Economic benefits from a small footprint

Mining provides huge economic benefit from a small footprint. No other land use earns anywhere near as much as mining does.

The reason for this is simple. Minerals are concentrated into economic ore deposits in very few places, and then they must be found. As the easier-to-discover and access resources are developed, the search proceeds for resources that are more difficult to detect, and more difficult to extract, with upward pressure on costs. Exploration and mining technologies continue to advance to meet these challenges.

At the Macraes gold mine in East Otago, it is estimated that it would take 767 years to earn from farming the amount earned from mining, off the mine footprint. And the opencast mining method used at Macraes means that as mining progresses, most land is returned to productive grazing use. Indeed, the rehabilitated land at Macraes is more productive than pre-mining. This is a common outcome when land is mined and later returned to agricultural use.

The footprint

A large opencast mine, such as Macraes, has a working footprint of 300-500 ha, or 3-5km2. An underground mine typically has a surface expression of between 5 ha and 20 ha. The Stockton coal mine is an exception to the rule, having a working footprint close to 1000 ha, or 10km2. The reason for this is that mining has a long and continuous history at this site, since 1885. The management of the site is a “legacy issue” – it will take time in the harsh climate of sub-alpine Westland to bring this site into the same pattern as most contemporary mines in New Zealand. Learn more on Mining 101.

A mine’s footprint is constantly changing because site rehabilitation begins when mining begins and continues until after a mine closes. As mining proceeds in one direction, land that is no longer needed for mining is returned to a former or desired land use. This process, and the conditions that a mining company has to meet, is established through the resource consent process under the RMA.