Mine closure is a legitimate element of the mining cycle
and like mine development involves technical planning, permitting, and finally
construction. Closure begins with the mine's operational footprint and
transforms the site so that it meets the explicit requirements of the owners and
regulators. Implicitly, the closure will increasingly need to meet the
requirements of other interested parties such as the local community, workforce,
and future land users.
Golden Cross is the first modern mine closure in
New
Zealand. It operated for 6 years as a
mid-size gold and silver mine winning ore from both underground and open pit
sources, and processing via a carbon in leach circuit including a cyanide
recovery stage prior to tailings disposal. The mine is situated in a sensitive
high rainfall environment, and is complicated by the existence of a large
ancient landslide underlying most of the tailings dam and waste rock
embankment.
The regulatory process for mine closure in
New
Zealand is not clearly understood by operators
or regulators alike. The Golden Cross mine was permitted under the Mining Act
1971 and closed primarily under the Resource Management Act. This switch of
legislation, the parallel reorganisation of many government departments, and
change in societal expectations with respect to long term environmental
stewardship during the life of the mine resulted in the requirements of closure
being significantly different to the expectations at
permitting.