Council reveals huge move to raise barrage this year
CONSTRUCTION to raise the Fitzroy River Barrage could start this year.
Rockhampton Regional Council plans to increase the storage capacity of the barrage by almost 10,000 ML, with favourable outcomes of feasibility study and failure impact assessment reports.
Fitzroy River Water is preparing detailed designs for the changes, while working through approval with the State Government.
With some "relatively minor” changes to the barrage gates and parts of the structure, water could be stored at 0.5m above the current operating level.
The changes are expected to cost between $500,000 and $1 million.
Fitzroy River Water manager Jason Plumb said this would not increase Rockhampton's water allocation, but reduce the chances of the water level dropping below acceptable.
Typically, the region uses a little less than half the annual water allocation of 50,000ML.
But Mr Plumb said it was important to ensure the barrage would continue to serve our region through population growth in the future.
The increased storage was identified through a Regional Water Supply Security Assessment in partnership with the State Government in October 2015.
This report assessed Rockhampton's water source and supply infrastructure and future security based on population projections.
"This work included surveying the more than 40km of the river channel upstream of the barrage to accurately calculate the volume of water stored behind the barrage and use this volume along with other information to model just how secure our water supply is,” Mr Plumb said.
"This work found that at current levels of usage and without any water restrictions imposed, the barrage might be at risk of water supply failure on average about one in every 108 years.
"Considering that this level of security does not include using water restrictions to limit water use and conserve remaining supply, this is a relatively good level of security.”
Mr Plumb said water efficiency would be a priority, but the changes to the barrage would provide stability into the future.
He said the feasibility and failure impact assessments confirm the height can safely be increased without risk to the community downstream of the barrage in the event of structure failure.
"Fitzroy River Water is now working closely with the Queensland Government through an approval process to ensure that any proposed changes to the barrage comply with relevant legislation relating to water resources, planning issues, and the environment,” he said.
"Working through this approval process will also include interacting with local stakeholders to ensure that important local wildlife such as Fitzroy River Turtles and the local fishery are not impacted.
"At the same time detailed design for the modifications is being finalised to confirm the detail associated with any changes to the barrage gates and structure as well as checking the extent to which the increased storage height changes the area covered by the storage through minor inundation of any low-lying areas.
"So far this analysis and preliminary mapping work shows that the vast majority of the increased storage volume is contained within the existing height of the river banks.
"Given the progress made to date and the work currently under way, we expect to commence consultation with the community in the second half of the year with project construction to commence in late 2019 and extend through to late 2020.
"In addition to increasing our storage volume, the raising of the barrage gate height will also reduce the chance of future sea level rise leading to the estuary water overtopping the gates at high tide and causing estuary water to enter the upstream freshwater, something that is almost certain to happen in the coming years given the predicted rises in sea level - so another way in which we will increase the security of our valuable water supply.”
Rockhampton mayor Margaret Strelow said the barrage was a foundational asset for the community.
"We are forever grateful for the vision and the doggedness of Mayor Rex Pilbeam who built the barrage in spite of some considerable push back from some members of the community,” Cr Strelow said.
"The move to raise the gates gives us an extra layer of water security at a very affordable price.”
Councillor Neil Fisher, chair of the airport, water and waste committee, said the project would help water security and keep the salt water from mixing with drinking water.
"The barrage itself serves two primary purposes - one is to separate salt water from fresh and the second is to provide extra depth of pondage to guarantee our water supply,” Cr Fisher said.
"The raising of the barrage is for two reasons - one is around water security and the other is to provide a higher barrier between the saltwater and the fresh in a freak king tide.”