Wellington Dam Upgrade
Client: Wellington Dam Alliance
Location: Wellington, WA
Built in 1933, strengthened in 1945 and enlarged in 1960, Wellington Dam near Collie in Western Australia is the state’s second largest dam with a current capacity of 186 gigalitres when full. In December 2009, as part of a state-wide dam safety and maintenance program, the Water Corporation (WA) started a $41 million project to strengthen the dam wall in order to bring it into line with current engineering standards. Work began in December 2009.
Substantive Temporary Works
The project involved installing a series of high-tensile steel cables vertically through the dam wall into the bedrock to improve overall stability. This is a commonly used technique for strengthening large dams. However, in this case access to the top of the 34 metre high wall is made virtually impossible because it has a smooth, curved surface with no flat walkway or road across for one side to the other.
But contractors had to be able to work on the dam’s top surface in order to drill a number of holes and insert the cables.
VDM Consulting was commissioned to solve the problem and did so by designing and fabricating a trafficable maintenance bridge and a system of self-launching rails that allowed large covered trolleys to run across the top of the dam carrying the drilling equipment and crews.
Although this was VDM’s only involvement in the Wellington Dam upgrade, it is difficult to imagine how the project would have gotten off the ground without such a unique solution which overcame the project’s primary challenge of safe and easy access.
Sometimes, temporary works end up being built in to the overall structure but in this case everything was removed after use and the dam stands stronger today with no evidence of the tracks and trolleys that helped to get the job done.
The solution designed by VDM Consulting was an innovative concept and this is believed to be the first time that access to a smooth, round topped dam has been gained in this way.