Quarries are warning that rising building costs will be propelled higher still by pressure on them to move further away from cities and towns.
Quarry land being cleared for housing in Three Kings in Auckland. Photo: RNZ / Kim Baker Wilson
It's worst in Auckland and the quarries say they want the government to step in before they are pushed out.
A score of quarries crush rock in and around the Auckland though just three huge ones near the Bombay Hills pump out most of the aggregate. However, they can't keep up, so big trucks full of rock are being brought in from Northland and Waikato.
See the quarry zones listed in the Auckland Unitary Plan here
Stacy Goldsworthy is one of the best technical brains in the business, and he's been studying how Auckland quarries are changing.
"What you've seen in Auckland's ramp-up in civil engineering project over the last couple of years [is] you have had a consolidation of the quarries [and] a lot more aggregate's being shipped in from further away, and that only adds to the cost of production, and that's passed on to the ratepayer in the end."
Trucking fees double the price of aggregate after just 30km.
Number crunching by the Aggregate and Quarrying Association (AQA) shows that 28 tonnes of basic aggregate costs $406 at the quarry gate and $821 once carted 30km away, and over $1000 at 60km.
Mr Goldsworthy chairs the association's technical committee, and runs a recycling quarry in Onehunga.
"At the moment you are seeing a lot of cost increases with aggregate," he said.
"If you take into account transportation and current quarries stay at their annual output cause most of them are at the maximum at the moment, you will see greater cost."
The pressure is likely to intensify as Auckland's expansion blueprint, the unitary plan, allows for more than 100,000 new houses to be built in the surrounding countryside.
The association's chair, Te Kuiti quarry manager Brian Roche, said councils and courts were too ready to shut down quarries or make it hard to open them where anyone lived.
He aims to make this an election year issue.
"There is no real recognition by politicians, local or national, of the importance of quarries to New Zealand, and increasingly quarries are being pushed further and further from urban fringes ... which is driving up the cost of buildings and roads and houses."
Auckland councillor Chris Darby who chairs the city's planning committee said the council was well across this: They had made the rules clear for quarries and were putting in buffer zones so housing did not encroach.
He said the industry had not lodged any court appeals about the 18 quarry zones outside the rural boundary and one inside that boundary, as set by the Unitary Plan, or against the regional policy on mineral extraction.
"We've been working very closely with the industry and the owners of the quarries for quite a few years now," said Mr Darby.
"We have also gone so far as identifying key transport roads for quarries to the Auckland markets. You have got to get it there by a significant number of trucking movements on roads that can handle those."
But Brian Roche said he had seen nothing since the Unitary Plan came in last year to convince him the Auckland Council understood quarries' issues.
The Economic Development Minister, Simon Bridges, said it was complex.
"There is a tension between needing land to open up for housing and keeping quarries in close proximity to urban areas to keep prices for raw materials down," he said.
He said the quarry industry could make submissions on proposed law changes around streamlining large projects around urban areas.
A $4 million, four year government-funded study into the quality and quantity of aggregate, and the demand for it across New Zealand, was due to finish next year, and would also help with making policy.
However, Mr Roche said that study was not looking into the geographical squeeze on quarries.