The first four of the new anchors have been installed in the spillway area of the concrete dam. In total, 92 of the cables will be installed by the middle of next year. The strengthening works cost Aus$38M (US$31.2M).
Hydro Tasmania has the work being done with holes up to 75m deep bored down through the dam and into the bedrock.
Bonded with grout in the foundation and otherwise held in the body of the 49m high dam within grease-filled tubes which are within plastic pipes, the corrosion-protected anchors are tensioned to approximately 1700 tonnes.
The level of Lake Catagunya has been lowered for the refurbishment works at the dam, which was built in the early 1960s in the Upper Derwent catchment.
Design of the strengthening works was performed by Hydro Tasmania Consulting.
Initial planning, in 2007, for the strengthening works had proposed building buttresses and so not need new anchor cables.
