Monthly Meeting
730pm Thursday 31st May 2012
Dr Philip Pells presents
"The Vanishing Thirlmere Lakes"
The Thirlmere Lakes are part of the Greater Blue Mountains World Heritage Area. These ancient lakes on Sydney's southern door-step have all but disappeared.
The five connected lakes are not supplied with water by rivers or streams but instead have for 15 million years relied on underground aquifers and rain. The lakes have dried out in droughts past, but then quickly refilled when rain returned. Not so this time.
Following 9 years of drought, the heavy rains of the past 18 months have failed to restore the ancient lakes.
Early last year the then Labor government released a report concluding that the near decade-long drought was responsible for the drying of the lakes.
Given the heavy rain following the drought, this explanation falls short of being convincing. Brian Marshall, a former professor of structural and engineering geology, has instead suggested "a strong possibility" that longwall mining in the area by Xstrata Coal has drained the water of the lakes. Xstrata refutes the suggestion.
The mystery of the lakes prompted a study by consulting geotechnical engineer and groundwater expert Dr Pells. The 18 month study is impressively comprehensive.
The conclusions reached are sobering and, if correct, have disturbing implications for coal mining and coal seam gas extraction.
About the presenter: Dr Philip Pells is a civil engineer who has specialised in geotechnical matters.
He was part of the design and construction teams for the Sydney Harbour Tunnel, the Sydney Opera House Car Park and the Eastern Distributor.
In recent years his work has been dominated by studies in relation to underground coal mining and now, CSG.
With Philip Hammon he has produced "The Burning Mists of Time", dealing with the history of oil shale mining in the Blue Mountains.
Philip is a Doctor of Science, a Fellow of the Australian Academy of Technological Sciences and Engineering, and a Fellow of Engineers Australia.
More details in the Hut News
730pm Thursday 31 May 2012
Conservation Hut, 88 Fletcher St,
Wentworth Falls. Here's a map
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