Oceana Gold has more than 200 resource consents for operating its Macraes mine in East Otago and at Reefton, on the West Coast, but a recent guilty plea to a consent breach has brought into sharp focus the reality of balancing economic interests against environmental.
The sustainability of mining, landscape issues and restoration of mine sites is at the heart of criticisms being levelled at the resource sector at present.
This issue was highlighted in April by a pollution charge stemming from the operation of Oceana's Reefton open pit mine, which opened in 2007, and sits in the Victoria Conservation Park.
The park is administered by the Department of Conservation.
Oceana pleaded guilty in the Environment Court to polluting the Buller Stream, near operations, having earlier paid fines of between $750 and $1000 for each of 15 infringement notices issued during the past five years.
The company is to be sentenced in early June.
Oceana's Dunedin-based chief operations officer, Mark Cadzow, said with up to 100 consents for Reefton, and more than 100 at the Macraes site, critics had to keep the Buller Stream infringements in context, that only one consent had been breached by the company in two decades.
"We're happy to work in the RMA [Resource Management Act].
It is the safeguard and part of our licence to operate.
"Nature and mining can co-exist together; it is not an `either/or' situation," Mr Cadzow said.
On the forthcoming sentencing, he said: "As part of that [restorative justice] process, the company acknowledges the effects of the offence and aims to agree with the prosecuting authority on measures to address it."
He said a balance had to be struck on what value Oceana Gold had to the community, such as $63 million paid to 780 staff and contractors last year, plus sponsorship and service support.
No consents had been breached at Macraes during its 20 yearsof operation, he said.
Mr Cadzow had been on the site in a variety of jobs since Macraes opened in 1990.
He said rectifying the Buller Stream issue had cost Oceana "several hundred thousand dollars" and during the past eight months the changes had been "100% effective", after a new "design solution" was put in place.
He described the problem as coming from access road water runoff, with the design solution being installation of improved pipework and also "fine particle containment", to keep the stream free of silt.
The problem had been identified and was being worked on before the first infringement notice was issued, he said.
Rain readings by Oceana, of up to 90mm falling an hour at times, were found to be far higher than any previous data collated, Mr Cadzow said.
During the past 20 years Oceana has moved 700 million tonnes of earth in order to process 75 million tonnes of ore through its gold recovery process, and in March poured its three-millionth ounce of gold.
Of eight open pits Oceana has created at Macraes, five have already been backfilled and rehabilitated as pasture or with tussocks - a total of 300ha rehabilitated.
Oceana's ongoing restorative programme, which costs up to $1 million some years, for the Macraes mine is targeting 80% to 90% be rehabilitated into grazing land, while 10% to 20% of the land footprint will be taken up by three lakes.
At present, two pits have water in them, and their sides could potentially be reopened for further mining, while the Frasers pit is 250m-300m deep, with mining planned to a further depth of 50m.
The mine's overall life span has been extended by six years, to 2016, based on recent estimates and results from an aggressive exploration programme.
Aside from rehabilitation measures required under the RMA, Oceana has: created a wetland walkway on a 13.6ha restored site, including bird hide and native vegetation; installed a heritage and art park and worked with the Fish and Game council on an onsite trout hatchery, with independent pasture and biodiversity reports, both regulatory and voluntary.
"We are only borrowing the land, not taking and destroying it, but [at Macraes] returning it to pasture.
There can be a balance between mining, tourism and conservation," Mr Cadzow said.
Cyanide remained an important element in the gold recovery process, but Oceana stopped using a cyanide tailings dam three years after operations began in 1990.
Of the cyanide used now at Macraes, none went to settling ponds, Mr Cadzow said.
The Reefton open pit, like its Macraes mine, will be rehabilitated when mining is completed, at an estimated depth of more than 250m, and rainforest regeneration will be boosted by replanting.
"It should be difficult to tell we've been here [at Macraes] in 20 years, except for the lakes," Mr Cadzow said.
Mr Cadzow (53) is a metallurgist and started with Oceana 20 years ago, in turn becoming its manager of processing, projects, mining, environment and sustainability, development, vice-president of exploration and development, and recently its chief operations officer.
