AN INTEGRATED WATER FUTURE FOR MELBOURNE S NORTH

Transcription

1 AN INTEGRATED WATER FUTURE FOR MELBOURNE S NORTH PRELIMINARY INTEGRATED WATER CYCLE MANAGEMENT PLAN An Integrated Water Future for Melbourne s North / 1

2 CONTENTS 1. Executive Summary 4 4. Defining a Preferred Future Shared vision 2. Introduction Defining options 2.1 The integrated water challenge Traditional option 2.2 What is integrated water cycle management? 2.3 Stakeholder engagement Recycled water option Integrated options 4.3 Developing a common evaluation framework 3. Background on Melbourne s North 3.1 Location Collecting data 4.5 Assessing results 3.2 Future land use 3.3 Key characteristics 5. Findings Impacts by Opportunities as identified in the Growth Corridor Plan 3.5 What happens when we urbanise an area? 6. The Challenges and Opportunities Ahead 7. Next Steps Acknowledgements 31 ABOUT US YARRA VALLEY WATER The largest of Melbourne s three metropolitan water utilities, Yarra Valley Water provides water and wastewater services to more than 1.7 million people and around 50,000 businesses in Melbourne s northern and eastern suburbs. Yarra Valley Water s purpose is to provide exemplary water and sanitation services that contribute to the health and well-being of current and future generations. It is also committed to providing water services within the carrying capacity of nature and helping to create better places for people to live. MELBOURNE WATER Melbourne Water is committed to enhancing life and liveability through provision of safe, secure and reliable water cycle services, desirable urban spaces and thriving natural environments supported by healthy waters and bays. It is responsible for the day-to-day management of Melbourne s water supply catchments, creating and supplying drinking and recycled water, removing and treating most of Melbourne s sewage and managing waterways and major drainage systems in the Port Phillip and Westernport region. 2 / An Integrated Water Future for Melbourne s North Front and back cover images courtesy Villa World Developments Pty Ltd.

3 FOREWORD We are pleased to present the results of work completed by Yarra Valley Water and Melbourne Water that investigates sustainable ways to provide water supply and sanitation services to new homes and businesses in Melbourne s Northern Growth Corridor. The principle of integrated water cycle management forms the basis of the Victorian State Government s Living Victoria Policy and its vision to create a smart, integrated and resilient water system for a liveable, sustainable and productive Melbourne. Integrated water cycle management considers the water cycle as a whole and how planning for each element of water services (drinking water, sewage, waterways, stormwater and groundwater) can merge to provide more sustainable economic, social and environmental outcomes. It links urban and water planning and brings forward new ways to reduce pressure on our drinking water supplies and stressed river systems. This preliminary plan analyses integrated options for both water supply and wastewater services in the Northern Growth Corridor. It provides a starting point for developing the Integrated Water Cycle Strategy for Melbourne s North and for upcoming conversations with stakeholders and the community, which we plan to kick off in the first quarter of While this discussion paper is an important step towards adopting an integrated approach to water services for Melbourne s North, there is also more opportunity to be unlocked and further work is now being done on the health of waterways in the north and future drainage options. The work completed to date makes a strong case for regional wastewater recycling. The outcomes of the additional work on waterways and drainage will be reviewed in the light of the consultative process and of the performance targets for the North that will be set out in the Office of Living Victoria s Greater Melbourne Integrated Water Cycle Strategy. This may mean that the solutions in this paper need to be revisited before the Integrated Water Cycle Management Plan for Melbourne s North is finalised. The Office of Living Victoria will shortly release for consultation the draft Greater Melbourne Integrated Water Cycle Strategy. It will include integrated water cycle management performance targets, which will set new standards for water services across Melbourne. These will include specific targets for the Northern Growth Corridor. The Melbourne-wide strategy and this preliminary plan use different baseline (or business as usual ) scenarios. However, both have consistent aims, and reach broadly consistent conclusions as to the directions for change and the scale of improvement in water system outcomes that can be achieved in the North. Bringing both plans for the North fully into alignment may require some re-computing of the results set out in this study. We remain committed to delivering integrated water services in ways that provide value for money while enhancing the liveability of Melbourne s North and look forward to your input, involvement and support. Tony Kelly Managing Director Yarra Valley Water Shaun Cox Managing Director Melbourne Water Mike Waller Chief Executive Officer Office of Living Victoria An Integrated Water Future for Melbourne s North / 3

4 1. EXECUTIVE SUMMARY The Victorian Government is committed to making the most of all the water available in Melbourne and Victoria s regional centres, not just the drinking water available to us in our catchment storages. By taking full advantage of the rainwater, recycled water and stormwater in our urban areas, we can green our urban spaces and make them nicer places to live and work in, reduce the heat island effect within developed areas, reduce the risk of urban flooding and improve our natural environments. Victorian State Government vision Image: Villa World Developments Pty Ltd. 4 / An Integrated Water Future for Melbourne s North

5 In Melbourne s bustling Northern Growth Corridor, a recent expansion to the Urban Growth Boundary has allowed for the creation of at least 90,000 new residential homes and up to 1,050 hectares of new employment land a scale that presents exciting new opportunities for water management in the region. To harness these opportunities, Yarra Valley Water and Melbourne Water have worked with key water industry stakeholders and academic experts to identify integrated water cycle management opportunities that minimise the impacts of urban development on the area s environment and specifically, the area s water cycle. It s an approach that helps realise a vision set by the Victorian State Government, which aims to achieve a smart and resilient water system for a liveable, sustainable and productive Melbourne by: Integrating urban and water planning. Increasing the use of alternative water sources to reduce pressures on drinking water supplies. Reducing stormwater runoff volumes and pollutant loads passing to the receiving waterways by naturally retaining and filtering the flow prior to discharge (additional nitrogen and phosphorous reductions in excess of 25 per cent and a suspended solids reduction of almost 10 per cent compared to a traditional approach). Reducing the frequency of stormwater discharges into the receiving waterways to a level deemed to be within the carrying capacity of those waterways (no more than 15 additional days of runoff when compared to pre-development levels). Reducing the volume of nitrogen discharged into Port Phillip Bay (which has a finite capacity to receive and naturally treat it) by 20 per cent compared to a traditional approach by recycling wastewater. Reducing the depletion of groundwater storages by 40 per cent compared to a traditional approach by maximising stormwater infiltration. As well as the potential to provide our services in a smarter and more sustainable way, there are a number of very real challenges. These include: Connecting to the city s existing water and sanitation infrastructure, which are remote from the area. Managing stormwater runoff in a different way, using it to enhance public health and liveability values whilst protecting the ecologically significant threatened frog populations prevalent along the middle and upper reaches of Merri Creek. This document provides a starting point for a broader engagement process which will underpin the Integrated Water Cycle Management Plan for Melbourne s North to be coordinated by the Victorian State Government s Office of Living Victoria. Specifically, it describes: 1. How the servicing objectives have been defined what do we want to achieve? 2. How a suite of servicing options performed against those objectives. 3. Which option maximises community value (the highest achievement of the servicing objectives for the lowest possible community cost) and represents the preferred future. The preferred future identified as a result of this work can be described as follows: Reducing pressure on drinking water supplies by almost 6,000 ML per year through the treatment and recycling of wastewater for non-drinking water uses. This preferred future also includes: Continued emphasis on water efficiency within households and businesses to drive down the amount of drinking water consumed through: Community engagement and education programs; Improved planning and building regulations; Continued technology advancements which deliver more water efficient appliances as rated by the Water Efficiency Labelling Standards (WELS). Maximising local opportunities such as stormwater harvesting for irrigation of sports fields and public open spaces. These activities enable further reductions in both drinking water use and the volumes of stormwater entering our waterways. This document provides a starting point for a broader engagement process. An Integrated Water Future for Melbourne s North / 5

6 2. INTRODUCTION Melbourne faces a future with an increasingly variable climate, a growing population and an ongoing need to maintain the health of Port Phillip Bay and our waterways integral to the liveability of our city. This is why Melbourne s water companies have been actively exploring avenues to see if our urban water infrastructure can be delivered in a better, more innovative way to prevent further and future strain on the environment. In August 2010, the Victorian State Government extended the urban growth boundary around metropolitan Melbourne to include an additional 16,300 hectares of total development area in the North, able to accommodate more than 90,000 new residential homes and up to 1,050 hectares of employment land (that can support business and/or industry to generate employment opportunities). This was accompanied by the Growth Areas Authority s Northern Growth Corridor Plan, defining the high level integrated land uses and transport plans for the area, to guide how development will occur over the next 30 to 40 years. This study considered the water cycle holistically. With Yarra Valley Water and Melbourne Water required to provide water supply, sanitation and stormwater services to this new development area, we collaborated to measure and compare the environmental impacts of various servicing options and to quantify the costs to the community. The result was this study that goes beyond the traditional approach to water cycle management. Project partners and stakeholders considered the water cycle holistically to best meet the government s vision and our community s needs and expectations through the development of long-term, flexible, and localised solutions. The study has been based on the high-level Northern Growth Corridor Plan with catchmentspecific detail. As the planning process evolves over time and developments are initiated, more detailed Precinct Structure Plans will be developed to identify localised solutions and projects. This study will ultimately inform the Integrated Water Cycle Management Plan for Melbourne s North, which in turn will inform the Northern Region Integrated Water Cycle Strategy and ultimately the Metropolitan Melbourne Integrated Water Cycle Strategy to be coordinated by the Office of Living Victoria. CITY SCALE Metropolitan Integrated Water Cycle Strategy REGIONAL SCALE Regional Integrated Water Cycle Strategy SUB-REGIONAL SCALE Integrated Water Cycle Management Urban Renewal Growth Corridor Planning LOCAL SCALE Precinct Structure Plans City-wide vision Cross-boundary infrastructure (wastewater, water, drainage, waterways) - pending deferral through local scale planning City-wide objectives, standards, indicators Regional vision Atlas of opportunities and constraints Regional infrastructure - pending deferral Regional objectives, standards, indicators Sub-regional vision Sub-regional infrastructure - pending deferral through local scale planning Sub-regional objectives, standards, indicators Local vision Local infrastructure - pending deferral through regional scale planning Local objectives, standards, indicators ASSET UPGRADES AND RENEWALS This diagram shows the hierarchy of integrated water cycle management planning in Melbourne as defined by the Office of Living Victoria. This document will contribute towards the completion of an Integrated Water Cycle Management Plan for Melbourne s North. 6 / An Integrated Water Future for Melbourne s North

7 2.1 The integrated water challenge In the face of challenges such as climate variability, a growing Melbourne, changing community expectations and cost of living pressures, it is imperative that water authorities consider new fit-for-purpose (rather than one-size-fits-all) approaches to managing the water cycle. The Victorian State Government is driving change through its Office of Living Victoria, to deliver better water services, improved local environments and increased liveability in Melbourne and Victoria s regional cities. Central to the government s vision for a more liveable state is the concept of integrated water cycle management. 2.2 What is integrated water cycle management? Integrated water cycle management (IWCM) is a multi-disciplinary and multi-objective approach, used to promote the sustainable use of all available water resources in ways that best deliver multiple community objectives. It means evaluating all aspects of the water cycle and approaches to water supply and demand management, stormwater management and wastewater treatment against multiple criteria, including environmental, social, technical and economic factors as well as those concerning biodiversity and public health. 1 Delivering integrated water cycle solutions requires consideration of: Investment at all spatial scales from individual households to entire cities Investment across temporal scales recognising that development will happen over the next 30 to 40 years. The role the growth area will play in the region and ultimately its contribution to metropolitan Melbourne. Involvement of all stakeholders including government institutions, community groups, property developers and householders. Compared to a traditional servicing approach, the adoption of integrated water cycle management solutions can deliver higher community value by optimising the benefits and costs of each investment in water cycle management resulting in improved drinking water security, better waterway health outcomes, improved urban amenity and reduced risk of localised flooding. 2.3 Stakeholder engagement The work completed to date has involved stakeholders from within the water industry as well as an expert reference group established to validate and fine-tune the options assessment tool (see page 20). Knowledge experts were drawn from Councils, the land development industry, government departments, other water businesses and universities. The process for future stakeholder and community engagement is defined at the end of this document. THIS WORK IS DESIGNED TO: Contribute to a secure water future in Melbourne s North by identifying regional and local water cycle initiatives that could contribute to a sustainable, productive and liveable region in the future. Identify integrated solutions with multiple benefits across the water cycle. Assess solutions using a holistic, multi-criteria approach to capture elements that cannot be effectively costed, such as values relating to the environment and community liveability. Set a direction for integrated water management that paves the way for future investment with only minor costs incurred in the short term. THIS WORK IS NOT DESIGNED TO: Meet a single objective at the expense of others. Identify specific projects at a detailed level. Provide a detailed business case including precise cost estimates and quantities for a variety of water solutions. Ignore emerging challenges because of the current favourable status of water supplies. Evaluate major water supply augmentations. Align with the direction of the State Government s Living Melbourne, Living Victoria water policy. 1. Office of Living Victoria, A New Era in Urban Water Cycle Management: Business Strategy (2012) 6. An Integrated Water Future for Melbourne s North / 7

8 3. BACKGROUND ON MELBOURNE S NORTH 3.1 Location Metropolitan Melbourne has four distinct growth corridors as shown below: West, Sunbury/Diggers Rest, North and South East. MITCHELL SUNBURY/DIGGERS REST GROWTH CORRIDOR MELTON NORTH GROWTH CORRIDOR HUME WHITTLESEA MELBOURNE S FOUR GROWTH CORRIDORS Existing Urban Area Growth Corridor Outer Metropolitan Ring Road BROADMEADOWS FOOTSCRAY MELBOURNE BOX HILL RINGWOOD WYNDHAM WEST GROWTH CORRIDOR DANDENONG SOUTH EAST GROWTH CORRIDOR CASEY FRANKSTON CARDINIA The Northern Growth Corridor covers three municipalities: Hume, including Greenvale, Roxburgh Park, Craigieburn and Craigieburn West. Mitchell, including Beveridge and Wallan. Whittlesea, including Epping North, South Morang and Mernda. 8 / An Integrated Water Future for Melbourne s North Right: South Morang is part of the thriving Northern Growth Corridor.

9 An Integrated Water Future for Melbourne s North Image: / Yarra 9 Valley Water.

10 3.2 Future land use It is predicted that the Northern Growth Corridor will eventually accommodate a population of 260,000 and has the capacity to provide 83,000 jobs. 1 Current planning policy allows for the creation of 90,000 new residential homes and up to 1,050 hectares of new employment land. The majority of new employment land for the northern metropolitan region will be located in the Northern Growth Corridor. EXPECTED NORTHERN GROWTH AREA DEVELOPMENT KALKALLO CREEK - TOTAL AREA 5,528 Ha Residential Development: 2,032 Ha Employment Development: 245 Ha Roads: 1,424 Ha Drainage: 388 Ha Public Open Space: 1,440 Ha Residential Lots: 38,475 MALCOLM CREEK - TOTAL AREA 138 Ha OLD SYDNEY ROAD HUME FREEWAY Residential Development: 30 Ha Employment Development: 0 Ha Roads: 13 Ha Drainage: 5 Ha Public Open Space: 90 Ha Residential Lots: 560 AITKEN CREEK - TOTAL AREA 416 Ha KALKALLO CREEK SUB-CATCHMENT Residential Development: 234 Ha Employment Development: 0 Ha Roads: 102 Ha Drainage: 41 Ha Public Open Space: 39 Ha Residential Lots: 4,435 MALCOLM CREEK SUB-CATCHMENT MERR SUB-CA MICKLEHAM ROAD YUROKE CREEK - TOTAL AREA 90 Ha AITKEN CREEK SUB-CATCHMENT CRAIGIEB Residential Development: 52 Ha Employment Development: 0 Ha Roads: 23 Ha Drainage: 9 Ha Public Open Space: 7 Ha Residential Lots: 985 SOMERTON ROAD YUROKE CREEK SUB-CATCHMENT HUME HIGHWAY Current Urban Growth Boundary Previous Urban Growth Boundary Developable Land (Residential) Developable Land (Employment) Constrained Land Waterway Catchment Boundary Waterways Major Roads 10 / An Integrated Water Future for Melbourne s North

11 MERRI CREEK - TOTAL AREA 7,485 Ha WALLAN ROAD Residential Development: 1,203 Ha Employment Development: 805 Ha Roads: 873 Ha Drainage: 324 Ha Public Open Space: 4,279 Ha Residential Lots: 22,775 DAREBIN CREEK - TOTAL AREA 2,027 Ha EPPING ROAD Residential Development: 1,049 Ha Employment Development: 0 Ha Roads: 471 Ha Drainage: 183 Ha Public Open Space: 324 Ha Residential Lots: 19,870 PLENTY ROAD DONNYBROOK ROAD PLENTY RIVER - NOT INCLUDED IN ANALYSIS I CREEK TCHMENT DAREBIN CREEK SUB-CATCHMENT The Plenty River area is already largely developed and the majority of infrastructure required to service it has already been delivered. URN ROAD PLENTY RIVER SUB-CATCHMENT EDGARS CREEK - TOTAL AREA 616 Ha HUME FREEWAY EDGARS CREEK SUB-CATCHMENT Residential Development: 153 Ha Employment Development: 0 Ha Roads: 67 Ha Drainage: 27 Ha Public Open Space: 370 Ha Residential Lots: 2, Calculated on the Growth Areas Authority s Northern Growth Corridor Plan. An Integrated Water Future for Melbourne s North / 11

12 3.3 Key characteristics The landscape of Melbourne s North is characterised by a large valley floor flanked by the foothills of the Great Dividing Range. Basaltic clay soils are present throughout the area; following rainfall they can inhibit infiltration which, in turn, can trigger surface runoff events. It is estimated that prior to European settlement, rainfall triggered surface runoff events approximately six days per year. Other significant landscape features include floodplains associated with Merri Creek, natural wetlands, and Melbourne Water s Greenvale Reservoir and Kalkallo Retarding Basin. Melbourne Water s Healthy Waterways Strategy indicates that protection and enhancement of frog habitat in the headwaters of the Merri Creek catchment is a priority, as is the protection and enhancement of riparian vegetation. The Strategy also highlights the importance of catchment-wide stormwater management for waterway protection as the new urban areas are planned and developed across the upper and middle portions of the catchment. In the middle and lower (existing urban) portions of the catchment, social values such as amenity are considered a priority for management. 3.4 Opportunities identified in the Growth Corridor Plan As identified in the Growth Area Authority s Northern Growth Corridor Plan, opportunities exist to improve the area s waterways, including enhancing existing farm drains to address flooding risks while restoring waterway health. The existing Kalkallo Retarding Basin, and other existing and proposed retarding basins that might be identified in future Precinct Structure Plans, can be expanded to serve some upstream development. The alignment of the outer Metropolitan Ring/E6 Road reservation will have an impact on waterways and the location of future stormwater infrastructure. Due to highly erosive waterways in the upper catchment, development may need to be carefully staged in some areas to allow for construction of appropriate downstream stormwater infrastructure. Melbourne Water s regional retarding basin at Kalkallo has the potential to become an important open space facility for Melbourne s North. It is required to manage the increase in stormwater flows from the new urban development area by temporarily storing and then slowly releasing them to reduce peak flows. 12 / An Integrated Water Future for Melbourne s North 3.5 What happens when we urbanise an area? Prior to European settlement, the characteristics of the natural catchment in Melbourne s North were very different to what we see today. The area was known for its grassy woodlands, native grasses and mildly undulating terrain. Many of the tributaries of the Merri Creek were ephemeral (meaning water only flowed during winter) and much of the rainfall that landed on the catchment was either evaporated or transpired by the native vegetation. The remainder of the water seeped into the ground and was either stored in sub-surface aquifers or became part of baseflow, which eventually made its way to the receiving waterways. With European settlement the area was turned into farmland. The grassy woodlands and native grasses were cleared to make way for crops and cattle grazing and people began to permanently inhabit the area. Although the natural environment was altered, it could be argued that it had the capacity to absorb these changes. With pressure on metropolitan Melbourne to absorb the forecast growth in population, urbanisation is now planned for the city s Northern Growth Corridor. When this transformation is complete, some natural characteristics will be irreversibly altered: Increased population triggers a demand for drinking water, which in Melbourne is typically imported from distant catchments. The increased population also produces wastewater, which is often pumped long distances to connect to Melbourne s centralised infrastructure and for eventual treatment at the Western Treatment Plant. Native vegetation is removed and replaced with roads, paving and other impermeable surface types. These surfaces are typically connected to piped drainage systems that discharge directly into the nearest waterway, often delivering flows up to 10 times greater than what would have previously been observed. As well as an increase in the volume of water passing to the waterway, the number of days in which surface runoff events are triggered each year also increases. This changes the natural hydrology of the receiving waterway (particularly if the waterway was previously ephemeral) as storm flows are delivered more frequently and at a greatly increased intensity which in turn damages the habitat relied upon by resident flora and fauna for survival.

13 With reduced permeable surface area, reduced native vegetation, and removal and reshaping of topsoil, much less rainwater is stored within the soil structure to make its way into sub-surface aquifers and baseflow. Traditional servicing approaches (such as importing water, exporting wastewater, and diverting stormwater to the nearest waterway) only go part of the way towards addressing these issues, creating the need for a more integrated approach. Given the reality that development will occur, this work has considered a range of options for compensating and offsetting the significant changes with the primary aim of mimicking natural conditions as much as possible. There is a wide range of issues to consider when thinking about providing water services to an area as large as the Northern Growth Corridor. We need to deliver better environmental, social and economic outcomes for the community when compared with a traditional approach. We need to increase environmental performance and clearly articulate how much it will cost to do so. We need to ensure that the infrastructure solutions we select are flexible and adaptive to inevitable change over time. And last but not least, we need to improve community and stakeholder understanding and acceptance of the benefits and costs associated with integrated water planning by involving them in the process. The process adopted included the following key steps: Sharing a vision. With the Government s Living Melbourne, Living Victoria s vision as foundation, project partners agreed on key drivers for integrated water cycle management in the growth area. Defining options. Project partners identified five options that covered a range of traditional and non-traditional (more integrated) approaches. Options were selected to represent the extremes of what is currently possible and could be implemented without infringing on current Victorian State Government policy (i.e. recycling to supplement the drinking water supply). Developing a common evaluation framework, to measure the performance of each option against the shared vision. Collecting data using a variety of modelling tools. Assessing results. Analysing outputs from the common evaluation framework including confirmation of costs and benefits. Recommending a preferred future for consideration by the broader community. FORESTED URBAN Precipitation 83,898 ML 83,898 ML Evaporation and Transpiration Permeable topsoil 72,103 ML 55,414 ML Less permeable subsoil on rock Water table Infiltration 8,470 ML 17,991 ML Runoff Infiltration 1,702 ML 1,623 ML Base flow 9,040 ML 1,453 ML Any urbanisation of a previously unspoilt environment will have some impact. This diagram compares pre-development to the preferred future described in this document. An Integrated Water Future for Melbourne s North / 13

14 4. DEFINING A PREFERRED FUTURE 4.1 Shared vision There is a wide range of issues to consider when thinking about providing water services to an area as large as the Northern Growth Corridor. We have the opportunity to: Provide infrastructure solutions that are more flexible and adaptive to inevitable change over time; Deliver better environmental, social and economic outcomes for the community when compared with a traditional approach; and Engage the community and stakeholders to understand their preferences. The process adopted so far includes the following key steps: Minimising reliance on climate-dependant water sources such as dams. Melbourne has just experienced its worst drought in 100 years, subjecting residents and businesses to severe water restrictions. Reducing nitrogen loads passing to Port Phillip Bay, the heart of Melbourne. The Bay has a specific capacity to accept nitrogen loads before the natural ecosystems within it are irrevocably harmed. Despite treatment of wastewater at Melbourne Water s Western Treatment Plant and water sensitive urban design principles becoming ever more present in the design of the stormwater system, nitrogen is still discharged into the Bay in large quantities every year. Protecting waterway health (quality and hydrology) to ensure the survival of waterway ecosystems and maintain amenity. Protecting waterway flora and fauna creates waterway corridors that all Melburnians can visit and enjoy. Minimising groundwater impacts, particularly for surrounding land uses that rely on this as a primary water source. Minimising the risk of salinity issues ensures there are plentiful groundwater supplies available for industries such as food production, which operate in surrounding regions. Maximising community benefit through the implementation of innovative projects such as: Maximising the use of regional wastewater treatment plants by exploiting their 'waste to energy' potential. The Kalkallo Stormwater Harvesting Project, which is an important test case for whether stormwater can be treated to a drinking water standard and what the drinking water regulations associated with this type of supply should be. 14 / An Integrated Water Future for Melbourne s North Melbourne s Thompson Reservoir. Image: Melbourne Water.

15 4.2 Defining options Options investigated can be categorised into one of the following three groups: Traditional option how land developments are currently serviced. This option represents the 'default future'. Recycled water option an improvement on the traditional option. Integrated options are purposely engineered to tackle the issues associated with stormwater runoff volume and frequency. These options represent the 'preferred future' in which water cycle services are designed to take account of all the impacts they have on the environment. It should be noted that all options incorporate water efficiency measures including Water Efficiency Labelling Scheme (WELS) star rated appliances, fittings and fixtures. These measures are extremely important in keeping household water consumption as low as possible and further reducing the requirement to augment Melbourne s water supplies in the future. Traditional and nontraditional options were investigated. An Integrated Water Future for Melbourne s North / 15

16 4.2.1 Traditional option OPTION 5 A TRADITIONAL APPROACH WITH A 5 STAR HOMES UPDATE Piped drinking water supply and sanitation services are provided, through connection to Melbourne s existing centralised infrastructure. Rainwater and stormwater is collected in pipes and treated through a series of settling ponds and wetlands prior to discharge into the receiving waterway. With the introduction of the 5 Star Homes standards in 2004, 30 per cent of all new residential homes now install rainwater tanks for toilet flushing and outdoor uses and it is assumed this trend will continue. (In areas where recycled water is provided, this is not the case.) Recycled water option OPTION 2 REGIONAL WASTEWATER RECYCLING Wastewater is collected and treated to recycled water standard at a regional treatment facility. The recycled water is then returned to residential houses via a third pipe system for non-drinking purposes such as flushing toilets, washing clothes and watering the garden. Piped drinking water supply and sanitation services are provided; however, drinking water pipes can be downsized as approximately 30 per cent of the water demand will be met by the recycled water system. Rainwater and stormwater are collected in pipes and treated through a series of settling ponds and wetlands prior to discharge into the receiving waterway. Please note, this option is not considered to be integrated as it does not address stormwater runoff volume and frequency reduction. Image: Yarra Valley Water. 16 / An Integrated Water Future for Melbourne s North

17 4.2.3 Integrated options OPTION 1 HOUSEHOLD RAINWATER HARVESTING Rainwater tanks are installed at each residential house to collect water that falls on the roof. The water is reused to flush toilets, wash clothes and water the garden. Any collected rainwater that is not reused is passed through an onsite rain garden, which only overflows into the piped drainage system during large rainfall events. Larger bio-retention systems (which include swales, infiltration basins, and street tree beds) and wetlands are located throughout the piped drainage system, effectively disconnecting it from directly discharging into the receiving waterway. Piped drinking water supply and sanitation services are provided. The drinking water pipes cannot be downsized, as they need to be able to supply the total water demand for each house in the event that the rainwater tanks are empty (which in Melbourne s North is at least 20 per cent of the time) and for firefighting. OPTION 3 REGIONAL WASTEWATER RECYCLING WITH DRAINAGE SYSTEM DISCONNECTION As per Option 1 minus rainwater tanks. To compensate for the loss of rainwater harvested, an increased amount of large bio-retention systems are required throughout the catchment to ensure the piped drainage system remains disconnected from the receiving waterway. OPTION 4 REGIONAL WASTEWATER RECYCLING COMPLEMENTED BY HOUSEHOLD RAINWATER HARVESTING A hybrid of Options 1 and 3; however, in this instance, recycled water is used for flushing toilets, washing clothes and outdoor uses, while rainwater is used to supply the hot water service (subject to Department of Health approval should it be applied on such a large scale). OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION 5 Traditional Option Recycled Water Option Integrated Options Rainwater tank on each property Targeted stormwater runoff management Sewer flows to the existing system No reticulated recycled water No rainwater tanks Regional treatment and recycling Minimal stormwater runoff management No rainwater tanks Targeted stormwater runoff management Regional treatment and recycling Rainwater tank on each property Targeted stormwater runoff management Regional treatment and recycling DEFAULT TRADITIONAL OPTION No rainwater tanks Sewer flows to the existing system No reticulated recycled water Minimal stormwater runoff management SEWERAGE Reticulated Sewerage Transfer to Existing Sewerage System Local Treatment and Recycling WATER SUPPLY Reticulated Potable Water Supply Reticulated Recycling Water Supply Rainwater Tanks with Onsite Reuse * STORMWATER Catchment Scale Flood Protection Stormwater Quality Treatment Targeted Runoff Volume and Frequency Reduction *30% of households An Integrated Water Future for Melbourne s North / 17

18 OPTION 1 Hot water service Customer paved areas Rainwater tank Car washing/ irrigation Rain garden Customer property boundary Roads/ paved areas Bio-retention in street or public open space Retarding basin Backup supply Drinking water supply Western Wastewater Treatment Plant Port Phillip Bay OPTION 2 Hot water service Driveway / Other impermeable surfaces Car washing/ irrigation Customer property boundary Roads/ paved areas Retarding basin Local wastewater treatment plant Drinking water supply Western Wastewater Treatment Plant Port Phillip Bay OPTION 3 Hot water service Customer paved areas Rain garden Irrigation Customer property boundary Roads / paved areas Bio-retention in street or public open space Retarding basin Regional wastewater treatment plant Drinking water supply Western Wastewater Treatment Plant Port Phillip Bay 18 / An Integrated Water Future for Melbourne s North

19 OPTION 4 Hot water service Customer paved areas Rainwater tank Car washing/ irrigation Rain garden Customer property boundary Roads/ paved areas Bio-retention in street or public open space Retarding basin Backup supply Drinking water supply Regional wastewater treatment plant Western Wastewater Treatment Plant Port Phillip Bay OPTION 5 Hot water service Customer paved areas Rainwater tank Other impermeable surfaces / driveway Irrigation Customer property boundary Roads / paved areas Retarding basin Backup supply Drinking water supply Western Wastewater Treatment Plant Port Phillip Bay WATER SOURCES Drinking water Wastewater Stormwater Recycled water Rainwater An Integrated Water Future for Melbourne s North / 19

20 4.3 Developing a common evaluation framework To determine which option most closely achieves the shared vision, a common evaluation framework (referred to as the 'Tool') was specially developed by the project partners. This innovative tool was peer reviewed using a panel of experts from: Water utilities Councils Department of Sustainability and Environment Department of Primary Industries Surface and groundwater researchers from Melbourne and Monash Universities The land development industry. The Tool is made up of 12 sub-measures (see table on page 30) which, if fully achieved, result in the delivery of the shared vision. Each sub-measure is assigned a score out of 100, which is calculated using the inputs from a variety of modelling tools. Scores were assigned on the following basis: Meets or exceeds world s best practice = 100/100 Meets current documented best practice = 50/100 Meets the minimum acceptable standard = 0/100 Given that not all sub-measures are equal, a scoring process was developed to assign individual weightings. This mathematical process allowed for a range of stakeholder opinions to be captured and used for sensitivity testing. End Use Studies Appliance Stock Surveys Soil and Vegetation Type 4.4 Collecting data Data required to populate the Tool was gathered from a number of sources including: Water Demand and Wastewater Flow Estimator. Household water usage patterns were constructed based on persons per house, land size, and the types of fittings, fixtures and appliances likely to be present. Corresponding wastewater flows were then determined. All data used by the Estimator has been gathered as a result of extensive consumption monitoring and research. Water and wastewater network models. These computer models are used to size pipes, pumps, tanks and other network assets by simulating how they perform on peak demand (very hot days when outdoor consumption is high) or discharge days (following heavy rainfall when infiltration into the pipes occurs). These models enable appropriate sizing to ensure industry design standards and agreed customer service levels are met. Stormwater models. Used to simulate how rainwater and stormwater runoff volume and frequency change following urbanisation. This computer model was also used to provide information about the performance of household rainwater tanks, how much infiltration and evapo-transpiration is likely to take place based on the soil and vegetation types present, and the impacts on groundwater base flows and aquifer storages. Financial models (see page 21). Used a Net Present Value (NPV) model, which accounted for upfront and ongoing costs incurred by all of the community including water utilities, developers and property owners. Water Demand and Wastewater Flow Estimator Rainfall/ Evaporation Data Land Use Data Computer Models of the Water and Wastewater Networks Computer Model of the Stormwater System Stakeholder Group Weights Each Sub-Measure Defined Sub-Measure Score Calculations Analytical Hierarchy Process Individual Raw Sub-Measure Scores Individual Weighted Sub-Measure Scores Individual Sub-Measure Weightings HOW THE MODELLING INPUTS COME TOGETHER Data Inputs Common Evaluation Framework Sum of Individual Weighted Scores to Determine Overall Option Score 20 / An Integrated Water Future for Melbourne s North

21 4.5 Assessing results The Tool produces an overall score for each option. In effect, this score represents the overall environmental performance of the option against the shared vision and allows all options to be equally compared. However, decision-making is not as simple as comparing option scores and choosing the highest one. Community cost is of fundamental importance to everyone, especially in today s tough economic times; cost of living and housing affordability pressures are very real. In order to address this environmental performance and cost nexus, the concept of a community value ratio was developed. In effect, it measures 'bang for buck', or how much it costs to achieve a unit of environmental benefit. Although the community value ratios provide a more holistic comparison of the options, there are other factors to account for during the decision making process. These include: Adherence to current Victorian State Government policies. Practicality how easily could the recommended solution be implemented and maintained into the future? Customer willingness to pay an option may have the best community value ratio; however, customers may not value the increased benefits and be unwilling to pay for them. Image: Melbourne Water. Calculating Community Value Upfront Costs (Water Companies, Councils, Developers, Customers) Ongoing Costs (Water Companies, Councils, Developers, Customers) ASSESSING RESULTS Overall Common Evaluation Framework Score Total Community (Financial) Net Present Cost = Community Value Ratio Revenue (Water Sales) Bulk Charges New Customer Contributions Depreciation Required Return on Investment An Integrated Water Future for Melbourne s North / 21

22 5. FINDINGS IMPACTS BY 2040 By 2040, full development will have occurred and there will be at least 260,000 more people living in Melbourne s North, consuming more than 17,000 megalitres of water per year. The tables below represent the findings from the options assessment process with particular reference to water consumption, nitrogen discharges to Port Phillip Bay, stormwater quality, the volume and frequency of stormwater discharges, and the likely impacts on groundwater reserves. WASTEWATER DISCHARGES (ML/DAY) WATER USE (ML/DAY) Drinking Water Recycled Water Rainwater 50 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION To Local Treatment Plant for Recycling To Western Treatment Plant OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION NITROGEN DISCHARGED TO THE BAY (TONNES/YEAR) Nitrogen to Waterways Nitrogen Discharged from Western Treatment Plant 250 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION , ,000 25, STORMWATER QUALITY STORMWATER (% REDUCTIONS RUNOFF COMPARED VOLUMES TO HAVING (ML/YEAR) NO TREATMENT MEASURES IN PLACE) Runoff Nitrogen Volume Pre-urbanisation Runoff Phosphorous Volume Following Urbanisation Suspended Solids OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION 5 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION , , ,000 5, TOTAL 240 TOTAL 198 TOTAL 157 TOTAL 152 TOTAL STORMWATER RUNOFF VOLUMES (ML/YEAR) Runoff Volume Pre-urbanisation STORMWATER RUNOFF FREQUENCY (DAYS/YEAR) Runoff Volume Following Urbanisation Additional Runoff Days 35,000 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION 5 30, , , ,000 10, , / An Integrated Water Future for Melbourne s North STORMWATER RUNOFF FREQUENCY

23 GROUNDWATER (ML/YEAR) Flow to Groundwater Pre-urbanisation NET PRESENT COSTS ($M OVER 25 YEARS) Flow to Groundwater Following Urbanisation Community Cost (Net Present Cost over 25 Years) 2,000 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION 5 2,000 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION 5 1,500 1,500 1,726 1,333 1,482 1,721 1,427 1,000 1, The table below illustrates the hydrological changes that take place as a result of each option. With a total water demand of 17,200 ML per year, the numbers indicate an abundance of water in excess of what is naturally required to maintain the surface and ground waters. This does not take into account the 12,700 ML per year of wastewater that will be generated by the future population which could also be recycled and reused. NATURAL WATER BALANCE (ML/YEAR) Inputs Pre Settlement Option 1 Option 2 Option 3 Option 4 Option 5 Rainfall 83,898 83,898 83,898 83,898 83,898 83,898 Outputs Evapotranspiration 72,103 53,221 50,820 55,414 54,387 50,752 Surface runoff 8,470 15,880 31,292 17,991 16,494 30,936 Rainwater reuse - 7, , Base flow 1,623 6, ,040 7, To groundwater 1,702 1, ,453 1, By 2040 there will be at least 260,000 more people living in Melbourne s North, consuming more than 17,000 megalitres of water per year. Image: Villa World Developments Pty Ltd. An Integrated Water Future for Melbourne s North / 23

24 These results were used to populate the Tool. When combined with the sub-measure weightings determined by the stakeholder group, the following overall scores were obtained. COMMON EVALUATION FRAMEWORK WEIGHTED SCORES (OVERALL WEIGHTED SCORE OUT OF 100) Maximum Score Average Score Minimum Score Current Best Practice (Australia) Current Practice 80 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION Average Score Average Score Average Score Average Score Average Score This graph illustrates the step change in environmental performance, possible with a more integrated approach (Options 1, 3 and 4). Integrated options can deliver a step improvement in environmental performance. 24 / An Integrated Water Future for Melbourne s North

25 The community value ratios revealed that the integrated options also represented better value for money when compared to more traditional approaches (i.e. lower community cost to achieve the same environmental benefit) as seen in the chart below. COMMUNITY VALUE RATIO (COMMUNITY NET PRESENT COST $M PER UNIT OF COMMON EVALUATION FRAMEWORK WEIGHTED SCORE) Ratio Based on Maximum Score Ratio Based on Average Score Ratio Based on Minimum Score 60 OPTION 1 OPTION 2 OPTION 3 OPTION 4 OPTION Average Score Average Score Average Score Average Score Average Score Lowest value is best. Initially it looks like integrated options are more expensive but before jumping to this conclusion we need to take account of the additional environmental and liveability benefits that come with the integrated options. Our methodology enables us to avoid the very difficult task of assigning a monetary value to these additional benefits by simply asking key stakeholders and the community whether they are willing to pay for them. These results have been interpreted as follows: Options that include using recycled water avoid construction of a large diameter wastewater tunnel between Yarra Valley Water s Craigieburn Wastewater Treatment Plant and the recently completed Northern Intercepting Sewer which has an upfront cost of $240 million. This means that despite the additional infrastructure required to treat and distribute recycled water to households, recycling is still at least NPV $94 million cheaper than not recycling even without taking into account the resultant environmental benefits. If cost were the only decision-making criterion, Option 2 (a traditional approach with centralised wastewater recycling) would be preferred. However, the environmental benefits can be improved under Option 3 by around 40 per cent for a small cost increase estimated at around four per cent. When community value is considered, Option 3 appears best value. This includes management of stormwater runoff by creating a disconnection between the drainage system and waterways. An Integrated Water Future for Melbourne s North / 25

26 PROPOSED WASTEWATER TUNNEL Wastewater Treatment Plant Possible Future Wastewater Tunnel Existing Wastewater System Major Roads Urban Area (Existing) CRAIGIEBURN CRAIGIEBURN Wastewater Treatment Plant CRAIGIEBURN ROAD EPPING NORTH AURORA Wastewater Treatment Plant HUME HIGHWAY SYDNEY ROAD GREENVALE WORKS TO CONNECT TO METRO WASTEWATER SYSTEM (8.3KM TUNNEL) SOMERTON ROAD HUME FREEWAY SOMERTON LALOR EPPING ROAD THOMASTOWN CAMPBELLFIELD METROPOLITAN RING ROAD NORTHERN RING ROAD WESTERN RING ROAD FAWKNER HIGH STREET This wastewater tunnel can be avoided by recycling wastewater and returning it to households for non-drinking water purposes. Management of stormwater runoff volumes is critical in order to limit the frequency at which surface runoff events are triggered. There are a number of ways this can be done; however, it is apparent that the final solution will involve a mix of allotment, street and public open space scale works. Most solutions involve retaining stormwater within the catchment to facilitate greener open spaces. In turn, this will assist with natural cooling and shade provision. The Growth Areas Authority s Precinct Structure Plans and Melbourne Water s drainage master plans (known as Development Services Schemes) provide the opportunity to further investigate which options and opportunities are most feasible for the given location. 26 / An Integrated Water Future for Melbourne s North