Buller's proposed new mine could employ over 200 and still be operating in 2060 if it gets the green light, according to the head of Perth-based coal developer Bathurst Resources.
Bathurst plans to begin an export coking and thermal coal opencast mine at Denniston late next year in a joint venture with L&M Mining but is yet to obtain resource consents.
Bathurst's managing director, Hamish Bohannan, told the Westport News the mine would create at least 200 jobs including miners, plant operators, accounting and support staff.
Bathurst hoped to employ as many locals as possible.
The mine could be in production for 40 or even 50 years.
"We're confident with good planning and a bit of good fortune it will certainly be well over a 30-year project so it will give long-term and permanent rewards for the community."
Bathurst's initial production target is 1 million tonnes a year, increasing to 2m tonnes a year - more than the current annual production at Solid Energy's Stockton opencast mine.
Mr Bohannan said production might eventually ramp up to a cap of 4m tonnes a year.
"Our plan is to be mining towards the end of the next calendar year, to start producing coal shortly thereafter but, of course, the first activity we'll see is some construction which would start next spring."
Timing depended on the resource consent process. He was confident Bathurst would get consent.
Conservationists yesterday expressed concern the proposed mine might threaten endangered species, such as Powelliphanta snails and great spotted kiwi, and destroy increasingly rare sandstone pavement vegetation.
Mr Bohannan said Bathurst would take environmental issues into account, and relocate any Powelliphanta snails and giant spotted kiwi found.