The ACT Government will begin engineering works on the Scrivener Dam after an annual safety audit and surveillance inspection.

The National Capital Authority’s (NCA) commissions on annual, independent, safety and surveillance inspection report advised that some of the anchor bolts on the dam were showing signs of corrosion.

Works will involve replacing 120 anchor bolts, which are part of the flap gate mechanism, which open in flood events to regulate the water level of Lake Burley Griffin.

According to the NCA, the anchor bolts encased in steel structures or concrete were not visible to previous safety audits and surveillance inspectors.

Redesign of the anchor bolt system will be a part of the engineering works to ensure easier future inspections, with a cathodic protection installed to minimise future corrosion.

To be funded within the NCA’s existing capital works budget, the works are anticipated to cost about $15 to $20 million.

NCA chief executive, Gary Rake said 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 $350000 spent so far this year,” Mr Rake said.

An ACT Government spokesperson said a contractor for the works has not yet been tendered because the department is not yet at that stage.

According to the spokesperson, while the current stage is to keep the public informed of the works, a tender process should take place within the next few months because the engineering works are due to begin in early 2012.

According to Mr Rake, the works will not interfere with the dam’s regular operations.

“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,” Mr Rake said.