Engineer sounds warning over Burdekin Dam
A dam engineer has warned that government-owned water corporation SunWater risks losing "the whole enchilada" if a long-proposed upgrade is not done to the Burdekin Falls Dam.
But SunWater says the dam is safe and that, while they are planning a new Comprehensive Risk Assessment and upgrade, a detailed business case is assessing the engineering options. A commission of inquiry is under way into the Paradise Dam near Bundaberg after experts warned the condition of its wall posed a serious risk to public safety.
Townsville engineer Dick Cerny, who has worked with Tasmanian Hydro and the Snowy Hydro schemes, said work on the Burdekin was needed too.
The State Government announced funding of $136 million for the Burdekin storage in 2017 but SunWater put the business case on hold, citing hydrology indicating "potentially significant increases" in extreme flood inflows into the dam.
Mr Cerny said he had been told the cost of a key element of the upgrade - raising the storage's saddle dam walls and installing post-tensioned anchors to the spillway - had blown out to more than $300 million.
"They've done their studies. They know they have a problem. The longer they wait, the more chance they will lose the whole enchilada," Mr Cerny said.
The dam's emergency management plan says its failure might occur if one or more of the dam's monolith columns become unstable.
The uplift on one of the monoliths is "approaching the design pressure", it says.
"It is possible that an unstable situation could eventuate that would lead to a dam failure. The most likely cause of a change that could lead to an unstable situation would be scouring at or near the toe of a monolith during a flood," the plan says.
The SunWater spokesman said the dam had performed well, including during last year's monsoon when water at a height of 6m flowed over the crest.
A detailed review of a new catchment hydrologic model confirmed potential flood flows, levels and probabilities and this information was being fed into a new Comprehensive Risk Assessment and engineering design solutions.
"It provides a better understanding of the magnitude and frequency of extreme flood events and allows for risk-based engineering principles to be applied," the spokesman said.
Retired Townsville engineer Tony Manning said the dam was "not unsafe" but that the upgrade was needed as part of a "real" stage two expansion. Stage two would create 50,000 permanent local jobs over the next 25 to 30 years.