Suma Park Dam upgrade, NSW

Client: Orange City Council
Location: Orange, New South Wales, Australia
Date: December 2010 – August 2016

Upgrading a dam to meet contemporary safety standards and increase storage capacity


Suma Park Dam is a 30.5m-high single-curvature concrete-arch dam near Orange, central NSW, Australia. Entura was engaged to develop a risk-based concept design to address the dam’s known spillway deficiency, and explore its uncertain seismic stability.  Orange City Council also expressed a desire to increase storage at the dam to firm up the yield from its integrated water supply system. Once the concept design had been accepted by the client and the NSW Dam Safety Committee, the detailed design, environmental studies and approvals and tender documentation were prepared.


Entura provided a complete service to Orange City Council including a probabilistic flood hydrology update; planning and supervising geotechnical investigations; three-dimensional finite element analysis of the arch dam and foundation; modernisation of the outlet works to meet safety standards; concept and detailed design;  environmental studies; preparation of approvals and tender documentation; and tendering and construction support.

Entura developed an innovative strategy of installing a crest wall on the main arch dam to maximise flow over the existing spillway, strengthening the stilling basin and reconstruct a saddle dam as a Fusegate spillway to operate in extreme floods. Innovative use of precast units allowed better access for construction and operations.  The design also accommodated increased storage and undertook the necessary environmental flows studies.  Electrical and mechanical components of the dam were also completely refurbished.

During the construction phase, undertaken by civil contractor Geotechnical Engineering, Entura provided construction support as Owner’s Engineer.


Entura’s comprehensive investigations and innovative design achieved the client’s goals of increasing the safety and storage capacity of the dam. Entura’s identification of a logical staging of remedial works allowed the client to spread the capital cost over two or more years to manage the budget for the Council. 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; and careful modelling of the dam under seismic loading demonstrated that no seismic upgrade was required. Rigorous environmental studies and community consultation allowed an increase in storage capacity for the future water needs of the community.