Queensland dams set for renewal under expansive improvement program

More than $69 million of staged strengthening works are set to commence at North Pine Dam as part of Seqwater’s Dam Improvement Program, with works planned to ensure the dam continues to operate safely in extreme weather events and provide sustainable water security.

Improvements on North Pine Dam are part of a larger raft of works currently under analysis within Seqwater’s asset portfolio, including Somerset and Wivenhoe Dams.  

Seqwater Interim CEO Will Harpham said the dam upgrades are in response to modern engineering and safety standards, with a particular focus on ensuring the longevity of these crucial assets for generations to come.

“South East Queensland dams were built to very high, internationally accepted safety standards, but most were built some decades ago in the 1960s and 1970s, some even earlier,” he said. 

“Since then, dam design and associated engineering standards, along with knowledge of weather and flood risks, have progressed.  
 
“Over the years there have been many changes that impact the way we manage our dams, including new ways of estimating extreme rainfall and flood events, and greater understanding of the size and severity of earthquakes.

“There has also been significant development and population growth downstream of our dams, advances in dam design and construction, and increased regulation for operating and maintaining dams to the highest environmental and safety standards.”
 
Furthermore, population growth in South East Queensland is putting greater demand on existing water supply assets, Harpham said, with expected climatic changes adding to this challenge. 

“Through the known impacts of climate change, we could also experience less reliable supply from our dams into the future, with research suggesting SEQ will see an increase in the annual average temperatures and levels of evaporation, as well as impacts to the volumes of inflows into our dams,” he said. 
 
“As part of our long-term water security planning, Seqwater is also investigating an expansion of the Gold Coast Desalination Plant, as well as exploring options for a second desalination plant for the region, due to the climate resilient benefits desalination provides.
 
“Current modelling, especially population growth, shows the next major enhancement of the SEQ Water Grid will be needed by 2035. 

“Water infrastructure is complex, and needs long lead times for delivery, which is why we are planning now, to ensure we’re well prepared for the future.”

Upgrades focus

“Every dam is different, and Seqwater assesses each dam upgrade project investment to ensure prudence while also meeting dam safety regulations, water security, environmental and community objectives,” Harpham said. 

While North Pine Dam continues to operate safely, the staged strengthening works will
deliver enhanced safety benefits and support the major dam upgrade planned for the site.

The staged strengthening works will involve installing more than 60 post-tensioned anchors
into the dam wall. The anchors will range from 42 to 94 metres in length and add up to around
100,000 tonnes of weight into the dam wall to further strengthen it.

SMEC has been awarded the contract for the staged strengthening detailed design. The
strengthening works are expected to commence on-site in 2025, with procurement underway
for a contractor to deliver the works.

Geotechnical drilling activities commenced in October 2023 as part of the pre-planning and
investigation phase to inform the Options Analysis.

“Since 2008, Seqwater has delivered 13 upgrades, including Leslie Harrison Dam at Capalaba, Sideling Creek Dam north of Brisbane and Ewen Maddock Dam on the Sunshine Coast,” Harpham said. 

“Work is also underway on the next tranche of upgrades at Somerset and Wivenhoe – two of our region’s gated dams. Early works and geotechnical investigations are also underway on the Lake Macdonald Dam Improvement Project.
 
“Upgrades for projects of this scale are extremely complex and require extensive planning to ensure these major investments deliver strategic outcomes.”

Expanding improvements

Following more than $500 million in funding approval by the Queensland Government, a suite of early and enabling works are expected to commence on-site at Somerset Dam in 2025, as part of the first stage of the Somerset Dam Improvement Project. 

“The early and enabling works will include the removal of the spillway gates, which are nearing the end of their service life, replacement of eight sluice gates, geotechnical investigations, temporary and permanent access road works, and the installation of a drainage curtain,” Harpham said. 

“Procurement is underway for the manufacture of the new, purpose-built and hydraulically operated sluice gates. A detailed business case on the Somerset Dam Improvement Project is also underway to confirm the preferred option for the major dam upgrade planned for the site.”

Geotechnical investigations have also commenced at Wivenhoe Dam, Harpham said, which are led by GHD to carefully assess the ground conditions and help to further understand the dam’s foundations. 

“The works will help inform the Wivenhoe Dam Improvement Project Options Analysis, which is underway and exploring technical options for the major dam upgrade planned for the site,” he said. 
 
“To support this next suite of upgrades, Seqwater is also seeking an Engineering Services Provider for its Dam Improvement Program. 

“The initiative seeks a highly proficient industry partner to drive a comprehensive range of engineering activities from the initial planning and design stages, through to construction completion to support in the delivery of the program by 2035. 

“A multi-stage procurement process is underway, and an Expression of Interest phase was recently completed, with submissions in the evaluation phase.”