Dam upgrade concretes itself in SA Water history as countdown begins to project completion

Rounding off one of the final stages of a $94 million safety upgrade of the Kangaroo Creek Dam, SA Water will soon be pouring its last batch of concrete, bringing the total amount used to around 35,000 cubic metres.

Work at the Adelaide Hills site began in January 2016, and is on track for completion this November. More than 500,000 construction hours to date have gone into carrying out what is one of the biggest single projects currently on SA Water’s books.

The upgrade will help to better manage any major floods and increase the dam's ability to withstand earthquakes, aligning it with updated safety guidelines set by the Australian National Committee on Large Dams (ANCOLD).

SA Water Acting Chief Executive Mark Gobbie said the sheer size of the construction site and the amount of activity happening there on an almost daily basis clearly demonstrates the magnitude of the project.

“However, it’s when you look at the many milestones that have been produced along the way, that it really becomes clear just how much has gone into delivering this upgrade safely and effectively,” Mark said.

1250 is the total number of people who have worked on the project to date.

“At any one time, there is up to 115 workers on site, which has included local suppliers providing the concrete, steel-fixing and formwork. This also equates to a little over the same number of hard hats, safety glasses and pairs of steel caps being put to good use each day,” Mark said.

33 is the average number of metres the dam’s concrete spillway has been widened, which is where water travels over to reach downstream, when the reservoir reaches capacity.

“We’ve recently completed widening and raising the spillway, which has been made possible through the controlled blasting removal of more than 330,000 square metres of rock from the nearby hillside,” Mark said.

“To help strengthen the dam structure against earthquakes, the embankment has also been widened by around 45 metres reusing rock material from the blasting activities, and raised by five metres to help improve its flood protection capacity.”

35 is how many pieces of heavy machinery have been used during construction.

“The variety of work required as part of this upgrade needs a variety of equipment, such as cranes, excavators, bulldozers, dump trucks, concrete pumps and drill rigs,” Mark said.

19,000 megalitres is the total capacity of Kangaroo Creek Reservoir, but early last year, the water level was gradually brought down to zero per cent.

“This was only the second time in the reservoir’s history it’s been emptied, and was to facilitate work on the upstream face of the dam embankment.

“Water released from the dam was either used to, where possible, support dilution flows into the Torrens Lake to help with the control of blue-green algae, or be fed into the Hope Valley Water Treatment Plant for drinking water supply.

“Rainfall and a small amount of water diverted from other parts of our network have since started to refill the reservoir, which is now sitting at around 35 per cent of capacity.”

28.8 metres is the length of the historic Batchelor’s Bridge which was revealed when the reservoir was emptied.

“Batchelor’s was one of six bridges built in the area between 1912 and 1925. It originally conveyed Gorge Road users across the Torrens, but was abandoned in 1966, just prior to construction of Kangaroo Creek, with the road's current alignment built higher into the mountain side,” Mark said.

10 is the number of tonnes of carp removed from the reservoir after it was emptied.

“We organised for a fisherman to collect the fish as we gradually lowered the water level. Around half of what he caught went to the Sydney fish market and the rest was supplied for fertiliser,” Mark said.

10,000 is the approximate number of people who travelled to the look-out on nearby Gorge Road to see a glimpse of Batchelor’s Bridge in the four months it was visible.

“This is in addition to the 450 or so people who have toured the site since construction began, including university study groups, visiting overseas engineers and community groups. It’s certainly one of our more popular work sites!” Mark said.

50 is the number of years between shifts for site supervisor David Owens.

“David was just 18 when he began work as a truck driver on the construction of the Kangaroo Creek Dam in 1968. He’s now come full circle and is working for our contractor Bardavcol on this latest dam upgrade,” Mark said.

“Having worked together almost every day over the past three years, the Kangaroo Creek crew have become pretty tight–knit and have achieved some minor milestones of their own.

“I’m sure the team has reached the thousands with the number of sandwiches and cartons of iced coffee consumed, and on a more serious note, have made safety part of their culture 100 per cent of the time.”

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