Entura completes Suma Park Dam upgrade in New South Wales

September 29, 2016

Specialist power and water consulting firm Entura has recently completed the Suma Park Dam upgrade in New South Wales, Australia, after developing an innovative solution to increase the height of the dam wall by three metres while maintaining regular operations.

Suma Park Dam is a 30.5m-high single-curvature concrete-arch dam near Orange, central New South Wales. Entura was engaged by Orange City Council in 2010 to develop a risk-based concept design to address the dam’s known spillway deficiency, and explore its uncertain seismic stability. Increasing storage at the dam to firm up the yield from its integrated water supply system was also a key objective for the council.

In 2013, the concept design developed by Entura was accepted by Orange City Council and the NSW Dam Safety Committee, allowing the project to proceed. Subsequent works undertaken by Entura included detailed design, environmental studies and approvals, and preparation of tender documentation.

Led by Entura’s Specialist Dams Engineer Paul Southcott, the innovative design process involved the project team creating a computer model of Suma Park Dam that allowed the design solution to be developed and assessed prior to implementation.

“A ‘water load’ or pressure was applied to the 3D design model allowing us to calculate the stress in the concrete wall, so when it came to the real thing we knew  how to strengthen it to make it safe,” said Mr Southcott.

“The solid concrete dam wall actually deflects, although it is too small to see it,” added Mr Southcott.  “As the water load changes, the deflections are very small and the computer models could show us that deflection.”

Mr Southcott explained that his team identified a logical staging of remedial works that allowed Orange City Council to spread the capital cost over two or more years to help manage its budget. Additionally, Entura’s recommendation to revise the flood hydrology resulted in a significant reduction of the physical scope of works required to bring the dam up to standard. Careful modelling of the dam under seismic loading demonstrated that no seismic upgrade was required.

During the construction phase, undertaken by civil contractor Geotechnical Engineering, Entura provided construction support as Owner’s Engineer. Precast parapet wall slabs were designed and built away from the dam wall and then brought in and placed on top of the existing dam wall in order to increase the height. A wheeled crane was used to place one piece and secure it, then it would drive along that piece to place the next piece, 87 times until all of the concrete slabs were secured.

The $18 million dam wall upgrade was officially opened last Friday by Mayor John Davis OAM and NSW Government Duty MLC for Orange, Sarah Mitchell.

As part of Hydro Tasmania, Australia’s largest renewable energy producer and water manager, Entura draws on more than 100 years of experience of planning, building, managing and maintaining the many dams of Tasmania’s hydroelectric power system.

Entura has undertaken detailed design for many of Australia’s key new dam projects over the past decade, including Wyaralong Dam and Bromelton Offstream Storage in Queensland, the Samson Brook Pipehead Dam in Western Australia, the enlarged Cotter Dam in the ACT, and the Meander Dam in Tasmania.