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Stantec to deliver reference design for Somerset Dam Improvement Project

Engineering and consulting firm Stantec has been awarded a $6 million design services contract to develop and detail the reference design for Seqwater’s Somerset Dam Improvement Project.

Stantec will investigate the potential for a dam upgrade to provide increased safety, consistent with the latest engineering standards and guidelines. An upgraded dam also has the potential to increase flood mitigation for downstream communities. The reference design is expected to be completed in 2021, with the dam upgrade construction then pending government approval and funding.

Somerset Dam is a dual-purpose water supply and flood mitigation structure owned and operated by Seqwater and located on the Stanley River near Kilcoy in Queensland. The dam also houses a 4-MW hydropower plant. Water from the dam is released into Wivenhoe Dam. Somerset Dam is 305 m long, 58 m at its highest point, and is comprised of 22 monoliths.

After a review identified improvements needed, Somerset Dam’s flood operation procedures were modified in 2016 as a precautionary safety measure and drinking water levels were lowered to maintain flood mitigation benefits. The proposed upgrade will explore raising the dam crest, constructing a downstream buttress, and modifying the gated spillway and outlet works. When the upgrade is completed, the normal full supply level will be reinstated while allowing the dam to mitigate potential floods.

“Since construction of Somerset Dam was completed in 1959, global understanding of dam safety risks and potential consequences has continued to evolve. In addition, there has been substantial population growth downstream and continuing changes in our climate,” said Mark Cordell, principal dams engineer at Stantec. “Working with Seqwater, we’ll bring local and global experience from dam improvement projects completed around the world to ensure the selected upgrade solution satisfies operational and flood mitigation requirements while meeting today’s engineering and safety standards.”

The reference design will contribute to the detailed business case that will inform the State government of the dam’s proposed upgrade options.

Stantec has nearly 100 years of hydropower and dam experience including feasibility studies, detailed design and construction management from more than 5,000 dam projects around the world.