John hollandJohn Holland

A 20-fold increase for the Cotter Dam.

Enlarged Cotter Dam

The enlarged Cotter Dam project involved the construction of a new dam, approximately 100 m downstream of the Cotter Dam in the Australian Capital Territory.

The original Cotter Dam was built in 1912 with a capacity of four gigalitres. After several years of severe drought in the ACT, the Dam had remained unused. The new enlarged dam increased the holding capacity to 78 gigalitres, a 20-fold increase. Water from the dam is pumped to the nearby Stromlo Water treatment plant and the water flows to several reservoirs in Canberra, serving the city of Canberra and neighbouring areas.

The new 80-metre high dam was constructed of roller compacted concrete (RCC), and is the highest dam of its type in Australia.

Our 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.

  • Customer
    ACTEW Corporation
  • Location
    Canberra, Australian Capital Territory
  • Specialisation
    Water & wastewater
  • Start
    November 2009
  • End
    October 2013
The project won the 2013 Engineers Australia Excellence Awards (Canberra Division) and received a Highly Commended Award at the 2013 Awards for Excellence in Concrete.
Our team delivered innovative and efficient best practice delivery methods for the project. The dam required over 1 million cubic metres of rock to be sourced 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.
Our team also developed concrete mixes that were self-compacting and a grout enrichment process to provide the required finish to exposed faces of the dam.


John Holland pays respect to the Traditional Owners and Custodiams of the land on which we work and live, and their connections to land, sea and community. We pay our respect to their Elders past and present and extend that respect to all First Nations peoples today.