Water treatment plant

During 2004 the company took the decision to construct a water treatment plant at a cost of A$28 million to assist with environmental management and mining operations. The plant will ensure process and other water is purified to a level compatible with the surrounding environment, prior to its release. 

Ranger is surrounded by Kakadu National Park, a World Heritage site, so water management is a major environmental issue. The site receives an average of 1.5 metres of rainfall each year measured over the last 25 years of operations, and there are limited options for releasing the water to the surrounding environment.

The treatment plant has been in the planning for some years, with the decision taken in 2004 to bring it forward to assist mining operations, as well as to be ready for the rehabilitation work when production ends.

Site construction began in April 2005 and finished within budget with a good safety record of only three medically treated cases per 150,000 hours of work. The plant will play a key role in Ranger’s water management system, allowing a progressive reduction of water storage on site.

The new plant can treat 1.5 million tonnes a year of water stored on site. The plant is designed for a life of 20 years, and will eventually become part of rehabilitation plans after closure.

The purification process includes pre-treatment or settling using a clarifier, ultra filtration using membranes and a process of even finer filtration known as reverse osmosis. The water is then be released into the environment either directly (treated pond water) or through wetland filters (treated process water). 

The plant can treat water at rates of 5,500 tonnes a day for pond water. It has been running since mid-January 2006, and controls are being fine-tuned to operate in automatic mode.