I saw the 60 Minutes segment on the 2011 Grantham floods last Sunday where they
raised again the issue that a wall at a local sand quarry breached which they say caused the loss of life at Grantham. This issue has been discussed for years – just google “quarry wall near grantham”. I have not read earlier reports but it surprises me that a matter involving simply ascertainable engineering matters such as volume of trapped water – height of the wall and nature of the breaches – would not have been reported on with some certainty in terms of flood effects on Grantham.
I posted on this in 2011 – Toowoomba flash flood shambles – and reading comments which ran for over a month – there is no mention of this sand quarry.
I have found a map of the quarry – exhibit 359 at the Queensland Floods Commission of Inquiry 2011 – The copy I took needed lightening – the pdf has rather a dark image – the map goes with exhibit 358. More recent map I just obtained from GoogleEarth – the flooded quarry is obvious inside that loop in Lockyer Creek just north of the end of the word Carpendale.
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In months to come we will see what the new inquiry brings.
Recent flooding in the Hunter with loss of life at Dungog shows that although the BoM get rain telemetry in real time – and allied with historic hydrology data should be able to highlight areas of danger – our modern and technology rich society at times can not produce useful warnings against effects of flash flooding.