Work is underway on stage one of a programme to ensure Ridgeway Dam, on the lower slopes of Mount Wellington, keeps supplying water to the Hobart community for another hundred years.
Built between 1912-18, the dam is soon to celebrate its centenary and while still strong and secure, work is needed to make sure it remains safe into the future.
Investigations into the dam by TasWater have shown the concrete walls need to be strengthened.
Currently test holes are being drilled into sections of the dam wall to assess the on-going integrity of the dam.
Contractors are using a diamond head drill to bore into the dam wall to depths up to 110 metres at angles of 60 degrees.
Following the investigative drilling TasWater then plans to reinforce the dam with additional cable anchors being inserted through the dam wall and deep into the rock structure below.
Further improvement is likely to include an impermeable membrane that will be attached to the upstream face of the dam wall.
This membrane will then provide additional protection by limiting the amount of seepage that could pass through the dam wall from the reservoir.
Ridgway is the main drinking water supply for the Kingborough municipality and when it’s full holds 940 megalitres.
The water contained in the dam is fresh off the slopes of Mount Wellington and because of its quality, needs minimal treatment before being distributed to customers.
As part of managing the current investigation TasWater has incorporated stringent precautions to protect the dam water from any potential contamination.
TasWater has several large storage dams around the state and maintaining their safety is a key role in guaranteeing not only the security of the community but also the states drinking water supply network.
The upgrade of the Ridgeway Dam will be funded as part of more than $330 million to be spent over the next three year on building new infrastructure as well as maintaining existing facilities.
Simon Pilkington, TasWater
