Water outputs

The water that we use in our mining and processing operations can be released to a variety of locations. The type of location is dictated by the environment in which the operation is located - for example, ocean, surface waters or evaporation on land.

Different qualities of water can be discharged in accordance with government regulations and we decide on the best way by taking environmental and community concerns into account at each specific site.

Our results

In 2006, we returned 625 million cubic meters of water to the environment.  Of this, 79 per cent was process effluent, 14 per cent was from stormwater diverted from our sites to prevent contamination, and a further 7 per cent was water removed to aid mine access (dewatering water).

Other water is lost through evaporation and seepage, entrainment of water in product or process wastes, and process water sent to third parties.

While discharge limits are usually set within permits and other legislation relating to operational conditions, understanding the environmental and social impacts resulting from water return activities is a requirement of our water standard. This is best managed at an operational level because of the site specific nature of water quality.

While each site measures and reports on water quality, these data cannot be aggregated meaningfully at a global level. However, some more common indicators are shown below as an indication of the type of aspects being managed.

In 2006:

• Seven operations discharged cyanide - 109 kilograms in total.
• Thirty seven operations discharged suspended solids - 2.5 million tonnes in total.
• Eleven operations reported biological oxygen demand (BOD). This can be aggregated to 56, 000 tonnes. 
• Nineteen operations measured total metal loading. Across the Group, this can be aggregated to 28 tonnes of arsenic, 12 tonnes of copper, three tonnes of lead, 1.6 tonnes of cadmium,  42 tonnes of zinc and seven tonnes of mercury.