Construction documents missing and key strength tests in doubt, dam inquiry hears


Bundaberg 4670

An independent Inquiry into the structural issues of Bundaberg’s Paradise Dam has heard documents relating to its construction are missing, and appropriate core testing of its strength may not have occurred after it was built.

Key points:

  • A commission of inquiry is yet to locate a full construction report for Paradise Dam
  • The inquiry was instigated after technical reports revealed faults originated in its initial construction
  • The dam wall stability is at risk and major flooding is possible if 2013 flood conditions repeated

Commissioner John Byrne gave his opening statement in Brisbane and said the commission would examine the root cause of the structural issues of the dam through documents and reports, and more than a dozen potential witnesses.

In November 2019, the Queensland Government announced an inquiry into the structural issues of Paradise Dam after technical reports showed the faults originated with its initial construction.



Photo:

SunWater is proceeding with work to lower the spillway by 5 metres to relieve pressure on the dam’s wall. (ABC News: David Shipton)

Mr Byrne said since the commission began its investigation, it had collected, collated, and made progress in analysing more than 30,000 documents and photographs.

“Some documents are of considerable length, and many deal with complex geotechnical, hydrological and engineering matters,” he said.

He said Paradise Dam, which was built by the State Government between 2003 and 2005, was an important asset to the community.

“I recognise that the dam and its future are important to communities in the Wide Bay Burnett region, especially those who rely on the Bundaberg Irrigation Scheme,” Mr Bryne said.

Documents missing

Counsel assisting, Jonathan Horton, however, revealed the commission was yet to locate documents relating to the construction of Paradise Dam.

“We have, for example, attempted to locate a construction report which ought to exist, but a full version of it has not been able to be found,” he said.

Mr Horton said Paradise Dam was constructed with roller-compacted concrete, (RCC) and was one of the first of its kind in Australia, but no strength testing was carried out to determine if the layers had bonded.

“No shear strength testing was undertaken,” he said.

“We wish to look more closely at what occurred in late 2005 and early 2006 with respect to decisions about what could and should be the subject of shear testing.

“What were the decisions made during the course of design and construction about cement content, composition of the RCC mix generally, and the use of bedding mix between layers?”

Inquiry to report by April

Three out of the 13 days of hearings will be heard in Bundaberg and the rest will be in Brisbane, with recommendations to be provided to the Premier Annastacia Palaszczuk and the Minister for Natural Resources and Mines by the end of April.

The commissioners are expected to consider SunWater’s technical reports from 2013 onwards that detail structural issues originated with its construction.

The terms of reference state they may seek information from individuals and government bodies involved in the design, construction, and commissioning of Paradise Dam.

A community wanting answers

Bundaberg Mayor Jack Dempsey hoped the inquiry would determine how one of Australia’s youngest dams came to be so flawed, and who was responsible.

“It’s one of the largest infrastructure failures in history,” Councillor Dempsey said.

“Only six months ago we had a reputation for the second most secure water supply in Australia, and that has been affected.

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“Council will be putting forward a submission, whether it be a written or verbal submission.

“We certainly want to ensure that all avenues are looked at, and this certainly goes to the structural investigation.”

Councillor Dempsey said the whole situation had caused friction in the Bundaberg community, with SunWater’s own technical reports stating if the dam failed more than 100 lives would be at risk downstream.

“People with concerns should know that the local disaster management group, and the district disaster management group are well prepared in terms of every contingency,” he said.



Photo:

Thousands of megalitres of water being released from Paradise Dam into the Burnett River following recent rain. (ABC News: David Shipton)

Questions over the future of Paradise Dam

SunWater is seeking a contractor to begin construction work to lower the dam’s spillway by 5 metres after legislation was rushed through State Parliament earlier this month.

Federal Minister for Water, Keith Pitt, said the State Government bypassed its own environmental laws by allowing the work to proceed without any other environmental or council approvals.

He said the focus should now be on the future of the dam and returning water security for the agriculture industry, which was estimating a $1 billion hit to the state’s economy.

“My view is very straightforward: we make safe, we repair, we restore, or we replace this critical piece of infrastructure for this region,” he said.

“I say to Premier Palaszczuk, safety has to be the first priority, but the second has to be how do we repair, restore, or retain that facility.”

“It will take more than a decade to build anything else or even to get the approvals could take 10 years.”

The long-term future of the dam will be determined by Building Queensland with a report due to be handed to the Government also at the end of April.

Source: https://www.abc.net.au/news




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