Because the mine site is very close to a World Heritage listed area, careful management of the land is very important. Read on to find out about the IMPACTS the Henty Mine has on the land, and the ACTIONS that are taken to minimise them.
All structures (buildings, roads, underground workings, stockpiles, tailings dams, etc) associated with any mine mean disturbance to the land on which they are constructed. For example, bush and topsoil must be removed from the area to be occupied by the structure. Often the land must be reshaped, for example steep terrain must be levelled to allow placement of buildings. Roads must be constructed through the bush to allow access to and from the mine site. The leach residue ponds cover part of the land.
Mine buildings at Henty Mine
The underground mine has minimal impact on the land. There is a small cleared area near the portal or entrance to the decline, to allow vehicles to park or manoeuvre prior to entering the decline.
The administration building, mill and workshop areas occupy the site of a former Hydro Tasmania cement plant. Many of the cement plant's foundations were reused in constructing the mine buildings and other structures. In addition, most of the mine's roads were originally constructed during previous forestry operations, or by the Hydro Tasmania during development of the nearby hydro-power schemes. Old gravel pits and Hydro Tasmania quarries are being used for storage of machinery, waste rock or top-soil cleared from the land during construction of tailings dams for later use in rehabilitation.
This means that additional disturbance to the land by construction of the Henty Mine has been kept to a minimum.
All disturbed areas on the mining lease are rehabilitated once they are no longer required for the mine's purposes. Rehabilitation involves replacing top-soil which may have been removed during construction of the facility and stockpiled for later re-use, and replanting the area with local native plant species. The mine has a nursery for raising seedlings of native plants to be used for revegetating and rehabilitating disturbed areas on the mine lease.
Nursery used for raising seedlings of native plants.
Seedling of native laurel growing in a rehabilitated area.
At the end of mining, all structures will be dismantled and removed. The land will be rehabilitated.
A number of materials are stored on-site at the mine for use in the mine's operations. Some of these materials could damage the land if allowed to spill. For example, sodium cyanide is used in the processing plant, and oil and fuels are used by the mine's vehicles and machines.
Mine personnel at Henty are very concerned to prevent contamination of the land by these materials. All storage areas for potentially dangerous substances are constructed on concrete aprons with walls, or bunds, around the edges to prevent spread of any spills into the soil.
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The fuel tank (left) and cyanide tanks (centre) are placed on bunded concrete aprons to capture any accidental spillage and prevent dangerous substances contaminating the land. The unit (right) is used to clean up accidental oil spills. |
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During the time that Hydro Tasmania was constructing dams for hydro-electric power, a species of dieback disease called Phytophthera was introduced to the area from contaminated sites elsewhere. Dieback affects trees, causing them to lose foliage and eventually die.
The disease is currently restricted to areas along the edges of roads and cleared sites on the mine lease. Spread of this disease further into the ancient rainforest areas by mine related activities is certainly undesirable and is being prevented by the control of vehicle movements at the mine. There is strict control on the movement of plants in or out of the mine site.
Another danger to rainforest is bushfire. If rainforest is destroyed by fire, it may take hundreds of years to regenerate. Although Tasmania's west coast usually has a very high rainfall, some summers remain relatively dry, meaning that there is potential for bushfires.
The mine has a well-equipped fire-fighting vehicle, which helps reduce the danger of bushfires during the summer.
Fire-fighting unit.
