The Mardi Dam is an off-river storage dam located near the Wyong River on NSW’s Central Coast, 100 kilometres north of Sydney. The dam upgrade project was undertaken to address the region’s projected demands for clean water and it included the building of a new water intake tower, a structure with a unique set of challenges for reinforcing. The new tower is a complicated concrete structure that rises 22 metres from the rock excavation level.
ARC worked together with Baulderstone to provide a prefabricated solution to the installation of steel reinforcement in the main part of the tower. The jump-form construction technique required a ‘building block’ approach. Each cage was to be placed on top of the adjoining pour and had to maintain the close-tolerance vertical alignment of the formwork.
We prefabricated the cages to specification in the factory, and then delivered them so they could be accurately positioned on top of each other on-site. Prior to construction, ARC modelled the reinforcement in 3D and then built a jig in the shape of the tower. The special curved jig we built for this project allowed control to be maintained for each cage to within a five millimetre tolerance.
The dam has a capacity of 7.4 billion litres, and is part of a system that supplies clean drinking water to almost 300,000 residents and businesses. The $59 million project will secure the water supply for New South Wales Central Coast’s Wyong Shire and Gosford City for the next twenty years.
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