Dam Improvement Program
Dams are long-life assets which require continual assessment, monitoring and maintenance to ensure they can provide water security for years to come.
Sunwater’s Dam Improvement Program (DIP) includes upgrades to some of our 19 referable dams to ensure their long-term viability so they can continue to:
- safely pass excess volumes of water during periods of extreme rainfall
- meet modern engineering design standards
- comply with the safety requirements set out in the Water Supply (Safety and Reliability) Act 2008 (Qld).
Dam safety is regulated by the Queensland Government which publishes the Dam Safety Management Guidelines outlining the processes and procedures dam owners need to follow. The Dam Safety Regulator also published the Acceptable Flood Capacity Guidelines which define the required capacity of spillways on referable dams based on predicted rainfall events and the overall hazard posed by the dam to communities downstream of it.
Why is a Dam Improvement Program needed?
Like all major infrastructure, maintenance and upkeep is required to ensure our assets can continue to operateat their best. This is especially true for some of our dams, some of which have been in operation for more than 50 years.
Advancements in knowledge and water infrastructure technology have enabled water resource providers to better understand and manage the impacts on dams caused by natural events, including floods, earthquakes, as well as the general wear on infrastructure over time.
The Queensland Government’s Guidelines on Acceptable Flood Capacity for Water Dams (AFC) influence which of Sunwater dams require upgrades. These guidelines define the magnitude and frequency of rainfall and flood events that are acceptable for dam stability and define the capacity of the spillway.
The Sunwater DIP will improve asset longevity and result in Sunwater’s dam portfolio having a risk profile that is demonstrably acceptable when assessed against Queensland Guidelines and industry best practice.
How are dams monitored?
For each of Sunwater’s referable dams, the Queensland Government issues a condition schedule that defines specific actions and responsibilities for dams, which include:
- regular surveillance, annual inspections, detailed five-year inspections, 20-year design reviews, and
- each dam having an Operation and Maintenance Manual.
Sunwater regularly monitor our dams by physically inspecting the structure and reading instruments that record water storage levels and water pressure within the dam and foundations. Each referable dam is surveyed every year using defined points to determine whether any movement has occurred.
Sunwater’s dam-specific Emergency Action Plans have defined ‘trigger levels’ for various observations and/or changes in data which may require escalation.
How are our dams assessed and prioritised?
For each referable dam, Sunwater complete a Comprehensive Risk Assessment (CRA) which is a staged process of systematically reviewing dam data, updating models and conducting a quantitative risk assessment on each dam. CRAs are completed on a rolling cycle, typically every five years.
The individual dam CRAs then feed into Sunwater’s overarching Portfolio Risk Assessment (PRA), which evaluates the CRAs to determine the priority of projects for the DIP.
A CRA includes:
- an update of hydrology models
- a summary of geological information at the dam
- a review of the ‘as built’ information from when the dam was constructed, including foundations, concrete strength and durability
- consideration of possible ‘failure modes’, with each then assessed for likelihood
- modelling of the potential impacts for those failure modes based on downstream communities in terms of societal risk and economic impact.
Sunwater works with the Department of Regional Development, Manufacturing and Water’s (DRDMW) Dam Safety Regulator and Shareholding Ministers on funding arrangements before commencing any project under the DIP.
All proposals for improvement to our dams start with a business case, but the specific works required for each project under the program can differ greatly.
Current projects within the Sunwater DIP
- Burdekin Falls Dam – detailed business case
- Paradise Dam – detailed business case
- Teemburra Dam – preliminary business case
- Leslie Dam – preliminary business case
- Coolmunda Dam – preliminary business case.
- Fred Haigh Dam – $2.6 million (2007)
- Bjelke Peterson Dam – $4.5 million (2008)
- Tinaroo Falls Dam – $24.5 million (2011)
- Kinchant Dam – $19.2 million (2014)
- Eungella Dam – $1.5 million (2016)
- Paradise Dam – strengthening concrete spillway base $30.1 million (2017)
- Burdekin Falls Dam – foundation drainage $5.1 million (2017)
- Fairbairn Dam – $170 million (2020).