Plans to extend Martha Mine under several Waihi homes causes controversy

Gold mining in the Coromandel could soon be expanded underneath people's homes to mine new gold.

Submissions on expanding Martha Mine in Waihi have closed today and opponents say the mine poses a risk to people's homes.

Waihi's Correnso mine is a seemingly neverending network of tunnels 150 metres below the east of the city. But almost all the gold in the walls is gone, and now the mine's operators want to expand into new areas beneath the town.

"Our expansion of Project Martha would put us under another 30 or 40 homes," OceanaGold senior community advisor told Newshub.

But mining under homes in the Coromandel town is controversial. In 2001 an old tunnel collapsed, creating a giant sinkhole right under someone's home.

Those who still live above the tunnels said they've been dealing with the effects of mining for years.

"All of a sudden the ground didn't feel as stable as it used to. We've had a light fitting dislodge from the ceiling and a pipe break as well, underground after a very large blast," resident Mike Moskal said.

The new development would see underground tunnels run from the bottom of the opencast Martha Mine under the local rugby park to the intersection of Mueller and Kenny streets.

But to start tunnelling they need to clear millions of tonnes of rock and rubble the cover the road in to the pit. It was blocked in 2016 when part of the north wall collapsed.

"We know that the old timers left a lot of the gold behind and so we'll be heading under the pit floor at well," Mr Wilson said.

Correnso is nearing the end of its life and has been operating in Waihi for four years. It runs 50 km underneath the town. If the consent for Project Martha goes ahead, it will extend mining for another 10 years.

The mine's operator OceanaGold says that's good news for the town.

"Project Martha keeps those 350 people employed, keeps the economy going," Mr Wilson said.

Some residents seem convinced.

"I think it's genuinely a net gain for the Waihi community," said resident Mark Samson.

But anti-mining group Coromandel Watchdog says mining under residential properties needs to stop.

"They've already gutted what was already a sacred mountain to tangata whenua and turned it into a pit, but now they want to go back in," said spokesperson Catherine Delahunty.

OceanaGold hopes Project Martha will be up and running by the end of 2019, but that depends on a green light from the both local and regional councils.