Macmahon was named as the preferred open pit mining contractor a year ago for the A$210 million work.

The contractor is already onsite at Warrawoona completing a separate package of civil works.

Macmahon will mobilise in early 2022 to ensure there is sufficient ore for when commissioning begins in the June quarter.

Calidus reported the project's mill had been successfully installed, taking project completion to 60%.

Construction of the plant is 63% complete.

"Every element of our exploration, development and production strategy is proceeding to plan," Calidus managing director Dave Reeves said.

"With only two complete quarters remaining to first gold production, works on site continue at pace on all work fronts.

"Concrete works are almost complete and the focus has turned to mechanical and structural installation, the highlight being the installation of the mill shell."

The mine, once operational, is set to produce an average 90,000 ounces of gold per annum - peaking at 105,000oz - over eight years, at all-in sustaining costs of A$1290 an ounce.

Calidus is also completing a definitive feasibility study on the nearby high-grade Blue Spec deposit, which could see production rise to 139,000ozpa.

Calidus shares were unchanged at 56c, valuing the company at $224 million. Macmahon was up 2.2% to 23c, valuing the company at $485 million.