Bibra, part of the Karlawinda project near Newman, will be developed as a large, low-grade pit.
"This is potentially one of the last solid WA open pit gold mining projects," Hellewell told the Resources Rising Stars conference on the Gold Coast yesterday.
"These things pretty much don't exist anymore."
Capricorn yesterday announced a 25% increase in ore reserves to 28 million tonnes at 1 gram per tonne gold for 892,000 ounces of gold, and a jump in resources to 45Mt at 1gpt gold for 1.4 million ounces of gold.
As a result, gold production at Bibra is forecast to increase from 660,000oz over 6.5 years to 820,000oz over eight years, including an increase of 16,000oz in the first two years of production.
Hellewell pointed out that the eight-year life put Bibra on par with many of its WA peers.
The final pit design allows for a four-stage open pit, up from three-stage, with a life-of-mine strip ratio of 4.8:1.
"By pushing some of the material movement back, we see very low-cost ounces for the first few years," Hellewell said.
Bibra is expected to produce 100,000ozpa at all-in sustaining costs of $1025 per ounce.
Hellewell said since the definitive feasibility study for Bibra was released in October, Capricorn had been focused on permitting and optimising the project.
Capital costs have already been reduced to $131 million from $146.3 million via a fixed-price plant contract with GR Engineering.
Based on the October feasibility study, and without the capex reduction or mine life extension, the project had a net present value of $144 million, an internal rate of return of 31% and a three-year payback period.
"We're clearly improving on the NPV of this project," Hellewell said.
"We've got some serious uplift in front of us."
Capricorn has already been in funding talks, with the upgraded reserve to underpin the final debt package.
Hellewell anticipates debt funding of around $100 million, with the rest in equity.
"We think we'll get our debt paid off in under three years," he said.
Based on a 56-week build, Capricorn is aiming for first gold in the September quarter of next year.
Shares in Capricorn closed at 7c yesterday, valuing the company at a little over $52 million.