Water use
Rio Tinto Coal Australia sites use a combination of fresh, poor quality and recycled water. We aim to minimise the use of freshwater, so that it is available for other uses, and maximise the amount of water that is recycled. For example, in pit water captured on the site is recycled and used for dust suppression, truck washing and coal processing.
Results
In 2007, all Rio Tinto Coal Australia sites met their statutory water allocations. However, both Rio Tinto Coal Australia Queensland and Coal & Allied operations exceeded their own voluntary freshwater use targets. Freshwater is defined as 'used' once it enters our operations - for example, via rainfall, groundwater seepage or pumped from an external source - and is immediately, or intended to be, used for coal mining and processing.
Our internal target for Rio Tinto Coal Australia Queensland sites was to use 170 litres of freshwater per tonne of product. The actual use was over target with 368 litres of fresh water per tonne of product used. This result was due in part to the prolonged drought throughout Queensland in the first half of 2007, which reduced the amount of in pit water available for recycling and increased our reliance on freshwater from regulated storages.
Another contributing factor to our result is that rainwater is often classified as freshwater. For example, all water with total dissolved solids below 1500 milligrams per litre and a pH between five and nine is reported as freshwater. Water collected from rainfall at our Queensland operations tends to meet these freshwater criteria and therefore is reported as freshwater use. This contrasts with our Coal & Allied operations in New South Wales where the quality of in pit water tends to be above this limit due to different mineralogy.
This means that heavy rainfall at our Queensland operations will impact our freshwater use. This occurred in 2007, with a significant isolated rainfall event at Hail Creek Mine resulting in a large volume of water, classified as freshwater, impounded in the pit.
Read Blair Athol Mine's results
Read Kestrel Mine's results
Read Hail Creek Mine's results
The 2007 target for Coal & Allied sites was to use 58 litres of freshwater per tonne of product. The actual use was above target with 114 litres of freshwater used. Like Rio Tinto Coal Australia Queensland sites, all sites exceeded their targets due to the prolonged drought in the first half of 2007. During these drought conditions, there was a greater reliance on fresh water from the Hunter River. However due to rainfall in June and the second half of the year more water was available for recycling. 