INTEGRATED WATER FOR CASEY CLYDE James Westcott 1, Andrew Chapman 1, Jamie Ewert 2, Brigid Adams 3 1. South East Water, Melbourne, Vic, Australia 2. Melbourne Water, Melbourne, Vic, Australia 3. Department of Environment Land Water and Planning, Melbourne, Vic, Australia ABSTRACT This paper addresses Integrated Water Management (IWM) within the Casey Clyde Growth Area (CCGA), a major growth region of Melbourne. The project was a pilot for the (former) Office of Living Victoria s (OLV) regional analysis, the lessons from which will be applied to IWM schemes across Melbourne and further afield. The paper focuses on the process taken to integrate water into urban planning, including the approach taken to engage with stakeholders, and deals with the economics of IWM in a greenfield area. INTRODUCTION The City of Casey is located approximately 40km south-east of Melbourne and is Victoria s largest municipality by population. It is one of Australia s fastest growing municipalities with the population expected to grow from 270,000 to 451,000 by 2036. The municipality has a mixture of established urban areas, growth areas and rural land. The Victorian government announced a major expansion to Melbourne s growth boundary in 2010. The CCGA was included as part of the expansion and significantly increased the amount of developable land within the City of Casey. The growth area will ultimately contain 50,000 properties and 130,000 residents. The development of the region provides an opportunity to shape water policy in the south-east of Melbourne for the next generation. From the outset of planning it was recognised that a highly collaborative approach between the relevant authorities was required in order to deliver a best for community outcome. South East Water, Melbourne Water, the Metropolitan Planning Authority (previously the Growth Areas Authority) and the City of Casey formed a working group to drive the process. During the development of IWM servicing options the Victorian Government established the OLV and in December 2013 released Melbourne s Water Future, detailing its urban water policy. The policy s vision was for: An integrated and resilient water system, which is planned and managed to support liveable and sustainable communities, protect the environmental health of urban waterways and bays, provide secure water supplies efficiently, protect public health and deliver affordable essential water services. (OLV, 2013) The OLV became a key project partner, with delivery against government objectives a key project requirement. The CCGA provided the OLV a robust pilot study for regional analysis and how it could be applied to other regions of Melbourne and further afield. BACKGROUND The CCGA has aspects specific to the region that are relevant in decision making for water management and services, see Figure 1 and Table 1. These include: The area drains to Western Port Bay, a Ramsar wetland, which has high ecological value. The State Environment Protection Policy schedule F8 essentially prohibits discharge of wastewater to streams and bay due to stringent quality requirements. Waterways in the region are highly modified and have low environmental value. Areas to the south and east of the growth boundary are low lying (<5m above sea level) and prone to flooding. It is on the edge of existing development, most of which is mandated for 3rd pipe recycled water and adjacent to Bunyip food belt, an agricultural area with growing demand for water. Significant water supply transfer systems are adjacent the area (Tarago pipeline, Cardinia outlet main, desalination to Cardinia pipeline).
This existing infrastructure offers various supply configurations. Eastern Treatment Plant (ETP) is nearby, producing large volumes of Class A recycled water. Unused Class A water is discharged via the South Eastern Outfall (SEO) to Bass Strait. Water Infrastructure Group s Eastern Irrigation Scheme provides recycled water to South East Water and to market gardens within the CCGA. The area is not within ETP s natural catchment, requiring extensive infrastructure to discharge to the nearest transfer assets. The transfer infrastructure is capacity constrained. INTEGRATED WATER OPTIONS Nine options were designed to provide water services (water, sewerage and drainage) while addressing regional constraints. These options were specifically designed using an IWM approach to deliver against the OLV objectives. The nine options were assessed against a base case of a conventional servicing solution, where all water and sewer services are supplied centrally and no recycled water is supplied. The options contained permutations of the following alternatives: Household water efficiency. Rollout of water efficient appliances and continuation of water efficient behaviours was assumed under all options, including the base case. Recycled water. Supply to residential households and open space from a centralised scheme (ETP), full local treatment or sewer mining. Rainwater tanks. 2kL or 5kL tanks were considered for residential households. The base case included partial uptake of rainwater tanks, representative of what is seen under the current building code. Stormwater harvesting Treatment to Class A and use within a 3rd pipe network. Harvesting and treatment considered within and outside of the growth boundary. Water sensitive urban design (WSUD) Local water quality treatment vs precinct scale WATER BALANCE The options provided a range of reductions for potable water, sewage discharge and stormwater runoff. The reductions were demand dependent with consideration given to the full range of end uses for alternative water. Table 2 shows the reductions which could be achieved and are summarised below: Potable water demand reduced by 46% to 62%, equivalent to 5 to 7 GL per annum. Sewer effluent discharge reduced by 53% to 67% for options with Class A supply from sewage treatment. Stormwater runoff reduced by 29% to 49% for options with stormwater harvesting or rainwater tanks. For options that are rainfall dependent, with either rainwater tanks or stormwater harvesting, the reliability of supply is a key issue. Complete reliability was not targeted due to diminishing marginal returns from additional storage. It was necessary to have a reasonable balance between reliability of supply and storage size, with the decision driven by practical considerations. STRATEGY REVIEW The OLV conducted a review of the CCGA analysis to ensure alignment with policy objectives and as a verification of the technical outcomes. All aspects of the water cycle were considered at a metropolitan scale to verify that the major cost drivers were included and that the results were realistic. There was a high level of agreement between the two approaches providing confidence in the results. The review highlighted the potential for greater WSUD within the growth area to minimise the required land take for wetlands. A further option was added to the analysis to take this into account. Savings within the wider system emerged as one of the key cost drivers which differentiated between the options. ECONOMIC ANALYSIS An economic analysis was conducted to ensure that all costs and benefits should be quantified as far as possible, rather than rely upon subjective measures such as multi-criteria analysis. The CCGA assessment focused on determining the best for community outcomes. All parties agreed that the distributional impacts and cost sharing arrangements should be determined once a
preferred option is identified. The assessment was developed to deliver the following outcomes: 1. Whole of community net benefit assessment 2. Validation of the preferred option 3. Analysis of distributional impacts and funding Figure 2 shows the net present cost of all options under a base case scenario, excluding environmental and social benefits. The majority of options were within 5% of a conventional servicing option. Without a major difference in cost between the options the analysis focused on the additional non-market benefits provided by each option. The environmental and social benefits were quantified as far as possible. Valuing many of these items was difficult due to a lack of market mechanisms or complete understanding of the impact of IWM options. Figure 3 shows the value of the environmental and social costs and benefits which could be quantified for each option. Compared to the overall cost of servicing CCGA the social and environmental benefits were less than 5% of the total cost. However it was recognised that this was likely to be an underestimate due to difficulties in quantification. For example there was no quantification of the community value provided by recycled water in offering freedom from water restrictions during a drought. No value was placed on this as Melbourne s desalination plant should theoretically eliminate restrictions, however the community may value using recycled water for some end uses. After inclusion of environmental and social costs and benefits, land take and other items recycled water or rainwater tanks become cost neutral options. The major cost drivers, which provided differentiation between options, were the long run costs of augmentation to the centralised water and sewer systems. Significant cost variables were tested, with key sensitivities being: Discount rate Headworks augmentation cost Sewer treatment augmentation cost Under the majority of scenarios an IWM servicing solution was either more cost effective or cost neutral, on a whole of community cost basis. The distribution impacts of some IWM options were difficult to determine as management responsibility had yet to be allocated. Rainwater tanks are a clear example. Historically tanks have been maintained by the householder, with minimal input from authorities. However to achieve the multiple benefits attributed to rainwater tanks through the IWM analysis, such as downsizing of the potable water system or stormwater quality improvements, more active tank management may be required. In fact without active management water authorities may not downsize other assets and achieve the infrastructure savings that are the basis of wide scale rollout of rainwater tanks. To understand the industry s view of this and other issues further stakeholder engagement was necessary. DESIGN CHARETTE A one day design charette was held with approximately 60 people from across government and the water industry in attendance. The key objectives of the charrette were to: Provide understanding to a wider audience of the option evaluation process. Develop in principle agreement for the delivery of IWM for CCGA. Identify critical issues and opportunities for the design and delivery of a preferred option. The charette provided a vehicle to engage with a wider audience than had previously been possible. It allowed for a much wider engagement of stakeholders and for input from more staff from preexisting stakeholders. The vast majority of attendees were in favour of an IWM servicing solution for the CCGA. The major technical concern raised was whether rainwater tanks are capable of delivering a significant reduction in flooding volumes, hence allow cost savings in drainage infrastructure. It was agreed that further work was necessary in this space. The key issues identified by the major stakeholders were: Equitable cost sharing Understanding of responsibilities for each party Risk management, including; o Responsibility for regulatory targets o Being the supplier of last resort, needing to be capable of delivering water cycle services if decentralised schemes are not sufficiently reliable Land take Greater clarity was required regarding who would own, operate and maintain IWM infrastructure.
There was concern that IWM would be used to push cost from one authority to another without a corresponding shifting of revenue. The interaction of water with urban planning was also highlighted. Some options may have a positive or negative effect on the precinct form, for example shifting water infrastructure into constrained land may allow additional space for community facilities. In other options the additional land take would be a critical consideration. If developable land is lost to water infrastructure it has a negative impact on housing affordability, one of the key targets for the growth area. DEVELOPER CONSULTATION Delivery of household assets, be it third pipe reticulation or rainwater tanks, is primarily provided by the land developer. For successful delivery of IWM it is critical that the development industry is able to see value and be able to market it to potential customers. A consultation session was run to ascertain the views of the land development industry. An invitation was extended to developers and landholders within the CCGA. The following comments were expressed on the day: Recycled water is now considered business as usual for many developers in Melbourne. Not being able to offer recycled water within a subdivision puts it at a marketing disadvantage. There is a willingness within the industry to fund and gift recycled water reticulation assets to the water authority. A major concern about IWM options was the loss of developable land for water storages and treatment facilities. A limited number of developers will actively seek to deliver beyond what is required from council or the water authorities. Generally the industry was supportive of, and expected, the continued rollout of recycled water. Hesitation was expressed regarding other IWM solutions. However much of the hesitation may be driven by a lack of clarity around what the options entail or an unfamiliarity with the requirements for the development industry. PREFERRED OPTION All options provided significant reduction in potable water demand. Options with sewage recycling minimised effluent discharge and options with rainwater tanks or stormwater treatment provided reductions in the runoff to Western Port Bay. The majority of options were within +/- 5% on a net present value basis. The cost differential between a conventional servicing option and one that provided non-potable supply was relatively minor, particularly after consideration of environmental and social costs and benefits. Based on the relatively minor cost differential, an expectation from developers that Class A water will be available, and government policy that IWM options are pursued, it was recommended to South East Water s Board that the area be mandated for third pipe. To ensure all developers deliver the necessary infrastructure the requirement was embedded in the precinct structure plans for the region. Importantly this option leaves open the decision regarding the source of Class A water. Recycled water is the traditional source however harvesting of urban stormwater also has merit in this location. The third pipe network supports both sources (at Class A standard) and enables future choice about local treatment options once the development has reached a critical mass. However it was recognised that the option to service the area with rainwater tanks, whilst having a similar cost benefit outcome as recycled water, had significant uncertainty regarding long term management and maintenance responsibility. Due to the operational concerns this option was not recommended. TRANSFERABLE KNOWLEDGE A number of lessons can be identified for other large scale IWM investigations. These findings include: For a major growth region an IWM servicing solution can be delivered at a cost equivalent to that of a conventional servicing solution. It is possible to achieve a win-win-win scenario where government, water authority and developer objectives are achieved. A win-win-win scenario is facilitated by a focus on the best for community solution by all stakeholders. The distributional impacts and any cost sharing arrangements should be agreed after the preferred option is determined. This can be achieved by making all costs and benefits explicit within the analysis, and giving consideration to the respective cost owner from the outset. Determination of the cost owner is
critical for understanding of the distributional impacts and can be difficult to analyse retrospectively. Early identification and understanding of major cost drivers for conventional servicing is critical. A rapid assessment can be made on the suitability or otherwise of IWM servicing solutions. A high level assessment of IWM viability can save time, money and ensures that commitment is given to a realistic solution. CONCULSIONS By their nature IWM schemes cross the boundaries between authority s areas of responsibility, and require high levels of engagement between internal and external stakeholders. From the work done in the CCGA a number of critical factors to development of a successful scheme were identified including a solid technical basis for design, robust economic analysis with cost sharing principles and buy in and willingness from all stakeholders to drive best for community solutions. The CCGA analysis demonstrated that IWM servicing solutions can be delivered to large scale development at a similar community cost to a traditional centralised servicing solution. IWM provides environmental, social and economic benefits and can deliver a servicing solution which delivers government, water authority and developer objectives. The project approach, process and learnings are applicable to all authorities who are considering the value of IWM for servicing of new growth areas. ACKNOWLEDGEMENT South East Water, Melbourne Water and the Department of Environment, Land, Water and Planning would like to thank the City of Casey and the Metropolitan Planning Authority for their assistance, guidance and patience during the process. Without the support of many internal and external stakeholders delivery of the CCGA IWM strategy would have been impossible. Special thanks to Hendry Young from SKM for his assistance with the technical analysis. REFERENCES Office of Living Victoria, 2013. Melbourne s Water Future, Victorian Government, Melbourne, Australia
Figure 1: The Casey Clyde Growth Area and surrounding infrastructure Table 1: Details of water infrastructure Water Sewer Westernport Bay SEPP Supply from Cardinia, Tarago, & Desalination Adjacent to existing recycled water areas Out of ETP catchment Limited trunk sewer capacity No treated effluent discharge Higher stormwater quality RAMSAR wetlands Waterways and drainage Filled in swamp Poor quality streams Known flooding issues Capped Catchment
Table 2: Annual volume reductions against the 2005/06 base case Option Potable Water Discharge to SEO Stormwater 1 Traditional Centralised 19% 21% 0% 2 ETP Recycled* 51% 67% 0% 3 Small STP* 51% 67% 0% 4 Large STP* 51% 67% 0% 5 Centralised SWTP* 51% 21% 49% 6 Decentralised SWTP* 51% 21% 49% 7 Combined STP & SWTP* 51% 67% 0-40% 8 Rainwater Tanks 46% 21% 39% 9 Large STP & Rainwater* 62% 53% 29% ETP Recycled, Rainwater & 10 in-catchment stormwater* *Including third pipe Class A water 62% 53% 29% Figure 2: Option Net Present Cost by cost owner 40.0 30.0 $ million 20.0 10.0 0.0-10.0 1 2 3 4 5 6 7 8a 9 10 Avoided bulk cost Land Heat island effect Household amenity Quality at Boag's Rock Phosphorus Nitrogen -20.0 Option Figure 3: Community Benefits and Disbenefits