A CENTURY-OLD dam at Jamberoo, built to supply Kiama with water, is to be the subject of a stability analysis report prepared by Kiama Municipal Council.
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Fountaindale Dam is a concrete arch dam constructed in 1909 by the NSW Public Works.
The dam is 15 metres high with a crest length of 89 metres.
It was designed to have a capacity of about 61 megalitres, but 106 years later its capacity has been reduced to about 20 megalitres by siltation.
Kiama council’s director of engineering and works Bryan Whittaker said the council has been liaising with the NSW Dam Safety Committee about the condition of the dam and compliance with the requirements of the Australian National Committee on Large Dams.
The Kiama council is soon to decommission Jerrara Dam after concerns were raised by the committee.
Mr Whittaker said the stability analysis on Fountaindale Dam is to be prepared and submitted by June 2016.
‘‘Decommissioning would only need to be considered if the stability analysis is unsatisfactory,’’ Mr Whittaker said.
A 2008 report estimated that decommissioning Fountaindale Dam could cost about $700,000, but this figure did not include any detailed environmental studies or management on the environmental effects of a decommissioning.
‘‘Because of its remote location, decommissioning would be a difficult process,’’ Mr Whittaker said.
‘‘There are no other dams like this one in the Kiama LGA.’’
Tenders have closed for the decommissioning of Jerrara Dam, for which the council had budgeted $1.3 million.
In October 2013, Kiama councillors voted 8-1 to decommission Jerrara Dam, arguing other options for the 53-hectare earth-fill embankment dam were too expensive.
In recent years, the dam has regularly been the subject of emergency warnings or ‘‘amber’’ alerts during heavy rain.
Though the integrity of the dam wall was never in question, the NSW Dam Safety Committee had concerns, which were based on updated climate forecasts, about overtopping at the dam in extreme weather circumstances.
Mr Whittaker said a report about the decommissioning of Jerrara Dam would go to Kiama council later this month to select a successful tenderer and work was expected to begin in early June.
