Enlarged Cotter Dam

Enlarged Cotter Dam, ACT

The Bulk Water Alliance included the delivery of the Murrumbidgee to Googong water transfer scheme, upgrade works to the existing Googong Dam Spillway and new pumping facilities at the Murrumbidgee River. The key deliverable for this Alliance, however; was the construction of the Enlarged Cotter Dam. 

The enlarged Cotter Dam expanded the storage capacity of the Cotter Reservoir from 4 Gigalitres (Gl) to approximately 78Gl – a twenty-fold increase – and is sited downstream of the existing dam. The new 80 metre high dam was constructed of roller compacted concrete (RCC), and is the highest dam of its type in Australia.

The team developed Quality Guidelines for the RCC production and placement, established new levels in safety management and championed the world-first use of a concrete paving machine for RCC placement. The team was required to source over 1.0 million cubic metres of rock for crushing to produce aggregates and sands for the 380,000 m³ of RCC that was required for the dam wall. The team worked 24 hours a day during the placement of RCC and developed placement methods required to achieve quality and safety standards. They also developed concrete mixes that were self-compacting and a grout enrichment process to provide the required finish to exposed faces of the dam. These innovative and efficient delivery methods affirmed the Enlarged Cotter Dam as world’s best practice.

Key Awards:

  • Engineering Excellence Award - 2013 Engineers Australia Excellence Awards (Canberra Division)
  • Highly Commended Award -2013 Awards for Excellence in Concrete