Parallel processes are underway within the project - construction of the initial stage, tendering of the next section to be built, and planning and landowner consultation for future phases. An initial ten-year construction plan has been fast tracked, with a target of five to seven years for the completion of the whole pipeline system. This is in response to prolonged dry seasonal conditions and severe water shortages in the Wimmera Mallee system.

The project concept

The Wimmera Mallee region, in western Victoria, is renowned as a successful dryland agricultural area, excelling in grain and livestock production. Average annual cereal yield is 3 million tonnes, with significant diversification into oilseeds, lentils and pulses.

The Wimmera Mallee region currently receives its water supply via a complex earthen channel network. The Wimmera Mallee Pipeline system will replace 17,500 km of open, earthen channels with a 9,000 km piped water distribution system, providing reticulated water to 9,000 rural properties and 36 towns, over an area of about two million hectares. A pressurised and continuous supply will replace the annual channel supply to farm dams and town storages across the region.

The Commonwealth and Victorian State Governments jointly launched their support for the WMPP on 24 June 2005 as part of the National Water Initiative. Both Governments have each committed $167 million towards the project, premised on the significant environmental benefits achieved through water savings and the economic benefits provided through an improved water supply.

The region serviced by the WMPP will contribute the remaining investment in the total project, making the WMPP a three-way partnership. The regional community’s share of the pipeline system cost will be paid for through the annual water tariffs and from the sale of water savings allocated for future regional growth and delivered through the new pipeline system. Significant investment on farm is required by landowners and includes replacing farm dams and channels with reticulation systems including tanks, troughs and pipes. This contribution is estimated at $82 million.

The WMPP enjoys strong regional support, with initial consultation during the development of the project identifying multiple benefits for the whole community. The pipeline will generate significant water savings, enabling the average annual seepage and evaporation losses of 103,000 ML to be allocated to other uses. The majority of these savings will be returned to Government for allocation to the environment, providing increased natural flows for the river systems and improving the ecology of the region. Further savings have been allocated for future economic growth, particularly in the agricultural and agribusiness sectors.

The pipeline system design principles are based on delivering water for urban supplies as well as stock and domestic use on farms within the large geographic area. Investigations of current peak demands and the broad range of economic, social and environmental uses for water within the region, provided the basis for determining the capacity of the pipeline system that will service the water needs of the region for the next one hundred years (see Table 1).

The design approach for flow rates, demand management within the system, and delivery pressure has been based on equitable sharing of benefits throughout the region. Water will be distributed to all customer groups within the area receiving a piped water supply in a cost effective manner, balancing the capital and operational costs in a technically sustainable way to provide a lowest whole-of-cost solution (see Table 2).

The WMPP will implement a water supply system that incorporates trunk and distribution pipeline works, pumping stations, water balancing storages, headworks, control systems and other ancillary works that are connected to create five separate supply zones drawing water from two sources of supply in the Grampians mountains and a sixth supply zone supplied from the Murray River.

Figure 1 presents a general layout plan of the trunk main components of each supply zone. The major trunk pipeline will transfer water under gravity from Lake Bellfield to Taylors Lake. The remainder of the pipeline system is a pumped system and so will be highly reliant on the regional power supply network. The trunk pipeline of each supply zone follows a route that extends between the towns situated within that zone, with a trunk pumping station and water balancing storage located along the trunk main alignment at nominated towns.

Trunk pumping stations transfer bulk water between the water storages and also service the local distribution pipe networks connected to the pumped trunk main, with flows delivered directly from the trunk mains to the distribution mains under trunk main pressure.

Project implementation

The first stage of works includes trunk pipelines, distribution pipeline networks, storages and pump stations for Supply System 1, Taylors Lake to Yaapeet, as well as the main transfer trunk pipeline from Lake Bellfield in the Grampians Ranges to Taylors Lake, which is a gravity feed cement lined steel pipe that varies in diameter from 1,035 mm to 711 mm.

A construction contract has been awarded to Mitchell Water, with the original two-year construction schedule fast tracked to achieve a target completion date of October 2007. Laying of PVC pipes has commenced, with multiple work crews focusing on trenching and drilling procedures. PVC pipe sizes vary from 50 mm up to 450 mm in diameter.

Specialist drilling crews have commenced work at key crossings, inserting sections of pipe under roads, railway lines and waterways, minimising local disturbance of vegetation and possible future soil erosion.

Landowners are investing in on-farm infrastructure including pipes, troughs, tanks and pumps in advance of the pipeline development. A condition of connection to the pipeline is that water is supplied directly into tanks, equivalent to three days supply. Changed water management due to the prolonged drought and severe water restrictions has already forced early on-farm reticulation improvements.

The project is providing opportunities for regional businesses to support construction activities, such as transport and logistics or accommodation. There is also an impact on local employment prospects, which offsets in part the impact that the drought is having on the local economy.

The tender process for the second phase of construction, Supply System 5 or Berriwillock and Culgoa, has begun, with preparations for an October 2007 completion of this section underway. This system will source water from the Murray River at Swan Hill, complementing the existing Northern Mallee Pipeline system.

Preparation is also occurring for the piping of the remainder of the system, with environmental assessment planned, cultural heritage consultations commenced and geotechnical investigations scheduled. Detailed laser survey data and aerial photography is proving to be a very useful tool in the investigation and planning of pipeline routes.

The next stages and future outcomes

A key pressure on the WMPP is to detail the scheduling of works for the completion of the pipeline. Lead times are required for tendering processes, to ensure that the various approvals are obtained, liaison with landowners is progressed and the design of remaining works initiated, with the culmination being the actual construction works. Continuing drought conditions, with regional water storages holding less than six per cent of capacity, are forcing reviews of the implementation planning and roll-out of the pipeline construction, with the intention of supplying piped water to the region as quickly and efficiently as possible.

A range of institutional changes is needed to support the new water supply infrastructure. A complete tariff review to incorporate the metering of water supplies to properties will enable water pricing to be volumetric based. Government policies supporting formal entitlement and water trading frameworks will be implemented in the region in the future. Management and delivery of the legal entitlement for environmental water generated from pipeline savings will significantly change the management of the regional water storages, particularly as less water is required for consumptive use with the advent of the pipeline system.

The greatest benefit of piping the WMPP is much improved security of supply. Farmers, community groups and businesses have started planning to take advantage of the increased security, which will lead to future investment in the Wimmera Mallee. As security of supply improves from 78 per cent to over 96 per cent through the WMPP, the region’s natural advantages of good soil and temperate climate, means that the region will become increasingly more attractive for new agribusiness initiatives. Economic opportunities available to the region will include diversification of agribusiness and the potential for new primary production, allowing the region to strengthen its future economic base.

A related benefit is improved water quality, which will enhance new business opportunities in the area.

Decommissioning of the existing channel infrastructure will result in significant landscape and topographic change across the region. The channels and bank network that criss-crosses the region, road and rail bridges, and the crossings and culverts, siphons and regulator structures of the channel system will no longer be required for water delivery. Consultative strategies are being developed to guide and regulate the decommissioning process. Some channels may continue to be required for local drainage functions, as well as to provide surface water supplements from the natural catchments of recreation lakes and natural wetlands.

The WMPP was developed as a sustainability response to managing water resources in the Wimmera Mallee region, and has an objective of balancing existing needs with future regional opportunities. An element of regional development potential underlined the need to plan for the future.

Extended drought conditions and the growing awareness of the impact of climate change on catchment and weather patterns have provided further impetus to the planning and implementation of the pipeline system. The regional community recognises that the construction of the WMPP will provide a future for the Wimmera Mallee.