The Environment Court will reconvene tomorrow ahead of its final deliberations on whether to allow an open-cast mine to go ahead on the West Coast's Denniston Plateau.
Conservation group Forest & Bird and the Australian mining company Bathurst Resources will be at the court in Christchurch to argue their cases.
The court had indicated that the mine was likely to go ahead if conditions could be found that could appropriately mitigate environmental damage.
Last week Forest & Bird suffered a major setback with a High Court appeal being thrown out.
The environment watchdog was appealing against interim resource consent given to Bathurst Resources Limited for the 188ha open-cast mine on the plateau near Westport.
It had argued that the Environment Court did not give proper consideration to the possibility of there being two open-cast coal mines simultaneously working the area when it gave Bathurst the go-ahead.
It said the effects of an unimplemented coal mining licence by state-owned Solid Energy for another mine, the Sullivan Mine, also on the Denniston Plateau, should have been taken into account, even though it has not been used and expires in 2027.
The cumulative effect of both mines operating at the same time were not properly considered, Forest & Bird claimed.
Buller Coal Limited, owned by Bathurst Resources Ltd, rejected the environmentalists' "narrow'' argument, as did the West Coast Regional Council and Buller District Council, which granted mine consents to Buller Coal last year.
In a 21-page judgement released last Thursday, High Court judge Justice John Fogarty concluded there was "no material error of law in this decision not to embark upon cumulative effect analysis''.
Forest & Bird's appeal was dismissed and costs were reserved.
Conservation Minister Nick Smith last month approved access rights to the Australian firm for the project, saying it would provide a $1 billion boost to the economy and create 225 jobs.