By Eliza Booth, Assistant Editor, Pump Industry magazine
As Australia continues to battle one of the worst droughts in living memory, more regions are looking to secure their water supplies now and into the future. One NSW council has taken this challenge on headfirst, constructing a purpose-built pipeline and accompanying floating pontoon pump infrastructure to increase water quality and flexibility for locals.
Guyra, in the Northern Tablelands of NSW, has been hit hard by the drought. Supplies in Guyra Dam were on track to run out in mid 2019 and proactive measures from the region’s Council and State Government were needed to keep households and businesses supplied with town water.
Fortunately, Armidale Regional Council had already embarked on the construction of a $12.85 million pipeline linking Guyra’s town water system to the much larger Malpas Dam.
The Malpas Dam to Guyra pipeline had been initiated in 2017 after previous extended dry periods raised issues of poor water quality when levels in Guyra Dam became low.
The pipeline gave the Guyra township access to Malpas Dam’s 12,000ML capacity, instead of relying solely on the 450ML Guyra Dam.
The State Government stepped up with a $12.375 million grant and the pipeline was given the green light in 2018. Just months later, the emerging severity of the drought gave the pipeline added urgency and value.
The project was fast-tracked and was officially opened in October 2019.
Urgent need for a secure solution
The development of a solution to Guyra’s water supply issues was of high importance to Armidale Regional Council.
Armidale Regional Council Mayor, Councillor Simon Murray, said that without the development of the pipeline, the Guyra Dam was on track to run dry in mid 2019.
However, with the addition of the new infrastructure, the town now has access to the higher capacity of the Malpas Dam, supplying Guyra with a higher quality, more flexible water source.
“The pipeline connects the Guyra treatment plant to the much larger Malpas Dam, which supplies the Armidale town supply and can now be used to supplement Guyra’s supply,” Mr Murray said.
“The Guyra town water supply previously relied exclusively on the Guyra Dam, which is relatively small. In the past, there have been times when dam levels fell to a point where the quality of water going to the treatment plant made it difficult and costly to treat to desired standards.”
Mr Murray said the project – which consisted of an 18km pipeline, intake at Malpas Dam, pumping station, integration with the treatment plant and electrical works – was essential in providing secure water supply to the town.
“The 18km pipeline was constructed in 2019 to improve water security for town water customers in the Guyra district.
It helps provide a more reliable water supply to existing residents and businesses, while enabling the Guyra district to achieve its potential as a hub for intensive agriculture,” Mr Murray said.
“The $12.85 million project was assisted by a $12.375 million NSW Government grant, following close liaison between Council and the NSW Member for Northern Tablelands, Adam Marshall.”
Constructing the pipeline and pump station
In 2019, works began on the construction of the pipeline and accompanying pump station following extensive stakeholder consultation and design stages.
“The project involved the design and construction of an 18km DN300 pipeline and pump stations to transfer raw water from Malpas Dam to the Guyra Water Treatment Plant. Pumping was designed to be conducted in two stages to lower operating costs,” Mr Murray said.
Two low-lift pumps were then set on a floating pontoon in the dam, which is able to rise and fall with the water levels, allowing pumping at variable dam levels.
“These pumps transfer water from Malpas Dam to a high-lift pump station comprising six identical vertical multistage centrifugal pumps (five duty and one on standby),” Mr Murray said.
“The high-lift pump station boosts the pressure of water arriving from the low-lift pontoon sufficiently to overcome the static head and friction loss, and eventually transfers water to the Guyra Water Treatment Plant.
“The high-lift pump station operates five duty centrifugal pumps which are capable of pumping 12L/s or 60L/s when all five pumps are running at full speed.
The maximum treatment capacity of Guyra Treatment Plant is 60L/s, so further expansion of the pump station is not warranted without an upgrade of the treatment plant.
“The project’s infrastructure also includes a Powdered Activated Carbon (PAC) plant. Malpas Dam has a history of occasional algal blooms and PAC dosing is essential to treat taste and odour issues.
“An electrical upgrade at Malpas Dam was also needed to raise the power supply to a required level.”
Overcoming project challenges
As with any major project, there are bound to be challenges and obstacles for contractors and project managers to overcome. Mr Murray said there were a number of challenges that needed to be mitigated to ensure a successful outcome.
“There were various critical paths in this project. The main challenges faced by the crew were: negotiation with landholders affected by the pipeline route; design approval from Essential Energy; procurement of a new voltage regulator and transformer; rock encounter; and other latent conditions during the construction phase,” Mr Murray said.
“Proper planning, site assessment and communication helped overcome all the obstacles. The major takeaway from this project was the need to allow enough time for processes beyond the Council’s control.”
Racing to beat the drought
With the drought choking the Guyra district, time was of the essence for contractors working on the project. Dwindling water supplies meant that Guyra was on track to reach ‘day zero’ in mid 2019, giving contractors the incentive to work quickly to complete the project ahead of time.
“Construction of the pipeline was expedited because of prevailing drought conditions, with supplies in Guyra Dam on track to run out in mid 2019.
While water from Malpas Dam was trucked to the Guyra treatment plant to supplement remaining Guyra Dam supplies, crews completed the pipeline ahead of schedule,” Mr Murray said.
“An official opening with Deputy Premier, John Barilaro, and the Member for Northern Tablelands, Adam Marshall, was held on schedule in October 2019.”
Maintaining the pumps
Now that the essential pipeline is online and operating, future maintenance is of the utmost importance to ensure the infrastructure copes with demand.
Mr Murray said that an ongoing maintenance plan was in place to ensure the pipeline and accompanying infrastructure remains in working order, even when the pumps are not in use.
“A daily/weekly/quarterly/annually maintenance plan is in place for the infrastructure and pumping equipment.
Even when the pipeline is not in use, Council will need to run the pumps every two to four weeks to clean the pipeline and keep the pumps in working order,” Mr Murray said.
Benefitting the region for years to come
With construction now fully complete, the Armidale region is able to reap the benefits of a more flexible, secure water supply. Mr Murray said these benefits also have the potential to increase economic development and job creation in the region.
“The pipeline has brought two supply systems together to create an integrated town water supply,” Mr Murray said.
“It provides greater flexibility in sourcing water for the town supplies and enables the current system to access water from the much larger Malpas Dam.
“The increased water security provided to Guyra town water users will also open the door for substantial economic development and job creation.
A number of horticultural industries have shown interest in investing in the area and are just waiting for a more reliable water supply before they commit.
“Guyra’s high number of sunny days and consistently cool conditions gives it incredible potential to become a hub of intensive glasshouse horticulture.
While planning approvals would require any new agricultural developments to be primarily water self-sufficient, the Malpas Dam to Guyra pipeline would help provide greater water security during extended dry periods.”
Mr Murray said that funding has also been confirmed to improve pipeline infrastructure connecting the 700ML Puddledock Dam, providing a backup to the network when the Malpas Dam is offline.