Oceana Gold is proposing a three-year development of a new pit for ore extraction to the north of its existing East Otago mine site, which could add a year to the mine's life.
The proposed Coronation pit and adjacent waste rock stack, are along the divide of the Shag and Taieri Rivers, between Sister Peaks and Highlay Hill.
Separately, Oceana's entire New Zealand operations in East Otago and at Reefton on the West Coast remain under review, as the country's largest miner battles rising costs and weakened spot global gold prices.
Up to 260 jobs at Reefton are under threat from a proposal to mothball that plant by 2015.
In resource consent applications just lodged with the Waitaki District Council, Otago Regional Council and Dunedin City Council, Oceana said the Coronation pit would cover about 62ha, while the waste rock stack would cover about 105ha.
The miner has produced 3.7 million ounces of gold in 23 years from its combined pit and underground operations at Macraes and from Reefton concentrate processed at Macraes.
Its mine life is set at 2020. About 6 million tonnes of gold-bearing ore is processed annually at present, with Coronation expected to contribute about 5 million tonnes.
''The Coronation project resource consents now being sought by Oceana Gold will extend the Macraes gold project mine life and its attendant benefits to the local and regional communities by an additional year of ore processing,'' the company said.
Public submissions on the application are open until August 30.
In Oceana's ''assessment of environmental effects'' in its multiple applications, the company said the proposal was of a similar nature to the effects from existing operations, although at a different location ''but at a much reduced scale'', and ''considered accepted''.
An assessment of effects on water quality has been undertaken, which recommends several measures to manage water quality to ensure compliance with expected standards at the various monitoring points.
''Aquatic ecology values and abstractive uses downstream from the Coronation project are not at risk,'' Oceana said.
The project includes possible construction of a storage dam on Camp Creek, a tributary of Deepdell Creek, to be used to supplement natural low flow periods.
The effect of the Camp Creek dam on the aquatic ecology values in the immediate vicinity ''will be minor'', while temporary changes to downstream water availability would not have an adverse impact on aquatic ecology values, but would have a ''minor effect'' for water users in the Mare Burn and Deepdell Creek catchments, Oceana said.
