Engineers are examining videos of historic underground tunnels in Tasmania’s Derwent Valley.
Further investigations revealed tunnels about six metres below the surface.
Derwent Valley Mayor Martyn Evans says the tunnels have now been filmed.
It is believed the tunnels date back to the 1830s and could have been used to transfer convicts and patients to the mental health hospital at Willow Court.
The council has announce the video and investigation after discovering last year a suspected air shaft, which was announced by Cr Bromfield at the Frascati Open day in January 2013.
Just examining the video footage it is clear that while there are older building materials used, there are also some more modern materials in use as well. There is also clear evidence of a drain, either storm water of sewage entering the tunnel.
