Dam probe’s counsel testing expert’s advice
ADVICE from an international dam specialist who worked on Paradise Dam will be a central theme of the inquiry into its construction flaws.
Senior counsel member, Jonathan Horton, QC, told the Commission of Inquiry that there will be an examination of quality processes and reporting since construction began in 2003.
He said in the preliminary hearing in Brisbane yesterday that the shear strength of lift joints was likely to a key aspect of the inquiry
Mr Horton said there was difficulty determining what testing had been completed on the dam while it was being built.
The commission had compiled 30,000 documents since it was formed in December but was unable to find the full version of a construction report which Mr Horton said should have existed.
There were quality control reports which suggested that there were problems with laying the roller compacted concrete (RCC), and the consequences of these were being investigated.
He told the commission that international dam authority Ernest Schrader was important to the construction process, and that he was being called as a witness to clarify the process.
Dr Schrader is an international authority of the RCC and also founded a method of testing lift joints, which had been used on the dam.
“He, as will be seen, played a central role in the dam’s design and construction and made a number of recommendations and judgments in the course of those stages, some of which are controversial,” Mr Horton said.
Mr Horton said the percentage of concrete used on the dam was alleged to have decreased by 30 per cent.
But he said that witnesses in the inquiry had different views on whether the decision was acted on.
He said 8536 cubic metres of bedding mix was reported to have been used.
Mr Horton said if this instruction was taken, then it was concerning because it appeared to contradict the dam’s specifications.
He said the strength and quality of lift joints would feature prominently in the investigation, and that quality had been measured by Dr Schrader.
The commission said the index is acknowledged, but not endorsed, by the Australian National Committee on Large Dams.
“There are questions about the extent to which it is appropriate to rely upon an index which is one man’s creation,” Mr Horton said.
He said there was no quantitative evidence showing the shear strength of the dam’s lift joints.
“We wish to look more closely at what occurred in late 2005 and early 2006 in respect to decisions about what could and should be the subject of sheer testing, and any analysis or observations from that time about whether the coreholes showed bonded or unbonded joints,” he said.
Commissioner’s opening statement
THE Commission of Inquiry’s chairman John Byrne said some of the 30,000 documents and photographs it has analysed were complex and technical.
It had also witnessed more than 12 witnesses, but was attempting to seek more information from the community.
“But much remains to be done, and quickly,” Mr Byrne said.
“The Commission is to complete its investigations and report to the Honourable the Premier and Minister for Trade and the Honourable the Minister for Natural Resources, Mines and Energy by 30 April this year.”