The company has been granted a resource consent by the Dunedin City Council to expand excavation of the top quarry at Logan Point, including knocking the top off a highly visible knoll, over the next 40 years.
The decision is subject to a series of conditions aimed at protecting surrounding areas, including one requiring new plantings before excavations to shield surrounding areas from the operation.
Blackhead general manager Tony Hunter told the Otago Daily Times he was "reasonably happy", even though submitters still had a 15-day period in which to appeal to the Environment Court.
"It gives us security for a long time and the town security of supply. We have got to wait for the process to be completed before we get too excited."
He believed the company had worked hard to ensure up to 100 quarry neighbours did not oppose the expansion plans.
The company had already employed a landscape architect and, in the past two weeks, completed planting natives around the site, and had publicly notified its intentions before required to by the council.
The consent application had attracted five submissions.
Two opposed the project, and one of those was made on behalf of four other people.
"Our neighbours as a whole are happy anyway because we have put a lot of effort into making sure they are happy before now," Mr Hunter said.
The quarry, on the lower slopes of Signal Hill, processed up to 260,000 tonnes of rock each year, mostly for Dunedin roading and building projects.
However, the site's top quarry, further up the hill and not visible from the flat, had only five years of accessible quality rock left.
The company had applied to extend its operation into land it already owned.
The land was zoned rural, where quarrying was an unrestricted discretionary activity under the Resource Management Act.
The decision by the council hearings committee, chaired by Cr Colin Weatherall, was dated October 27 and released to media yesterday.
One of those opposed, Ken Holman, of Signal Hill Rd, said he was "a little bit disappointed" by the decision, but not surprised.
He had no plans to appeal.
"I'm not too worried about it because I knew it was going to happen anyway," he said.
A submission to last month's hearing by his wife, Nicola Holman, also representing Mr Holman and three neighbours, had opposed the extension of the quarry.
Mr Holman also argued, in an opinion piece published by the Otago Daily Times, that extending the quarry would be "consenting to the destruction of a significant hilltop" within 3km of the Octagon.
Signal Hill was a "playground" for mountain bikers and walkers, and a picnic area was planned for a spot just 50m from the edge of the area now to be quarried, he said.
The city needed to debate the merits of having a quarry in its midst.
"It may have been acceptable 50 years ago, but now we are in the 21st century. Is it acceptable today?"
Mr Hunter said the city needed the quarry, and the excavations would be a "really gradual process" over decades.
"It won't be nothing today and all on tomorrow. No-one will really notice it," he said.
The committee's decision, signed by Cr Weatherall, accepted the proposal was consistent with the district plan and a rural zone was "the most appropriate location".
Expanding the quarry would also avoid the need to establish a new quarry elsewhere, with associated development and transportation costs and environmental impacts.
Noise and vibration could be managed and the risk of landslips was not expected to increase as a result of quarry blasting, but a monitoring programme would be put in place.
A site rehabilitation plan would also be required within the life of the quarry.
