The hum of Monica’s 12-metre high cutterhead as it began its rotations signified Snowy Hydro’s newest and most technologically advanced tunnel boring machine (TBM) is officially ready for action.

A ceremony to launch TBM Monica was held last Friday at the project’s Marica worksite attended by Monica’s namesake, Year 9 Tumut High School student, Monica Brimmer, Climate Change and Energy Minister, Chris Bowen, Snowy Hydro chief executive, Dennis Barnes, Snowy chief operating officer, Maia Schweizer, Snowy chief delivery officer, Dave Evans, Snowy Valleys and Snowy Monaro mayors, Crs Julia Ham and Chris Hanna.

Monica, the winner of the First Nations art and storytelling competition organised by Snowy Hydro in partnership with the Stars Foundation, along with TBM ‘Monica’, took centre stage at the commissioning of Snowy Hydro’s fourth TBM.

“It was a bit overwhelming, but I was happy to see my artwork on the machine,” Monica said.

"Having my name on it was impressive too.”

TBM Monica is among the world’s most advanced tunnel boring machines. It has been purpose-built to tackle the Snowy Mountains’ unique and highly variable geological conditions.

Along with the commissioning of the newest TBM, the ceremony was also an opportunity to announce Snowy 2.0 has reached a major milestone with the renewable energy mega-project now more than 70 per cent complete.

TBM Monica will begin tunnelling in the coming weeks and will excavate the portion of the 17-kilometre headrace tunnel that passes through the geologically challenging Long Plain fault zone.

“We’re making strong progress on Snowy 2.0,” CEO, Dennis Barnes, said.

“Like the original Snowy Scheme, Snowy 2.0 delivery is one of the most complex feats of engineering currently underway in the world.

“More than half of the energy storage Australia needs by 2050 will come from Snowy 2.0 alone, Mr Barnes said.

He thanked the project’s dedicated and skilled workers and the communities across the Snowy Mountains for being such an important part of the Snowy 2.0 project and being “part of our legacy”.

Minister Chris Bowen added the launch of Snowy 2.0’s Monica was a significant milestone.

“Today is a big day, a big day for Monica, big day for Australia and big day for Snowy Hydro...I’m also here to mark this project being 70 per cent complete,” he said.

“Today we take another step forward with the commissioning of this machine, which is in my view, far from boring.

“This is a very exciting machine, having walked one end of it to the other and seen all the technology, this is really cutting-edge stuff.”

Mr Bowen thanked the workers of the project for making the “dream a reality”.

“80 years ago, our grandparents and great grandparents had a vision, an idea, a dream that many thought was crazy - to carve into these mountains and create energy,” Mr Bowen said.

Also attending the unveiling were Member for Monaro, Steve Whan, Snowy Hydro board member, David Fredericks, Snowy Hydro First Nations Engagement Adviser and Yuin Elder Uncle Bunja Smith, Wolgalu Country Elder, Aunty Alice and daughter, Olivia Williams, and Snowy Hydro staff and site workers.

Almost one kilometre underground at the project’s Lobs Hole worksite, the focus is shifting from tunnelling and excavation to preparing the intricate fit-out of a complex underground power plant the size of Sydney Opera House.

To prepare for this, 46 permanent concrete pours have already been completed.

More than 733,000m3 of underground excavation - equivalent to 293 Olympic-sized swimming pools of material - has taken place in the huge subterranean caverns that were created using drill-and-blast techniques, some of which were pioneered on the original Snowy Scheme.