The plan was included in an announcement to the stock market, in which the company estimated its proposed Bendigo-Ophir gold project, near Tarras, had risen nearly $600m to $5billion in projected revenue.
But an environmental group told the Otago Daily Times it remained concerned about the size of the mine and the effect it could have on nature.
Australian mining company Santana Minerals released its completed pre-feasibility study for the project to the ASX yesterday.
Chief executive Damian Spring said in the study that its higher level of accuracy had confirmed the ‘‘robustness’’ of the project, as first outlined in its earlier scoping study.
The initial years of gold output had been upscaled in proportion with a deliberate decision to enlarge the mine pre-strip — which involved mining the initial waste rock to expose the first mounds of gold ore — from 32m tonnes to about 40m tonnes, after geotechnical reports recommended changing the slope of the pit walls to yield higher strip ratios.
The high-grade deposit combined with strong gold prices resulted in a ‘‘vastly improved’’ overall present value after tax, Mr Spring said.
‘‘We still believe we can improve the project from here and will be working to that end while advancing permitting.’’
Pre-production capital expenditure for the enlarged pre-strip was estimated at $146m, bringing the total pre-production capital for the project to $375m — an increase of more than $100m from the scoping study’s estimate of $256m.
Mr Spring told the ODT enlarging the pre-strip was a ‘‘staging decision’’ which would allow them to target the high-grade portion of the ore body.
It would now be able to produce an average of 125,000 ounces of gold each year over the mine’s now nine-year lifespan.
The increase in total pre-production capital was largely due to the pre-strip changes, but was also due to an increase in capital expenditure for their processing plant, he said.
The study estimated the project could now generate total revenue of $5b, at the current price of gold — an increase of about $600m than previously estimated in its initial scoping study.
Revenue to the New Zealand government, comprised of royalty and corporate tax payments, had also risen from about $900m to $1.1b.
Sustainable Tarras spokeswoman Suze Keith said once Santana Minerals started mining, they would just keep going.
‘‘The scale of this thing is enormous. It’s highly invasive, highly damaging, highly risky.’’
With about 40% of shareholders from New Zealand, Mr Spring said the project was ‘‘truly shaping up to be a home-grown success story’’.
Its team had been working in line with Resource Management Act consenting, and was pleased the certainty and significance of the project had secured it the opportunity to participate in the fast-track approvals process.
‘‘While we are confident we have met — and will continue to meet — all previously expected standards, the overwhelmingly positive economics of our proposed development add significant weight to our inclusion in this process and highlight the many benefits it brings to both the region and the nation.’’
