Impoundment Management
We manage impoundment facilities at active, inactive and closed sites around the world to store primarily two types of material—bauxite mine tailings and bauxite residue. Both are referred to generically as “tailings.”
An “impoundment” is defined as any dam or other engineered structure intended to confine a body of water (fresh, alkaline or acidic), mine tailings, refining residue, or any other solid or liquid waste material.
Bauxite mine tailings create a mud-like residue that remains after the bauxite is washed at the mine site. Bauxite residue, which is a byproduct of the alumina refining process, consists of mud, some residual caustic soda and, in some cases, a coarse sand fraction.
We design our impoundments to our internal and international standards. We strive to achieve a comprehensive understanding of our impoundment risks and opportunities, implement suitable and effective controls, and manage our impoundments safely and efficiently.
In 2021, we revised our mandated Global Impoundment Policy to further ensure our impoundments comply with our own rigorous internal standards and guidelines, which may exceed governmental regulations in some countries where they are located, and also the Global Industry Standard on Tailings Management or the laws and regulations of the country in which a facility is located (whichever are higher). We also use the policy to encourage leading management and governance practices at joint ventures and locations where we do not have direct control of operations. The policy excludes hydroelectric and freshwater concrete dams, which are governed by the laws of the countries in which they are located.
In addition to our internal impoundment policy and standards, we are committed to conform with the Global Industry Standard on Tailings Management along with all ICMM members. The first objective is to ensure compliance of extreme and very high consequence category tailings by August 2023.
Our strategic long-term goal for bauxite residue addresses a key business challenge: reduce bauxite residue land storage requirements per metric ton of alumina produced by 15 percent by 2030 from a 2015 baseline.
Through 2021, we achieved a 14.8 percent reduction against the baseline. We expect to see continued improvement with enhanced solar drying and residue filtration technologies. Filtration is now fully operational at our Kwinana and Pinjarra refineries in Australia, improving the overall efficiency and safety associated with the stored tailings by removing water.