Designed and built over a period of more than a century, the original 18,000 km earthen channel system is one of the largest of its type in the world and is controlled entirely by gravity and a myriad of control gates. However, it has long been acknowledged that the system is extremely wasteful with a high degree of leakage, evaporation and contamination.

The system’s owner, Grampians Wimmera Mallee Water Corporation (GWMWater) determined that it could replace the channel system with approximately 9,000 km of pressurised pipeline.

Jointly funded by the Australian Government, Victorian Government and the regional community, the $688 million Wimmera Mallee Pipeline Project (WMPP) was initially estimated to require a 10 year construction phase. However due to the region’s ongoing drought conditions and water storage capacities dropping below 10 per cent for several years, the project was fast-tracked and will be completed within just four years.

Mitchell Water Australia Pty Ltd was awarded contracts for the design and construction of six of the seven supply systems that form the entire project for GWMWater, and has been on track to complete construction within just three years save for recent inclement winter weather.

The pipeline network covers some two million hectares – an area that would comfortably fit the Melbourne metropolitan region several times over.

The WMPP has provided significant benefits for the regional community, including 83,000 ML of water savings generated to be returned to the natural waterways; security of supply for towns and farms will increase to 96 per cent; consistent and improved water quality will be available across the whole system; water will be made available for new enterprises, business development and agricultural diversification; and, water will be made available for recreation lakes for the first time in many years.

Mitchell Water Project Director Rob Shelton says that the contracted timelines have challenged the scheduling of works, procurement of materials, statutory approvals, access to skilled labour, and the mobilisation of a workforce of over 200 personnel in a regional area.

“This has also been accomplished during an extremely high level of activity in the pipeline industry as well as the construction industry at large,” Mr Shelton says.

“By using a combination of our conventional trenching machinery, which has now been updated by the inclusion of three new Wolfe trenchers, as well as our in-house designed and developed vibratory plough and high speed roundabout trencher, we have been able to achieve trenching rates of over 25 km per day,” he says.

“The specification called for topsoil stripped from the right of way to be replaced within just three days. I am particularly pleased that while achieving such high rates of production, we have also been able to accomplish zero lost time injuries in more than 900,000 man-hours onsite,” Mr Shelton says.

The sheer scale of the project means that pipe was manufactured all over Australia and, at one point, was even imported from New Zealand.

As well as using its own in-house pipeline construction equipment, Mitchell Water has also taken advantage of some of the latest computer-operated machine control technology.

All ploughing and trenching equipment is GPS controlled to ensure pipelines are laid to line and grade, with the design information uploaded into machinery for automatic excavation. A series of GPS base stations are used due to the remoteness of some of the construction.

A geographic information system (GIS) with over 250 discrete layers of data being utilised during the implementation of the project. Mitchell Water says that using GIS to manage the quantity and quality of data has proven very efficient.

Environment

Ecological, soil, vegetation and cultural heritage information, detailed aerial survey and contour information, pipeline design, cadastral and landowner contact details, lengths of pipes and valve types, construction progress and ‘as constructed’ data is all being tracked and recorded.

An extensive liaison process with more than 4,000 landholders has provided the basis for managing the interface between Mitchell Water, landowners and customers. This is viewed as a critical reason for the success of the project thus far, with no construction stoppages as yet due to landowner issues or concerns.

Contractor and client representatives working closely to address key procedures such as environmental management, cultural heritage, pipeline design and delivery of plans, have contributed to the success of the project.

All Mitchell Water staff also undertook a compulsory environmental care course including training in environmentally sustainable work practices.

Conducted by the Victorian Department of Sustainability and Environment, the course provided Mitchell Water and GWMWater staff with an understanding of the key environmental issues relating to the project, as well as practical training and an understanding of the required actions.

Regular toolbox meetings provided refresher information on key safety and environmental issues, with participation by client staff as required.

Providing water to the Wimmera

During the four year construction phase there has also been an imperative to maintain water supply to customers.

This has proven to be difficult due to severe water restrictions, low storage capacities, extremely low rainfall and the need to maintain dual supply arrangements – annual channel supply and emergency pipeline supply combinations across the region.

Furthermore, varying standard industry practice to provide water to customers prior to full commissioning and handover of the system has been achieved through a co-operative approach between Mitchell Water and the client.

By aligning construction priorities with practical requirements, emergency water supplies were made available to customers well before the contract completion.

For example, in Supply System 1 rural and urban customers were supplied within just 12 months of the award of the contract for over 1,200 km of pipeline.

During this time water supply to several towns was critical and an extensive water-carting program was supplying farms with both domestic and stock water. Water quality in many towns had deteriorated significantly, with water carried in earthen storages and dams for more than two years.

Mr Shelton says that the construction program also delivered a range of economic benefits to the region.

“By constructing the project without the use of camps we became one of the largest tenants in the region renting up to 40 homes and units at any one time.

“We firmly believe that we must engage with the local community on projects such as this.”

“Residents and communities must see that there is a spin off for them. We have a ‘Local First’ policy that ensures that if local industry and services can meet our standards of quality, cost, delivery and general performance, then they will see the benefits,” Mr Shelton says.

Last year the Industry Capability Network awarded Mitchell Water its Certificate of Recognition for outstanding commitment to Australian industry in acknowledgement of the company’s involvement with local industry and service providers.

Mitchell Water will continue to complete the WMPP project, expected to supply water via all supply systems in early 2010.