Of the 120,000 megalitres harvested from the Grampians bulk water supply reservoirs every year, the urban and rural customers serviced by the open channel system use approximately 17,000 megalitres. The remaining 103,000 megalitres are lost through evaporation and seepage. The WMPP will reticulate water to about two million hectares of dryland farming and 36 towns.

Planning for the future

A feasibility study was completed in June 2001, confirming that ‘piping the system’ would deliver social, economic and environmental benefits to the region and provide sustainable water management.

A business case detailing preliminary design parameters and cost benefit analysis of the pipeline proposal was submitted to both the Australian and Victorian Governments in 2004.

The business case identified that the project would deliver a reliable, higher quality water supply across the region 24 hours a day, 7 days a week, for domestic and stock uses on farms, as well as for urban supplies. The project will return of 83,000 megalitres of water to government for a range of uses, including environmental releases to rivers and streams; 20,000 megalitres of water for urban, rural and commercial growth and development; and, up to 4,000 megalitres of water for 11 nominated recreational lakes and other water bodies in the region with a high conservation value.

The pipeline enjoys strong regional support, particularly as impacts of the continuing dry seasonal conditions affect catchment storages and agriculture generally. The construction of the pipeline, initially proposed over a ten year timeframe, will be completed within five years. Construction commenced in November 2006.

The fast tracking of the project, in response to continuing drought conditions and low storage inflows, has resulted in project activity in every section of the pipeline. A rolling program involving preliminary assessments, design, planning and consultation, land liaison, tendering and evaluation, contract negotiation as well as construction and reporting, has impacted on every part of the region, as works continue on multiple fronts.

While the dry conditions have provided challenges in servicing the water needs of the regional community, the fast tracking of project construction has provided a positive result for the region. Focus on supplying towns as soon as possible during construction, balancing the construction processes and contractual arrangements, while also meeting the water requirements of customers, has tested traditional pipeline practices.

Continuous pipeline construction, throughout the cropping, growing and harvesting cycles, has been negotiated with landowners to minimise impacts. Opportunities to cut hay from pre-harvest crops, late sowing on rehabilitated areas, avoiding tree belts and crop trial sites, and providing temporary fencing for stock management, are all examples of negotiated arrangements with landowners. Landowner co-operation has been outstanding, with the inconvenience of the pipe construction process balanced by landowner enthusiasm for the project.

WMPP innovations: survey technology

Light Detection and Ranging (LIDAR), an aerial survey technology, has proven to be a cost effective and efficient tool for the WMPP. GWMWater extended existing survey data to incorporate full coverage of the WMPP area.

The data provided co-ordinates with both height and horizontal accuracies to provide quality survey information – a valuable resource for the design and construction of the pipeline, minimising the extent of on ground survey required.

Aerial photography for the region has been produced to support the survey data. The photography has been used for vegetation surveys and to assist with landholder planning for on-farm works, providing useful bench-marking data on the region.

The data has proven a useful tool for consultation purposes, strategically demonstrating management options at the farm, district, sub-catchment, catchment and regional levels.

As well as supporting WMPP survey needs during construction, LIDAR provides a valuable tool in assisting with the planning for decommissioning of channels. Community based committees of management are also utilising the data to develop future management options for recreational lakes and weirs, modelling the opportunities to maximise local drainage.

Web-based data to assist landowners with their on-farm reticulation planning and implementation was made available through the publication of online Geographical Information Systems (GIS) information, incorporating the LIDAR information. The website provides searchable land information, aerial photography, pipeline routes and contour data at the land parcel level, enabling detailed planning of the siting and measurement of tanks and on-farm reticulation systems.

Construction methodology

Laying small diameter polyethylene (PE) pipe in WMPP has utilised an innovative methodology. Using Global Positioning Systems (GPS), the lengths of pipe are laid to grade by a plough. GPS enables hydraulic control of the depth and route of the pipe as it is pulled through the soil. A vibrating tip on the plough creates a tunnel of fine soil, allowing the pipe to move through the soil easily as it is installed.

550 meter lengths of PE pipe of 50 and 80 mm diameter have been successfully ‘ploughed.’ Key advantages of this method are the higher installation rates than traditional trenching techniques and the minimal soil disturbance. This has been specifically utilised in environmentally and culturally sensitive areas to minimise the impact of construction on vegetation and local habitat.

Traditional trenching methods for laying PVC pipes and steel pipe are being used for the larger diameter pipes. Soil management is a priority in both agricultural and native vegetation areas, due to the variable depth of topsoil across the region. Removal of topsoil is restricted to three days, to minimise erosion risks and maintain nutrients and existing seed material, assisting with the reinstatement of the area following construction.

Land liaison

GWMWater’s strong commitment to land liaison procedures and ongoing communication of construction activities with customers and other stakeholders has been acknowledged by customers.

A series of information sessions has targeted each supply system during the preliminary design period. These sessions provided general construction information, broad timelines and sought feedback on local issues and concerns. The iterative consultation and parallel technical assessment refines the design information, incorporating landowner, community, environmental and technical factors, prior to the tendering process.

The project has also targeted special events, such as the Farming with Pipes Expo, field days and community functions to provide information to the regional community.

A team of land liaison officers consults with landowners prior to construction, developing construction ‘line lists’ and access agreements in advance of construction, as well as preparing for metering and tapping installations. This process has assisted in minimising landowner issues during the construction of the pipeline.

Mintern Civil has been awarded contracts for the installation of tapping points and meters in Supply Systems 1, 2 and 5. Meters are installed and operational in Supply Systems 1 and 5.

A number of regional businesses have provided goods and services to pipeline contractors, including transport and logistics, accommodation, fuel and vehicle maintenance. Local employment opportunities have also been boosted by the pipeline project.

The Wimmera Mallee Pipeline Project is on target for completion within five years – delivering a water management system for a sustainable future in the region.