Australian utility SA Water has tasked SMEC to deliver the concept design for important upgrades to Mount Bold Dam – the largest dam in South Australia – enabling the structure to meet the current Australian National Committee on Large Dams (ANCOLD) guidelines. 

Mount Bold Dam is considered critical infrastructure as it is the largest storage in the region with a total capacity of around 46 billion litres, providing 40% of metropolitan Adelaide’s water supply.

The new upgrade will bring Mount Bold Dam in line with current guidelines through strengthening the central arch section of the dam wall by buttressing with mass concrete, and strengthening the existing gravity dam abutment sections with post tensioned anchors through to bedrock. It will also remove the existing spillway gates and need for manual operation, provide a free-flow staged spillway to safely pass the full range of floods, including flood attenuation for frequent floods, and incorporate an embankment saddle dam to prevent flow over a low-lying section on the reservoir rim.

Ultimately the upgrade will strengthen the dam to safely pass flood and seismic events, while also providing limited flood protection to the downstream community.

“We are proud to be chosen as the project’s concept designer,” commented SMEC project Design Manager Francisco Lopez. “This is a crucial role helping to safeguard one of the Adelaide community’s most important infrastructure assets. A lot has changed since the dam was first constructed in 1938 and upgraded in the 1960s, which means there is a need to reassess and upgrade Mount Bold Dam to meet current ANCOLD guidelines and industry standards. For instance, the capacity to withstand the probable maximum flood and seismic loadings are the two key areas which will be addressed during the concept design phase.”

Constructed between 1932 and 1938, Mount Bold Dam was designed and built as a water supply dam with the purpose of maximising storage levels. The dam is a critical and cost-effective water supply asset while also providing some flood mitigation benefits to downstream communities through controlled releases of water. Water is also pumped into Mt Bold Dam from the River Murray.

SA Water anticipates that detailed design of the upgrade will be started and completed in 2022. Construction is planned to commence in 2023 and take approximately three and a half years to four years to construct, delivering a more secure and safe asset for the future.