Water Quality - FAQs
The production of alumina requires a considerable amount of water. Alcoa fully appreciates that water is a valuable community resource in Western Australia and as a company has demonstrated a strong commitment to water conservation. Alcoa is assessing water conservation carefully as part of the Pinjarra Efficiency Upgrade.
Q How much water does the Pinjarra refinery use?
Alcoa uses water in both bauxite mining and alumina refining. Alcoa's Huntly mine, which provides bauxite to the Pinjarra refinery, used 510 ML (mega litres) during 2002/2003 while the refinery uses over 6,000 ML of water each year.
Q Where does the water come from?
The Huntly mine obtains most of its water from the Banksiadale reservoir, which is a dedicated supply, located close to the Huntly administration facility.
The Pinjarra refinery takes its water supply from groundwater and surface water sources. Groundwater allocation is abstracted from five production bores while the surface water is taken from three dams. The refinery also uses treated sewage water from the Pinjarra township.
Q What is the water used for?
Water is primarily used at the Huntly mine to maintain a safe working environment by suppressing dust generated by road traffic, for the control of dieback and for cleaning and hygienic use. 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 recycling.
Q What happens during a drought?
During drought conditions, Alcoa purchases water from the Water Corporation. This occurred during 1999-2003 when the Huntly mine had to supplement its water supply by purchasing water from an adjacent Water Corporation source. The Pinjarra refinery has obtained additional ground water (under licence) or purchased water from the Water Corporation.
Q What are Alcoa's water conservative objectives?
Alcoa has set a global objective to reduce water consumption to 20% below the year 2000 rate by 2003. This target has been surpassed at the Huntly mine.
For example, the average consumption of water at Huntly for the suppression of road dust fell by 50% from 2000 to 2003. Similar reductions in water use have been achieved for the clean down and dust suppression of fixed plant and future reductions are targeted during the coming years.
As part of its water conservation strategy for the refinery, Alcoa is seeking to achieve a 20% reduction in the use of high-grade water by 2005.
Q What impact will the Pinjarra Efficiency Upgrade have on Alcoa's water use?
Water conservation measures at the mine are forecast to reduce overall water usage to 490ML compared to a usage rate of 645ML in 2001/2001 and 510ML in 2002/2003.
The refinery Efficiency Upgrade will result in an increased water demand of approximately 1100 ML. Options for the additional water supply include using recycled water from the Water Corporation Gordon Road sewerage plant, desalination and reducing evaporation at the refinery.
Q Where will the water come from to meet demand?
Alcoa is undertaking new measures at the Huntly mine to develop additional water sources including the construction of large storage sumps (10-80ML) within the McCoy mining region to capture run-off from haulage roads and other paved areas. The run-off from the Banksiadale reservoir is expected to increase by 270ML per annum through changes to surrounding vegetation. These initiatives are expected to remove the need for the Huntly mine to require any purchases of supplementary water after the 2003/2004 summer (except in unusual circumstances) even taking into account the impact of the Pinjarra Efficiency Upgrade.
A number of new water initiatives are being investigated for the refinery, including taking treated sewage water from Mandurah, reducing evaporation from the water storage lake using a cover, collecting water lost as steam, using saline Murray River water through desalination, and exploring the Cattamarra aquifer to further define the sustainable yield of underground water.
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If you have an specific question that is not covered here please email pinjarraupgrade@alcoa.com.au or visit the Pinjarra Refinery Efficiency Upgrade website. New questions and answers will be posted to this page on a regular basis.
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