Kangaroo Creek Dam upgrade hops over finish line

After nearly four years of construction, SA Water has completed a $94 million safety upgrade of the Kangaroo Creek Dam in the Adelaide Hills.

Work began in January 2016 and focused on significantly widening and strengthening the dam’s concrete spillway – which carries water safely to the River Torrens if the water level exceeds the dam’s full supply – as well as the rock-fill embankment.

These works have helped to strengthen the dam structure against earthquakes and improve its flood protection capacity, aligning it with updated safety guidelines set by the Australian National Committee on Large Dams (ANCOLD).

SA Water’s General Manager of Asset Operations and Delivery Mark Gobbie said the Kangaroo Creek upgrade was one of the utility’s largest projects in recent decades, in terms of job creation, delivery time, scale and complexity.

“It was also one of the most popular, with around 10,000 people travelling to the nearby look-out on Gorge Road to see a glimpse of the historic Batchelor’s Bridge which was revealed when the reservoir was emptied in early 2018,” Mark said.

“This is in addition to the 750 or so people who toured the site at various times throughout the project, including university and TAFE students, visiting overseas engineers and community groups.

“Besides the obvious changes to the dam spillway and embankment, another noticeable difference at the site now is the volume of activity.

“From more than a hundred people on site at any given time during construction, to now just a handful who are cleaning up and removing equipment and machinery, it’s a very stark contrast and certainly signals the end of what has been a massive feat for all involved.”

Some minor revegetation is planned at Kangaroo Creek in April next year, primarily hydroseeding where the site compound was located during construction.

As work wraps up at this site, SA Water has entered the early planning stages for its next dam safety upgrade at Mount Bold Reservoir, south of Adelaide.

“With a capacity of around 46 billion litres, Mount Bold is our largest reservoir and functions as a storage for both natural inflow and water directed from the River Murray,” Mark said.

“This stored water can be diverted via the Onkaparinga River to the Happy Valley Reservoir, where it’s then put through the nearby treatment plant before being supplied to a substantial part of metropolitan Adelaide – around 450,000 homes and businesses.

“All of our reservoirs discharge water over a spillway, however Mount Bold also has eight large adjustable gates to assist with managing outflows. A smaller scale version is also in place at Myponga Reservoir.”

Initial consultation on the planned safety upgrade at Mount Bold has begun with stakeholders such as the City of Onkaparinga.

“As we progress further in the planning and design stage, including confirming timeframes and assessing required works, there will be opportunities for the wider local community to share their views and priorities,” Mark said.

“We will also continue to provide updates in the lead-up to and during construction.”

The Mount Bold upgrade is part of a $91 million investment proposed in SA Water’s next four-year plan – as submitted in early November to the Essential Services Commission of South Australia (ESCOSA) – which will also see the start of upgrades to dam structures at Baroota and Hindmarsh Valley.

ESCOSA is currently taking public submissions as part of its review process of the utility’s 2020-2024 plan, with a final decision expected in May 2020.

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