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Asset upgrades bolster water security across southern Tasmania

Following the largest capital works program in Taswater’s history, the utility has opened the upgraded Bryn Estyn Water Treatment Plant, with the asset’s delivery establishing a new era of water security for 200,000 customers across southern Tasmania.

Delivered through the TasWater, UGL and CPB Contractors Alliance on time and under its $243.9 million budget, the upgraded treatment plant will provide safe and reliable drinking water for Hobart, Glenorchy, Kingborough, Brighton, Derwent Valley, Southern Midlands, Sorell and Clarence for decades to come.
TasWater Chief Executive Officer George Theo said the opening marked a major milestone for water security in greater Hobart.
“This is a landmark day for southern Tasmania. The upgrade of the Bryn Estyn water treatment plant ensures safe, clean drinking water will be available for generations of Tasmanians from Kempton to Snug, and New Norfolk to Sorell,” Theo said.
“Drinking water for around 200,000 customers is in safe hands with the new plant able to treat 160 ML of water per day.
“And the plant has been designed for future population and economic growth in the region, with the potential to be expanded to treat another 40 ML of water per day if required.”
Taswater General Manager Project Delivery Tony Willmott said the new technologies embedded into the asset are also more robust, allowing the utility to manage raw-water treatment processes much more effectively.
“The new plant has been designed to be able to produce 160 ML reliably each day to enable the supply of water to customers across greater Hobart,” he said.
“The conditions in the river have required us to adjust our treatment processes, too. The change in water quality conditions previously impacted how much water the plant could treat each day.
“But these upgrades enable the plant to treat a much wider range of water quality conditions in the river. The treatment capacity has been greatly improved.”

Focus on security

The Bryn Estyn treatment plant provides around 60% of greater Hobart’s water, with the two other sources Mount Wellington and also the Mount Field source through the Lake Fenton pipeline, Willmott said.
“Both sources can be impacted, certainly through summer, when conditions are dry on the mountain,” he said.
“The new plant gives us the ability to ramp up production. The network expands from New Norfolk to Kempton in the north, and as far down as Margate and Snug in the south, when required.
“We’ve got the ability to continue to produce compliant water across a wide water-quality envelope, which provides us with the ability to future-proof supply.”
Willmott said there are plenty of features around the new treatment plant pre-installed to enable the utility to increase supply in future.
“We have planned for the future by sizing all of the major pipelines throughout the plant to 200 ML for future growth, with offtakes already installed to ensure we are ready for the next filter to be built when required. This means that any future upgrades can now be more easily constructed to increase production capacity,” he said.
“We’ve also installed large concrete plinths within our chemical dosing areas so that when we require another hopper for chemicals, it’s ready to go. All of this future proofing will ensure that  it is very easy to upscale treatment at the site. Most importantly, we are no longer reliant on aging infrastructure at the end of its lifespan.”
Although the plant has always produced water compliant with the Australian Drinking Water Guidelines, Willmott said there were issues keeping up with demand due to water quality.
“Usually after heavy rainfall you would think we would have plenty of water to treat and supply wouldn’t be a problem. But the increase in turbidity previously slowed down our ability to treat, but the new plant can handle this providing more flexibility,” he said.
“We can now top up network supplies through this new plant much more efficiently when other sources are not available.”

Moving parts

Willmott said a lot of thought has been put into repurposing or reusing as much of the old plant as possible, including keeping more recently upgraded elements of the treatment train to avoid wasting investment.
“The new plant wraps around the older assets, which were required to remain in service during the construction phase. That added an extra challenge, the team had to make sure the plant continued supplying our customers,” he said.
“While we have reused and upgraded the main raw water and treated pump station, the more recently upgraded chlorination system was also kept because we didn't want to demolish assets if we could reuse them properly.
“The two former plants are both still in existence and we haven't demolished them. We are currently making a decision about their future. We are also considering if the assets could provide an educational benefit for school groups.”
Some of the new additions to the upgraded plant includes a new Lamella clarifier, an ozone disinfection tank and production system, an activated-carbon filter, a new UV-disinfection system and a new interstage pump station.
Other improvements have also been made to the power supply, Willmott said.
“While undertaking the upgrades we also took the opportunity to upgrade the high-voltage supplies into the site. We worked closely with TasNetworks to replace the former single overhead power supply with a 9km duplicated underground supply from the township of New Norfolk,” he said.
“This aspect of the project alone was a considerable challenge given the topography and geotechnical conditions. We really appreciated this support from TasNetworks, as it has made the site far more resilient.
“We have a backup power supply now, which was certainly a high-level risk for us in terms of bushfires or storm damage.”

Immediate benefits

While the upgrades are certainly an investment for future water security, Willmott said the benefits of the improvements have already been felt.
“We are already seeing improved water quality as a result of the upgrades,” he said.
“Our operators have seen how quickly they can treat water across a wider raw water quality range. Historically, cold can cause issues with coagulation, but the new plant deals with these issues wonderfully.
“Recently we conducted a performance test and it produced water at a rate never seen from the site before at this time of year.
“The benefits have been immediate. The water has always been compliant with drinking water guidelines, but it’s now an even better standard of water supply. And we are seeing much better chlorine residuals in the network.”
Willmot said the upgrade project has also already been great for the Tasmanian community, with around 80% of the contracts for the project awarded locally to small and medium-sized businesses.
“We had around 150 people onsite each day throughout the process lifecycle. That has seen direct and indirect employment for over 2000 people, which is a great economic boost for the community,” he said.
“The improved asset has also provided our Operators with significant learning opportunities as they have commenced operating the new technology, which is much more advanced. So, our employees' skill-sets have grown, as well.”