There is a revolution underway in Tasmania: to bring water to underutilised agricultural land with soil that has the potential to produce an abundance of crops, as well sustaining an intensive dairy industry. Pipelines are central to this revolution.
The state-owned company Tasmanian Irrigation Pty Ltd (TI) is developing a suite of irrigation schemes, delivered by a funding model of public-private partnerships involving local farmers and the state and Australian governments.
The flagship project, just completed, on schedule, is the $104 million Midlands Water Scheme (MWS), the largest built in Tasmania. It utilises a 137 km pipeline from Arthurs Lake to Jericho, in central Tasmania. It delivers up to 38,500 ML of water a year to of 55,484 ha of irrigable land, the most familiar farmland in the state as it borders the main highway between Hobart and Launceston.
Polyethylene pipelines – transforming agricultural enterprises
The MWS provides a fascinating case study for the pipeline industry, particularly for the advantages of a polyethylene (PE) solution for a distribution pipeline in difficult terrain and the benefits that came from procuring project materials from Australian suppliers like Qenos and local company Zezt.
“The MWS transforms farming down the spine of Tasmania,” TI Chief Executive Chris Oldfield said.
“It services farms between Campbell Town in the northern midlands and Kempton in the southern midlands. Traditional production here has been in poppies, cereals, canola, pasture seeds, lucerne, potatoes and pasture for livestock finishing. This scheme brings the potential for dairy conversions and perennial horticulture. That is revolutionary.”
The scheme is complex, running through a remote and challenging landscape, from the central highland lakes to the sometimes-arid plains of the Tasmanian midlands. The area’s low rainfall produces the nation’s most prized superfine merino fleeces but excludes intensive cropping and dairying.
The scheme’s natural 600 m fall from the highlands has allowed a 6.5 MW power station to be installed to supply hydroelectricity to drive the scheme and enough surplus to put into the state grid to power 4,155 homes.
At the peak of construction more than 220 people were employed. Of the $104 million cost, irrigators paid $25 million for water entitlements and are looking at spending another $62.5 million on their own dams, pipes and pivot irrigators. The summer irrigation season began in October and is delivering on average about 50 ML per day.
“The MWS has been lauded as environmentally and culturally sustainable in terms of hydrology, construction and operation,” said Mr Oldfield.
“It is also the boost the Tasmanian economy has been waiting for, now being more dependent than perhaps the mid-19th century on agriculture for its economic well-being.
“In the space of five years we have seen $1 billion invested in irrigation to transform Tasmanian agriculture. Of that, $628 million will have come from the pockets of our own farmers, $259 million from the Australian Government and $110 from the Tasmanian Government. This is bigger than the Ord scheme in Western Australia (a scheme which saw the development of dams and irrigation channels on the Ord River in the east Kimberley).”
A challenging landscape calls for inspired solutions. In this environment where water is precious, underground piping was seen as the only means of delivery. Transporting water through channels was dismissed as a high proportion of the precious water supply would be lost to seepage and evaporation.
Choosing to bury the pipe network offers the best long term solution for the land owners and the environment but it introduces a range of installation challenges. The variation in system requirements along the network, challenging terrain and changing geology are all factors in the assessment of the most suitable material for the task.
The MWS used Ductile Iron Cement Lined pipe and Mild Steel Cement lined pipe for the 34 km from Arthurs Lake to the power station (due to the high pressures) and Qenos PE pipe for the 103 km distribution pipeline from the power station to the midlands farms.
Advantages of a polyethylene solution
Qenos says there are multiple factors that must be considered in the choice of a piping solution. Perhaps most importantly, the chosen material needed to achieve the 100-year working life of the project at operating pressures.
Faced with a hostile environment, it was also necessary to find a solution that was flexible enough to match difficult terrain, while also strong enough to handle the difficulties that come with installation and transport.
The project decided on PE piping, produced by a local Tasmanian company Zezt, using specialised PE resin manufactured in Australia by Qenos. With an Australian support team, Qenos was also able to offer timely and valuable support to both the manufacturer and the irrigation project managers.
A PE solution was ideal because of its ability to cover the sheer range of different piping system elements that were required. With one size of pipe bringing water into the dams and power stations, and another size needed to get the water out onto local farms, PE provided a very flexible solution.
There was considerable variation across the range of pipe sizes, with some as large as a metre in diameter and as long as 21 m. By using lengths that were double the normal supply length, fewer joints needed to be made on site and this significantly reduced installation times.
Thanks to the high melt strength of the selected Alkadyne HDF145B PE resin, the large diameter pipes were formed with tight dimensional tolerances enabling closely aligned welded joints that were easy to construct.
Qenos’ Product Development Executive Dr Predrag Micic, identified that these extra-long pipes were crucial for achieving a cost-effective solution.
“These joints are as strong as the body of the pipe – no other pipe material gives you that,” said Dr Micic. “The weld just becomes part of the whole structure.
“Polyethylene is a fantastically environmentally sound product and lots of polyethylene gets collected and recycled, protecting the natural resources of Australia.”
Qenos’ Market Segment Manager Gerald Beckton pointed to the high degree of accuracy that could be delivered with a PE solution. The absence of ovality and the high level of consistency in wall thickness that comes with using Alkadyne HDF145B PE made installation easier, while also minimising the cost of materials for the project.
“For the installer who is welding these pipes together it means that the pipes match very well, allowing you to minimise heat soak time and ensure the quality of the welds,” said Mr Beckton.
Local companies add value to a local project
The Tasmanian Irrigation Project is about more than just growing the value of agriculture in the state, it also demonstrates the capability of a team of Australian manufacturers and contractors to deliver a world-class solution.
As the only Australian manufacturer of PE pipe, Qenos was well-positioned to handle the supply of materials for the project. What’s more, the Qenos PE pipe was converted into high precision pipe for the project by Zezt, a local Tasmanian pipe manufacturer based in Wynyard.
By engaging suppliers and contractors across the state, the project has not only improved the water supply to farmers but benefited the manufacturing sector as well.
Qenos transforms ethane gas sourced from Bass Strait into PE, so Qenos was able to offer a 100 per cent Australian manufactured product to address the needs of Tasmanian communities without relying on foreign suppliers.
As Dr Micic highlighted: “[This project] is all about value that is kept within Australia. Qenos has recently invested $200 million into expanding our capacity to serve the Australian market. This is multiplied downstream as the resin is converted by Australian businesses with the economic activity and employment staying onshore.”
The flexibility of local supply makes it easier to respond to changes within the project. If a specific section of installation progressed faster than expected, the local supply chain was able to respond and step up production. Likewise, if the installation hit a slow patch, provision of piping could easily respond to suit.
“Being a local supplier, we are able to meet demand for pipe as the projects came on, handling the variable demand while also providing next day delivery logistics,” said Mr Beckton.
“We engaged with both the pipe supplier and the asset owner and were available to discuss a tailored supply.”
As a result of this timely delivery, the supply of piping met all of the deadlines which the client set for this project, allowing the entire work to progress without any major disruptions.
The Tasmanian Irrigation Project is a unique initiative, spread across an entire state, with a number of different components. The success of this project was highly dependent on one product – the polyethylene resin needed to construct this resilient and long lasting pipe network.
The combination of Qenos resin manufactured into pipe by Zezt and welded and installed by local contractors enabled the speedy and economic supply to a project with a varied and demanding range of installation conditions.
This article was featured in the February 2015 edition of The Australian Pipeliner.
If you have news you would like featured in The Australian Pipeliner contact Managing Editor David Convery at dconvery@gs-press.com.au
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