Land

Mining operations have a significant effect on relatively small areas of land. In all of Australia, mining leases take up 0.06% of the area of the entire continent, but the area actually disturbed by mining is only about 0.02%. At Olympic Dam, the Special Mining Lease covers an area of 18,000 hectares (ha), of which 1,320 ha (7.3%) is disturbed by the facilities needed for mining, such as the processing plant, ore stockpiles, roads, mine buildings and the tailings retention facility. Part of the reason for the disturbed area being relatively small is that the Olympic Dam is an underground operation, so there are no huge open cut pits on the site.

Area covered by the Olympic Dam operation

The area covered by the Olympic Dam operation is insignificant compared with the vastness of the Outback.

Some of the effects (IMPACTS) that the Olympic Dam mine has on the land, and how they are being managed and reduced (ACTIONS) are summarised below.

Impact	Action
The tailings retention system changes the shape and appearance of the landscape. These evaporation ponds are part of the Tailings Retention System.	During mining, as much of the solid tailings as possible are used in the backfill material used to fill empty, mined out stopes. The remainder of the tailings are deposited in specially designed tailings storage facilities, where the tailings consolidate and dry out. When the tailings storage facility is full, it is capped with impermeable materials such as clay to prevent any contaminated material from moving out into the local environment. The tailings are then covered with top soil and replanted with native vegetation.
Underground mining leaves large empty holes (mined out stopes) below the surface, which could lead to concentration of radioactive radon gas, lowering of the local water table as the mined out areas fill with ground water, ground instability leading to possible collapse and rock falls.	Stopes are progressively backfilled using a backfill material made from waste rock, coarse tailings, fly ash from a coal fired power station, quarried limestone and cement. The Tailings Retention System from the air. As much of the brownish dried tailings in the storage impoundments (bottom and centre) as possible is re-used in the backfill material used to fill mined out stopes.
Olympic Dam uses water from the Great Artesian Basin (GAB). A feature of the landscape at the edge of the GAB is the mound springs. The mound springs are special land features made from build up of minerals deposited from evaporating artesian spring water. In some cases, unique wetland ecosystems have developed around these springs. Extraction of too much water from the Great Artesian basin could cause some natural springs to dry up, resulting in damage to or loss of these ecosystems. Aerial view of a mound spring.	The Olympic Dam mine has a legal limit imposed on it on the amount of water it can extract from the Great Artesian Basin. The limit is 42 ML/day, but because of careful management and recycling of water at the mine and in Roxby Downs, only about 32 ML/day was used during 2000. WMC undertakes extensive monitoring of the borefields and mound springs, and there is no evidence of damage to any mound springs caused by the Olympic Dam operation. Lush vegetation at a mound spring near Lake Eyre South.

Impact

Action

The tailings retention system changes the shape and appearance of the landscape.

Evaporation ponds

These evaporation ponds are part of the Tailings Retention System.

During mining, as much of the solid tailings as possible are used in the backfill material used to fill empty, mined out stopes. The remainder of the tailings are deposited in specially designed tailings storage facilities, where the tailings consolidate and dry out. When the tailings storage facility is full, it is capped with impermeable materials such as clay to prevent any contaminated material from moving out into the local environment. The tailings are then covered with top soil and replanted with native vegetation.

Underground mining leaves large empty holes (mined out stopes) below the surface, which could lead to

concentration of radioactive radon gas,
lowering of the local water table as the mined out areas fill with ground water,
ground instability leading to possible collapse and rock falls.

Stopes are progressively backfilled using a backfill material made from waste rock, coarse tailings, fly ash from a coal fired power station, quarried limestone and cement.

Tailings Retention System

The Tailings Retention System from the air. As much of the brownish dried tailings in the storage impoundments (bottom and centre) as possible is re-used in the backfill material used to fill mined out stopes.

Olympic Dam uses water from the Great Artesian Basin (GAB). A feature of the landscape at the edge of the GAB is the mound springs. The mound springs are special land features made from build up of minerals deposited from evaporating artesian spring water. In some cases, unique wetland ecosystems have developed around these springs. Extraction of too much water from the Great Artesian basin could cause some natural springs to dry up, resulting in damage to or loss of these ecosystems.

Aerial view of mound sping

Aerial view of a mound spring.

The Olympic Dam mine has a legal limit imposed on it on the amount of water it can extract from the Great Artesian Basin. The limit is 42 ML/day, but because of careful management and recycling of water at the mine and in Roxby Downs, only about 32 ML/day was used during 2000. WMC undertakes extensive monitoring of the borefields and mound springs, and there is no evidence of damage to any mound springs caused by the Olympic Dam operation.

Lush vegetation at a mound spring

Lush vegetation at a mound spring near Lake Eyre South.

The Arid Recovery Project

Large areas of Australia's arid interior ecosystems have been damaged because of overgrazing by cattle and sheep, and the introduction of feral animals such as cats, rabbits, and foxes. WMC is a major sponsor of the Arid Recovery Project, which aims to restore 60 square kilometres of arid land near the Olympic Dam mine. So far all of this has been fenced off with rabbit, cat and fox-proof fences, and all rabbits, cats and foxes have been destroyed in a 30 square kilometre fenced area within the total enclosure. The native vegetation within the fenced area has been allowed to regenerate. Progressively, rare or endangered native animals which formerly lived in the region are being re-introduced. Research being conducted by WMC and other environmental scientists involved in the project will find out more about the most effective ways to conserve Australia's arid environments.

Rehabilitated area in the Arid Recovery Project

Part of the area rehabilitated in the Arid Recovery Project.