, or harvest rainwater such as a building with large roof) or a ‘sink' (eg: large water-using business or park). Links can then be made between these sources and sinks that takes into account the water flow through the municipality and the pollutants it is picking up along the way. This is also known as ‘closing the water cycle loop’.

The interactions between supply, stormwater quality and quantity, wastewater quality and quantity, land use, climate, social capital and the receiving waterways (rivers and bays) are explored.

Applying the city as a catchment philosophy to the City of Melbourne’s management of water is an adaptation strategy done in response to climate change. It provides a basis for moving towards an informed city as an ecosystem approach that encompasses greenhouse mitigation and habitat protection and stretches beyond single municipal boundaries.

Where to from here?

The City of Melbourne is seeking public feedback on the concept of applying the city as a catchment approach to its sustainable water management.

Once adopted, Council can then implement and encourage parks planning, roads maintenance, building and construction practices to better provide for water saving, water harvesting and improving water quality and the health of our waterways. An example of parks planning using the city as a catchment philosophy is shown in the parks scenario’s outlined in Attachment 1 of this report.

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2 2. BACKGROUND

What has City of Melbourne already achieved in sustainable water management?

Total Watermark 2004 introduced the City of Melbourne’s commitment to sustainable urban water management covering the total water cycle including water supply, stormwater, wastewater and groundwater.

This was followed in 2005 with the release of the WSUD Guidelines which provide staff and the broader industry with guiding principles, case studies and fact sheets demonstrating how sustainable water management practices can be integrated into a range of urban landscapes.

Additional policy and guideline commitment for sustainable water management includes:

Construction Management Guidelines setting out Council’s best practice requirements for stormwater management procedures on development sites. It also provides requirements that can be transferred into contracts for city development including in parks.

Greening Your Building Toolkit has been established to help facilities managers to save water, energy and waste.

Corporate Reporting of water consumption and stormwater quality improvement (reduction in total suspended solids reaching our waterways)

Environment Local Law addressing waste, stormwater, and noise management.

Since 2002, the City of Melbourne has been saving water whilst meeting additional sustainable water objectives, including:

finding ways to save mains water through efficiency, design and behaviour changes;

minimising wastewater disposal to sewer through demand management, and recycling where practicable;

treating stormwater to meet water quality objectives for harvesting and reuse and/or discharge to waterways;

protecting groundwater from contaminants and disruption; and

managing catchment hydrology, particularly for aquatic habitats.

In addition to this, the City of Melbourne is committed to advocating for logging to cease in the water catchments in order to increase water harvesting and supply opportunities into our mains water system.

This report does not set out the detail of the water management projects undertaken to date, as this will be provided in a forthcoming review of Total Watermark. The report does however set out the positive progress of Council in achieving its targets for water saving and water quality (Section 5.3 of this report).

Why is the City of Melbourne improving its water management approach?

Total Watermark (2004) outlines the City of Melbourne’s water policy and is being updated to incorporate the outcomes of this report. The proposed city as a catchment approach provides a holistic understanding of the integrated benefits of sustainable water management practices across aspects of the urban water cycle. In terms of stormwater management it provides a greater emphasis on harvesting stormwater as an alternative water supply with benefits associated with mains water conservation and reductions in pollutant loads discharged to receiving waters.

With rapid progress in the WSUD field, it is now considered necessary to update the WSUD Guidelines with city as a catchment work along with the need to introduce new examples of design, technology, environmental and risk management. The WSUD Guidelines are expected to be completed by September 2008 and applied across the Inner Melbourne Action Plan (IMAP) area incorporating the Cities of Melbourne, Port Phillip, Yarra and Stonnington.

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To date, water conservation and stormwater quality improvements are driven out of separate water management programs at both the state and local government level. Better accounting is needed of the multiple benefits that are achieved across programs and across the urban water cycle.

City as a catchment is a climate adaptation strategy that outlines multiple sustainable water management targets enabling the inherent benefits across all streams of the urban water cycle to be realised. It also provides a basis for the development of implementation plans that clearly demonstrates how selection of on-ground works and local government reforms relate to water conservation, best practice stormwater quality improvement and/or wastewater minimisation.

How does the City of Melbourne work with its stakeholders?

The City of Melbourne joins with a range of stakeholder to deliver its sustainable water management program. This includes, but is not limited to, partnerships with:

• Inner Melbourne Action Plan (IMAP) which is working on three projects related to water management. Action 9.1 is addressing consistency of environmental targets across the IMAP Councils, Action 9.3 is addressing consistent guidelines and local policies for implementing WSUD, and Action 9.6 is addressing water management in parks including irrigation efficiency and alternative water solutions.

• the Lower Yarra Stormwater Quality Improvement Program with Melbourne Water which provides assistance and funding to deliver WSUD project in the ground.

• ICLEI Water Campaign and has currently achieved Milestone 4 in Community Water Use and Milestone 3 in Corporate Water Use. This means that Council have met the policy and planning components of the ICLEI Water Campaign and are currently working through the documentation of water savings and water quality improvements.

• the Lower Yarra Litter Strategy program with four Councils, Melbourne Water and Sustainability Victoria to deliver litter reduction projects.

• the Yarra River Investigations and Response Program with EPA to assist and fund stormwater pollution improvement projects.

• Clinton Climate Initiatives to deliver building retrofit works for Council buildings for water, energy and waste.

• City of Melbourne has its own Sustainable Water Use Reference Group chaired by Cr Brindley to pursue sustainable water management projects in parks, business and across the community. Partners include City West Water, South East Water, and the Plumbing Industry Commission.

The City of Melbourne also manages the following regulatory water commitments:

• Water Management Plans: In 2006 with the introduction of water restrictions, the City of Melbourne was required to submit a Water Management Plan for each of its sporting fields.

• WaterMAPS: In mid-2007, the State Government introduced a mandatory requirement that all sites using more than 10 ML/yr of water needed to submit a water action plan (known as a WaterMap) to their water retailer. The City of Melbourne submitted WaterMaps for its large gardens and for Town Hall.

• Environment Resource Efficiency Plans: At the end of 2007, the State Government introduced mandatory requirements for organisations to undertake an Environment Resource Efficiency Plan covering water, waste and energy management for any site that exceeds either 120 ML of water or 100 TJ of energy. No sites in the City of Melbourne trigger the requirement for an EREP.

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3 3. THE BASIS FOR CITY AS A CATCHMENT

In a time of drought, climate change and population growth, it is necessary for urban communities to incorporate design strategies that provide resilience to future uncertainty.

In earlier days, it was an urban challenge to provide piped water, sewerage services and flood mitigation. These remain challenges today, but can be managed in ways that also ensures that water can be reused where possible, and waterways are protected from run-off pollution.

Moving towards a ‘water sensitive city’ (Figure 1) can provide solutions for water management.

Figure 1 Urban water management transition framework: water supply city to water sensitive city (Brown et al. 2008)

A traditional water supply city is based on a single centralised infrastructure which provides limited flexibility for water management and reuse in times of changing climate.

The framework for a water sensitive city focuses on the links within and between the urban water cycle, built form and landscape, and organisational and community values.

This approach uses diverse infrastructure associated with the harvesting, treatment, storage and delivery of the water sources of both centralised and decentralised water supply schemes. Any stormwater or wastewater not harvested is treated prior to discharge to the environment.

This mixes water management infrastructure with the reintroduction of waterways back into the urban landscape and promoting new forms of urban design and architecture within the built environment.

For local government this means demonstrating full commitment to sustainable water management by implementing WSUD across all their assets (including parks and gardens, building and roads). Local government influence must extend beyond adoption within the public domain, through education, incentives, partnerships and regulation to facilitate the uptake of WSUD in the private domain (including commercial and residential sites).

The City of Melbourne is a recognised leader in the application of WSUD, relying to date on demonstrative, opportunistic and ad-hoc implementation for its early projects. Committing to the principle of city as a catchment provides a more strategic approach to implementing sustainable water management practices into the urban landscape. This will strengthen organisational commitment that will facilitate the rollout across Council land and buildings, residential and commercial/industrial sectors of the community.

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How is climate change likely to impact on water management in the City of Melbourne? Victoria is expected to become drier with annual average rainfall decreasing by 2-4% by 2030 with most of the decrease expected in Spring (5-11% by 2030). The projected decrease in rainfall and more evaporation, along with warmer temperatures, is likely to increase drought risk and severity1.

By 2030, the decline in annual rainfall and higher evaporation is expected to cause less run-off into rivers. For Melbourne, average stream flow is likely to drop 3-11% by 2020 and 7-35% by 20502.

One of the major impacts of the rainfall decline in southern and eastern Australia has already been a reduction in surface water available in our centralised water catchments. Victoria has experienced a 20% rainfall decrease since the mid 1990’s, translating into an inflow reduction of about 40%3. Without new alternative sources of supply these reductions in water storage pose a large threat to the water security of the City.

Table 1: Projected seasonal changes (%) in Melbourne rainfall

Even though the overall rainfall for Victoria is expected to decrease extreme rainfall events are projected to increase. The future precipitation regime will have longer dry spells interrupted by heavier precipitation events4.

By 2050, higher sea-levels and more intense storms, coupled with increased storm surge heights of approximately 20%, will greatly expand the area likely to be inundated by storm events. Modeling indicated that most of this height increase was due to sea-level rise, with a small fraction due to wind speed increase5.

Increased storm intensity and longer dry spells need to be considered as part of the City of Melbourne’s on-going commitment to sustainable water management. It is important that water sensitive urban design works that are used to meet sustainable water management goals take into account the impact of climate change.

1 CSIRO, 2007b 2 CSIRO, 2007b 3 CSIRO, 2007b 4 CSIRO, 2007b 5 CSIRO, 2007b

2030 Low 2030 High 2070 Low 2070 High

Summer 0 to -5% -5 to -10% -5 to -10% -20 to -30%

Autumn 0 to -5% 0 to -5% 0 to -5% -5 to -10%

Winter 0 to -5% 0 to -5% 0 to -5% -10 to -20%

Spring -5 to -10% -10 to -20% -10 to -20% -30 to -40%

Average seasonal changes (%) in Melbourne rainfall for 2030 and 2070 relative to 1990, for the CCAM Mark 2 Model (CSIRO 2007).

Table 2: Percent change in average intensity of 1-in-40 year rainfall in South Central Victoria.

DJF MAM JJA SON SON ANN

2030 2070 2030 2070 2030 2070 2030 2070 2030 2070 2030 2070

+12% +11% = +28% -4% -18% -4% = -4% -18% -10% -1%

CCAM (Mark 2) percent changes in average intensity of 1-in-40 year rainfall in South Central Victoria, relative to the average simulated for 1961-2000. (ANN = Annual; DJF = December, January, February; MAM = March, April, May; JJA = June, July, August; SON = September, October, November) (CSIRO 2007).

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44. FRAMEWORK FOR A WATER SENSITIVE CITY:

A STRATEGY FOR RESILIENCE

Water sensitive city aims to implement best practice water sensitive urban design techniques to conserve, reuse and recycle water, and manage the quality of stormwater run-off. Water sensitive city provides a framework of adaptation for climate change by responding to varying water supply opportunities. Risks and opportunities for water management need to be considered on the basis of infrastructure renewal, climate change impacts, urban consolidation and population growth.

What is the national context for implementing a Water Sensitive City?

The National Water Initiative (NWI), which is the national water reform framework for Australia, commits all states and territories to innovation and capacity building to create Water Sensitive Australian Cities.6 While the attributes of a water sensitive city are not stipulated in the NWI, leading thinking and research in the area of best practice urban water management sets out the following fundamental principles that would underpin a water sensitive city. They are:

1. Intergenerational equity – communities and their governments will understand and agree that current development must not compromise the ability of future generations to enjoy secure water supplies and healthy natural water environments.

2. Triple bottom line approach – government and urban water managers will measure the ‘value’ of water and water services in social, environmental and economic terms rather than financial ‘cost’.

3. Integrated approach – water resources including water supply, sewerage and stormwater services will be managed as part of a total water cycle. Government and urban water managers will choose to invest in water supply and sewerage options that are beneficial to waterway and ecological health, and community wellbeing. Outcomes will also be understood to be part of a larger nutrient and energy cycle and urban water managers will choose water sources that do not produce excessive greenhouse gases or nutrient discharges.

4. Diverse water sources – government and urban water managers will invest in a diversity of water sources underpinned by a range of centralised and decentralised infrastructure providing cities with the flexibility to access a ‘portfolio’ of water sources at least cost and with least impact on rural and environmental water needs.

5. City as a catchment – government and urban water managers will minimize importing potable water, and exporting of wastewater, from and to areas outside of the boundaries of the city, and will instead optimize the use of water resources within a city in a ‘fit-for-purpose’ capacity. A water sensitive city will be viewed as a catchment where stormwater and treated wastewater are important water sources.

6. Ecosystem services – waterways will be valued as an integral part of the city, and ecological health will be actively protected. Water managers will recognise that healthy ecosystems and waterways provide important ecosystem services that make the city more liveable and mitigate the impact of a city on the environmental values of aquatic systems within and downstream of the city.

7. Resilience to climate change and variability – diverse water sources will ensure that the city can adapt to both water-scarce and water-abundant conditions. Because waterways will be protected, these will also be resilient, helping to provide amenity for the community. WSUD will also provide micro-climate benefits and act as heat sinks which will be particularly important under projected global warming conditions and the extreme variability of Australia’s climate and stream flows.

8. Social capital – a smart, sophisticated and engaged community, living and engaging in a sustainable lifestyle that is sensitive to the inter-dependent nature of the built and natural environments. Social capital will extend to the professionals and practitioners in the water sector.

9. Business case – governments, businesses and the private sector will have the institutional and economic incentives to invest in sustainable solutions.

What are the main steps to implementing a Water Sensitive City?

6 Clause 92

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Three attributes are considered fundamental to implement into the urban environment of the water sensitive city7. These are described in detail below, and include: 1. access to a diversity of water sources (both centralised and decentralised); 2. provision of ecosystem services for the built and natural environment; and 3. socio-political capital for sustainability (which we have called Community Engagement).

4.1 ACCESS TO A DIVERSITY OF WATER SOURCES

Drinking water from the tap is provided to a very high quality in Melbourne. This service is reliant on stormwater runoff in catchment areas and is vulnerable to drought and climate change.

To reduce the vulnerability of water supply cities need to reduce their demand, and source their water in various ways8, including consideration of:

rainwater harvesting from roofs; stormwater harvesting from roads, footpaths, gardens and other open space; water recycling, including:

- greywater recycling at the household and business scale - blackwater recycling (including water/sewer mining) with small scale treatment plants - large scale use of recycled water for industrial/commercial purposes - precinct recycling with “third pipe” supply of recycled water to households

use of groundwater where available; pipelines and interlining grids between water storages at large and medium scales; desalination of water at a large or medium scale; injection of purified water back into the drinking water supply via water recycling or desalination aquifer storage and recovery combined with water harvesting or water recycling.

Not all of the above solutions are suitable for sites in the City of Melbourne because of geography, geology, topography and wider environmental concerns. A hierarchy of sustainable water management solutions best suited for the City of Melbourne is set out in Section 5.1 of this report.

7 Wong and Brown (2008) 8 Prime Minister’s Science, Engineering and Innovation Council

What is ‘fit –for-purpose’ water use?

Qua

lity

of a

ltern

ativ

e w

ater

so

urce

Quality of water required for urban demands

High

Low

Mains drinking water

LowHigh

Wastewater

Stormwater runoff

Rainwater runoff (roof)

Water cascade

Catchment runoff

Greywater

Hot water system

Shower & bathroom taps

Clothes washing

Toilet flushing

Garden irrigation

Human consumption -kitchen

Irrigation of sporting facilities & parks

Qua

lity

of a

ltern

ativ

e w

ater

so

urce

Quality of water required for urban demands

High

Low

Mains drinking water

LowHigh

Wastewater

Stormwater runoff

Rainwater runoff (roof)

Water cascade

Catchment runoff

Greywater

Hot water system

Shower & bathroom taps

Clothes washing

Toilet flushing

Garden irrigation

Human consumption -kitchen

Irrigation of sporting facilities & parks

Figure 2 Consideration of cascading quality in defining preferred demands for alterative water sources (modified after Holt, 2003) The concept of ‘fit-for-purpose’ water use helps to prioritise alternative water sources to different water demands based on a cascading range in quality (as shown in Figure 2). With the exception of wastewater, the closer the match in quality of the source and demand the less treatment required (and generally the less energy intensive most cost efficient). If the preferred source-demand arrangement is not viable then consider other combinations in the context of local site conditions.

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C i t y a s a C a t c h m e n t 1 0

Table 3 Advantages and challenges associated with alternative water sources in the City of Melbourne

Water source Advantages Challenges Recommendations

Mains water Inexpensive supply (because externalities remain unaccounted for and supply was heavily subsidised by government in its establishment phase)

Existing infrastructure is accessible and regulations/approval process are well understood

Reliant on single source of supply that is venerable to drought

Population growth and urban consolidation across the City of Melbourne, and beyond, are placing greater pressure on mains supply

Climate change will result in less runoff due to higher temperatures and lower soil moisture levels (irrespective of rainfall conditions)

No ecological protection 1. issues associated with

environmental flows downstream of water supply reservoirs, and

2. no means to reduce stormwater or wastewater discharges to the environment

Demand management to reduce water use

Harvest alternative sources of water to conserve mains water

Roof runoff

Multiple water cycle benefits (mains water conservation and reducing stormwater volumes and pollutant loads discharged to the environment )

Minimal treatment required as roof runoff is considerably cleaner than other alternative sources of supply

Provides resilience to climate change

Volume of supply to meet competing demands

Reliability of supply Potentially higher pollutant

concentrations conveyed to receiving waters from other landuse practices across catchment because runoff is not diluted with cleaner roof runoff (treatment of stormwater quality from sources, such as roads, is important to counteract this potential issue)

Decentralised system requiring minimal infrastructure and maintenance. Greatest water conservation and ecosystem protection benefits achieved when used for indoor demands such as toilet flushing and/or hot water

Also viable for other purposes such as garden irrigation when other sources are not a practicable supply option

Stormwater runoff

Multiple water cycle benefits (drinking water conservation and minimising stormwater discharge to the environment thereby reduce pollutant loads to receiving waters)


Reliability of supply Land uptake for treatment and storage

requirements in confined spaces

Decentralised system – preference is to supplement open space irrigation. Water not harvested should be treated to improve water quality and manage flows prior to discharge to receiving waters

Provides landscaping and aesthetic values

Wastewater

Multiple water cycle benefits (water conservation and minimising wastewater discharges to receiving waters)


Constant supply

High energy expenditure for treatment to meet end use water quality requirements

Limit direct pathway for ingestion to minimise health risk

Storage requirements if supply-demand profile does not match

Possible increase in salt and nutrient levels in supply, irrigation rates need to be well managed to ensure excess runoff does not enter waterways and impact ecological health

Broader sustainability impacts should be considered (such as, energy) especially if treatment facility is not currently available

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4.2 PROVISION OF ECOSYSTEM SERVICES FOR THE BUILT AND NATURAL ENVIRONMENT

Landscapes are the product of natural (ecological landscapes) or built forms. The water sensitive city recognises the ecological landscapes are bound by built landscapes including roads, roofs, impermeable surfaces, etc. Ecological and built landscapes are not static but shaped by local microclimates interacting within a regional and global ecosystem. At the local scale, landscapes can be categorised as a ‘source’ (eg: sites that can harvest stormwater such as a road, or harvest rainwater such as a building with large roof) or a ‘sink’ (eg: parks, sporting fields or large water-using business). Water cycle links can be made between these landscapes. The design of these landscapes may encompass the perspectives of nature conservancy through to creating urban ecologies, all of which are dependant on sustainable water management practices to ensure their longevity. Three broad functioning themes are defined by Wong (2007) to help characterise design objectives, distinguished by the degree of urban density and complexity. They are:

Nature Conservancy – conserving and protecting biodiversity in flora and fauna across terrestrial and aquatic environments;

Natural/Urban Interface –managing the urban/natural environment interface, protecting areas of significant conservation value, and mitigation and rehabilitation of environmental impacts associated with catchment urbanisation. The focus is the transitioning of natural environments into a more complex and balanced landscape of natural and created features that provide enhanced physical, biological and social outcomes; and

Urban Ecology – urban design where the role of bio-mimicry in promoting ecosystem services is actively integrated into the urban landscape. Natural features, built landscapes, art and science all influence the design of the urban landscape.

The City of Melbourne recognises the biodiversity value of water sensitive urban design features in the urban environment. To further enhance this, WSUD works will seek to provide diverse planting to support local biodiversity.

4.3 COMMUNITY ENGAGEMENT FOR SUSTAINABILITY

Organisational commitment and community acceptance for WSUD is fundamental to implement and improve Council’s capacity to deliver city as a catchment as a guiding principle within a water sensitive city.

Local government and communities play an increasingly important role in moving sustainable urban water management practices into mainstream practice. Projects should be led by local government and involve community participatory action models, including scenario workshops for jointly envisaging sustainable water futures, and different types of community-based deliberative forums designed to deliver jointly developed strategies and local WSUD plans. This will provide the greatest chance of gaining community ownership for WSUD projects undertaken on their allotment and in their streetscapes, open spaces and neighbourhoods.

The mainstream uptake of WSUD requires behaviour changes and uptake of the principles and practices of sustainable urban water management practices across the private domain. For this to occur Council must empower the community to get involved and collectively contribute to reducing demands on potable water supplies and protecting downstream environments through minimising the generation of wastewater and stormwater.

Investment must be directed at translating good scientific water cycle management insights into raising community awareness of the issues and WSUD solutions. This creates confidence across the community that the challenges and opportunities to the decentralization of infrastructure will provide safe, reliable and cost effective solutions that have enhanced environmental and social outcomes.

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5 5. CITY OF MELBOURNE: A WATER SENSITIVE CITY

The City of Melbourne is located at the bottom of the Port Phillip Bay catchment and is home to three important waterways; the Yarra River, Maribyrnong River and Moonee Ponds Creek. They all provide important habitat, aesthetic, recreational, tourism and economic value to industry and the broader community. The area of land within the municipality is 3244 ha (3650 ha of waterways are included such as Victoria Harbour, Yarra River, etc).

By identifying the movement of water, expressed as a water balance, through the City of Melbourne municipality it is possible to better implement sustainable urban water management. Council can act immediately on land and buildings they own and could have a profound influence over private practices (commercial and residential) through education, policy reform, fiscal incentives and enforcement.

The remainder of this section presents the City of Melbourne water balance and pollutant budget. Information on water demands, mains water supply, wastewater, groundwater, water conservation and stormwater treatment was sourced from a variety of documents and databases as listed in Appendix 1.

What is a ‘water balance’?

A water balance assesses the movement and transformation of water including potable water to sewer, how much water is used as irrigation and lost as evapo-transpiration or to groundwater, and wastewater generation. The water balance helps to understand the amount of water needed on a site, and the alternative water sources that are available to help meet this need.

Figure: Water balance schematic for a site.

This water balance is then considered in the context of opportunities to minimise importing mains water through demand management, by implementing stormwater harvesting and water quality improvement through applications of Water Sensitive Urban Design in a ‘fit for purpose’ capacity. The minimisation of wastewater is also considered.

Under the city as a catchment approach, a ‘stormwater pollution budget’ can also be developed by assessing the surface type that the likely rainwater would fall on, and calculating the pollutants that the stormwater would pick up from the different landuse practices. By understanding the amount of rain falling on either roads, footpaths, open space, roofs or other impervious areas then we know the amount of total suspended solids (eg grit, tyre and car residue), total phosphorus (detergent and fertilisers) and total nitrogen (air-borne pollutants and fertilisers) that will need to be managed in the municipality.

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5.1 WATER BALANCE FOR THE CITY OF MELBOURNE

City of Melbourne’s water balance shows potable water use alongside rainfall. The stormwater runoff is substantial showing the potential for harvesting to help meet a local water demand. Increased stormwater treatment and harvesting, water saving and climate change are reflected in the Target 2020 water budget.

Figure 3 Water balance for the City of Melbourne – showing baseline and targets

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Where is water being used in the City of Melbourne?

Figure 2 shows that commercial practices place the greatest demand on mains water supply (18,243 ML/yr) followed by residential (5,541 ML/yr) and Council (1,585 ML/yr) demands.

Even though Council’s demand represents a relatively small proportion of the total, Council has an important role to play in providing leadership in the community. The implementation plan, detailed in Section 7 provides greater detail on the direct contribution Council can make towards achieving sustainable water management targets.

Approximately 88% of potable water is used and then discharged to sewer as wastewater (22,510 ML/yr) from the municipality. Demand management practices to stimulate their uptake across the commercial sector are critical to conserving mains water and reducing wastewater flows across the municipality.

Approximately 11% of mains water (2,959 ML/yr) is used for outdoor purposes including residential garden watering and irrigation of public open spaces. At a Council level, irrigation of its public open spaces represents 65% of Councils potable water use. Ample stormwater is available to meet the municipality’s mains water demands such as irrigation requirements by tapping into catchment drainage that flows adjacent to parks and gardens.

Where and how much rain is falling in the City of Melbourne?

The mean annual rainfall volume across the municipality is 21,260 ML, of which approximately 63% (13,470 ML) is discharged as surface runoff, 1% (220 ML) is returned to the atmosphere via evapo-transpiration processes and 35% (7,560 ML) infiltrates into the underlying soils. Approximately 1% (280 ML) of the infiltrated runoff contributes to groundwater recharge across the municipality.

A total of 4,230 ML/yr of roof runoff is generated across residential and commercial sites providing an abundance of water that could be harvested and used for garden irrigation, toilet flushing, hot water and laundry purposes. Private impervious areas and roads are other sources of runoff that could be harvested to provide a valuable supply.

How is climate change factored into the city as a catchment strategy?

The rainfall data used across the Victorian water industry is based on historical rainfall patterns. It is acknowledged that these patterns show higher rainfall than has been experienced in the past ten years and also acknowledged that future rainfall is forecast to be less than that shown in historical rainfall patterns.

The targets for water saving have factored in reduced rainfall of 3% by 2020 which is an average figure used by the City of Melbourne and guided by CSIRO findings set out in Section 3 of this report.

The City of Melbourne strongly advocates that rainfall data to be modified in the water modelling tools used by the industry to reflect the growing understanding of climate change impacts on rainfall and storm events.

How much of local water needs can be met by the rain falling in the City of Melbourne?

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The water budget shows that combining stormwater and roofwater runoff could, on paper, meet 70% of potable water needs of the residents and businesses in the City of Melbourne.

This offers great potential, however in reality all 70% is not available for use as it is unfeasible to build such large storage capacity to capture all of this rainfall. A preliminary feasibility study looking at seven parks and one boulevard in the City of Melbourne shows that the stormwater harvesting potential for these sites will on average meet 43% of the water needed for the site. This gives a general idea of the stormwater harvesting capacity that is available for the City of Melbourne and would increase to providing well over half the water needs once good water demand management practices are in place. See Attachment 1 for the stormwater harvesting examples for the City’s parks and boulevards.

Stormwater harvesting will not provide all of our water needs, but forms a fundamental component of integrated urban water management. The benefits of stormwater harvesting reach beyond mains water conservation in that it reduces stormwater pollutant loads discharged to receiving waters and thereby helps protect the health of our water bodies at the same time.

Where else should water be sourced in the city as a catchment?

Stormwater harvesting can provide for a significant proportion of local water needs (and at the same time improve water quality). Before harvesting, it is necessary for all sites to reduce their water demand in the first place. From there, site managers can consider a range of other alternative water sources and assess their suitability for each site.

An alternative water source hierarchy has been established overleaf for site managers to follow. It reflects the principles of the city as a catchment. The hierarchy helps to provide a range of alternative water supply options that are suitable for a site and help to prevent the vulnerability of relying on one centralised water supply option. For example, this approach enables reliance on local stormwater harvesting in wetter years, or desalination supplementing a centralised infrastructure scheme in a dry year.

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ALTERNATIVE WATER SOURCE HIERARCHY

Which alternative water sources provide the best environmental solutions for City of Melbourne? A fundamental principle of city as a catchment is to emphasise decentralised water supply options that reduce reliance on potable water brought in from outside the catchment. The following general hierarchy for considering sustainable water management solutions in the City of Melbourne is recommended. Alternative Water Sources from within the Local Catchment 1. Undertake water demand reductions Save water in buildings through efficient fittings, appliances, good design and good behaviour. Save water in open spaces through good design and planting along with moisture-sensitive irrigation if needed at all. 2. Consider rainwater harvesting Smaller rainfall volumes are easy to harvest because the equipment required (such as tanks or storage pond, lakes) to hold this volume of runoff can be relatively small, yet able to help meet some of the residential and Council demands on mains water supply. Typically 90% of rainfall volume is attributed to frequent events smaller than the one in three month annual recurrence interval (ARI).

Rainwater harvesting also helps to reduce stormwater pollutants, most particularly nitrogen loads from atmospheric pollutants.

3. Consider stormwater harvesting Stormwater harvesting allows for a much greater amount of rainwater to be harvested once it has landed on roads, footpaths, open space and other impermeable areas. Stormwater requires treatment therefore requiring more management, financing and energy than rainwater harvesting. Stormwater harvesting generally requires planning for large storage areas once the water has been captured and treated. Stormwater harvesting provides the greatest reductions in stormwater pollutants compared to other alternative water sources. In particular, it reduces total suspended solids (grit, car and tyre residue etc).

4. Consider water recycling

This hierarchy is shaped by the City of Melbourne’s carbon neutral commitment and the energy and lifecycle implications of water recycling (greywater and blackwater).

Each of the alternative water sources has unique reliability, energy cost, environmental risk and economic profiles. It is necessary to consider the circumstances of every site to determine the best option for saving water, sourcing alternative water and reducing stormwater pollution.

Alternative Water Sources from beyond the Local Catchment If the above hierarchy of sustainable water management solutions is not able to meet water conservation and water quality targets, then it is recommended that water sources generated from outside the municipality, but transverse the City of Melbourne be considered to supplement supply. This includes:

5. Wastewater conveyed along the Melbourne Water Sewerage Transfer Network. Sewer mining is an option for alternative water sourcing on sites that have limited space or other constraints. It does have significant energy implications that need to be managed, but has the benefit of a certainty of supply (unlike rain-dependent options) and much less storage requirements.

6. Stormwater in the Yarra River, Maribyrnong River and Moonee Ponds Creek

Drawing water from waterways requires full consideration of environmental flow requirements of that waterway. The City of Melbourne is in the unique position of being at the ‘bottom of the catchment’ and as a result is able to draw water without environmental and habitat implications. The limitation though, is that the water in these lower reaches is saline and requires significant treatment and desalination.

7. Groundwater Groundwater is unlikely to be a significant resource across the municipality because of the shallow, saline water table across the Yarra Delta region9. If extracted, groundwater would need to be desalinated.

The City of Melbourne is located on unconsolidated quaternary alluvium deposits and therefore it is characterized by a very low storage potential for ASR. The potential for groundwater extraction and Aquifer Storage and Recovery (ASR) is limited across the municipality.

Table 1 summarises the advantages, challenges and recommendations of mains water and alternative water sources across the City of Melbourne. Council’s WSUD Guidelines advise on how to implement these alternative water options on different sites within the municipality.

9 broad scale potential mapping exercise undertaken by Dudding, et al., (2006)

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5.2 POLLUTANT BUDGET FOR THE CITY OF MELBOURNE

The health of the Lower Yarra River, Maribyrnong River and Moonee Ponds Creek estuarine environments and open water features of the City of Melbourne are strongly influenced by stormwater discharges to these waterways. The combination of all of these factors (and others) leads to a deterioration in waterway health. In many urban environments this is compounded by physical changes to waterways, such as channelisation, concrete lining and sheltered harbours.

Stormwater pollution loads have a major impact through:

increased loads of toxicants and anthropogenic chemicals (e.g. organochlorine compounds such as pesticides and herbicides, and heavy metals). Chemical organic compounds are often associated with organic solids in stormwater or sorbed onto sediment.10 These compounds can be toxic to some aquatic organisms and can be bio-accumulated through the food chain creating long lasting impacts.

increased nutrient inputs. An excess of nutrients (especially nitrogen and phosphorus) can lead to eutrophication resulting in the growth of undesirable algae and aquatic weeds, shortages of dissolved oxygen, and blooms of cyanobacteria (which pose a serious health hazard to humans and animals). This reduces the ability of water bodies to support aquatic habitat and recreation.

increased loads of suspended solids. Suspended solids are soil and organic particulates transported by stormwater to the receiving waterways during runoff events. Suspended solids increase the turbidity of the water, decreasing the penetration of light into the water, and consequently reducing or sometimes completely inhibiting photosynthesis by aquatic organisms. Nutrients, heavy metals, hydrocarbons and organic chemicals may also be transported with suspended solids, by adsorbing on to the particle surfaces. This also negatively affects aquatic benthic communities in water bodies.

increased salinity disturbances. Estuarine environments are essentially characterised by variations in salinity. However the efficiency of conventional urban drainage systems results in both a significant increase in the rate and volume of runoff. As a consequence urban estuarine ecosystems have to cope with an increased salinity gradient. This factor alone would have ecosystem health impacts (i.e. reduced ecosystem diversity).

What are the stormwater pollutant loads in the City of Melbourne?

The stormwater pollution budget for the City of Melbourne (Table 4) shows that private impervious surfaces, roof areas and roads generate the greatest volume of runoff across the municipality.

Land uses responsible for the greatest loads of pollutants in the City of Melbourne are:

- Roads and other impervious surfaces for total suspended solids.11 The generation of total suspended solids is very high in the City of Melbourne for both Council land and non-Council land. TSS is primarily generated from roads, and is therefore very high in the City because of its highly urbanised nature and road coverage.

- Roof areas for nitrogen loads Like TSS, nitrogen in stormwater is generated from roads, footpaths and driveways, however one of the other primary generators is roofs (as roof water picks up atmospheric pollutants which largely includes nitrogen). Nitrogen is particularly relevant for non-Council land because of the large amount of roof space.

Table 4 Stormwater pollutant budget for the City of Melbourne – 2005 base year (1959 rainfall data and Fletcher (2005) storm flow concentration parameters)

City of Melbourne managed assets Private ownership Total

Roads Public open space

Nature strips

Roof Other impervious surfaces

Pervious areas

Flow (ML/yr) 2,840 967 113 4,230 4,990 326 13,466

Total Suspended Solids (kg/yr) 875,000 12,500 1,470 108,000 860,000 4,230 1,861,200

Total Phosphorus (kg/yr) 1,660 99 12 591 1,450 34 3,845

Total Nitrogen (kg/yr) 6,740 920 107 10,000 11,500 310 29,577

10 Ferguson 1994 11 based on updated stormwater flow concentration parameters used by Coomes (2007) using Fletcher (2005) recommendations

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5.3 WATER CYCLE MANAGEMENT TARGETS FOR THE CITY OF MELBOURNE

What regulation protects waterway health?

The State Environment Protection Policy (SEPP) (Waters of Victoria) sets a statutory framework for the protection of the uses and values of Victoria’s fresh and marine water environments as required by the Environment Protection Act 1970. The SEPP binds all sectors of the Victorian economy and underpins numerous policy documents, planning schemes and catchment management strategies across the State. It identifies a number of beneficial uses of Victoria’s waterways including natural aquatic ecosystems and associated wildlife, water-based recreation, agricultural water supply, potable water supply, and commercial and recreational use of edible fish and crustaceans. SEPP (Waters of Victoria) requires that runoff from urban areas must not compromise the beneficial uses of the receiving waters. Several provisions of SEPP (Waters of Victoria) specifically refer to stormwater pollution and require that measures be implemented to control its environmental impact.

Targets for best practice stormwater quality improvements were introduced in 1999 for the mean annual load reduction in litter, sediment and nutrients. Over the last decade there has been progressive industry-wide adoption of WSUD to achieve these targets for the protection of receiving water from urban stormwater discharges. In October 2006 these targets were mandated targets for residential subdivisions under Clause 56-07.04 of the State Planning Provisions. These targets are: 80% reduction in total suspended solids 45% reduction in total nitrogen 45% reduction in total phosphorus 70% reduction in litter

What are the total water cycle targets for the City of Melbourne?

The City of Melbourne has the following targets for total water management in the municipality:

Water Saving Targets

The City of Melbourne seeks to save water to help reduce the reliance on drawing water from the Port Phillip, Westernport and neighbouring catchments. Saving water consists of reducing the demand for water, and finding alternative water sources. Table 3 sets out the Council’s tremendous progress towards its water saving targets and subsequent revised targets.

Water Saving Targets Base Year

Existing Targets established in

Total Watermark 2004

Progress Comments Recommended Revised Targets

99/00

40% reduction in potable water consumption per employee by 2020

48% reduction per employee. Water use down from 181 litres/ person/day to 95 l/p/d (target is 109 l/p/d). 38% reduction in total commercial water use from 18,243 ML/yr to 11,430 ML/yr. The target is 13,327 ML/yr factoring employee growth.

Remarkable progress by the commercial sector and well exceeding target already. Recommended revised target of 50% reduction per employee (91 l/p/d) The revised total commercial water consumption target is 11,127 ML/yr factoring employee growth (from 323,000 in 99/00 to 335,000 in 2020).

50% reduction in potable water consumption per employee by 2020.

99/00

40% reduction in potable water consumption per resident by 2020

39% reduction per resident. Water use down from 296 l/p/d to 179 l/p/d (target is 178 l/p/d). To date, 21% reduction in total residential water use from 5541 ML/yr to 4399 ML/yr. The target is 7461 ML/yr factoring residential growth.

Great progress by residents. Much of the savings due to water restrictions – water use likely to increase once these restrictions are lifted. In light of this, it is considered appropriate to retain 40% water saving target per resident. Refined resident population forecast of 120% increase (not 141% used in Total Watermark 2004) gives revised residential water consumption target of 7419 ML/yr.

40% reduction in potable water consumption per resident by 2020

99/00

40% reduction in potable water consumption by Council by 2020

29% reduction in Council use. Water use down from 1,686 megalitres per year to 1,197 ML/yr. The target is 1012 ML/yr.

Very good progress by Council. Council will continue to reduce demand to meet water saving targets, and is also committing to increased alternative water sourcing which will help achieve the target


99/00 12% ‘absolute’ water saving target by 2020

Currently 34% absolute saving.

Absolute saving already exceeds the target and challenge remains to keep an absolute saving while the population grows by 120% With the above increase in commercial water saving, along with a revised population the expected absolute water saving will nearly double to 22%

22% ‘absolute’ water saving target by 2020

Table 3: Review of City of Melbourne water saving progress and proposed revised water saving targets

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Recommended revised water saving targets, as devised from the analysis in Table 3, are:

50% reduction in potable water consumption per employee by 2020

40% reduction in potable water per resident by 2020


22% ‘absolute’ water saving target by 2020

Alternative Water Use Targets

Under the city as a catchment, the alternative water use target is a stepping stone to achieve:

• the water saving target (reduced reliance on potable water),

• the stormwater quality target (reduced amount of stormwater entering the waterways),

• the wastewater quality target (reduced amount of wastewater entering the sewer).

To date there have been no targets set for the municipality for alternative water use. This is analysed in Table 4 with alternative water use targets recommended.

Alternative sources of water are one way of saving potable water; however it is important that it is considered only after, or in conjunction with, all efforts to reduce demand have been made including efficient fittings and appliances. Treatment standards need to match the proposed reuse standards.

Alternative Water Use Targets Base Year

Existing Targets Progress Comments Recommended New Targets

N/A None in place

Total amount of alternative water sourced by Council is 4% or 74 megalitres

Alternative water sourcing commenced in 2007 for Council with the operation of the Royal Park wetlands and the use of watering trees by trucks and bollards with recycled water.

Council to source 30% or 480 megalitres of its water needs from alternative water sources by 2020

N/A None in place

Total amount of alternative water sourced by non-Council land managers is 1% or 238 megalitres

Alternative water sourcing has commenced. This is the best data available to date.

Non-Council land managers to source 9% or 2,800 megalitres of its water needs from alternative water sources by 2020.

Table 4: Review of City of Melbourne alternative water use progress and recommended alternative water use targets

Recommended alternative water use targets, as devised from the analysis in Table 4, are:

Council to source 30% (480 ML) of its water needs from alternative water sources by 2020 (99/00 base year)

Non-Council land managers to source 9% (2,800 ML) of its water needs from alternative water sources by 2020 (99/00 base year)

To assist in meeting the above targets, Council will put into practice the following process targets:

100% of Council’s development projects to show consideration of sourcing alternative water.

100% of private development sites requiring approval for a ‘legal point of discharge’ to show consideration of sourcing alternative water.

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Stormwater Quality Improvement Targets

Meeting best practice stormwater quality targets will help protect the ecological quality and health (along with recreational and tourism value) of the Yarra River, Maribyrnong River, Moonee Ponds Creek and Port Phillip Bay. Meeting these targets also ensures that litter is prevented from entering water bodies.

Flood management remains the primary objective for stormwater solutions to ensure protection of lives, property and the local environment. Stormwater quality targets have recently been set and these have been enhanced through further analysis as shown on Table 5. Pollutants loads further specified in Appendix 1.

Stormwater Quality Improvement Targets Base Year

Existing Targets adopted in May 2008 Progress Comments Recommended revised and

new targets 20% reduction in total suspended solids on Council land by 2020

2005

20% reduction in total suspended solids (grit, tyre and car residue) by 2020

4% TSS reduction for Council land 3% TSS reduction for non-Council land 3% average across municipality

Target consistent with best practice standard of 80% reduction in TSS

20% reduction in total suspended solids on non-Council land by 2020 15% reduction in total phosphorus on Council land by 2020

2005 Total phosphorus None in place

6% TP reduction for Council land 3% TP reduction for non-Council land 4% average across municipality

Target consistent with best practice standard of 45% reduction in TP

25% reduction in total phosphorus on non-Council land by 2020 30% reduction in total nitrogen on Council land by 2020

2005 Total Nitrogen None in place

11% TN reduction for Council land 2% TN reduction for non-Council land 4% average across municipality

Target consistent with best practice standard of 45% reduction in TN

40% reduction in total nitrogen on non-Council land by 2020

20% reduction in litter on Council land by 2020

2005 Litter None in place

Reduction in litter can be achieved in different ways including: - behaviour change (less litter) - wsud infrastructure treatments - street cleaning practices - end of pipe litter traps. This stormwater quality target relates to wsud infrastructure treatments. Detailed analysis has not yet been undertaken.

Target consistent with best practice standards of 70% reduction in litter.

20% reduction in litter on non-Council land by 2020

Table 5: Review of City of Melbourne stormwater quality progress and recommended stormwater quality targets

It is noted that pollutant removal from non-Council land is attributed to the installation of rainwater tanks and rain gardens.

Recommended stormwater quality targets, as devised from the analysis in Table 5, are: 20% reduction in total suspended solids (grit, tyre/car residue etc) on Council and non-Council land by 2020 15% reduction in total phosphorus (fertilisers, detergent, etc) on Council land by 2020 25% reduction in total phosphorus (fertilisers, detergent, etc) on non-Council land by 2020 30% reduction in total nitrogen (airborne pollutants, fertilisers, etc) on Council land by 2020 40% reduction in total nitrogen (airborne pollutants, fertilisers, etc) on non-Council land by 2020 20% reduction in litter on Council and non-Council land by 2020

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Wastewater Reduction Targets

Reducing the amount of wastewater will reduce the energy requirements and ecological pressures at metropolitan treatment centres whilst allowing for expected additional demand from forecast population growth.

Wastewater Reduction Targets Base Year


WSUD Guidelines 2005 Progress Comments Revised

recommended targets

99/00 20% reduction of wastewater by 2020

29% reduction of wastewater entering the sewerage system. Flow reduction from 22,510 ML/yr down by 6,424 ML/yr

Wastewater reductions arise from using less mains water, and capturing it for reuse. The target will need to be met despite continued population growth.

30% reduction of wastewater by 2020

Table 6: Review of City of Melbourne wastewater reduction progress and recommended wastewater reduction targets

Recommended wastewater reduction target, as devised from the analysis in Table 6, are:

30% reduction in wastewater across the municipality by 2020

To assist in meeting the above wastewater targets, Council will put into practice the following process targets:

100% prevention of wastewater pollution into land, waterway and groundwater sources

100% prevention of drainage connections to sewer to reduce overflow potential

Groundwater

Protecting groundwater is an important component of protecting our catchment. Progress in this area is analysed in Table 7.

Groundwater Management Targets Base Year


WSUD Guidelines 2005 Progress Comments Recommended

Retained Target

N/A

Where groundwater needs to be re-injected to prevent land subsidence, it needs to be of equal or better quality to the water in the aquifer.

Council has not yet introduced protocols for considering groundwater management and is not able to report on this target. Council has determined that it is not generally appropriate to source groundwater for alternative water use because of the shallow aquifers and saline water.

Council needs to establish partnerships and processes to better manage and analyse groundwater use. The existing target to be retained.


Table 7: Review of City of Melbourne groundwater management and recommended groundwater management targets

Council will put into place the following process target:


General

All principles and targets are supported by decision-making guidelines for project managers, and decision-makers to use at an operational level.

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66. CURRENT STATUS OF SUSTAINABLE URBAN WATER

MANAGEMENT PRACTICES

The City of Melbourne is widely recognised as leaders in the application of water sensitive urban design.

City as a catchment forms the nexus between the drivers for improved water management and the goal of ecologically sustainable development. It encompasses all elements of the urban water cycle and draws on WSUD tools and resources to manage each element in a way that is integrated with the other elements of the water cycle and with the urban design and built form.

The following list summarises the key strengths of the City of Melbourne and their approach to sustainable water management practices. They include:

Senior staff support and commitment;

High level policy on sustainability, commitment to water cycle management targets and WSUD;

WSUD guidelines and a widespread appreciation of tools and resources available to Council;

Dedicated WSUD officer and a water reference group that meets with key industry stakeholders on a bimonthly basis; and

Demonstration sites showcasing:

o best practice demand management strategies that provide mains water saving through efficiency and design for Council owned buildings (such as, the CH2 office) and across Council managed assets (such as, landscaping and water efficient irrigation systems installed across parks and gardens)

o best practice application in stormwater quality improvements to meet water quality objectives for harvesting and reuse and/or discharge to waterways (such as, Royal Park wetlands, Docklands and numerous rain gardens located in streetscapes, car parks and public open spaces), and

o wastewater recycling projects;

The City of Melbourne already has a water management process in place, which includes a range of programmes and reports, as shown in Figure 4. The introduction of a city as a catchment approach to water management across the municipality will further inform the strategic, planning and implementation stages of the process.

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Figure 4 Existing water management activities in Council

Water Sensitive Urban Design

Water management process Programmes and reports

STRATEGIC

• Total Watermark • WSUD Guidelines • Growing Green -Environmental

Management Plan for Parks

• Water Sensitive Cities (this report)

PLANNING

• Water Conservation Plan • Stormwater Management Plans • Targets for urban water cycle

management

FUNDING

• Lower Yarra Stormwater Quality Improvement/Living Rivers programs

• Smart Water fund • Urban Stormwater Fund • Sustainability Fund • Others

IMPLEMENTATION PLANS

• Parks and planning city as a catchment action plan (underway)

• Capital works programs, roads and drainage

MONITORING AND REPORTING

• Annual corporate reporting on water saving and water quality

• WaterMAPS for sites over 10ML • Lower Yarra Stormwater Quality

Improvement program • ICLEI Water Campaign

6.1 LINKING WATER QUALITY AND WATER CONSERVATION

Quantifying targets for the City of Melbourne enables implementation plans to be developed.

Simultaneously considering management targets for different aspects of the urban water cycle highlights where complimentary benefits are found (see Appendix 2).

This study shows the greatest improvements in stormwater quality are attributed to stormwater harvesting schemes – schemes which also provide great water saving benefits. For example, achieving water conservation targets through stormwater harvesting using storage ponds (for example, Royal Park wetland and harvesting scheme) or rain water tanks reduce stormwater volumes as well as pollutant loads discharged to the environment. To date, these water conservation projects are rarely, if ever, considered in retrofit situations for their contribution to improving stormwater quality.

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7 7. DEVELOPING A STRATEGY FOR RESILIENCE

7.1 IMPLEMENTATION HIERARCHY

City as a catchment provides the policy platform for integrated water management. Implementation then takes place using a range of tools and resources designed by the City of Melbourne including:

o WSUD Guidelines,

o Draft Climate Neutral Sustainable Water Schemes Framework, and

o Draft Risk Management Framework for Sustainable Water Schemes.

The integration of these key pieces of work will ensure all civic and external projects plan for more sustainable water needs and carry these through to implementation.

The City of Melbourne prioritises action for the city as a catchment strategy by:

Firstly, saving water and preventing stormwater pollution at source by using non-structural techniques including demand management strategies which engage, communicate and educate to bring about behavioural change. Other strategies include regulation, town planning controls and fiscal incentives.

Secondly, saving water and preventing stormwater pollution at source by structural techniques to treat and/or harvest alternative water supplies.

Thirdly, saving water and preventing stormwater pollution in system by structural techniques. Such infrastructure is installed within drainage/stormwater systems to manage stormwater quality and quantity before it is discharged to receiving waters.

These measures are preferable to treating and/or harvesting stormwater at the end of pipe where the quality of water and velocity of flow make sustainable water projects less efficient and effective.

How does the city as a catchment philosophy apply at a site-by-site level?

The following decision-making guidelines have been set out to guide sustainable water management on a site-by-site basis.

1. All City Sites as Catchments

All city sites (buildings, roads, open space) are to be considered holistically to contribute to sustainable water management across the municipality. Over time this will build resilience to the ongoing pressures of urban consolidation and climate change on water resources and aquatic environments.

2. Community Engagement

Community engagement is integral component of all projects and needs to include: a) information sharing and feedback from relevant stakeholders and community about water options and

potential issues; b) community consultation to direct the scale of the project.

3. Decentralised Water Solutions

Fundamental to achieving the city as a catchment philosophy is the incorporation of local decentralised solutions. To achieve this all city sites, planning or building proposals, and council managed projects need to: a) identify a site as a water source or sink (that is, a site water budget) and identify opportunities on the site

itself and on adjacent/nearby sites that could use surplus water from the site or supply a source of water if a site deficiency exists;

b) account for costs and benefits of decentralised water options in terms of water, energy, building materials/infrastructure/technology, and risks; and

c) consider habitat enhancement for biodiversity, birdlife and microclimate benefits.

4. Hierarchy of Sustainable Water Solutions

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A hierarchy of guiding rules have been set out to promote the adoption of sustainable water management practices across council managed assets, residential and commercial/industrial land uses.

The hierarchy establishes a general approach based on least cost, least energy intensive options in the first instance through to more complex solutions in which the water cycle benefits need to be considered in context of the projects affect on broader sustainability sectors (such as energy).

Water hierarchy decision guidelines are:

(1) Protection of receiving waters including waterways, harbours, bays or groundwater. Recreational, tourism and economic uses of waterways must not negatively affect their social or ecological values. To protect receiving waters:

a) all planning or building proposals need to demonstrate no net negative effect on receiving waters in terms of quality and/or quantity;

b) all road renewal projects and street tree replacement to promote passive irrigation where possible, and meet best practice stormwater quality standards by applying water sensitive urban design (such as, rain gardens);

c) all new building and other infrastructure in the municipality must treat catchment runoff to meet best practice stormwater quality standards by applying water sensitive urban design (this generally requires to the 3 month ARI peak flows to be treated);

d) infiltration into the water table is encouraged when treatment ensures water quality meets best practice stormwater quality standards through integration with WSUD (such as, rain gardens).

(2) Demand management conserves water and minimises the generation of wastewater:

a) all new building, other infrastructure and private open space works need to minimise water consumption through the installation of demand management fixtures, fittings, appliances and educational signage;

b) all refurbishments, upgrades and extensions need to minimise water consumption through the installation of demand management fixtures, fittings, appliances and educational signage; and

c) all council managed assets (including buildings, parks, gardens and sporting facilities) need to consider opportunities to retrofit demand management landscaping, fixtures, fittings and appliances.

(3) Stormwater quality improvement to protect receiving waters to be considered in all urban design works:

a) treatment is to reduce total suspended solids, total nitrogen, total phosphorus and litter to best practice standards; and

b) WSUD treatments to be integrated in various stages of the water cycle, where appropriate, and recognising where existing water quality treatment is already occurring upstream.

c) WSUD treatments are to be modelled to demonstrate achievement of best practice water quality. Models for private land are requested to be provided to Council so that Council can acknowledge the contribution of private land to improving waterway quality.

(4) Stormwater harvesting to conserve water and protect receiving waters is encouraged and must: a) quantify stormwater quality benefits in addition to the water saving benefits; b) all stormwater harvesting projects must incorporate a ‘fit-for-purpose’ approach to water use, that is

reuse water is more suitable for gardens and toilet flushing than potable water;

c) opportunities for harvesting stormwater are to explored for future linkages between alternative schemes to further diversify and expand decentralised supply options.

(5) Greywater/wastewater harvesting to conserve water and protect receiving waters is encouraged following implementation of water saving measures. Such schemes need to address: a) risk management to ensure protection of public health, receiving water and environment; b) greenhouse reduction measures.

(6) Groundwater as a water source is generally not considered viable within the municipality due to its shallow and saline nature, however if opportunities are identified then the user has a responsibility to ensure: a) over the long term, there is no net change in the water quantity; b) water injected should be of equivalent or greater quality to the receiving groundwater.

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7.2 ACHIEVING 2020 INTERIM TARGETS ACROSS THE MUNICIPALITY

The City of Melbourne has committed to a range of integrated water cycle management targets directed at water conservation, stormwater quality and wastewater minimisation.

To attain the 2020 targets, it is necessary to undertake the following on-ground works across the public and private sectors:

WSUD projects for Council managed assets:

• undertake alternative water sourcing for a range of parks and gardens in the City of Melbourne to meet 61% of Council’s irrigation demand. Scenario’s are outlined in Section 8 of the report for seven parks and one boulevard

• double the current annual rate of uptake of WSUD projects treating road runoff driven through the Lower Yarra Stormwater Quality Program;

• double the current uptake rate of tanks for harvesting roof runoff across Council managed assets;

WSUD projects across private non-residential sector:

• proceed with proposed water harvesting and treatment schemes at Royal Botanic Gardens, Southern Cross Station, Melbourne Museum, MCG, Melbourne Convention Centre and Flemington Racecourse;

• proceed with the rollout of water conservation projects currently being trialled including installation of waterless woks, cooling tower program, fire sprinkler testing program, green hotels and sustainable office building program; and

• increase uptake rate of rainwater tanks on private non-residential properties to 50 times the current uptake/installation rate a year (300 tanks per yr)

WSUD projects across private residential sector:

• increase uptake of water demand management in households through flow restrictors and showerheads.

• rate of rainwater tanks for toilet flushing on private residential properties to 1000 installation a year.

This is further detailed in Appendix 4. The modelling of progress in meeting targets by 2020 have been reflected in the proposed targets set out in Section 5.3 of this report.

The City of Melbourne has applied the city as a catchment model to seven parks and one boulevard to assess how much water can be sourced from within our own city catchment. This preliminary study, setting out scenario’s only is set out in Attachment 1 to this report and public feedback is welcomed.

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REFERENCES

Brown, R. and Clarke, J., 2007, Transition to water sensitive urban design: the story of Melbourne, Australia. Melbourne: Facility for Advancing Water Biofiltration, Monash University.

Brown, R., Keath, N. and Wong, T., 2008 – submitted, Transitioning to the water sensitive city: Historical and future transition states. 11th Int. Conf. on Urban Drainage, Edinburgh, Scotland.

COM, 2004 Total WaterMark, City of Melbourne.

COM, 2007a, Strategic objective four: environmentally responsible city – draft, City of Melbourne.

COM, 2007b Water management in the IMAP region – draft, City of Melbourne.

Coomes (2007) Municipality Based Stormwater Quality Targets Pilot in the City of Melbourne, Coomes Consulting, 30 July.

CSIRO (2007b) Climate Change in Australia - Technical Report 2007

Dahlhaus P.G., Heislers D.S., Brewin D., Leonard J.L., Dyson P.R. & Cherry D.P. (2004) Port Phillip and Westernport Groundwater Flow Systems, Port Phillip and Westernport Catchment Management Authority, Melbourne, Victoria.

Dudding, M., Evans, R., Dillon, P. and Molloy, R. (2006) Developing Aquifer Storage and Recovery (ASR) Opportunities in Melbourne Report on Broad Scale Map of ASR Potential for Melbourne, prepared for the Smart Water Fund, SKM and CSIRO.

Ecological Engineering, 2006, WSUD case studies for the City of Melbourne, report prepared for the City of Melbourne.

EDAW, 2007, Open space analysis City of Melbourne.

Melbourne Water, 2005, WSUD engineering procedures: stormwater, CSIRO Publishing, ISBN 0 643 09092 4.

Meyer, J.., Paul, M. and Taulbee, W. 2005, Stream ecosystem function in urbanising landscapes, Journal of North American Benthological Society, 24(3): 602-612.

Holt, P. 2003, Electrocoagulation: Unravelling and Synthesising the Mechanisms, PhD thesis, Department of Chemical Engineering, University of Sydney, pp. 228.

PMSEIC, 2007, Prime minister science engineering and innovation working Council, Water for our cities: building resilience in a climate of uncertainty, June 2007.

UTS, 2002, Melbourne End Use and Water Consumption Influences Study, Report to the Water Resources Strategy Commission, University of Technology, Sydney, CSIRO and University of Waterloo.

Victorian Stormwater Committee, 1999, Urban Stormwater Best Practice Environmental Management Guidelines, CSIRO Publishing, ISBN 0 643 06453 2.

Wong, T. 2006, Water Sensitive Urban Design – The journey thus far, Australian Journal of Water Resources, special issue of Water Sensitive Urban Design, 10(3): 213-222.

Wong, T. 2007, Building water sensitive cities, discussion paper, EDAW.

Wong, T and Brown, R., 2008 – submitted, Transitioning to water sensitive cities: ensuring resilience through a new hydro-socio contract, 11th Int. Conf. on Urban Drainage, Edinburgh, Scotland.

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APPENDIX 1

STORMWATER POLLUTANT LOAD DATA

Table 1 Stormwater pollutant load reduction targets translated to annual loads and implementation points (kg/yr)

Pollutant Land ownership Pollutant generation baseline year

2020 target load reduction

% removed to date

1999/2000 (20:11:11)

Total 1,861,200 372,240 4%

Council 888,970 177,794 4%

Private residential 291,669 58,334 1%

Commercial/industrial 680,561 136,112 4%

Total 3,846 423 4%Council 1,771 195 6%

Private residential 623 68 1%

Commercial/industrial 1,453 160 4%

Total 29,577 3,253 4%Council 7,767 854 10%Private residential 6,543 720 1%

Commercial/industrial 15,267 1,679 2%

TN

TP

TSS

Table 2 Assessment of future reductions in stormwater pollutant loads and percentage attainment of stormwater quality targets

Pollutant generation baseline year

% removed by 2020

1999/2000

Total 1,861,200 20%Council 888,970 15%Private residential 291,669 46%Commercial/industrial 680,561 16%

Total 3,846 23%Council 1,771 17%Private residential 623 59%Commercial/industrial 1,453 15%Total 29,577 37%Council 7,767 28%Private residential 6,543 109%Commercial/industrial 15,267 10%

Pollutant Land ownership

TSS

TP

TN

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C i t y a s

a C a t c h m e n t 2 9

APPENDIX 2

SOURCE OF INFORMATION TO CALCULATE WATER BALANCE AND POLLUTANT LOADS

Information details Sourced

Water demand figures COM COM (2007a); COM (2007b), Stark data spreadsheet (COM) for 2006/2007

Water demand figures private and commercial

COM (2007a)

Uptake rates of demand management strategies

Smartwater rebates data, City West Water and South East Water

Uptake rate of rain tanks for residential properties

Smartwater rebates data, City West Water and South East Water

Stormwater pollutant generation and flow volumes

MUSIC V3

Rainfall and evaporation data Bureau of Meteorology, Melbourne Regional Office (#086071)

Implementation of stormwater treatment measures

Lower Yarra Stormwater Quality Program database (Melbourne Water)

Royal park wetland data Stark data spreadsheet (COM) for 2006/2007

Mean annual flow in Yarra River Mean daily flow data for Yarra River @ Fairfield, Merri Ck @ Northcote and Gardiners Ck @ Gardiner (Melbourne Water data)

Wastewater generation figures for COM

Mains water minus human consumption (UTS report, 2002) minus outdoor demands for irrigation

Wastewater flow volumes conveyed in the transfer network

Melbourne Water data

Groundwater /infiltration losses MUSIC, Dudding, et al. (2006) & Dahlhaus, et al. (2004)

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APPENDIX 3

DETAILED SPREADSHEET OF CURRENT WSUD PROJECT BENEFITS

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APPENDIX 4

EXAMPLE OF FUTURE WSUD PROJECTS REQUIRED TO ATTAIN 2020 TARGETS

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ATTACHMENT 1

EXAMPLE IMPLEMENTATION PLAN CITY AS A CATCHMENT - PARKS

The City of Melbourne (CoM) is well known for its magnificent gardens and parklands cherished by the community for their recreational, cultural and heritage values. Overall the City of Melbourne has 560 hectares of open space comprising 109 major parks, gardens, squares and reserves.12

Irrigation demand for City of Melbourne’s parks and gardens accounts for 61% of all water use across Council managed assets which is equivalent to 4% of all water use across the municipality.

Recent water restrictions and the consequent reduction in irrigation rates across the City of Melbourne’s parks and gardens has resulted in a significant deterioration in the health of many trees and shrubs. For the long term survival of these urban landscapes and preservation of their values to the community, alternative water supplies need to be identified and implemented.

Open spaces provide a diversity of values and benefits for the community ranging from visual amenity, conservation through to recreation. Values linked to the parks and gardens in the City of Melbourne include: • Heritage (historic buildings and structures, plantings, water features or garden layouts) • Culture (aboriginal sites) • Environment (remnant indigenous vegetation, significant fauna habitat) • Community (resource for passive and active recreation, social engagement, rejuvenation,

spiritual connections)

What are the broad principles of the city as a catchment strategy?

The City of Melbourne is pursuing the city as a catchment strategy as a way of implementing holistic sustainable water management. The city as a catchment:

o recognises the important role of the natural catchment but works primarily with the artificial city catchment (including its roads, roofs, impermeable surfaces) to minimise mains water consumption, minimise wastewater generation and reduce the impact of stormwater discharges on receiving waters.

o minimises importing potable water, and exporting of wastewater, from and to areas outside of the boundaries of the city, and instead optimises the use of water resources within a city.

o focuses on the links within and between the urban water cycle, built form and landscape, recognising that organisational and community values play an important role in urban design decisions and water management practices.

o uses diverse infrastructure associated with the harvesting, treatment, storage and delivery of the water sources of both centralised and decentralised water supply schemes. Any stormwater or wastewater not harvested is treated prior to discharge to the environment.

Applying the city as a catchment philosophy to the City of Melbourne’s management of water is an adaptation strategy done in response to climate change. It provides a basis for moving towards an informed city as an ecosystem approach that encompasses greenhouse mitigation and habitat protection and stretches beyond single municipal boundaries.

12 EDAW 2007

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How can the city as a catchment approach be implemented in City of Melbourne’s parks and gardens to help achieve best practice sustainable water management?

To consider ways that the City of Melbourne can provide water security for its parks and gardens while at the same time reducing the amount of stormwater pollution entering water bodies, this report has developed city as a catchment based scenarios for seven parks and gardens and one boulevard.

The case studies identify and quantify stormwater harvesting opportunities which meet the city as a catchment goals of reducing potable water demand and stormwater pollution. The sites include:

Kings Domain Fawkner Park Yarra Park Fitzroy Gardens

Flagstaff Gardens Treasury Gardens Alexandra Gardens Victoria Parade

The collective results of the above scenarios show that 98% of the total demand for the eight sites (475 ML) can be harvested from the total stormwater runoff generated from catchments surrounding the parks.

Once harvested, there is a need to store the water so that it is available during drier parts of the year. As storage bodies need to meet costs and site constraints, it is not possible to store all stormwater on a site. These scenarios show that 43% of the annual irrigation demand for the eight sites investigated can be supplied, using harvested stormwater.

This demonstrates a positive solution to sourcing water in the local catchment which can be combined with water demand management of up to 40% to reach an average water saving potential of 80% across CoM’s parks and gardens from 1999/2000 levels. It is then possible to continue through the alternative water use supply hierarchy to see if other sources (eg water recycling) are suitable for any given site.

Stormwater harvesting schemes proposed for Fitzroy Gardens, Treasury Gardens and Yarra Park would remove a significant proportion of stormwater generated across their surrounding catchments from the drainage system. This will provide great downstream water quality benefits, through reduced pollutant loading associated with catchment urbanisation. Other sites were more constrained, limiting the extent of runoff harvested from surrounding catchments

13. Figures shown in Table 5.

How can City of Melbourne progress the concepts in this report?

The City of Melbourne is seeking public feedback on the scenarios in this report for parks and gardens. Please note, that the designs in this report are conceptual only, and have not yet been adopted by Council.

Council will undertake community engagement to determine a program of action for the scenarios/case studies in this report, along with similar design solutions for further parks, gardens and boulevards.

Table 5 Summary of mains water conservation through stormwater harvesting

Figure 5 shows the location of the parks included in this study and areas of parkland currently irrigated. Catchment areas identified as potential sources of runoff for harvesting stormwater are illustrated according to their surface characteristics and catchment areas.

13 Site inspections were carried out at each of the parks in March 2008.

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Figure 5 Overview map parks and catchments

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7.3 FRAMEWORK FOR CONSERVING POTABLE WATER ACROSS PARKS AND GARDENS

In 2007, the City of Melbourne held a collaborative planning process, known as a water charette, to set a framework for water conservation across all parks and gardens in the City of Melbourne.

The following priorities to manage and reduce the water demand across all parks and gardens were established:

Demand management: improve irrigation system efficiencies through the installation of sub-surface and moisture

controlled irrigation systems; landscape changes in areas of parks and gardens, considered to be of lower significance,

with drought tolerant plant selection (e.g. warm season grasses) and mulching; and leakage repair.

Use of alternative water supplies (local catchment): passive irrigation diverts runoff from hard surfaces onto garden beds and trees; rainwater and stormwater harvesting; and sewer mining and grey water reuse > high energy demand.

Trading between parks to achieve City of Melbourne’s desired water demand’s at all sites.

Whilst considering water saving only, it is recognised that there are also stormwater pollutant reductions associated with stormwater harvesting schemes which feeds into the broader city as a catchment strategy.

7.3.1 Policy context This Implementation Plan – Parks and Planning has been developed within the context of a number of State Government, regional and Council plans and strategies. They include:

• City of Melbourne Parks Policy – The Parks Policy sets out Council’s vision for the City’s more than 500 hectares of parkland.

• City of Melbourne Water Conservation Plan, October 2006 – This strategy provides Council with a water conservation plan aimed to protect the horticultural assets in the City’s public open spaces.

• Park Master Plans – Master Plans that outline the long term vision and guide development have been prepared for most of the City’s major parkland areas. These plans have been prepared with extensive community involvement.

• Inner Melbourne Action Plan (IMAP) – IMAP is a collaborative project between the Cities of Melbourne, Port Phillip, Yarra and Stonnington with the aim to strengthen the liveability, attractiveness and prosperity of the region by implementing a series of actions and strategies. As part of the IMAP initiatives, the publication ‘Water Management for Open Space’ focuses on best practise for water reduction, reuse and recycling options for parklands.

• City of Melbourne Sustainable Water Target and Strategic Framework – This strategy sets out the City of Melbourne’s target of using no potable water by 2012 to maintain its parks and gardens.

7.3.2 Water conservation target for parks and gardens For the purpose of this study, the City of Melbourne set a desirable irrigation demand target of 40% from the irrigation demand recorded in 1999/2000. The equivalent irrigation demand for each site takes into account water efficient demand management practises (as outlined in section 7.3) while ensuring maintenance of vegetation health. The desirable demand volumes are not a fixed value. Adjustments should be made according to individual site requirements during the functional design phase.

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7.3.3 Model set up The Model for Urban Stormwater Improvement Conceptualisation (MUSIC) has been used to model catchment runoff using rainfall data recorded at 6 minute intervals from 1986 to 2006 in Melbourne14.

Catchment areas potentially available for harvesting and their characteristics have been interpreted from Council and Melbourne Water drainage network plans and Google Earth® aerial imagery. More detailed drainage network information will be required to undertake subsequent functional and detail designs of the options proposed in this report.

The monthly distribution of the annual irrigation demand has been determined for each park individually and is based on irrigation figures provided by Council, recorded prior to water restrictions in 1999/2000. Where more than one storage facility is required as part of the proposed stormwater harvesting strategy, the total site demand has been allocated to a pro rata demand to determine optimum storage sizes. The pro rata demands are relative to the inflow volume that the catchment contributing to each individual tank generates.

7.3.4 Treatment requirements for harvested stormwater Currently there are no guidelines outlining requirements for the treatment of harvested stormwater as an alternative water supply. Treatment of harvested stormwater is necessary to minimise the risk of deterioration of the water supply infrastructure. The treatment required for harvested stormwater depends on its source, storage arrangements, use and method of delivery (i.e. drip or spray irrigation).

All parks investigated in the case studies are currently fitted with spray irrigation sprinkler systems. These systems are currently not in use due to water restrictions however, it is envisaged to use these sprinklers in the future once water restrictions are lifted on a more rationed basis then previously. The future use of spray irrigation in the City’s parks where public access is unrestricted will require treatment to Class A standard using UV treatment. Sub-surface irrigation does not require UV treatment.

Water quality treatment measures have been conceptually sized for each storage tank proposed, with respect to satisfy the objectives of stormwater treatment performance of 80% reduction in total suspended solids, 45% reduction in total phosphorus and total nitrogen. The sizing is based on best practice recommendations outlined in Melbourne Water (2005), which takes into account the size of the contributing impervious catchment area.

Table 6 summarises the land uptake required for a rain garden or wetland sized to meet Best Practice design standards.

Where opportunities for treatment using rain gardens and wetlands are limited, consideration of other measures to protect the alternative water supply is required, further consideration of treatment requirements and associated costs should be undertake as part of the detailed design phase at each site.

14 BOM Station 86071

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Table 6 Summary of stormwater treatment measures

7.3.5 Diversion options Most of the parks and gardens discussed in this report are of high heritage significance. The implementation of underground storage facilities to collect harvested stormwater is likely to be the more appropriate application. There are a number of ways to intercept and divert from existing stormwater drainage to underground storage systems:

• Diversion via gravity to a storage system placed below the invert of the existing drainage pipe

• Diversion from the existing drainage pipe via a separate pipe connecting the storage system with the existing pipe

• Diversion to the storage system via a weir, placed in the existing pipe system

A detailed investigation, with respect to the suitability of these methods for each of the proposed storage systems, will be required as part of the functional design phase.

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7.4 CASE STUDY – KINGS DOMAIN

The Domain Parklands consist of a number of parks, gardens and reserves including Kings Domain, the Shrine Reserve, Alexandra Park, Alexandra Gardens, Marquis of Linlithgow Reserve and Queen Victoria Gardens. The irrigation demand referred to in this case study excludes the Shrine Reserve, Alexandra Park, Alexandra Gardens and Queen Victoria Gardens. Alexandra Gardens are investigated in a separate case study as part of this report. The 36 ha parklands are located south of the CBD adjacent to the Melbourne Royal Botanic Gardens and bordered by St Kilda Road to the west, the Yarra River to the north and Domain Road to the south. Mature exotic and native trees set in extensive lawns are one of the major assets of the park. Sites such as the Sidney Myer Music Bowl (SMMB) and the Shrine of Remembrance are located within the parklands (as shown in Figure 6) as well as a number of monuments, memorials, fountains and ornamental ponds.

Figure 6 Aerial views of Kings Domain (courtesy of City of Melbourne website)

From the Shrine of Remembrance and Government House hills, the majority of the landscape in the vicinity of the parklands generally drains north-west towards the Yarra River. This catchment offers a number of stormwater harvesting opportunities.

Prior to this study being undertaken a number of stormwater harvesting projects have been commissioned or suggested for the Kings Domain precinct. A summary is listed in Table 7.

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Table 7 Current and proposed stormwater harvesting projects for Kings Domain

7.4.1 Harvesting opportunities Most of Kings Domain is located on a hill top and therefore harvesting stormwater from adjacent catchment areas is limited. Catchment areas identified as available for stormwater harvesting are shown in Figure 7. The west catchment (predominantly St Kilda Road) provides the largest potential supply volume to be harvested. Catchments include:

• Gardens catchment

• West catchment (St Kilda Road)

• West Sidney Myer Music Bowl (SMMB) precinct catchment

• East Sidney Myer Music Bowl (SMMB) precinct catchment

• Shrine catchment (part of separate project undertaken by Irwinconsult Pty Ltd)

Figure 7 Kings Domain MUSIC model

7.4.2 Storage requirements Excluding the Shrine, suitable sites for underground storages have been identified in three locations as shown in Figure 8. The relationship between total irrigation demand and potential supply of harvested stormwater for Kings

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Domain is shown in Figure 9 and summarised in Table 8. The desirable irrigation demand for the site is 69 ML/yr, the current demand is 100.2 ML/yr. The volume potentially available to be harvested is 61% less than the current irrigation demand and 43% less than the desirable irrigation demand at the site. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 29.5 ML/yr. A summary of the harvesting options identified for Kings Domain is shown in Table 8.

Figure 8 Kings Domain storage locations and extents

Figure 9 Kings Domain demand and supply

Table 8 Kings Domain harvesting options summary

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1.4.2.1 Storage 1: Queen Victoria Gardens lawns

Storage 1, capturing stormwater from the gardens catchment and west catchment would ideally be located beneath one of the Queen Victoria Gardens lawns. Based on advice by the City of Melbourne, a location further downstream within Alexandra Gardens has been avoided, to not impede on the utilisation of this intensively used park. It is worth noting that positioning the storage facility within Alexandra Gardens may provide a greater harvesting volume potentially available. At the time of the site visit it was noted that two trees in the immediate vicinity of the proposed location were of insignificant size and poor health. Therefore their replacement may be considered acceptable to allow for an underground storage system to be installed. An optimum size of 2000 m3

has been determined for Storage 1, providing 32.9 ML/yr (representing 55% reliability of supply) as shown in Figure 10.

Figure 10 Kings Domain storage 1 sizing diagram

1.4.2.2 Storages 2 and 3: Sydney Myer Music Bowl (SMMB) precinct

Roof runoff from the Sidney Myer Music Bowl roof has previously been identified as a potential source of water supply. The existing constructed ponds near the Sidney Myer Music Bowl were empty at the time of the site inspection. They could double as water features and storages (modelled as Storage 2 and Storage 3), collecting runoff from the SMMB precinct. Alternatively an underground storage could be located within the SMMB site. Based on the existing drainage configuration at the site, it is likely that two storages would be required. An optimum size of 50 m3 has been determined for Storage 2 and for Storage 3, providing 2 ML/yr (representing 52% reliability of supply) for both storages as shown in Figure 11 and Figure 12.

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The proposed 520 m3 storage (identified in Table 7), could supply approximately 0.9 ML/yr, but would increase the overall volume of water conserved by only another 0.2 ML/yr.

1.4.2.3 Storage 4: Shrine

The proposed 1 ML (1000 kL) storage system, collecting runoff from the Shrine, has been investigated as part of this case study (modelled as Storage 4). It could potentially supply 4.6 ML/yr of harvested stormwater. The reliability of supply for this storage system is 81% as shown in Figure 13.

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7.5 CASE STUDY – FAWKNER PARK

Fawkner Park is characterised by its extensive lawns and playing fields crisscrossed by many straight avenues lined with mature exotic and native trees (as shown in Figure 14). Extending over about 41 ha, the park is located south of the CBD, adjoined by Toorak Road to the north, St Kilda Road to the west and Commercial Road to the south. The landscape in the vicinity of the park generally drains in south-west direction towards the intersection of St Kilda and Commercial Roads.

Figure 14 Aerial view of Fawkner Park (courtesy of City of Melbourne website)

Prior to this study being undertaken a rainwater harvesting project associated with the southern pavilion was commissioned for Fawkner Park. No future harvesting projects have been proposed. Details are listed in Table 9.

Table 9 Current and proposed stormwater harvesting projects for Fawkner Park

7.5.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 15. They comprise of:

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• Gardens catchment (excluding southern pavilion roof)

• West catchment (St Kilda Road roofs)

• East catchment

The gardens and east catchment provide the largest potential supply volume to be harvested. The roof areas of buildings along St Kilda Road backing on to Fawkner Park (west catchment) have also been identified as potential sources for harvesting. However, the drainage information available did not provide entire certainty about the viability of this option. Two scenarios, including and excluding these roofs, have therefore been investigated. Further detailed investigations of the drainage network are required to ascertain which scenario can be realised. Volumes that may be available for harvesting from the St Kilda Street roofs have not been included in the summary of mains water conservation shown in Table 5.

The low point in the south-western area of the park has historically been prone to water logging, particularly during the winter months. There is anecdotal evidence that groundwater is being pumped from the foundations of buildings backing onto Fawkner Park around this area. Opportunities to harvest this water, believed to be currently discharged to the road drainage, should be investigated further.

Figure 15 Fawkner Park MUSIC model

7.5.2 Storage requirements A location most suitable to position the underground storage facility has been identified at the drainage line low point in the south-western corner of the park as shown in Figure 16. It is worth noting that the 2006 Masterplan for Fawkner Park highlights the fact that there was little community support for a water feature that could double as storage for recycled stormwater, and therefore an underground storage is recommended.

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Figure 16 Fawkner Park storage location and extents

The relationship between the irrigation demand and potential supply of harvested stormwater for Fawkner Park is shown in Figure 17. The desirable irrigation demand for the site is 86. 3 ML/yr, the current demand is 57.5 ML/yr. The volume potentially available for harvesting is 67% less than the desirable irrigation demand and 50% less than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 57.5 ML/yr if the west catchment is included or 58.4 ML/yr if it is not included. A summary of the harvesting options identified for Fawkner Park is shown in Table 10.

Figure 17 Fawkner Park demand and supply

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Table 10 Fawkner Park harvesting options summary

An optimum size of 1000 m3 has been determined for the storage facility, providing an irrigation supply volume of 28.8 ML/yr (representing 33% reliability of supply) if the west catchment is included, as shown in Figure 18. If the harvesting of roof runoff from the west catchment proves unviable, the volume of irrigation volume still required increases only slightly to 58.4 ML/yr (as shown in Figure 19). Sourcing runoff from the east catchment only would mean that the location of the underground storage could be positioned anywhere along the southern perimeter of the park

Figure 18 Fawkner Park storage sizing diagram including west catchment

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Figure 19 Fawkner Park storage sizing diagram excluding west catchment

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7.6 CASE STUDY – YARRA PARK

Yarra Park, is 35 ha in area and characterised by open lawns crisscrossed by straight paths lined with exotic and native trees. The parklands are located at the eastern boundary of the COM municipal boundary, south-east of the CBD, bordered by Punt Road to the east, Wellington Road to the north and the Yarra River to the south. The railway reserve between Richmond Station and Flinders Street Station divides the park into a northern and a southern part. The northern part surrounds two of Melbourne’s major sporting venues, the Melbourne Cricket Ground (MCG) and the Richmond Cricket Ground (as shown in Figure 20). Its lawns are frequently used for car parking on match days. The southern part accommodates a number of sporting ovals. As the City of Melbourne will not maintain irrigation in the southern part of the park in the future, the irrigation demand for this part has been excluded from the demand figure.

Figure 20 Aerial view of Yarra Park (courtesy of City of Melbourne website)

The landscape in the vicinity of the park is crossed by a ridge running north-south through the eastern section of the park. From this ridge the surface drains in two directions, towards the south-east and the south-west. Both catchments provide a number of harvesting opportunities.

Prior to this study being undertaken the MCG commissioned rainwater harvesting projects for its grounds. No future harvesting projects are currently known. Details are listed in Table 11.

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Table 11 Current and proposed stormwater harvesting projects for Yarra Park

CURRENT PROJECTS PROPOSED PROJECTSMelbourne Cricket Ground (MCG): noneThe MCG already treats stormwater runoff from its site in a gross pollutant trap and harvests roof runoff in a tank near the north-western corner of the building to supplement the irrigation demand for the site. Arup are currently looking at harvesting opportunit ies from the MCG hardstand area.

7.6.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 21. The north-west catchment provides the largest potential supply volume to be harvested. Catchments include:

• Gardens catchment (excluding MCG)

• West catchment

• North-west catchment

• East catchment

• South catchment

Figure 21 Yarra Park MUSIC model

7.6.2 Storage requirements Suitable sites for underground storages have been identified in two locations as shown in Figure 22. The two storages will allow the capturing of runoff from catchments to either side of the ridge. Storage 1, proposed to be located at the westernmost corner of the park, collects runoff from the gardens catchment, north-west catchment, west catchment and south

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catchment. Storage 2, proposed to be placed underneath the lawn adjacent to the corner Vale Street and Punt Road, collects runoff from the east catchment.

Figure 22 Yarra Park storage location and extents

The relationship between irrigation demand and potential supply of harvested stormwater for Yarra Park is shown in Figure 23. The desirable irrigation demand for the site is 38.1 ML/yr, the current demand is 32.7 ML/yr. The volume potentially available for harvesting is 36% less than the desirable irrigation demand and 26% than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 13.8 ML/yr. A summary of the harvesting options identified for Yarra Park is shown in Table 12.

Figure 23 Yarra Park demand and supply

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Table 12 Yarra Park harvesting options summary

Yarra Park Storage 2 TotalPro rata irrigation demand (kL/yr) 30,838 7,234 38,072Volume of supply (kL/yr) 19,400 4,900 24,300Shortfall in supply (kL/yr) 11,438 2,334 13,772Proposed storage volume (m3 = kL) 200 200 400Storage footprint required if 2 m deep (m2) 100 100 200Reliability of supply (%) 63% 68%

Storage 1

An optimum size of 200 m3 has been determined for both storage facilities, providing 19.4 ML/yr irrigation supply (63% reliability of supply) for Storage 1 and 4.9 ML/yr (68% reliability of supply) for Storage 2 as shown in Figure 24 and Figure 25 respectively.

Figure 24 Storage 1 sizing diagram

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7.7 CASE STUDY – FITZROY GARDENS

Fitzroy Gardens (as shown in Figure 26) are one of the major 19th century landscaped gardens in the City of Melbourne comprising historic buildings, sculptures, ornamental ponds and fountains, and horticultural elements. The gardens of about 28 ha in area are located east of the CBD and are bounded by Clarendon Street, Albert Street, Lansdowne Street and Wellington Parade.

The landscape in the vicinity of the gardens generally drains north-south. Central to the gardens is a landscaped open channel running north-south, collecting and conveying stormwater runoff from the gardens to its southernmost point. This location provides an opportunity for intercepting the drainage system running through the gardens as well as others from external catchments.

Figure 26 Aerial view of Fitzroy Gardens (courtesy of City of Melbourne website)

Prior to this study being undertaken a stormwater related project has been suggested for Fitzroy Gardens. A description is listed in Table 13.

Table 13 Current and proposed stormwater harvesting projects for Fitzroy Gardens

7.7.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 27. The east catchment provides the largest potential supply volume to be harvested. Catchments include:

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• West catchment including west gardens catchment

• North catchment

• East catchment

Figure 27 Fitzroy Gardens MUSIC model

7.7.2 Storage requirements A location most suitable to position the underground storage facility has been identified at the depot site in the southern part of the park as external and internal drainage flows to or near this low point. There are plans to remove the depot from the gardens providing room for treatment and storage. Alternatively the storage could be placed underneath the existing carpark/storage area of the depot. Only little, if any, landscaping within the gardens will be affected. The location and possible extents of the storage is shown in Figure 28.

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Figure 28 Fitzroy Gardens storage location and extents

The relationship between the irrigation demand and potential supply of harvested stormwater for Fitzroy Gardens is shown in Figure 29. The desirable irrigation demand for the site is 118.5 ML/yr, the current demand is 51.5 ML/yr. The volume potentially available for harvesting is 33% less than the desirable irrigation demand, but higher than the current demand.

The stormwater volume harvested from the Fitzroy Gardens catchments could potentially be supplemented by excess volume not harvested from the neighbouring Treasury Gardens catchments. Due to the relatively low irrigation demand in Treasury Gardens and its relatively high volume of supply, a substantial amount of excess water leaves the system unutilised (refer Table 5 for figures). In addition to this option further demand management initiatives and/or alternative water supplies may be required to cover the shortfall of supply of 39.6 ML/yr. A summary of the harvesting details for Fitzroy Gardens is shown in Table 14.

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Figure 29 Fitzroy Gardens demand and supply

Table 14 Fitzroy Gardens harvesting options summary

The existing ponds in the gardens may also provide opportunities to store water. Detailed investigations are required to explore this option, and heritage issues would need to be addressed.

An optimum size of 5,000 m3 has been determined for the storage facility, providing 67% reliability of supply as shown in Figure 30. This provides an irrigation supply volume of 78.9 ML/yr.

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Figure 30 Fitzroy Gardens storage sizing diagram

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7.8 CASE STUDY – FLAGSTAFF GARDENS

Flagstaff Gardens, about 7 ha in size, are positioned in the centre of the city, adjacent to the northern boundary of the CBD. La Trobe Street borders the gardens to the south, King Street to the west, Dudley Street to the north and William Street to the east. The gardens are of state heritage significance being the site of Flagstaff Hill, a vantage point dominating the site, used for communication among the early colonial settlers. Mature exotic and native trees set in open lawns and flower beds create Flagstaff Gardens’ character.

The gardens (as shown in Figure 31) accommodate a historic cottage, a number of monuments, memorials and sculptures, a bowling club and tennis club. The landscape in the vicinity of the gardens drains from Flagstaff Hill to all directions, with the majority of the topography draining south towards La Trobe Street. This catchment offers the greatest amount of stormwater harvesting opportunities.

Figure 31 Aerial view of Flagstaff Gardens (courtesy of City of Melbourne website)

Prior to this study being undertaken a rainwater harvesting project was commissioned for Flagstaff Gardens. No future projects are currently known. A description is listed in Table 15.

Table 15 Current and proposed stormwater harvesting projects for Flagstaff Gardens

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7.8.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 32. The gardens catchment provides the largest potential supply volume to be harvested. Catchments include:

• Gardens catchment (excluding bowling club and tennis courts)

• Bowling green and club house roof located within gardens catchment

• Tennis courts located within gardens catchment

• North catchment

• East catchment

Figure 32 Flagstaff Gardens MUSIC model

7.8.2 Storage requirements Suitable sites for underground storages have been identified in two locations as shown in Figure 33.

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Figure 33 Flagstaff Gardens storage locations and extents

The relationship between irrigation demand and potential supply of harvested stormwater for Flagstaff Gardens is shown in Figure 34. The desirable irrigation demand for the site is 21.8 ML/yr, the current demand is 20.3 ML/yr. The volume potentially available for harvesting is 60% less than the desirable irrigation demand and 57% than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 12.9 ML/yr. An alternative option may be recovering groundwater from the nearby Flagstaff underground station.

Figure 34 Flagstaff Gardens demand and supply

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A summary of the harvesting options identified for Flagstaff Gardens is shown in Table 16.

Table 16 Flagstaff Gardens harvesting options summary

The volume of water generated from the proposed 140 kL storage system, collecting runoff from the synthetic green and club house roof of the bowling club, has been included in this case study (modelled as Storage 3). This storage system provides an irrigation supply volume of 1.3 ML/yr (representing 50% reliability of supply) as shown in Figure 35.

Figure 35 Flagstaff Gardens storage 3 sizing diagram

Storage 1, capturing stormwater from the gardens catchment, tennis courts and east catchment would ideally be located beneath the lawn adjacent to La Trobe Street in a natural low point. The 2000 masterplan discusses the intention of designing a new water element in the low lying south-eastern lawn to recall a former pond. This may provide an opportunity for creating a water feature that could double as storage system. An optimum size of 50 m3 has been determined for Storage 1, providing an irrigation supply volume of 6.6 ML/yr (representing 38% reliability of supply) as shown in Figure 36.

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Storage 2, collecting runoff from the north catchment, is proposed to be located under the footpath/parking bay area on the south side of Dudley Street. The storage system should be located as close as possible to the intersection Dudley Street/King Street to maximise the catchment area available for harvesting. An optimum size of 100 m3 has been determined for Storage 2, providing an irrigation supply volume of 1 ML/yr (representing 49% reliability of supply) as shown in Figure 37.


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7.9 CASE STUDY – TREASURY GARDENS

Treasury Gardens (as shown in Figure 38), located between the eastern boundary of the CBD and Fitzroy Gardens are with a size of about 6 ha relatively small compared to the other parks included in this study. They are bordered by Wellington Parade to the south, Spring Street to the west, Treasury Place to the north and Lansdowne Street to the east. The gardens, which have been recommended for inclusion in the Victorian Heritage list, provide spacious lawns traversed by avenues of mature exotic trees. A number of monuments, memorials, sculptures and an ornamental pond are also features of the gardens.

Figure 38 Aerial view of Treasury Gardens (courtesy of City of Melbourne website)

The landscape in the vicinity of the gardens drains in south-eastern direction towards Wellington Parade which presents a number of stormwater harvesting opportunities.

Prior to this study being undertaken a stormwater harvesting project has been flagged for Treasury Gardens. No current projects are currently known. A description is listed in Table 17.

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Table 17 Current and proposed stormwater harvesting projects for Treasury Gardens

7.9.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 39. The far north catchment provides the largest potential supply volume to be harvested. Catchments include:


• North catchment

• Far north catchment

Figure 39 Treasury Gardens MUSIC model

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7.9.2 Storage requirements The proposed storage system would ideally be located in a natural low point beneath the lawn in the south-eastern corner of the gardens. The location and possible extents of the storage is shown in Figure 40. The existing pond may also provide an opportunity to store water. Detailed investigations are required to explore this option.

Figure 40 Treasury Gardens storage location and extents

The relationship between the irrigation demand and potential supply of harvested stormwater for Treasury Gardens is shown in Figure 41. The desirable irrigation demand for the site is 23.4 ML/yr, the current demand is 12.2 ML/yr. The volume potentially available for harvesting is 30% less than the desirable irrigation demand, but higher than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 7 ML/yr. A summary of the harvesting details for Treasury Gardens is shown in Table 18.

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Figure 41 Treasury Gardens demand and supply

Table 18 Treasury Gardens harvesting options summary

An optimum size of 500 m3 has been determined for the storage facility, providing an irrigation supply volume of 16.4 ML/yr (representing 70% reliability of supply) as shown in Figure 42.

Figure 42 Treasury Gardens storage sizing diagram

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7.10 CASE STUDY – ALEXANDRA GARDENS

The historic Alexandra Gardens form a relatively small part of the Domain Parklands, about 5 ha in size. The gardens, located just south of the CBD across the Yarra River, are bordered by Kings Domain to the south, St Kilda Road to the west and the Yarra River to the north and east. Alexandra Gardens feature mature exotic trees and extensive open lawns that are intensively used for a number of events. Sites such as the historic rowing boathouses along the Yarra are part of the gardens as well as a skate park (as shown in Figure 43).

Figure 43 Aerial view of Alexandra Gardens (courtesy of City of Melbourne website)

The topography of the gardens slopes gently north-west towards the Yarra River. All drainage from the gardens discharges into the river.

Prior to this study being undertaken a project related to stormwater harvesting has been flagged for Alexandra Gardens. No current projects are known at this stage. A description is listed in Table 19.

Table 19 Current and proposed stormwater harvesting projects for Alexandra Gardens

Information available from the City of Melbourne describes the water pooling system as being an underground holding tank, collecting water from a regularly flooded lawn in the gardens. The outflow discharges into the Yarra River. The structure was designed by Connell Wagner and built around 1998-99. As no further details on the size of the structure or its outfall arrangement could be obtained it was not possible to investigate its possible integration in this stormwater

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harvesting strategy. The proposed feasibility study will be essential for refining the stormwater harvesting strategy for the Domain Parklands area. The location of the structure beneath the lawn at the rear of the boathouses is marked in Figure 44.

Figure 44 Location of water pooling system

7.10.1 Harvesting opportunities Catchment areas identified as potentially available for stormwater harvesting are shown in Figure 45. The west gardens catchment provides the largest potential supply volume to be harvested. Catchments include:

• West gardens catchment

• Skatepark catchment

Figure 45 Alexandra Gardens MUSIC model

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7.10.2 Storage requirements Suitable sites for underground storages have been identified in two locations as shown in Figure 46. The locations were chosen to minimise disruptions that could affect the useability of the gardens. Storage 1, proposed to be located underneath the lawn within the river bank in front of the boathouses, collects runoff from the west gardens catchment. Storage 2, proposed to be placed underneath the lawn within the river bank in front of the skatepark, collects runoff from the skatepark catchment.

Figure 46 Alexandra Gardens storage location and extents

The relationship between irrigation demand and potential supply of harvested stormwater for Alexandra Gardens is shown in Figure 47. The desirable irrigation demand for the site is 24.6 ML/yr, the current demand is 34.8 ML/yr. The volume potentially available for harvesting is 82% less than the desirable irrigation demand and 87% than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 20.2 ML/yr. A summary of the harvesting options identified for Alexandra Gardens is shown in Table 20.

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Figure 47 Alexandra Gardens demand and supply

Table 20 Alexandra Gardens harvesting options summary

An optimum size of 50 m3 has been determined for both storage facilities, providing an irrigation supply volume of 2.9 ML/yr (representing only 17% reliability of supply) for Storage 1 and 1.5 ML/yr (only 19% reliability of supply) for Storage 2 as shown in Figure 48 and Figure 49 respectively.

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7.11 CASE STUDY – VICTORIA PARADE

Victoria Parade is one of the major thoroughfares of inner Melbourne, running in east-west direction. It touches the CBD at its north-eastern corner at the intersection La Trobe Street and Spring Street. The boulevard is characterised by mature exotic trees set on linear lawns separating the tram line in its centre from the three lane roadways to the north and to the south. The northern half of the reserve is part of the City of Yarra, the southern part belongs to the City of Melbourne.

7.11.1 Harvesting opportunities The topography in the vicinity of Victoria Parade slopes from a high point near the corner of Brunswick Street to all directions. Due to the reserve being raised above road level and underlying drainage leading away from the site, Victoria Parade does not provide many stormwater harvesting opportunities. Drainage that could potentially be intercepted only provides runoff from a catchment of negligible size. The installation of a storage facility would not be feasible with respect to the minimal volume of stormwater potentially harvested. Alternative catchment areas to be taken into consideration are roofs of buildings along the boulevard. The City of Melbourne and public institutions could benefit from collaborating on a rainwater harvesting project. As an example roof areas of St Vincent’s Hospital and the Catholic University were investigated. Their locations are shown in Figure 50. Both catchments provide equal supply volumes to be harvested.

Figure 50 Victoria Parade MUSIC model

7.11.2 Storage requirements Storage facilities could be installed in the basement or on the roof of the buildings from where the harvested water would need to be transferred to a watering truck. Harvesting from a nearby source provides the benefit of greater energy efficiencies than transporting treated stormwater from the Royal Park wetlands for example.

The relationship between irrigation demand and potential supply of harvested stormwater for Victoria Parade is shown in Figure 51. The desirable irrigation demand for the site is 7.3 ML/yr, the current demand is 9.3 ML/yr. The volume potentially available for harvesting is 70% less than the desirable irrigation demand and 76% than the current demand. Further demand management initiatives and/or alternative water supplies are required to cover this shortfall of 5.1 ML/yr. A summary of the harvesting options identified for Victoria Parade is shown in Table 21.

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Figure 51 Victoria Parade demand and supply

Table 21 Victoria Parade harvesting options summary

An optimum size of 50 m3 has been determined for the two storage facilities, providing an irrigation supply volume of 1 ML/yr (representing 30% reliability of supply) for Storage 1 (St Vincent’s Hospital) and 1.1 ML/yr (representing 30% reliability of supply) for Storage 2 (Catholic Church), as shown in Figure 52 and Figure 53 respectively.

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City as a Catchment - Attachment 2Attachment 2

Agenda Item 5.4Environment Committee

8 July 2008

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Attachment 3 Agenda Item 5.4

Environment Committee 8 July 2008

1

List of people targeted for the public consultation. Name Organisation Rob Gell Access Environmental Adrian Marshall Adelaide City Council David Crofts Agile Alun Chapman AILA Jane Homewood ARUP Rob Turk Arup John Pritchard Australian Local Government Association Raj Manihar Baw Baw Shire Council Dr Stella Clark Bio21 Australia Ltd Brooke Ryan Brooke Ryan Landscape Architect Harry Leather Citi Cite Alan West City of Kingston Gavin Mountjoy City of Maribyrnong Fiona Sicurella City of Maribyrnong Gavin Mountjoy City of Maribyrnong Martin Hartigan City of Port Phillip Lalitha Ramachandran City of Port Phillip David McCaffrey City of Port Phillip Paul Smith City of Port Phillip John Wisniewski City of Stonnington Sarah Buckley City of Stonnington Alan Cadogan City of Sydney John Milkins City of Whittlesea Sylvana Predebon City of Yarra Jessica Rae City of Yarra Damien Connell City West Water Anne Barker City West Water Gayle Seddon City Wide Sally Capp Committee for Melbourne David Gould Committee for Melbourne Future Focus Group Jonathon McLean Coomes Consulting Blair Nancarrow CSIRO Aust. Research Centre for Water in Society Carol Howe CSIRO Manufacturing and Infrastructure Technology Michelle Bennett Darebin City Council Deni Greene Deni Greene Consulting Paul Starr Department of Environment, Water, heritage and the Arts Brod Street Department of Transport Jane Niall Department of Innovation, Industry & Regional Development Jo Beatty Department of Sustainability and Environment Cathy Bates Department of Sustainability and Environment Genevieve Overell Department of Planning and Community Development Clem Gillings Department Planning & Community Development Carol Jadraque Earth Systems Tony Wong Edaw Australia Sara Lloyd Edaw Australia Peter Holt Energetics

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2

Jamie McCaffrey EPA Caroline Chandler EPA Jessica Davison EPA Kate Brennan Federation Square Adrian Burrage Forum Future Melbourne Panellist Anne Turley Forum Panellist Don Henry Australian Conservation Foundation Helen Hayes University of Melbourne Jennifer Cunich Property Council of Australia Kate Noble Australian Conservation Foundation Arron Wood Future Melbourne Reference Group Cheryl Batagol Future Melbourne Reference Group George Pappas Future Melbourne Reference Group Nick Low GAMUT, University of Melbourne Dr Carly Green GHD Barbara Norman Global Cities Institute, RMIT University Chris Ziguras Global Cities Institute, RMIT University John Fien Global Cities Institute, RMIT University Paul James Global Cities Institute, RMIT University Ralph Horne Global Cities Institute, RMIT University Gary Workman Green Plumbers Karl Shanley Hobsons Bay City Council Ian Innes Wardell ICLEI Wayne Wescott ICLEI, Local Governments for Sustainability Rozi Boyle Marsden Jacob Donna Lorenz Maunsell Tony Ware Melbourne Cricket Club Chris Chesterfield Melbourne Water Phil Edwards Melbourne Water Jamie Comley Melbourne Water Sharyn RossRakesh Melbourne Water Matt Francey Melbourne Water Dr Rebekah Brown Monash University Dr Grace Mitchell Monash University Peter Morrison Monash University Patrick Moriarty Monash University/GAMUT Patricia Vickers-Rich Monash Unversity Paul Murfitt Moreland Energy Foundation Pablo Brait Municipal Association of Victoria Dr Patrick Greene Museum Victoria Kate Smolenska MWH Simon Fjell Permapave Mike Scott Planisphere Haydn Wood Plumbing Industry Commission Shayne LeCombre Plumbing Industry Commission Janty Rhodes Port Phillip and Westernport Catchment Management Authority David Buntine Port Phillip and Westernport Catchment Management Authority Paul Doman Project Planning and Management Pty Ltd Scott Willey RAIA

Mike Berry RMIT Global Studies Social Science and Planning Dr Nira Jayasuriya RMIT University

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3

Richard Barley Royal Botanic Gardens Nigel Finney Savewater! Shelley Ikin SKM Shaun Cox South East Water Mark Chicoine South East Water Glenn Goldsmith South East Water Keith Johnson South East Water Leon Harvey Storm Consulting Mary Trigger Sustainable Gardening Australia Katherine Pengilly Sustainable Melbourne Fund Clement Mariotte The Climate Group Rupert Posner The Climate Group Patrick Green The Melbourne Museum Dr Chris Ryan University of Melbourne Prof. Jim Falk University of Melbourne John Langford University of Melbourne Dr Alice Howe University of Newcastle Prof Simon Beecham University of South Australia Peter Boyle URS Wayne Kayler-Thomson VECCI Dianne Moy VEIL, University of Melbourne Kirsten Larsen VEIL, University of Melbourne Phillip Eversit Veolia Water Systems Tony Barton VicRoads Vince Punaro VicRoads John Denton Victorian Government Architect's Office Daniel Khong VicUrban David Hunt VicUrban Ross Young Water Services Association Australia Kein Gan Yarra Valley Water Tony Kelly Yarra Valley Water

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Agenda Item 5.4 Environment Committee

8 July 2008

FINANCE ATTACHMENT


There are no direct financial implications arising from the recommendations in this report.

Joe Groher Manager Financial Services

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Agenda Item 5.4 Environment Committee

8 July 2008

LEGAL ATTACHMENT


No direct legal issues arise from the recommendation made in the report.

In seeking to achieve the best outcomes for the local community having regard to the long term and cumulative effects of decision, section 3C(2) of the Local Government Act 1989 (“Act”) provides that Council must have regard to the following facilitating objective, among others:

“(a) to promote the social, economic and environmental viability and sustainability of the municipal district;”

Section 3D(2) of the Act states that the role of a Council includes:

“(c) maintaining the viability of the Council by ensuring that resources are managed in a responsible and accountable manner;”

Finally, section 3E(1) of the Act provides that the functions of a Council include:

"(h) any other function for the peace order and good government of the municipal district.”

Kim Wood Manager Legal Services

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Documents

DRAFT TOTAL WATERMARK – CITY AS A CATCHMENTENVIRONMENT COMMITTEE REPORT Agenda Item 5.4 8 July 08 DRAFT TOTAL WATERMARK – CITY AS A CATCHMENT Division Sustainability and Regulatory