Wivenoe was at risk of collapse, court told
WIVENHOE Dam risked collapse if water was not released in the wake of the extraordinary weather that fuelled the tragic Grantham and Toowoomba floods in 2011, a Sydney Court has been told.
Brian O'Donnell, QC, for Seqwater, said dam engineers had no choice but to release water from Wivenhoe during the deluge between January 9 and 11, 2011.
"In a nutshell, we will say the large releases were necessary for the structural safety of the dam,'' Mr O'Donnell told the flood class action being heard in the NSW Supreme Court.
He also attacked experts who had the luxury of time and hindsight to give their versions of how Wivenhoe should have been operated during those frantic few days.
Heavy rain produced a massive inland wave of water, not connected to dam operations, which hit Toowoomba and the Lockyer Valley town of Grantham on January 10, claiming more than 20 lives.
Mr O'Donnell yesterday completed his opening in a class action brought by Maurice Blackburn against the state of Queensland as operators of the Wivenhoe and Somerset dams during the 2011 floods.
Maurice Blackburn lawyers are arguing that dam operators allowed too much water to build up in the dam, forcing them to release large volumes.
Maurice Blackburn alleges the released water contributed to a downstream flood which caused extensive damage in Ipswich and Brisbane and other areas before peaking in the Brisbane River on January 13, 2011.
Mr O'Donnell said the extreme intensity of the rainfall changed dam operations as engineers dealt with a dramatic increase in inflows.
"It was a constant process of modelling, adjusting, adjusting loss rates, and so on, and that took a good deal of time,'' Mr O'Donnell said.
He said experts offering alternative models did not to go through that process but merely took inflow figures which occurred during the event and worked with those figures.
There were also issues which arose during the event such as gauges not working or producing readings which appeared "odd''.
Mr O'Donnell said it was not Seqwater's case that the engineers would have done things differently if they had more time.
"But it is to be borne in mind that they had time pressures, whereas some of the experts ... have had no time pressures,'' he said.
"They've had unlimited amounts of time, and to undertake modelling which might seem unrealistic as something to be done in real time ...''
The hearings resume today.