Engineering for complex terrain and environmental sensitivity

Set within the Dungowan Valley, the project is situated downstream of the existing Dungowan Dam. Its design includes an upper reservoir, a vertical pressure shaft, headrace and tailrace tunnels, underground caverns, and access tunnels. Water is pumped to the upper reservoir during periods of low electricity demand and peak renewable energy production and released to generate power when demand peaks or renewable energy is lower. This operational flexibility helps smooth out fluctuations in renewable energy supply.

To deliver this outcome, the design must respond to the site’s natural features and subsurface conditions. Managing groundwater, ensuring structural stability, and maintaining watertightness across the system’s components are critical to the project’s success and longevity.

Technical investigations informing design and risk management

To satisfy these design requirements while reducing risks associated with natural ground conditions, a robust site investigation program carried out by an experienced team is essential. To achieve this, Électricité de France Australia Pacific Pty Ltd (EDFA) engaged SMEC to undertake geotechnical and hydrogeological investigations in the early stages of design and planning.

SMEC has delivered desktop studies, geological mapping, geophysical surveys, and has completed an initial drilling campaign, including a deep borehole (640 m). The program included sophisticated in-situ testing and measurements, laboratory testing, and expert interpretation of results, supported by associated site management including safety oversight and drilling supervision. These inputs help define the geological context, support siting decisions, and inform environmental and constructability reviews. With geotechnical investigations completed, SMEC is undertaking periodic groundwater monitoring on site.

The insights gained to date are already influencing more resilient design outcomes and enabling early identification of potential ground risks. This phase of work also reflects SMEC’s broader capability in delivering infrastructure across challenging terrain, where integrated geotechnical and hydrogeological knowledge is essential. Lessons learned from the project will contribute to future off-river hydro schemes, where early site understanding can unlock smarter and more sustainable solutions from the outset.

Applying geotechnical expertise to de-risk delivery

SMEC’s geotechnical expertise has played a crucial role in shaping the early phases of the Dungowan PHES project, significantly reducing uncertainty and informing key design decisions. Subsurface investigations and geological modelling to date have defined the broader geological context and will be used to guide the optimal siting of key infrastructure, including reservoirs, access points, and the underground powerhouse.

These early stages of analysis have also underpinned environmental risk assessments and constructability reviews, identified potential challenges and informed targeted mitigation strategies. As the project advances into the next phase of design, continued geological monitoring and data collection will be essential to ensure informed decision-making and guide delivery. This approach not only supports the structural integrity and constructability of the asset but also strengthens its long-term environmental resilience.

As Australia continues to invest in clean energy infrastructure, projects like Dungowan PHES show how technical insights can enable more regenerative, future-ready outcomes.

1. Austrade. (n.d.). Clean energy: Wind, solar, storage & transmission. Austrade International. https://international.austrade.gov.au/en/do-business-with-australia/sectors/energy-and-resources/renewable-energy