Overview
The Mardie Salt & Potash Project in Western Australia is one of the world's largest solar salt developments. Located on a low-lying coastal plain in the Pilbara region, the project covers approximately 130 km², with more than 100 km² dedicated to evaporation ponds and crystallizer basins.
The operation uses seawater, solar energy, and natural evaporation to produce more than five million tonnes of salt annually, along with sulphate of potash fertilizer recovered from residual brine. With an anticipated operating life exceeding 60 years, the project required a containment system capable of supporting long-term production while performing reliably in one of Australia's most demanding environments.
Effective management of hypersaline brine across a vast network of ponds and levees was central to the project's design. The selected containment solution needed to reduce brine losses, support production efficiency, and provide long-term durability under extreme climatic conditions.
Challenge
Containing and managing hypersaline brine at Mardie presented several engineering challenges. The evaporation ponds hold millions of cubic meters of seawater that become progressively more concentrated through an evaporation cycle lasting up to 18 months. Across a project of this scale, even small seepage losses can affect both operational efficiency and long-term water management objectives.
The containment system also needed to withstand the harsh Pilbara climate. Surface temperatures regularly exceed 40C, exposing materials to intense heat, high UV radiation, and significant thermal cycling. Over its service life, the liner would experience continuous exposure to concentrated salt solutions, fluctuating temperatures, water loading, and operational activities associated with salt harvesting.
Construction presented additional challenges. Due to extreme daytime temperatures, installation crews were required to work predominantly at night to maintain safe working conditions and ensure consistent welding quality.
The project therefore required a durable containment solution capable of delivering long-term performance under demanding chemical, mechanical, and environmental conditions.
Solution
To support long-term brine containment, the project team specified a GSE® HD geomembrane liner system throughout the evaporation ponds and crystallizer basins. The geomembrane was selected for its low permeability, chemical resistance, and proven durability in demanding containment applications.
The liner met the requirements of the GRI-GM13 specification and incorporated enhanced stress crack resistance of at least 1,000 hours to improve long-term resistance to thermal, mechanical, and chemical stresses encountered during operation. Large factory-manufactured panels in 1.2 mm and 1.5 mm thicknesses were supplied to create a continuous containment barrier beneath the ponds.
Extensive hydrostatic puncture testing was conducted using site-won soils to verify liner performance under anticipated operating conditions. Particular attention was given to dynamic loading from harvesting equipment to ensure the geomembrane could withstand operational demands throughout the facility's service life.
The geomembrane formulation incorporated UV-stabilized resins and antioxidants to provide long-term resistance to weathering and exposure in Australia's northwest climate. Representative liner samples were also subjected to independent laboratory testing to validate performance under the expected mechanical and environmental conditions.
The completed liner system reduces brine losses through seepage, helping to improve production efficiency by retaining more brine within the evaporation process. It also helps limit infiltration to underlying soils and groundwater while providing a robust, long-term containment solution for the project.
By selecting a GSE HD geomembrane rather than relying solely on conventional earthen containment methods, the project achieved a thinner containment profile, faster construction, and reliable long-term performance across one of the largest solar salt developments ever constructed.
