Alcoa RSA1E
Alcoa’s Pinjarra Aluminium Refinery is approximately 80 km south of Perth. One of the projects in the Refinery was the conversion of an approximately 17 ha of the existing wet mud lake into approximately 11 ha of new RSA1E dry stacking area in accordance with the residue long term planning strategy. To achieve the project objectives, it was necessary to remove or dewater the highly caustic tailings in the residue area.
Prefabricated Vertical Drains
The ground was composed of a 2 to 3 m thick capping layer following by up to approximately 16 m of highly caustic and very soft saturated tailings.
The solution for removing caustic water from the tailings included the installation of approximately 248,808 lm of wick drains aka prefabricated vertical drains (PVD) to depths of 10 to 18 m. Given that the purpose of the works was caustic fluid management, the wicks were installed in triangular grids at 2.3 or 4 m spacing.
