First stage of dam upgrade done
AGING valves in Stanthorpe's Storm King Dam have been replaced by Southern Downs Regional Council, completing the preparation work to strengthen the dam wall in early 2012.
The job is the first stage of more than $1 million worth of upgrades to Storm King Dam required by the State Government.
Director of engineering services Peter See said the dam was capable of withstanding any major floods likely to occur in its lifetime.
"However, the State Government has decreed that, because it is upstream of Stanthorpe, it must be able to withstand the worst flood possible," he said.
"This flood is unlikely to occur, however, should it occur in the future, these works will ensure that Stanthorpe will not be affected by the dam failing."
Mr See said the valve replacements were not directly related to dam safety but, as part of the dam safety upgrade works, they were being replaced as a proactive measure while work crews were focused on the dam.
The 57-year-old valves weigh half a tonne each and were replaced in a precision operation that saw trained council staff working in the enclosed space of the dam wet well.
The wet well controls the flow of water from the dam into the main trunk supplying the water treatment plant.
This was the first time the valves have been replaced since the dam was built in 1954.
Council staff replaced the main valve which controls the flow of water through the trunk main and is used if water flow from the dam to the water treatment plant needs to be shut off. It also replaced the valve used to lower the dam water level through water release into Quart Pot Creek.
"To enable replacement of valves, the wet well in the dam wall had to be shut down and a by-pass line installed over the dam wall to the raw water trunk main," Mr See said.
"The bypass work was a substantial and complex job requiring multiple pieces of equipment and 20 staff working simultaneously."
To strengthen the dam wall, a structural engineering company specialising in post-tensioning work will be contracted to anchor steel cables vertically through the dam wall into the bedrock.
"When we do the stabilisation of the dam wall, the water level will need to be lowered to half a metre below the dam wall to allow access for the work," Mr See said.
"Currently the dam is at full capacity."
This work continues the council program of maintenance and replacement to water mains around Stanthorpe.
Council recently upgraded water infrastructure in the Stanthorpe main street and, since 2010, council has replaced more than 130 valves and hydrants along the Stanthorpe water mains.