FENNER CONFERENCE ON THE ENVIRONMENT
Sam Austin (BE Civil) is General Manager, Asset Services, Yarra Valley Water. He is responsible for optimising commercial returns from Yarra Valley Water's investments in water and sewerage assets and the service levels delivered through these assets. He manages YVW's environmental and operational risks and plays a key role in servicing new urban growth areas. He is ultimately responsible for ensuring the Yarra Valley's water and sewerage systems meet the daily and future needs of customers. He also manages the primary regulatory interface with the Environment Protection Authority and the Department of Human Services.
Case study: Water management planning, Hume corridor in Melbourne
Mr Sam Austin
Darryl Low Choy spoke of the high-level planning issues in south-east Queensland. I am going to take you down to a local level, the provision of sewerage and water infrastructure to the Hume corridor in Melbourne.
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Yarra Valley Water was formed in 1995. We are the largest of the three retail water companies in Melbourne. We buy our water about 180 GL of water in our case from Melbourne Water. We are still owned by the state government, despite a common misconception of our customers, who think we are privatised. We are not. We serve about 650,000 properties, 1.5 million people. We have an operating licence, we have a customer contract that defines the levels of service we have to provide, and we operate under a commercial board from the private sector.
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The Yarra River runs through the centre of Yarra Valley Water. To the west of us, the city retailer is City West Water, and to the south, South East Water.
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The work that we have been doing over the last few years has been targeted at reducing the environmental footprint of the provision of water and sewerage services in Melbourne. We have identified four key points that define the footprint that our provision of water and sewer services makes. They are the impact of the extraction of water, both in quality and in the impact on the waterways; the effect of treated wastewater back into waterways and oceans; greenhouse gas, in particular, which we believe is our highest environmental impact; and closing the nutrient loop, taking nutrients back to the land.
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The Hume corridor is about 15 km of land between Craigieburn and Wallan. Those of you who have driven up the Hume Highway would know that Craigieburn is starting to develop very quickly. Between there and Wallan there is a lot of small farming development. Up to Wallan, fundamentally, that land is all owned or optioned by developers. And there is a real opportunity for us to look at how we provide the sewerage services.
The bulk of sewerage services in Melbourne are provided by a treatment plant to the west, at Werribee, and to the east at Carrum. That is some 40 to 50 km to the south of the Hume corridor, so there is a real opportunity to avoid transporting that quantity of wastewater away and potable water in from the eastern suburbs where the water is captured.
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This is a greenfields area, with minimal infrastructure. Strong growth is forecast for the next 50 years, but the extent is very uncertain. A lot of the area is outside the urban growth boundary. Nevertheless, the development industry is buying land and optioning land outside the growth boundary, with the intention of getting that land rezoned. So the exact extent of the development is uncertain, and that makes planning for it very difficult for us as well. It could vary from 55,000 residential lots down to as low as 14,000. So one of the things we have got to do is to give ourselves flexibility in the provision of that infrastructure.
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Conventional servicing would have the water all pumped up from the south; sewerage from Kalkallo, which is halfway between Craigieburn and Wallan, would be pumped over the hill back to Craigieburn and would then gravitate to the treatment plant at Werribee, which is some 25 to 30 km away. To the north of Kalkallo we would be servicing the area with a local treatment plant. That is the conventional way of doing it, so that is what we call our Base Case.
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We have then looked at a number of options: water efficiency; water efficiency and third pipe systems; water efficiency and stormwater recycling; very high water efficiency that we call AAAAA; rainwater tanks; greywater systems; and a combination of all of those. And we have done a life-cycle assessment, looking at the savings of potable water, the impacts of the greenhouse gas that is generated to provide that service, and what happens to nutrients.
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Of the three bars in this graph, the blue bar is the savings in potable water use as compared with the Base Case, the magenta bar is greenhouse, and the yellowy bar is nutrients. So they are the savings from the Base Case. The AAA water-efficient appliances give us roughly a 15 per cent saving in all three from the Base Case.
Some conclusions out of that are, firstly, that the best environmental benefits come from rainwater tanks and greywater systems very high potable water reduction, good greenhouse savings, good nutrient savings. We get good results, though, with demand management, and demand management is very cheap and very efficient.
There is a correlation between water and energy, and that is because most of the water has to be pumped from the south up to the north. So where we can reduce the water consumption, we have a corresponding reduction in greenhouse generation.
On the basis of comparisons between third pipe recycling and stormwater recycling, we get better benefits by recycling of sewerage wastewater than we do by recycling stormwater.
I indicated that the best environmental benefits were from rainwater tanks and greywater recycling, but the problem with those is that fundamentally they don't work in Melbourne all year round. Greywater recycling doesn't work in Melbourne in winter, simply because the evaporation rates and rainfall are such that we have an excess of water in winter. That means that you still have to take away the greywater during winter, so you are forced to build a sewerage system for winter, even though greywater systems work perfectly well in summer.
It is the same with rainwater. When we have gone back and looked at all of the 100 years of rainfall records, we have found that water tanks can't provide a reliable water source 100 per cent of the time. So we are forced to put in a reticulated water system to provide that service for the one year in 10 or one year in 20 when the rainfall is not adequate to meet the demands for potable water from rainwater tanks.
What we have looked at next is taking the options at the left on the graph, and looking at the feasibility of implementing those.
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So we have again compared them with the Base Case that I outlined before. We have looked at high- and low-growth scenarios. At this point we haven't done anything much about trying to optimise the staging of infrastructure, because it is early days in working out what the strategy is. We have looked at potable water savings and energy as the key environmental issues, and we have done our financial analysis based on total community costs, not just Yarra Valley Water costs.
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If we look at costs, what we find is that they are not enormously different. But the third pipe recycling from our sewerage treatment plant is marginally less in cost than anything else. That is a big change from most other areas. In most other areas where we look at, third pipe recycling it is considerably more expensive than Base Case provision, because you are putting in three pipes instead of two. In this area, simply because of its location and the fact that all of the water has to be pumped from the east and it is a long way to take the sewage away, means that in this case third pipe recycling is financially viable compared with traditional servicing.
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You can see in this slide that the smallest amount of potable water used for residential purposes is in the recycled option. More potable water is used if you use rainwater tanks, simply because rainwater tanks are not 100 per cent reliable and in very dry seasons they have to be topped up.
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To look at energy consumption: there is not a huge difference but the recycled comes out slightly in front of the Base Case.
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But, importantly, when we look at total energy used in the households, and we add on the energy used for hot water heating, the amount of energy that is used for hot water heating is about the same as that used by the water company in providing the water to the property. That is an important issue, because in Melbourne the government has a 5-star initiative that requires new home builders to choose either a rainwater tank or a solar hot water system. Our belief is that all customers in the Hume corridor should be choosing a solar hot water system in lieu of a rainwater tank, because we believe that the provision of recycled water through a third pipe system gives an environmental outcome superior to that of the provision of a rainwater tank. In addition, the community gets the benefit of the hot water through the saving in energy that is used in heating water on the property.
I will turn now to water balances, because one of the things we have to deal with is the quantity of water.
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With current recycling, if approximately 132 KL comes into the house, 160 KL goes out as sewage because it is topped up with 28 KL of recycled water from the recycling system. Some water is used on the garden, and some for public open space. But there is a surplus. That surplus has to be dealt with. Whether it goes to agricultural use, whether it goes into local waterways, that surplus has to be dealt with.
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If we go to very efficient water appliances within the house, because there is less water used there is a slightly greater surplus of water that we have to deal with.
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But if we go to a rainwater tank as well as a third pipe system, we have a large surplus of water to deal with. That leads us to the conclusion that rainwater tanks are not preferred with recycled water third pipe systems in this particular catchment.
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To give you a feel for what we have to do with the surplus water: for those of you who know Melbourne and Albert Park Lake, if we had rainwater tanks we would need a storage dam 7.6 times the size of Albert Park Lake to store that surplus water during winter for later use. So when you are watching the Grand Prix tomorrow, have a look at the size of Albert Park Lake and you will get a feel for the size of it. It's a massive dam. It is not very practicable at all. Even under the low-growth scenario we need massive storage dams during winter, to store the water for potential use in some form or other for agricultural purposes elsewhere.
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There are similar numbers for third pipe recycling. The excess is not quite as big if we just have third pipe recycling but it is still an excess. We still need a lot of land to irrigate during summer, and a big dam to store the water in during winter if we are not permitted to discharge to local waterways. This is both an opportunity and a logistics problem. An opportunity exists if an agricultural use is available in close proximity, but the cost of water storage and potential transfer to places of use will make the water expensive.
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One conclusion that we have come to for the Hume corridor is that third pipe wastewater recycling and high-demand management is our preferred option. It has got the lowest potable use, it has got the second lowest surplus of water, which means it is more manageable for us, and it avoids the high cost of management of rainwater tanks, from the perspective not only of making sure that the quality of water in the rainwater tanks is maintained, but also the issue of dealing with surplus water. It is very cost competitive, it has got the best nutrient outcome and it's got good greenhouse results.
The other conclusion, which I mentioned, is that while all recycling options do create recycled water, more importantly they create a surplus of recycled water. The disposal of that surplus water is a major infrastructure and logistics problem. We have got to find a reliable use for that water, at a location that is economically viable, and we are still working on that.
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There are very big benefits from choosing solar hot water over rainwater tanks as part of the Victorian government's 5-star housing rules. Ideally, we would like the government to be mandating solar hot water, and taking the rainwater option away from those customers.
There is another important leaning for us. While I haven't presented it here, we have done this sort of work in other areas, but you can't just extrapolate from what we find in other areas to what we can learn here. It is very specific to local circumstances.
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Here you see our ideal outcomes for the Hume corridor.
All homes and businesses use recycled water the way we arrange it is that the developers pay for all of the plumbing and the reticulation works, and Yarra Valley Water pays for the arterial infrastructure and all of the treatment.
All homes have solar hot water services. We would like to get some discharge to local waterways of that excess volume of effluent, but that is a matter that we need to negotiate with our local Environment Protection Authority.
All houses should have 5-star water conservation appliances.
And we would like to use anaerobic sewage treatment processes so that we can harvest the energy and put it back into the grid.
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What's happening now? This is still very much work in progress. If you drive up the Hume Highway now, as I said, you will find green fields; you won't find housing developments. They are probably 18 months to three years away.
We are talking to the government about decoupling the solar hot water and rainwater tank arrangements. We are having someone go through all of our numbers for us to make sure that we have got them right. We are proceeding with infrastructure layouts, looking at triple bottom line assessments for the various lower-level options. We are talking to all of the stakeholders the local council, the developers, the planning department within government and looking to get a general acceptance of this strategy and locking that into the appropriate planning scheme arrangements.
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Discussion
Question: Sam, I agree with you, you are quite right that you start with all the options on the table, you look at them in your local context and you will come to a local best bet. You didn't seem to consider indirect potable reuse. Is there a particular geographic or social constraint in your district, your jurisdiction, why that isn't in the mix of consideration any longer if it ever was?
Sam Austin: You are right, indirect reuse into potable supplies is much more a broad Melbourne issue, I think, than a local issue. You would be aware that it is a political issue as well. Fundamentally, I think if Melbourne is to go to potable reuse of recycled water, then that is going to be a Melbourne-wide decision; it is not going to be a decision that relates to the particular corridor development. But, that being said, there is the infrastructure necessary to take treated wastewater across to a nearby potable water reservoir. Logistically it is quite possible.
Question: I am not quite sure why you regard surplus water as a problem, particularly in the current climate and with the likelihood of 30 per cent drying of the southern half of the continent. In last week's Time magazine, the front page article was about how it is better to buy locally rather than to buy organically with the coming peak oil crisis, the cost of energy is going to go up and what we really need is local agriculture. Is there some restriction leading to your not developing a local agriculture with this surplus water?
Sam Austin: The surplus water is only an issue in the logistics of dealing with it. I think you are right, if we could generate some agricultural use of this excess water that is not needed for the residential and industrial development, that would be a win-win outcome. The particular land in that area is not ideal agricultural land it is relatively poor quality. But I do agree with you that the creation of an industry that could benefit from the use of that water is a highly desirable outcome.
Nevertheless, there is a logistical issue that as an infrastructure provider we have to deal with.
Question: I understand and respect the utility's narrow view of the world, but it seemed to me there were two seminal planning issues there, given the benchmarks already achieved.
One is the notion of no discharge. Surely that is environmental water, any that is there. And the other one is mentioned already, the indirect potable reuse. The benchmarks are already established, so why would we be planning, in a water-stressed state or metropolitan region like Melbourne, not to achieve a benchmark in terms of utility services?
Sam Austin: I don't think I can add to my comments about potable reuse in my previous answer. The logistics are there, the infrastructure is relatively simple for potable reuse to potable supplies. Whether the community in Melbourne is ready for that I am not sure. Premier Bracks has made public statements that Melbourne does not need to do potable reuse at the moment. Time will tell how good that prediction actually turns out to be.
