UP to $20 million will be pumped into Scrivener Dam next year, to replace the dam’s anchor bolts, which are showing signs of corrosion.

The work will involve replacing 120 anchor bolts, which are part of the flap gate mechanism that opens in flood events to regulate the water levels of Lake Burley Griffin. According to the NCA, the anchor bolts were not visible to previous safety audits and surveillance inspectors.

NCA chief executive Gary Rake said as part of the management of Scrivener Dam, the NCA commissions an annual, independent, safety and surveillance inspection report.

“The 2011 report, received three weeks ago, advised that some of the anchor bolts on the dam were showing signs of corrosion,” Mr Rake said

“The NCA immediately commissioned further inspections and tests to assess the extent of the corrosion.”

The engineering works will be funded within the NCA’s existing capital works budget. To enable an immediate start, two other projects have been deferred.

“The Bowen Place crossing upgrade and renewal of the National Capital Exhibition will be placed on hold,” he said.

“We understand the community will be disappointed by this announcement. However, the engineering works at Scrivener Dam require immediate action in order to complete the works within the recommended timeframe.

“The NCA remains committed to these projects. We have scheduled the Bowen Place upgrade to recommence in 2014, and the National Capital Exhibition renewal in 2016.”

The majority of the anchor bolts were encased in steel structures or concrete.  The non-destructive testing involved either cutting away small sections of non-structural concrete, or drilling small holes through the steel structures and using an endoscopic camera to inspect the previously hidden bolts.

“Yesterday we received advice that all the hinge bolt anchors will need to be replaced within one to two years. It is anticipated this work will take 50 to 80 weeks to complete, so work needs to commence shortly,” he said.

The anchor bolt system will be redesigned as part of these engineering works to ensure that future inspections can be conducted easily. We will also install cathodic protection to minimise future corrosion.

He also reassured the public that Scrivener Dam is well-managed and safe.

“The NCA spends more than $1 million on the operation and maintenance of Scrivener Dam each year. In the last two years, more than $1.3 million has been invested on upgrading the facilities, with a further $350,000 spent so far this year,” he said.

“Undertaking these works will not interfere with the regular operation of the dam. We have been advised by independent engineers that Scrivener Dam remains safe and fully functional. All risks associated with these works and the day-to-day operation of the dam
are being appropriately managed.”

The NCA has taken immediate action to ensure Scrivener Dam remains fully functional.

More information at www.nationalcapital.gov.au