Environment

Argyle conducts its operations in ways that ensure environmental disturbances are minimised, and where possible are rehabilitated as soon as practical.

Activities at Argyle are assessed according to various project approvals provided by Government. Argyle complies with federal and state environmental legislation and policies.

Argyle operates under an environmental management system certified to the ISO14001 standard, which promotes continual improvement and ongoing review of environmental targets and performance.

Argyle's environmental management programme includes a range of projects to prevent, minimise, mitigate or remediate environmental impacts. The program encompasses functions such as:

• Conservation of natural resources to promote efficient use of water and energy.
• Protection of rare endangered or priority plant species to preserve the original flora and fauna of the area by use of a ’Permit to Clear’ system of control of land disturbance.
• Management of exotic species to eradicate non-native or destructive fauna and flora including feral cats, donkeys and weeds.
• Promoting environmental awareness throughout the workforce.
• Performance monitoring and measurement to monitor the effectiveness of environmental management programs including surface and groundwater quality, stream flow and vegetation growth on rehabilitated land.
• Protection of indigenous heritage sites.

Other activities of note that Argyle's environmental management system encompasses are rehabilitation, greenhouse emissions and waste and water:

Rehabilitation

Argyle's mining is carried out in the catchment of Lake Argyle and therefore erosion minimisation is a major objective of Argyle's rehabilitation programs. Surface instability can hamper revegetation of disturbed areas and increase the potential for sediment.

All mining areas are rehabilitated as soon as mining plans permit. At this stage, alluvial mined areas are the priority for rehabilitation. Following mining, overburden and surface soil are returned to the area and stockpiled vegetation that was removed is re-spread over the surface. The area is then planted with seed, becoming well established within several seasons.

Argyle works with indigneous elders to ensure that the vegetation planted includes species that meet cultural and practical needs. Local indigenous people are often employed to conduct seeding and other rehabilitation activities.

Greenhouse emissions

Argyle's owner, Rio Tinto, is a signatory to the greenhouse program, and therefore Argyle is an active participant in the program, seeking to improve its greenhouse gas emissions performance through the implementation of energy efficiency programs.

The majority of Argyle's greenhouse gas emissions result from the combustion of fossil fuels in vehicles and equipment and the use of explosives.

In 1996, Argyle changed its principal electrical energy source from on-site diesel generation to the Ord River hydroelectric power generation on the dam at Lake Argyle. Approximately 80 per cent of Argyle's electricity is supplied from the Ord hydro-electric power station, with the diesel fuelled generators at the Argyle mine site supplying the difference.

Other initiatives resulting in improved greenhouse gas balance include energy audits and revegetation. In addition, electricity usage is tracked across site to concentrate initiatives in high energy use areas. Some examples include changing out of electricity bulbs from incandescent bulbs to energy-efficient bulbs at Argyle’s accommodation camps, the use of additives in diesel (to improve efficiency), reduced idle times in the Process Plant and changing pumping practices.

Waste and water

Argyle aims to minimise the production of waste material and reduce any potential environmental or health effects.

Most of Argyle's mineral waste at the mine site is represented by waste rock that is discarded in the process of extracting diamonds from the ore. Waste rock from the AK1 mining operation varies in nature from quartzite to shales and mudstones and is placed on waste rock dumps adjacent to the pit.

Tailings from the process plant are sent to the main tailings dam. Coarse tailings are transported by conveyor to the coarse tailings disposal area and are then utilised in the construction of the tailings dam embankment. Fine tailings are pumped via a pipeline to the dam.

Other types of inert non-mineral waste are disposed of in landfill, while hazardous waste and chemicals are disposed off-site in accordance with regulatory guidelines.

A hydrocarbon management programme commenced in 1993, in order to minimise the environmental impact of oils and greases that are used at the mine site. Oily wastewater treatment facilities have been constructed at both the alluvial and main processing plants. In addition, hydrocarbon contaminated soil is taken to two bioremediation sites that exist on site.

Argyle has had in place a metal salvage and recycling program since 1992. All commercially viable scrap metal is collected and materials that can be re-used on site are stockpiled.

A major environmental objective for Argyle is the successful management of water resources.

Argyle is continually implementing initiatives to increase the recycling of the water used at the AK1 processing plant each day to minimise demands from Lake Argyle. Most of the water used in the processing plant comes from rain water and pit dewatering. Water from the tailings dam is also recovered and re-used in the process.

The process plant water reservoir also collects treated water from an oily wastewater treatment plant that receives input from the process plant, mine workshops and light industrial areas.

The AK1 pit is below the natural water table and therefore pit drainage is constantly required. Three bores and a sump pump run continuously in order to lower the watertable under the pit.