Deep Water

This is from the display board adjacent to the concrete block cut from the dam wall.

In 2006, this 17 tonne concrete block was cut and removed from the upstream face of Warragamba Dam wall to establish a new low level water supply outlet. This new outlet allows access to water deep in the dam that was previously inaccessible.

Over a period of 16 days, a team of eight divers, working at a depth of 85 metres, used a specially designed remote controlled cutting rig to remove the block. The specialist 'saturation' divers, breathing a mixture of helium and oxygen, worked in shifts from a diving bell.

After each shift they returned to a pressurised living chamber on top of the dam.

Downstream, a long disused pumping station was expanded and equipped with new pumps to move the water up and into the pipeline to Prospect Reservoir.

The new outlet and pumping station provide access to an additional 170 billion litres of water stored in Lake Burragorang, approximately five months water supply in times of severe drought.

Night scene, bell on left, steel frame with concrete block, both against rear of dam wall
The diving bell and cutting rig against the upstream wall of the dam.

The steel frame holding the concrete block, operator next to it
The concrete block inside the cutting rig was craned up to 100 metres to the top of the wall.

Elevation plan of upstream face of dam showing new outlet near river bed
This diagram shows the position of the new deep water outlet in the dam wall.

Updated at 19:50 EST on Sat Jul 28, 2012