2013 – Cotter Dam construction challenges and innovations

B. Perrin and J. Vida

The Cotter Dam project represents the most significant infrastructure project in the Australian Capital Territory (ACT) since Parliament House in 1988. Enlarging the Cotter Dam has increased the Cotter reservoir capacity from 3 GL to 78 GL, representing a 35% increase of ACTEW Corporation’s total reservoir capacity for the ACT region and providing water security to facilitate future population growth.
At 87 m high, Cotter Dam is the tallest Roller Compacted Concrete (RCC) dam in Australia. Construction began in October 2009, with excavation of the dam foundation commencing in March 2010. With typically 05H:1V slopes up to 115 m high, excavation posed a number of challenges. RCC placement commenced in August 2011 and continued until December 2012.
Innovation and continuous improvement were crucial to the success of the project. From development of specialised mechanical tools for the abutment excavation, to use of precast, to mechanical paving of the downstream RCC steps, construction practice on Cotter Dam established a number of new benchmarks for RCC dam construction.
This paper will describe the construction innovations used to overcome the challenges associated with construction during foundation preparation and RCC placement for the Cotter Dam Project.

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