QLD – Somerset Dam Improvement Project

Author: Michel Raymond.

A recent assessment of Somerset Dam, in South East Queensland, has indicated improvement works may be required earlier than previously planned.

Somerset Dam is a 60m high concrete gravity dam on the Stanley River, upstream of Wivenhoe Dam. Somerset Dam is operated in conjunction with Wivenhoe Dam for water supply and flood mitigation.

Construction started on Somerset Dam in the 1930s, but was temporarily stopped during World War II. The dam was commissioned in the 1950s.

In 2010 Somerset Dam was recognised as an Engineering Heritage National Landmark – described as the first major dam in Australia designed specifically to provide flood mitigation as well as storage for urban water supply.

Temporary full supply levels were introduced at Wivenhoe and Somerset dams this year as part of Seqwater’s Dam Improvement Program. The temporary levels are equivalent to storage volumes which are 80% of the design full supply volume for Somerset Dam and 90% of the design full supply volume for Wivenhoe Dam.

Seqwater Chief Executive Officer Peter Dennis said an interim flood operations strategy was implemented for Somerset Dam.

“Wivenhoe Dam’s full supply level was lowered to maintain the downstream flood mitigation benefits provided by both dams,” Mr Dennis said.

“It’s important to recognise that Somerset Dam managed both the 1974 flood, the largest since the dam was built, as well as the 2011 large flood event. We also need to make sure that Somerset Dam can handle floods much larger than these floods.”

Mr Dennis said geotechnical investigations were underway at Somerset Dam to inform the scope, design and timing of the upgrade.

The temporary full supply levels will remain in place until dam improvement works at Somerset Dam are completed.

For more information about the Somerset Dam Improvement Project, visit www.seqwater.com.au/damimprovement/somerset.