In 2011, a milestone for our new waste recycling centre was achieved. A new waste management facility was built, with the contract for running the facility awarded to a local waste company. We are currently in the process of establishing ongoing waste and recycling programs to significantly reduce the amount of waste sent to landfill, as well as recycling stockpiled steel, cans, bottles and other materials onsite. Performance indicators have been put in place to increase the percentage of waste we recycle. During 2011, approximately 600 tonnes of waste, including oil, grease and vehicle batteries, was recycled at an off-site facility. We expect the new waste station will be fully operational in 2012.
Waste rock and tailings
Mining operations produce waste rock and tailings. At the Prominent Hill operation, waste is managed on site in disposal facilities in accordance with the OZ Minerals Waste Rock Management and Tailings Management standards. These standards define the requirements for the management of waste rock and tailings to prevent environmental impacts, promote beneficial post-mining land uses and reduce post-mining rehabilitation and closure liability.
To prevent or minimise the potential environmental impacts associated with waste rock and tailings disposal, a range of strategies is implemented during project development and operations, including:
- geochemical characterisation of acid-generating materials, resource modelling;
- selective handling and encapsulation of waste rock;
- disposal of tailings into specially designed and engineered facilities;
- linking operational planning to long-term closure management; and
- the containment and treatment of mine waters to meet regulatory discharge criteria.
Over the reporting period, Prominent Hill produced approximately 60 million tonnes of waste rock, with approximately 14.3 million tonnes considered to be potentially acid forming.
Most of the waste rock generated was placed in rock dumps within the mining areas with a proportion of non-acid forming rock used for the construction of mine infrastructure, such as the tailings storage facility and roads. Potentially acid forming rock is encapsulated with non-acid forming rock material within the integrated waste landform stockpiles.
We encapsulate potentially acid forming rock and prevent surface water runoff using physical control measures to prevent impact to the environment. To ensure our control measures are effective, we conduct ongoing monitoring of surface water to detect any potential changes in downstream water quality from baseline values, including metal concentrations and acidity.
In 2011, approximately 9.7 million tonnes of tailings were produced. All tailings are contained within the tailings storage facility.
Water sampling is conducted after heavy rainfall events at sites around the tailings storage facility and surrounding waste rock to ensure there is proper containment of heavy metals and acid generating rock material.
Hazardous and non-hazardous waste
All hazardous wastes, non-hazardous wastes and wastewater are managed in compliance with applicable laws and regulations, as well as in accordance with OZ Minerals Sustainability Standards. Prominent Hill generated 620 tonnes of hazardous waste during 2011, of which most is waste oil, grease and vehicle batteries. A total of 1,321 tonnes of non-hazardous waste was generated at Prominent Hill during the reporting period, comprising mainly general waste, paper and timber.