However, the resource consent extension included plenty of horse-trading with the Department of Conservation (Doc), including land covenants protecting adjacent land, more than $350,000 towards habitats and education, plus ongoing work commitments.
Because of overlapping boundaries, the consent extension was sought from the Dunedin City Council, Waitaki District Council and Otago Regional Council. The latter oversaw proceedings.
Submissions closed in August and a three-day hearing was held in October.
Oceana wanted to expand its Coronation area, started in 2014, from 62ha to 85ha and increase ore take 70% from 5million tonnes to 8.5million tonnes.
The application was heard by commissioners Peter Garvan, Colin Weatherall and Dr Brent Cowie, representing the three councils.
In their 273-page decision, they commended Oceana and Doc for coming to an agreement.
''It includes some rather innovative proposals, such as the lizard habitat research, which could have benefits far beyond Macraes Flat, and the provision of monies for the Habitat Enhancement Fund, which can be used to provide wide benefits,'' the decision said.
When considering ''positive effects'', the decision noted that ''perhaps most significantly'', granting the applications would provide ongoing employment for nearly 600 people, with all the flow-on benefits for communities such as Palmerston and Waikouaiti, and for Dunedin.
The ORC granted 19 permits, mainly for discharge and water permits and two for land use, ranging from 10 to 35 years, while the councils of Waitaki and Dunedin granted one each for land use, for 35 years each.
The commissioners found the effects of discharges to air and noise effects from the proposed Coronation North pit on any local residents ''would be no more than minor''.
''We conclude that although the visual impacts of the proposed waste rock stack will be high, when viewed from the north or northwest, so few people will see this that the actual effects are moderate only, and as such, we consider them to be acceptable,'' the commissioners said.
Proposed conditions of the land-use consent requires an archaeological survey of the Coronation North site and the Coal Creek dam, if that is constructed.
''We have imposed such condition. Given this, we consider that the effects of the proposal on historic and heritage values will be avoided or mitigated,'' the commissioners said.
In their overall conclusions, the commissioners said the strong social and economic benefits of the proposal, and ''comprehensive mitigation package'' agreed with Doc substantially outweighed the proposal's significant adverse effects on the life-supporting capacity of some terrestrial and aquatic ecosystems.
''While the proposal will have strong adverse effects on significant indigenous vegetation and the habitats of significant indigenous fauna, these effects, too, are addressed fully by the comprehensive mitigation package agreed with Doc,'' the commissioners said.
They said the proposal did not in their view adversely affect any outstanding natural landscapes or features.
The effects on historic heritage, and on Maori and their culture and traditions, were avoided or mitigated by the consent conditions, they said.
However, the commissioners said there were unavoidable adverse effects from the proposal on habitat availability for each of the Taieri flathead galaxiias, and koura - freshwater crayfish.
''The galaxiid is widespread in streams in and around Macraes Flat, and the evidence was that it is a very resilient species that can thrive in ephemeral streams.
''Its local success was as much due to the absence of predatory trout, as any other factor,'' they said.
For that reason, provision and maintenance of a trout barrier on the Mare Burn was important.
Koura can live in still water and habitat would be created to mitigate effects on their stream habitat in the area.
While the effects on landscape were significant, that was only when seen from small local roads to the north of the waste rock stack. The effects were barely visible, if at all, from other viewing points.
The proposed 69ha Coronation North Pit site lies on a north-facing slope, and is farmland owned by Oceana, leased back to the previous landowner.
The pit, waste rock stack and 100m buffer zone is about 539ha and encompasses significant habitat for indigenous fauna, such as lizards, skinks, birds and flora, supporting 11 distinct vegetation communities.
However, the commissioners said the extensive mitigation package agreed with Doc would protect similar values in perpetuity on adjacent land, and they were therefore satisfied those effects were appropriately mitigated.
The waste rock stack was initially proposed to cover up to 230ha, but in its modified form would now cover 206ha, developed in three stages.
Two reasons for the change were to avoid a site with historic heritage values, following concerns of Heritage NZ and to potentially minimise the effects of the rock stack on ecological values.
On the question of effects of noise on local residents, evidence noted that in calm conditions with a temperature inversion layer, some noise would ''likely be heard'' from the haul trucks.
However, it was also noted such conditions were uncommon at Macraes and wind caused background noise in any case, meaning noise effects on local residents would be less than minor, the commissioners said.
