Case study Aurora Estate (Epping North)

Figure 4.9: Impressions from Aurora Estate, Epping North

Introduction:

The Aurora Estate in Epping North is a residential development under construction of approximately 650 ha and 10.000 lots (see also Figure 4.9).106 The estate is developed as a demonstration for sustainable urban design, including relatively high dwelling densities, energy efficient homes, public transport, social infrastructure, the implementation of fibre optic connections to each home and the implementation of water sensitive design features.

The topography of the area is undulating and located on newer volcanic plains and consists of basalt plain interspersed with stony rises. A few small watercourses are running in the north south direction. The site also consists of cleared pastures scattered with remnants of red gum woodland. It contains remnants of native grassland, but this is severely degraded by weeds.107

Initiative:

By the end of the 1990s, the former Urban and Rural Land Corporation (now VicUrban after a merger with the Docklands Authority) was looking for a new benchmark for sustainable urban design after completion of Roxburgh Park Estate, which was a benchmark for sustainable building in the 1980s and 1990s. In its search for a new benchmark for sustainable urban design the developer of Aurora Estate found the area of Epping North most suitable. At that time, Epping North was located between two growth corridors (Hume and Whittlesea) that were designated by the Victorian Government. However, Epping North was considered more suitable for development than the top ends of the Hume and Whittlesea growth corridors because it was closer to the existing public transport system, the area had less environmental value and the land was affordable. At this moment, Epping North is also one of the growth areas that are determined in Melbourne 2030. The area had no existing infrastructure, was affordable, had low environmental value and was relatively close to the existing public transport system. In 1998 the developer started land procurement procedures in Epping North. At that time the area was not serviced with any infrastructure before development.

Because no infrastructure existed at the location, various options were considered to service the area in 1998. For one of the first times in urban development in Melbourne externalities were taken into account. It appeared that the construction of a new sewage treatment system, that also could provide Class A recycled water for outdoor purposes and toilet flushing, was financially advantageous compared to extending the existing sewage system in adjacent areas and treat the pollution of Port Philip Bay caused by the estate afterwards (the externalities in this case are the costs for treatment afterwards). The understanding of the financial value of these externalities was the main driver for the

106 _{Source: Coomes Consulting (2007)} 107 _{Source: McLean (2004)}

development of Aurora, because it made a new treatment plant the cheapest option. The sustainability commitment of the developer and the state government amplified this driver on the background.

WSUD Goals:

For the (conceptual) design of Aurora Estate the developer has adopted the Ecological Sustainable Development (ESD) principles (see also Chapter 4.2: Case study Melbourne Docklands). For Aurora these principles include the following components: water, housing density, energy use, public transport, social infrastructure, and information technology.

Water Sensitive Urban Design principles were used to minimise the impact on the environment and meet the demands of the water component of the ESD principles. It was aimed to create a new WSUD benchmark that considered water supply, wastewater and stormwater as integral streams. The built form was included in the strategic planning of the project and WSUD techniques applied at the estate level, streetscape level and allotment level.

The WSUD goals for Aurora were108:

• to minimise the amount of potable water imported to the site

• to minimise the amount of wastewater generated from the development • to maximise the use of recycled wastewater

• to maximise the use of rainwater for those end uses not considered acceptable to be supplied by recycled water

• to minimise the stormwater pollutant loads discharge from the site • to implement mimicked natural stormwater flows

In August 2006 a Sustainability Covenant is signed by the EPA Victoria, the developer, the water company and the local council. In this statutory agreement, which is formed under the Environmental Protection Act 1970, the actors agree to work together to increase the efficiency with which resources are used in Aurora and reduce the ecological impact of Aurora.109 In the Covenant for example the commitment of the developer to implement water saving appliances and WSUD features is determined.

Relatively high dwelling density:

Part of the sustainability principles for Aurora is achieving high dwelling densities in order to keep Melbourne as compact as possible. Therefore, the dwelling densities are significantly higher in the Aurora Estate than in other residential subdivisions across Melbourne. In Aurora the average dwelling density in the built area is 22 dwellings per hectare.110 The Victorian Government aims in Melbourne 2030 for 15 dwellings per hectare in new residential subdivisions, which is already higher than the average dwelling density in older residential subdivisions.

The water system:

Within the urban design of a relatively high dwelling density, the water system in Aurora is designed to meet the WSUD goals that are described above and consists of three important parts: demand management, wastewater treatment and re-use, rainwater harvesting and stormwater treatment. The indoor household demand is being reduced with 26% to 130 l/person/day by the implementation of water saving fittings and appliances in comparison to the average water demand. 111 This water consumption is being used in a water balance model called Aquacycle to calculate the water demand of the estate for different scenarios over a twenty year historical period using a daily time step to simulate the actual inflows and outflows of the system, including rainfall, evaporation, storage, irrigation and household demands. Aquacycle is being developed by the Co-operative Research Centre for Catchment Hydrology to investigate the use of locally generated stormwater and reclaimed

108 _{Source: McLean (2004)} 109 _{Source: EPA Victoria (2006)} 110 _{Source: McLean (2004)} 111 _{Source: McLean (2004)}

water as a substitute for imported water.112 Figure 4.10 shows the water balance at the estate level of Aurora.

Figure 4.10: Water balance of Aurora at the estate level (Source: McLean (2004))

The water balance shows that potable water supply is partly being substituted by recycled water, raintank water and stormwater runoff in WSUD streetscape features. If this substitution is added to the demand reduction that can be achieved through household demand management, the volume of imported potable water can be reduced by 70% in comparison to a conventional development.113

Supply of recycled water:

Recycled water is being supplied to each household in Aurora by a third pipe system. The third pipe system in Aurora is different to the third pipe system of the Hunt Club Estate, because the source of the recycled water comes from the development itself. A wastewater treatment plant, which is built near the Aurora development treats the wastewater of Aurora to Class B water. This is standard treatment of wastewater in Melbourne. After the first treatment step, the water is stored in a reservoir (dam) with a capacity of ca 300 ML before it is treated to Class A water. The Class A water is distributed through the third pipe system for outdoor purposes (gardening and car washing) and toilet flushing. With the storage reservoir the system has at all times sufficient resources to provide enough water when the demand is high (in summer).

For the reticulation of the recycled water a similar system is used to the third pipe system in the Hunt Club Estate, including purple pipes, appliances and fittings, removable taps, warning signs etc. However, the water company uses a slightly different approach and requirements towards the development of the system than the water company in the Hunt Club Estate. For plumbers this means that some technical details have to be constructed differently.

112 _{Source: Mitchell (2000)} 113 _{Source: McLean (2004)}

Rainwater harvesting:

Next to a connection to the third pipe system is every home supplied with rainwater harvesting systems that collect rainwater from roofs and store this in rainwater tanks with an operational capacity of 2.300 litres.114 _{The rainwater tanks are located underground and do not require any garden space.} Before the rainwater is being used for domestic hot water use115 it is treated with a first flush device and UV disinfection unit. Rainwater harvesting systems have been tested in 2003. This test provides an indication of the likely Aurora environment in 10 to 15 years time and has produced optimistic results.

Collection of rainfall of roofs is a technology of over 3000 years old. In Australia the use of rainwater tanks is an established technology and common practice in rural and remote areas. Regulation and guidelines exist for the use of this technology. In 2004 in Victoria, 13% of the households had rainwater tanks (3% in Melbourne and 36% of all households in the rest of Victoria), of which 11% used rainwater as the main source of drinking water.116

Stormwater treatment:

Stormwater treatment features are being incorporated on different scale levels throughout the estate. The stormwater treatment features at the different level all function in similar ways: a soil passage before discharge of the runoff to the main stormwater drain.

At the allotment level, raingardens that are located in back yards provide treatment of stormwater runoff from allotments before this is being discharged to the rear easement drain (see Figure 4.11). According to McLean (2004) typically 50% of stormwater runoff from allotments discharges to rear easement drains, which is a limitation for the ability of treatment features at streetscape level to sufficiently treat stormwater runoff. Without the incorporation of raingardens an end-of-line measure would be required to meet the treatment targets of Clause 56 (removal of 45% of total nutrients and 80% of suspended solids).

Figure 4.11: Raingardens in Aurora: photograph (left) and cross-section (right, Source: VicUrban (2007c))

At the streetscape level, vegetated swales and bio-retention strips provide treatment before discharge to the main stormwater drain (see Figure 4.12 and Figure 4.13). Vegetated swales treat road runoff, while the bio-retention strip in Figure 4.13 treats runoff from a car park. Besides removal of suspended solids and nutrients the bio-retention features at streetscape level are also capable of removing hydrocarbons and heavy metals. The WSUD features at the streetscape level are being designed for a

114 _{Note: In Australia a difference is being made between stormwater run-off and rainwater. Rainwater is precipitated water that}

is collected from roof surfaces. Stormwater run-off is precipitated water that has been flowed over other paved and unpaved surfaces, such as streets.

115 _{Note: In Australia hot water systems that provide hot water for cooking are existing in most kitchens.} 116 _{Source: Australian Government (2004)}

five year Average Return Interval (ARI). This is equal to the ARI that is used for the design of the streets.

Figure 4.12: Vegetated swales in Aurora: photographs (above) and cross-section (below, Source: VicUrban (2007c))

Enabling factors:

• Sustainability: The developer of Aurora wanted to create a new benchmark for sustainability. An important aspect of sustainability in Aurora is reducing the water demand of the estate and minimising the pollution load from the development towards receiving waters. Also the Victorian Government and the water authorities had sustainability on the agendas. However, the sustainability driver was sitting on the background for the uptake of the third pipe system. The real driver for the uptake of the third pipe system was the lack of infrastructure at the site and the necessity to service the area.

• Location characteristics: The location characteristics determined that the Epping North was chosen for the demonstration project for sustainable development. The location of Epping North for the development was favoured above the growth corridors of Hume and Whittlesea, because it was closer to the existing public transport system, had less environmental value and was affordable land.

The fact that the area was lacking infrastructure offered an opportunity for the installation of a new sewage treatment plant that could produce recycled water, because the area had to be serviced somehow. Two options were considered: connection to main sewer pipes in nearby areas, or installation of a new sewage treatment plant. Because of the acknowledgement of externalities (see below) the latter would be cost neutral and contribute to the sustainability drivers of reducing water demand and minimising environmental impact.

Furthermore, the availability of scale at the location was essential to keep the cost per allotment relatively low by dividing the extra costs for the third pipe system over many allotments. The cost of the treatment plant is relatively independent to its size.

Finally, the possibility to expand to future development increases the operational flexibility for the water company.

• Acknowledgement of externalities: For the choice between connecting the new development to the existing sewer system in nearby areas and installing a new treatment plant that could also provide in recycled water externalities were taken into account for one of the first times in urban development in Melbourne. If waste water would be discharged to Port Philip Bay, Melbourne Water would have had to remove the N and P loads from this discharge. The costs for this would have been $2,7 million. In 2001 the extra costs for uptake of the third pipe system were approximately $2500 per allotment. The acknowledgement of externalities ($2,7M) made the uptake of a new treatment plant for Aurora therefore cost neutral.

• Commitment of stakeholders: According to the interviewees commitment and support from especially the highest management levels was important to get things of the ground. For example, the development of Aurora was initiated by the general manager of the developer who was prepared to demonstrate the opportunity for innovation. Also the upper management of the water authorities and the governmental agencies supported the development of Aurora. To ensure the ambition of the highest management levels was taken over by lower levels within the organisations, the Environmental Protection Agency, local council, developer and water company have defined this commitment in the Sustainability Covenant. Lower organisational levels were also educated about the planned concepts for the same purpose (see below).

• Knowledge, experience, trust and education: Knowledge and experience resulting in trust of the planned technologies are crucial factors for introducing innovations in Aurora. Various interviewees have mentioned that lack of knowledge and understanding of a third pipe system and its risk has resulted in agency reluctance. However, there has been a lot of education over the last few years to address this problem. In the development process of Aurora, the engineering company played a key role in educating the other stakeholders. The engineering company put all the stakeholders around the table and informed them about the options for Aurora. This has resulted in a document with all the plans and strategy for Aurora (“Integrated Water Management”). This document is being reviewed by leading water professionals across Australia. Also experiences from Sydney and Adelaide where third pipe systems already had been implemented assisted in removing agency reluctance.

The main concern for the regulators and water company were the potential health risks. This was also the case for the rainwater for hot water systems. To remove these concerns, trail systems were implemented under conditions that are similar to Aurora. The developer got all the stakeholders together to explain the outcome of the trails. By showing it was a viable option to introduce this technology in the urban area based on test results the developer changed the perceptions towards the risk. The results of these tests are taken up in a database of the Co- operative Research Centre for Water Quality that will assist in future decisions in relation to rainwater harvesting systems.

After decision makers have decided about the implementation of innovative technologies, it is also crucial that grass roots people that have to get the systems of the ground have full knowledge. According to the interviewees, this group of people will have to deal with understanding of the technology, implementation of the system, a testing regime to monitor the system, and how to deal with events or incidents. For Aurora, the engineering company has set up an education program to educate the people that are involved with the implementation of the new techniques, such as the third pipe system and the rainwater for hot water systems.

Throughout the development process new knowledge is continuously being gained. Because Aurora is being developed in several stages, developments in earlier stages can be evaluated before they are included in next stages. According to the council, especially the raingardens will be carefully evaluated, because this de-central system is impossible to control by the local council. The council is afraid that the raingardens will be used improperly by the residents, so that they will not sufficiently be able to treat stormwater runoff anymore.

According to most interviewees, reluctance because of insufficient knowledge should not be an impediment anymore, because experiences and lessons are being shared among stakeholders and there is a more co-operative approach now between the Victorian water authorities. However, the interview with the council revealed that their conservative attitude towards WSUD may be caused by insufficient knowledge and understanding of the concept.

• Robustness of the system: Robustness of the implemented systems is important to minimise the probability of failure. Several examples of creating robustness of the implemented systems can be found in Aurora.

At first, 2 summer handovers of the water treatment assets are being used to increase the robustness of the assets. After this period it is expected that possible hidden failures of the design of implementation have been revealed. The council who takes the assets over from the developer has therefore a lower risk of having to invest extra capital.

At second, the water company who is responsible for the supply of recycled water is seeking for methods to increase the robustness of the system to prevent calamities. The water company is confident that during construction everything is fine in relation to cross-connections, but not when the handyman takes over. Therefore it is working on something that gives users a direct warning if they drink recycled water. The water company has regarded three options:

- Testing of users. This is being done (once per 5 years) in Sydney and Adelaide where older and bigger schemes are present. However the water company believes this method is intrusive towards the users and does not guarantee that someone drinks recycled water the day after the test.

- Colouring. The water company does not think this is a good option either, because colouring can cause stains and does not look good in toilets.117

- Taste (salty or bitter). The water company is working together with the industry to find a suitable substance to put in the water, so that users that drink recycled water will spit it out immediately.

117 _{Note: The recycled water in Aurora is not expected to be coloured in contrary to the recycled water from the Eastern Irrigation}

Scheme that is used in the Hunt Club. The EIS also treats industrial waste, which causes the colour. In Aurora only domestic