Case study: Diversity in environmental management
Environmental management is a cornerstone of OceanaGold, the operator of the Martha open pit at Waihi, Coromandel, and the nearby Favona Correnso underground mine (also the portal to the Moonlight and Trio ore bodies). The company has approvals for a new underground gold and silver mine under East Waihi, called Correnso, which would be also accessed via Favona.
Mining at the world-class Martha ore deposit is due to be completed within the next few years, raising the question of the future of this site. On this, the community and iwi have been consulted. At this stage, the most likely result will be a lake occupying the former pit. This would five years to fill, both from natural supply, and consented take from nearby waterways.
The rock waste left over from crushing, grinding and chemical processing of gold and silver-bearing ore is referred to as “tailings”. This material, and other waste rock, is managed at two waste impoundments or tailings storage facilities near Waihi. Topsoil and clay are layered over rock, and pasture and native vegetation sown and planted, to recreate the patchwork rural landscape of the region. Over time the site is being returned to grazing, the former land-use.
A side-effect of the tailings dams has been to create areas popular with waterfowl, and wading birds or shore birds, among them, the NZ dotterel. The appearance of this threatened native species to the Coromandel and other parts of New Zealand inspired a partnership between NWG and the Department of Conservation, called the New Zealand Dotterel Watch Programme. Centred at Opoutere, on the Coromandel peninsula, conservation work includes predator control, and chick banding and monitoring.
Once compromised as a result of mining in Waihi before 1952 when there was little appreciation or understanding of the environment and no protective legislation, the Ohinemuri is now one of the top trout streams in the North Island because of water treatment, and riparian conservation efforts made by NWG. As part of this work, NWG has planted more than 450,000 native trees and shrubs along waterways. Environment Waikato presented an award to NWG for this work in 2012.
NWG has carried out restoration of historic heritage, for example, the Cornish Pumphouse, a relic of Waihi’s early mining history. The company runs education programmes in Waihi on its mining operations with over 6,000 students visiting the site each year, and the Martha mine attracts as many as 40,000 visitors a year. The company is a leading stakeholder in Waihi’s plans for community development, against the day mining operations in this region eventually cease.
A trust with funding has been set up to manage areas and sites after mining operations at Waihi cease. Trustees include representatives of iwi, local government, land owners, and the community.
Updated Feb 2018