WMPP: large and in charge

The largest infrastructure project in Australia, the Wimmera Mallee Pipeline Project (WMPP) involved replacing 17,800 km of open channel systems with 8,800 km of pipeline, and was delivered in record time and under budget.

The project is a partnership between the Victorian Government, the Federal Government, GWMWater and the regional community. The Commonwealth and Victorian governments jointly launched their support on 24 June 2005 as part of the National Water Initiative. This was in response to prolonged dry seasonal conditions and severe water shortages in the Wimmera Mallee system.

The project involved a water supply system that incorporates trunk and distribution pipelines, pumping stations, water balancing storages, headworks, control systems and other ancillary works. These are connected to create seven separate supply systems. Six of these are supplied from reservoirs in the Grampians and one from the Murray River near Swan Hill.

Construction commenced in November 2006 and was constructed in seven stages. Mitchell Water Australia constructed supply systems 1, 2, 3, 4, 6 and 7, while Nacap Australia constructed Supply System 5.

Mitchell Water constructed approximately 8,000 km of pipeline, 27 pump stations, 18 lined earthen storage dams and 27 storage tanks, while Nacap Australia constructed about 830 km of pipeline, five pump stations, a filtration station, three lined earthen storage dams, and two storage tanks.

The main transfer trunk pipeline from Lake Bellfield in the Grampians Ranges to Taylors Lake near Horsham, is a gravity feed cement lined steel pipe that varies in diameter from 1,035 mm to 711 mm.

The pipeline systems, which consists of PVC and PE pipe varying from 575 mm to 50 mm in diameter, have been installed to generate significant water savings. It is estimated that the new system will save an average annual seepage and evaporation losses of 103,000 ML/a of water.

Fast tracking

Initially planned to be completed over 10 years, WMPP was fast tracked and construction was completed in just over three years.

Mitchell Water and Nacap Australia were awarded design and construction contracts, contributing to the saving of millions of dollars on project cost estimates by the client.

The tight project time frame presented challenges for planning and design, landowner consultation, works scheduling, material procurement programs, statutory approval, access to skilled labour, and the mobilisation of a workforce greater than 200 in a regional area.

WMPP: well equipped

To aid in the quick construction delivery of the project, the contractors incorporated some of the latest computer-operated machine control technology.

Both Nacap and Mitchell Water had a number of pipe installation crews using a combination of conventional trenching machinery, as well as an innovative vibratory plough and high speed “˜Roundabout’ trencher to lay up to 25 km of pipe a day. To minimise impact on the environment and private landholdings, the construction specification called for topsoil stripped from the right-of-way, to be replaced within just three days, which was achieved even at the height of production.

Mintern Civil from Horsham was another significant contractor on the project, undertaking the installation of approximately 9,000 tapping connections to the pipeline and meter installations, providing water supply to the rural properties.

The connections were primarily
20 mm diameter and similar in nature to urban style meter installations. The tapping connections followed the installation and testing of the trunk and distribution pipelines.

All ploughing and trenching equipment was controlled by a Trimble GPS machine to ensure pipelines were laid to line and grade, with design information uploading into trenching machinery for automatic excavation. A series of GPS base stations were used due to the remoteness of some of the construction.

Given the compressed timelines, it was realised that the project would not be able to be achieved on time using conventional field-based survey methods, and thus previously collected airborne laser survey information was used.

Stakeholder liaison

A key element to the fast tracking of the project was the decision taken by project team members to manage the landowner consultation program. This involved the initial pipeline alignments and network layout being determined by the GWMWater WMPP engineering team. This allowed the appointed contractors the freedom to prepare detailed designs and then build the infrastructure without the worry of also carrying out the land liaison activity.

“We worked closely with the client to address key procedures such as environmental management, cultural heritage, pipeline design and delivery of plans,” Mitchell Water General Manager Rob Shelton said.

The company used a “˜plan, prepare, construct and rehabilitate’ procedure that minimised disruption and impact on the environment, regional farmers and landholders.

GWMWater, along with Maloney Field Services, also undertook a very comprehensive upfront landholder liaison process which explained the pipeline construction process, obtained access agreement, construction line list information and supply tapping point requirements from the landowners.

CNC Project Management undertook the cultural heritage surveys and preparation of Cultural Heritage Management Plans for most of the systems.

In addition, contractor and GWMWater occupational health and safety staff worked closely to ensure an outstanding safety record was achieved on the project. Regular toolbox meetings also helped to deliver a refresher on information for key safety and environmental issues.

Keeping the water running

With the drought in Victoria it was important that water supply was maintained to the customers during the construction phase. This was a challenge for the project due to 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.

GWMWater also varied standard industry practice to provide water to customers prior to the full commissioning and the handover of the system.

Future expansions

There is a possibility of extending the pipeline following interest from farmers and landholders residing on the fringe of the pipeline’s reach.

GWMWater Managing Director Jeff Rigby said “We’re moving into a phase now where we can look at following up with previously interested people and look at whether that interest is still there, and on what terms and conditions we can contemplate a future supply to those customers.

“Up until now our focus had been on upgrading the service for existing customers. Now the company is able to turn its attention to potential new customers building on the regional development benefits that the project will deliver,” Mr Rigby said.

Pipe Suppliers

  • Tyco Water – steel pipe
  • Iplex – PVC and PE pipe for Mitchell Water
  • Vinidex – suppliers for Nacap

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