Hawkeswood Mining’s Low-impact Gold Project In Central Otago

A new Central Otago alluvial gold mine is set to be a low-emissions operation, thanks to a large floating dredge and dump trucks, project proponent Hawkeswood Mining says.

The company received yesterday minerals mining permit 60908 for its project from New Zealand Petroleum & Minerals, covering 70 hectares between Miller’s Flat and Ettrick.

It acquired the dredge from Waikaia Gold, which at 270 tonnes, and 40 metres by 14 metres, took 35 truck-and-trailer loads to move from Waikaia to Miller’s Flat.

“Using the floating plant as opposed to land-based plant saves on 80,000 truck movements, reducing the CO2 footprint of gold production,” company managing director Andrew Hawkeswood says.

“It’s the most modern alluvial gold dredge in New Zealand, and we are very happy to have it.”

Reliance Engineering and Equip Engineering worked together to build the plant in Nelson, with design input from Waikaia Gold’s Warren Batt and Noel Becker, and Sam and Buzz March of March Construction.

Also helping to reduce CO2 emissions are Hawkeswood Mining’s plans to use 105-tonne dump trucks to move overburden, instead of conventional 60-tonne trucks.

The company is set to be the first in New Zealand to import 2023 model Volvo R100E trucks, which are lower noise, lower emissions, and have corresponding, relatively high fuel efficiency.

Hawkeswood Mining is currently applying for resource consents for its Miller’s Flat project from Central Otago District Council, and Otago Regional Council. If successful, it would provide 20 jobs.

The project will entail moving 8.4 million cubic metres of overburden and processing 175,000m3 of gold-bearing wash from a layer having a base 8-15 metres below ground surface.

“The larger trucks will mean 64 cubic metres per load, instead of 36m3, meaning 100,000 fewer truck movements over the life-of-mine, further reducing emissions,” Hawkeswood says.

The operational improvement will reduce the life-of-mine from an original estimate of 14 years to five years.

“We also intend to limit overburden removal covering the gold-bearing gravels to only four days a week. This reduces impacts on the local community, while offering a good lifestyle for our miners.”

The proposed mining area occupies a terrace adjoining the Clutha River in farmland, and alongside the Clutha cycle trail, in a part of Otago with an extensive history of gold mining.

“We have received a fair bit of interest in the project, so we’re proposing to build a viewing platform for passing cyclists so they can see our operation in action,” Hawkeswood says.

Elsewhere, bunds to a maximum height of 4 metres along the site boundaries and planted will reduce noise, dust and visual impacts.

Hawkeswood is encouraged by exploration work to date over ground formerly held by Waikaia Gold. (This company recovered more than 80,000 oz of gold from Waikaia, Southland, in 2013-2019.)

Over the last three years Hawkeswood Mining has drilled more than 300 bore holes and completed 2000 cubic metres of bulk sampling, under Minerals Exploration Permit 60712.

“We’ve done more than 12 months of hydrology testing with surprising results: virtually zero groundwater inflow from the Clutha; 98 per cent comes from the east,” Hawkeswood says.

“Lowering the water table at the proposed mine site has had very little impact on the water tables of neighbouring properties.”

At any time the working area of the mine will be around 4 ha, as the operation moves from the north of the permit area southwards, and as mined land is progressively rehabilitated into farmland.

Excavators will move overburden into dump trucks for transport and temporary storage pending mine site back filling and rehabilitation, and the gold-bearing wash layer into a floating plant.

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