A potential threat to Christchurch's water supply is causing concern among residents and community leaders in the west of the city.
A group of six residents met with the owners of Winstones Quarry on Yaldhurst Road last week to voice their concerns over the expansion of the quarry.
They said as well as well as potentially encroaching on their properties, the penetration deeper into the ground could contaminate Christchurch's drinking water.
A Yaldhurst resident neighbouring Winstones Quarry, Anna Youngman, said after meeting with Winstones' representatives last week, she was still not satisfied with plans to expand the quarry.
Ms Youngman said as well as the nuisance caused by dusts and noise from the quarry expanding across a wider area, residents are worried about the quarrying activity going deeper.
Quarrying companies are only allowed to go down to a level with at least a one metre buffer above the water table, but some, including Winstones, are applying to dig four metres below the water table.
"This will affect the ground water level in Christchurch, and we're all on wells in this district. Once they quarry below that level, and the ground water comes up, we're just going to have pollution and massive problems."
Chairperson of the Riccarton-Wigram community board, Mike Mora, said while there were risks to water caused by machinery that can potentially leak fuel and oil, that was not the biggest concern.
"We all know that most quarries are used as landfills when their quarrying days finish. They use them for landfills. That's really an issue: how do we restore land that's been quarried?"
Deputy-mayor of the Christchurch, and councillor for Riccarton-Wigram area, Vicki Buck, said a total of nine quarries had recently applied to go below the ground water buffer zone.
Ms Buck said the consent applications will be publicly notified soon.
She said the research and science will be examined during the consenting process, but believed many people will feel it was just not worth the risk.
"I think that in Christchurch because we derive our water from the groundwater aquifers, they are incredibly important. I think to take risks with those would be very unwise."
Mr Mora questions the need to be extracting gravel from the ground, and says the beds of Canterbury's major rivers should be utilised as a source for shingle.
"The river beds, are building up, higher and higher. Higher than the surrounding land, and that means that if we don't take the aggregate out of the river beds, our stock banks need to be built up higher. That's a dumb situation to be in. We're very lucky to have a mountain range to the west of our city to provide us with aggregate for the next million years."
Winstones Quarry could not be reached for comment.