The reason why land settlement is damaging five properties in Waihi is expected to be clarified in the coming weeks as the results of a drilling programme are analysed.
The residents of 47-53 Gladstone Road are negotiating with the Newmont Waihi Gold and the Hauraki District Council over the best course of action after sudden ground movement damaged their properties.
The ore body lies deep beneath Waihi East.
Newmont says it is unlikely its operations caused the problem, but the mining company is offering to relocate affected residents, purchase the damaged properties and provide assistance with relocation, legal and other associated costs.
Newmont Waihi Gold general manager Glen Grindlay says while the cause of the ground movement is still unknown the mining company has the skills, resources and ability to act quickly and provide assistance to residents during a difficult and stressful time.
“Our main concern at the present time is the welfare of residents during the festive season.
“Newmont Waihi Gold has agreed with Hauraki District Council that we will assist by looking after residents whose homes are showing signs of significant damage due to this localised ground movement by offering to purchase.
“Investigations take time, people need help now, and for this reason we have become involved now. The cause of the ground movement can be worked out later and this will take many months, but right now we have the ability to provide assistance to residents who want help.”
The offer is without any admission of responsibility or liability for the ground movement, says Glen.
At an Environment Court hearing in December consulting engineer Trevor Matuschka told the commissioners the subsidence could be related to an 1800s tramway line that ran through the area. A gully was filled with mining rock to take the track. The depth of the gully is unknown.
Trevor says the eastern boundary of where the land is settling appears to coincide with about where the tramline was located. The houses have settled 100-150mm towards the west.
The subsidence area is located between Gladstone and Walmsley Roads, directly over the site of the proposed Correnso mine, which Newmont Waihi Gold is in the process of seeking a resource consent.
Waihi East residents are opposing the consent application.
Waihi East Residents Group secretary Roger Wainhouse says there are about 27 houses involved and the mining company is only looking after six of them.
He says the slumping is because of the dewatering associated with existing mining at Favona and Trio. Correnso is the mine Newmont wants to work next, says Roger.
“The trouble is it goes under all the houses in Waihi East. They are going to tunnel in from the Favona mine and Trio mine and do it all from underground.
“They want to tunnel in from a couple of kilometres away and mine under us. Have you seen the signs here which say no mining under our homes? Well, this is what we are doing to try and protect ourselves.
“The mining company say they have rights to do it. We want to be compensated, and they don’t want to compensate us.
“At the moment we have had a lot of slumping because of the mine’s dewatering which has altered the land a bit, which is not in the residents’ best interest.
“We said to them, ‘look; you’ll have to look after us, you’ll have to buy ours houses, replace our houses with something similar.
“That’s the trouble. They are only coming to the party with the ones that have slumped and that’s only six of them.”
Newmont is proposing to mine from 150 metres beneath the surface down to 350 metres.
Newmont proposes a daytime-only blasting regime with three daytime blasting windows between 7am and 8pm, each with a blast duration of no more than 18 seconds and a maximum vibration magnitude of 5mm/s at the nearest privately-owned house.
This is less than the blast vibration conditions for Favona and Trio mines that provide for eight blast windows, with the maximum vibration limited to 6mm/s for the four daytime windows, and 1mm/s for the four night time windows. No blasting is provided for on Sunday and public holidays.
The December hearing was adjourned to February to hear more technical information on blasting vibration effects.
More information about the proposal and the consent application submissions are available here: