LAST week the Advertiser revealed that Xstrata Coal has recently experienced twice the amount of subsidence than what was predicted while extracting two longwalls in Tahmoor.
This week, we asked the company if it was confident that such anomalies would not occur while mining under the railway.
The communications manager for Xstrata Coal, James Rickards, said that Tahmoor colliery had done extensive ground surveys.
``In both longwalls the observed subsidence returned to predicted levels as the mining progressed westward toward the rail line,'' he said.
``Mining now approaches the rail line and subsidence is now occurring at predicted levels. The consistency of the geology provides confidence that predicted levels will continue.''
The company could not explain why the extra subsidence had occurred but was investigating.
The Advertiser asked if Xstrata would hold off mining underneath the railway until the cause of the extra subsidence was determined.
The answer appears to be no.
Mr Rickards said a management plan had been developed with the rail infrastructure manager and government regulators including measures to ``accommodate'' possible subsidence impacts well in excess of those predicted.
``In the past 14 months Tahmoor Colliery has invested over $5million for the testing and installation of specialised equipment, electronic monitoring and comprehensive inspection systems,'' he said.
Email a friend