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Water management
Alcoa recognises that in Australia, water is a relatively scarce resource of significant value to the community. For this reason Alcoa’s refineries in Western Australia were designed to maximise the recycling of water and other water collected within the refinery and residue areas, so that process waters are discharged.
Alcoa uses water at its Wagerup alumina refinery and to a much lesser degree at its Willowdale bauxite mine. At the refinery, water is used to dilute caustic for use in the refinery process and to wash residue sand and mud to recover caustic for re-use. Water is also lost as steam through stacks and vents, is used to cool process circuits through evaporation and is lost from mud drying and from sprinklers for residue dust control.
The Wagerup refinery takes the majority of its water supply from surface water sources, while some groundwater also used. Groundwater is abstracted under licence from depressurisation bores underneath the residue drying area while surface water is taken from three licensed sources; Yalup Brooks, South Samson Drain (includes Black Tom Brook) and the Harvey River main drain. The North and South Yalup Brooks flow into the upper dam which is used as the source for potable water for the refinery. South Samson drain flows in the detention pond which is the main water source for the residue sprinklers.
With the introduction of Wagerup Unit Three, additional water will be required to meet the expanded refinery needs. Alcoa has considered a number of different sources to meet this additional water requirement. Possible additional water supplies could be obtained through additional abstraction of water from Harvey Main Drain, Wellington Dam or by facilitating efficiency gains within the irrigation district to free up water for transfer to Alcoa.
Studies into potential water supplies for the expanded refinery are continuing.
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