Eildon Dam Improvement Works
Eildon Dam is located at the foothills of the mountains in Victoria and, with the state’s second largest storage capacity, it supplies vital irrigation water to the Goulburn Valley via the Goulburn River.
Prior to the upgrade, a review had identified that the existing dam had insufficient spillway capacity, embankment vulnerability and that the spillway would be unstable in a major flood event. Subsequently, the Eildon Alliance was established to design and construct the $52 million of required improvements and did so, three months ahead of the contract date, while absorbing the time impact of significant additional works.
The alliance partners of Goulburn-Murray Water, John Holland, Hazell Bros and GHD, undertook extensive design, modelling, risk assessment, programming and costings to establish the budget and the scope of work. Principal works undertaken included:
- Strengthening the concrete spillway by the installation of 257 rock anchors, 25 metres into the underlying rock bed. This was an alliance proposal as an alternative to the previous solution of massive upstream training walls and represented a $5M saving.
- The top 2m of clay core was reconstructed due to its poor condition, and then the embankment was raised by 5m. In order to complete these works, the roadway and top 6 metres of the existing dam required removal until suitable foundations were obtained.
- Filters and rock protection were removed and replaced from the top 11m of the downstream face of the embankment using 53.000m3 of clay fill, 77,000m3 of manufactured filters and 180,000m3 of processed rock. Upon completion of the embankment a precast parapet was installed and the road reconstructed.
The main challenge was in sourcing of the embankment material as the quarry for the existing dam was still exposed and had become unstable over time. To minimise the traffic through the township and rectify the problem of the quarry stability it was decided to use the existing quarry for all rock product.
A community reference group comprising community and business leaders and conservationists was established as the primary conduit between the project and the community. This ensured no major issues eventuated and contributed to a very successful project outcome from the community’s point of view. As a contribution to the community a new boat ramp was constructed by the alliance.
- High commendation in the Engineering Excellence Awards 2005
- Victorian CASE Earth Award construction excellence for projects >$10m