Environmental success for Eagle nickel

In December 2007, the Michigan Department of Environmental Quality (MDEQ) issued Rio Tinto with mine, air and groundwater discharge permits for its Eagle nickel project.

Michigan's nonferrous metallic mine law is considered to be the most stringent in the US. Commenting on the evaluation that Eagle underwent, a MDEQ spokesman said: "This review process is one of the most rigorous that's ever been done probably in any state in the nation for a project like this."

The region around the Eagle deposit, in Marquette County, northern Michigan is a gently rolling, densely forested, rocky environment dotted with lakes and laced with innumerable streams that feed rivers inhabited by game fish. With moose, deer, wolves and black bears, it's an environment about which people care very much, whether they live in its midst, or hunt, hike and fish amongst its watercourses and woodlands.

Environmentalists had argued that the mine would endanger nearby watercourses, asserting that "no sulphide mine is ever safe". "We can easily demonstrate that that isn't so," said Jon Cherry, the Eagle project general manager.

The Eagle orebody will be mined underground using long hole stoping; therefore no waste rock will be left at the surface after closure, as it will all be consumed during the backfill process. The orebody will be reached by a long inclined tunnel that will minimise any risk of interference with the nearby watercourses.

Extracted nickel ore will be shipped to a local mill and then, in concentrated form, to Canada for smelting and refining. Because the mine will have such a small footprint, locals can continue to use the area for recreation, and after it is exhausted, nothing will remain on the surface.

Treated water will have to be stored in holding tanks to prevent the entry of rainwater before it is released to the environment. "My treated water is allowed to contain only two nanograms of mercury per litre - that's parts per trillion - but Michigan rainfall already contains 20 nanograms of mercury per litre - I can't let them mix!" said Jon Cherry. "The treated water will be of better than drinking water quality."