AN innovative, unmanned submarine that uses sonar technology will now be used by Snowy Hydro to monitor the condition of six trans-mountain tunnels across the Snowy Scheme.
The tunnels transfer water from east to the west of the dividing range. Inspecting these tunnels in the past was massive operation, requiring the tunnels to be drained of water, essentially shutting down part of the Snowy Scheme and several power stations.
A new high-tech device known as an 'unmanned underwater vehicle' (UUV) will now be used to inspect the tunnel's conditions. Using multi-beam sonar technology, the UUV produces an image of the tunnel wall as it is 'swims' through the tunnel.
The unmanned submarine is almost four metres in length, nearly a metre wide, and weighs over 600kg.
The sub is inserted into each tunnel by crane and is directed through the tunnel via remote operation.
Each tunnel inspection can take up to 18 hours to complete.
The images produced are assessed by geotechnical experts to gain an understanding of the condition of each tunnel and identify any areas, which may require further investigation.
The findings are also correlated with detailed geological mapping to assess the probability of any partial or complete blockages and determine maintenance requirements.
Chief Operating Officer of Snowy Hydro Ken Lister said, "The use of the unmanned sub for tunnel inspections now means that it can be done more frequently, more safely and without the need to shut down power stations or drain the tunnel. This multi-million dollar investment is a great outcome for the business, for the safety of our people and contractors and is part of our wider program of Scheme upgrades and ongoing maintenance".