At Prominent Hill, we have a mining lease and exploration tenements. The total tenement area owned by OZ Minerals is 400,000 hectares (4,000 square kilometres), which includes a mine footprint of 3,556* hectares. In 2011, 50 hectares were disturbed for mining and excavation purposes, while 10 hectares were rehabilitated. We have exploration tenements of approximately 107,000 hectares in Carrapateena (1,070 square kilometres), 350,000 hectares in Cobar, New South Wales and 95,000 hectares in Cambodia.
* The mine footprint area has been recalculated since 2010 to exclude existing pastoral tracks.
An understanding of our potential to impact on habitats is vital in order to manage and minimise impacts. Additionally, it may provide us with opportunities to contribute to the conservation of species and ecosystems. The OZ Minerals Biodiversity Management Plan (BMP) requires the management of biodiversity and minimisation of adverse effects on flora and fauna throughout the mine life cycle.
In 2011, OZ Minerals’ BMP was reviewed and updated. Our BMP includes items such as a continued and enhanced monitoring plan, fox baiting, cat trapping, Significant Environmental Benefit (SEB) fence line monitoring, opportunistic bird and other wildlife surveys and new trench monitoring surveys with the development of the Ankata underground mine.
The Significant Environmental Benefit (SEB) offset area involves the ongoing protection of land within the Mount Eba Pastoral Lease. Through management of the SEB offset area, OZ Minerals aims to protect and enhance habitat for two bird species, the chestnut-breasted whiteface and thick-billed grasswren (eastern subspecies). The thick-billed grasswren is nationally vulnerable and the chestnut-breasted whiteface is classified as rare in South Australia. Both of these species are listed on the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species.
After first being identified in 2006, Prominent Hill has continued to record these species in surveys. Flora and fauna monitoring is conducted in spring and autumn each year, with 2011 marking the sixth consecutive year of surveys.
The 2011 survey efforts identified four new species that have not been seen in the Prominent Hill region since historical times as a result of the favourable environmental conditions. This includes two animals, the plains mouse and brown quail and two plant species, the thick twinleaf and black’s bindyi. The plains mouse is nationally vulnerable and the brown quail is classified as vulnerable in South Australia. The thick twinleaf and black’s bindyi are both classified as vulnerable in South Australia. These species are listed on the IUCN’s Red List. We will continue to monitor these species.
A statistical analysis was conducted on the collected flora and fauna data from all surveys. The analysis found that there was no statistically significant difference between each of the years indicating that the impacts of our Prominent Hill mine on the local ecosystems are minimal.
Land management trials for future rehabilitation began in 2011. These trials are designed to test a number of different vegetation rehabilitation techniques in preparation for when sections of the mine are closed and allotted for rehabilitation.
In 2011, OZ Minerals continued exploration in Cambodia in the Mondulkiri Province. This area is located with the outer boundaries of the Phnom Prich Wildlife Sanctuary. A group of unlicensed miners have been working in this same region for a number of years. Very few of these people are from Mondulkiri Province and are regarded as ‘artisanal influx*’ miners as they have recently migrated to the area. Artisanal miners are usually small-scale miners that use rudimentary methods to conduct their activities.
The Cambodian Government indicated its desire to remove illegal mining, logging and poaching in this and other areas. Practices typically used in this type of small-scale mining are dangerous and can cause significant environmental damage – cyanide and mercury are often used in an uncontrolled manner. The government began a program to request these groups to leave the area in 2009. This was undertaken through a series of public meetings and notices. The number and presence of artisanal miners varies with the weather and a number of other factors. At the end of 2011, there were seven mine pits with active artisanal miners. Throughout the government’s process, OZ Minerals has regularly engaged with relevant authorities and advocated that the people involved are treated with respect and dignity.
After concluding that the Cambodian assets did not fit with OZ Minerals’ strategy in regard to scale and overall preference for mid-tier copper projects, OZ Minerals signed an agreement, in February 2012, with Renaissance Minerals to sell these assets.
*As defined by the International Council on Mining and Metals, www.icmm.com/library.
Water and diesel supply demand model
In 2011 a water and diesel supply and demand model was developed at Prominent Hill. The final outcome is a comprehensive model encompassing all aspects of our operation, based on our operational mass balance (inputs and outputs) for water and diesel. The model has been tested and will now be developed into an operational model through the addition of real time data. The model is designed to assess the efficiency of water and diesel in each process of our operation and identify steps in which water and energy can be conserved.
The model will be capable of predicting times of resource shortages and improving emissions’ calculations. Additionally, the supply and demand model will be able to evaluate cost benefits associated with process improvements introduced in our operation.