Underwater Cutting of Additional Inlet for Low Level Water Access

Overview

Warragamba Dam, located in New South Wales, is an essential water source for the state. The dam had no access to obtaining water at the low levels, meaning that around 10% of its capacity was not accessible in the event of a water emergency.

The client was looking for a specialised deep water coring and cutting solution that would allow access to these lower water levels.

Scope

The project had the following specifications:

Structure	Dam wall
Application Type	Structural Modification
Operating Environment	Underwater - up to 90m depth
Quantity	1 block
Cross Section	Steel reinforced concrete
Cut Dimensions	4m (w) x 2m (h) x 1.75m (d)
Cut Volume	14m3
Cut Mass	33.6t
Method	Remotely Operated Tooling

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Solution

• Coring underwater of 6 holes through the dam wall (1.75m thick). Two of these holes were for bearing packs. The other four were for a plunge type wire saw to cut between them.
• Deployment of remotely operated tool (ROT) into the water, to a depth of 90m.
• Once coring and cutting was complete, the concrete bock dropped onto bearing packs and was pulled into a purpose built frame that lifted it to the surface.

Benefits

• Deployment of ROT internally overcame underwater and depth limitations.
• Improvement in safety due to removal of divers and purpose built frame for removal of concrete block.
• Improvement in speed and quality of cutting through state-of-the-art monitoring systems. Project was completed successfully in around 4 days on site.
• Reduced contractor footprint.