Case Studies 2007 : Coal
Sustainability website / Case Studies 2007 / Xstrata coal / Improving water quality at Xstrata Coal’s Ulan Mines
Improving water quality at Xstrata Coal’s Ulan Mines
The Ulan mine creates a significant water surplus, generating approximately 8.2 megalitres per day over its operational requirements. The excess water requires underground dewatering and the management and monitoring of water usage and quality.
Previously, surplus mine water was discharged, by licence, into the Goulburn River. However, studies have shown that this was not a sustainable solution in view of the volume of water produced by the underground mine as well as the variation in water quality. In response, Xstrata Coal formulated and implemented a comprehensive, long-term water management strategy for the mine while ensuring the responsible management of water.
The key elements of the water management strategy are based on an understanding of the amount of ground water produced and how these levels respond to mining and climatic variables; an appreciation of the onsite water quality and quantity; and the development of a site water management plan to effectively manage all water-related activities. Part of the water management plan involved developing a water treatment facility to enable water to be discharged offsite without negative environmental impacts.
Prior to implementation of the water management plan, Xstrata Coal carried out comprehensive consultation with all stakeholders including the mine management, the local community, downstream water users and regulatory bodies such as the Australian Government Department of Environment & Conservation and the Department of Natural Resources. The aim of the consultation process was to understand and to meet expectations as well as discussing the management of any effects from the discharged water.
A new technology was developed to manage water quality through a desalination treatment using reverse osmosis. A Reverse Osmosis Plant was installed, taking into account the surrounding environment and watercourse of Ulan Creek. Extensive stabilisation works were undertaken on the sandstone rock bar at the discharge point within the creek to ensure the stability of the watercourse.
The water treatment plant started operation with a six month trial in June 2006 which included the discharge of 977ML to the Goulburn River over a four month period (at an average of 7.53ML per day). Ecological monitoring of the water during the trial showed that the water discharged was of a good quality. The mine maintains 50 percentile and 100 percentile concentration limits of 800 µs/cm2 and 900 µs/cm2 respectively, which was established against a background water quality within the Goulburn River that ranges from 300 µs/cm2 to 1100 µs/cm2. Additionally there was an increase in the richness of macro-invertebrate species for the duration of the trial and positive results on the creek stability both pre- and post discharge.
Following the success of the trial, the plant was awarded its final licence for operation by the Department of Environment and Conservation in June 2007 which allows the release of up to 12 mega litres per day of water to the Goulburn River.
The discharge of treated water to the river has had positive impacts on the ecosystems reliant on the river, particularly during the recent drought conditions, which had reduced the Goulburn River and most other waterways in the area to dry sandy beds with small water holes. Discharged water from Ulan mine restored the river’s flow and monitoring has shown increased biological and ecological activity within the receiving watercourse and adjacent riparian areas.
The controls used by Ulan’s water management plan are acknowledged as industry best practice and the new technology developed to support the water treatment plant has generated significant interest from other local mining operations and from within the coal mining industry.
Phil English, Environment and Community Manager at Ulan Coal Mine said: “We are pleased with the outcome of this project which has been successful and timely. We have pushed the boundaries in developing the water management plan and demonstrated how mines can successfully operate with excess water.”
The project demonstrates how excess water can be responsibly used by mining operations to bring about environmental, community and business benefits.