A communications breakdown between the company and a neighbouring landowner sparked a claim Featherston Resources Ltd (FRL) had changed the project so much it should not be allowed to continue without a new consent.
The company argued yesterday a resource consent committee hearing was not able to rule on those matters, just a variation to an original consent that would mean the company would not have to plant trees screening the mine from Moonlight Rd.
The mine was originally approved in 2000, with a non-notified Dunedin City Council consent.
The Middlemarch quarry contains an estimated 20 million tonnes of diatomite, and the company has a 20-year mining permit from 1993. The company has leased a 40ha area from Holcim New Zealand, and plans to mine about 16ha.
There were two submitters at the hearing, Holcim New Zealand, which owns the site, and neighbours Anton and Elizabeth Gibson.
Before Crs Colin Weatherall, Andrew Noone and Teresa Stevenson, and Strath Taieri community board chairman Barry Williams, FRL chief executive and managing-director Emma Weston said previous landowners had not wanted the row of trees.
In 2010, there was a dispute with the Gibsons, who then owned the neighbouring land, over money in relation to the trees, and there were threats of trespass action.
It became obvious to the company, she said, the trees could not be planted.
Because of that the resource consent condition requiring screening trees could not be completed, and a variation to the consent was needed.
Council planner Darryl Sycamore recommended in a report the variation be granted.
For the Gibsons, counsel Kelvin Campbell said the original consent for the mine was based on an understanding the land now owned by the Gibsons would be bought by the company, but that had not occurred, and had been the subject of a High Court case.
There was also to be an on-site processing plant to dry, crush and bag the diatomite, but that had been built near Mosgiel.
Mr Campbell said the plot of land was inside the land owned by the Gibsons, and there would be problems with dust as the material was taken from the site on trucks, rather than processed there.
It was "a new beast, so much different from the old beast" that it required a new consent.
Mrs Gibson said the company had been "bullish" in its approach to the couple, and they had been "bullish" back. The couple had not told the company it could not plant trees, but did say company representatives could not enter their land.
Landscape architect Michael Moore told the committee of his plans for plantings for rehabilitation of the land, and for a pond, where the mining site had been, once mining was complete.
Ms Weston said the company planned to mine 3ha at a time, then fill and rehabilitate the land as mining continued.
Mr Williams asked Ms Weston how much faith people could have in the company, when it had changed the site of its processing plant after the council had spent money on road sealing with the plant in mind.
Ms Weston acknowledged there had been changes, but said her job was "to take the company forward", and all she could give was her "assurance going forward".
Background
Diatomite: Fossilised remains of up to 100,000 different varieties of microscopic water-borne algae called diatoms, impregnated with silica, which when mined resembles hard fertiliser such as limestone or phosphate.
Uses: Fertiliser: insect repellent; whitewash; oil contamination clean-up; toxic waste thickening; soil remediation; waste water treatment.
The company: Privately-owned Sydney-based Featherston Resources Ltd has since 1997 spent more than $10 million on research and development for commercialising Middlemarch diatomite deposit. Last year it completed a processing plant, costing nearly $1 million, near Mosgiel.
