Major contractor, Andy Divall, in the box cut at the mine, where they will soon begin tunnelling.

Major contractor, Andy Divall, in the box cut at the mine, where they will soon begin tunnelling. Photo: Rohan Thomson

A small fortune is being spent at Majors Creek east of Canberra trying to find the primary source of gold that has sparked exploration since the 1850s.

Unity Mining's longer-term aspirations of Dargues Gold Mine near the village extends beyond the mine's current five-year time frame and is evident in preparatory work including access roads leading to the new underground mine.

Unity Mining general manager, markets and strategy, Ben Hill, said exploratory drilling would continue across a large area known as the Braidwood granidorite.

General manager of the mine, Scott Jones, in the box cut at the mine.

General manager of the mine, Scott Jones, in the box cut at the mine. Photo: Rohan Thomson

A 35-metre deep excavation has been carved through a slope of oxidised granite, creating what will be the box cut entrance of the underground mine.

Tunnelling is expected to begin in about six weeks. Shaped like a tight corkscrew, the tunnel will descend at a grade of one-in-seven metres to an initial depth of 500 metres.

At that grade, they will tunnel for 3½ kilometres to get down 500 metres.

''The drilling Cortona (former mine owner) had done to build the resource only went down to what's outlined here,'' Mr Hill said, pointing to a three-dimensional diagram of the mine's vertical descent.

''There's almost no drilling behind these zones, so they are key targets in our mid-term exploration plans, to add further resources to what is already here and where we already plan to build the mine.''

General manager Scott Jones said blocks of ore would be drilled and blasted, with sections then being taken out and trucked to the surface.

Those sections would be backfilled later with a paste fill, comprising waste rock and concrete, to stabilise the mine.

They expect to extract 5.5 grams of gold per tonne of rock and earth. In the initial five years the mine is expected to produce 50,000 gold ounces.

''There are other lodes which we know the old timers have mined. They have mined underground, they were closer to Majors Creek.''

Unity has paid Palerang Shire Council $600,000 for upgrading the Braidwood-Majors Creek road and awarded a $6.6 million tender to Goulburn earth-moving contractors Divalls to build a 3.5 kilometre access road, bitumen sealed on the steep pinches, and other works.

Divalls, which also builds roads for wind farms, will put down a hard surface for workshops, offices, a run-of-mine pad, ore stock pile, crusher plant and milling and tailings dam.

Principal Andy Divall said his work force had expanded to 23 people, including eight from Braidwood.

''This is our biggest contract so far. It gives us security for the next 12 months,'' Mr Divall said. Divalls will also haul ore off site for final processing.

Mr Hill said Unity Mining, which also operates in Tasmania, liked to be close to a residential community, rather than run a fibro, fly-in-fly-out project.

''Our people can live in the community, play in the footy team. It is attractive for recruiting.''

Among applicants for the 120 jobs on offer are many from Western Australia, from miners who had earlier left eastern Australia.

Staff will include metallurgists, geologists, field workers, environmental monitors and labourers.

Unity is deepening a sediment pond on the site which received 279 millimetres of rain over four days in June. It is addressing concerns from the Environmental Protection Authority on a flocculant used to settle dirty water after the rain.