Alkane Resources is seeking state government approval for open-cut and underground mining at the San Antonio and Roswell deposits which are adjacent to and under the highway, south of Tomingley.

They would provide more ore for TGO's existing processing plant and potentially extend its life by a decade.

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Alkane Resources managing director Nic Earner reports that TGO's current workforce of about 170 would rise if the extension got the green light.

The $120 million TGO was launched in January 2014 with open-cut mining replaced by underground mining in 2019.

Mr Earner said at the height of the open-cut mining, "we had around 220 to 240 direct employees and a lot more contractors".

"So when we return to open-cut mining it's that sort of employment levels we should see," he said.

The managing director said most TGO employees came from surrounding communities.

"Almost all of our employees come out of Narromine, Peak Hill, Dubbo and Parkes," he said.

From his office in Perth, Mr Earner confirmed the company would need to realign the highway to begin open-cut mining again.

"The highway diversion quotes are around 20 to 25 million dollars," he said.

Alkane Resources is consulting with Transport for NSW on the design of a new section of the highway to "ensure there'll be no need to close the highway during routine blasting operations".

The realigning of Kyalite Road to make certain it is "outside the 500-metre blast exclusion zone" is also on the company's agenda.

Alkane Resources is promising "extensive community consultation" on its Tomingley Gold Extension Project along with talks with stakeholders such as Narromine Shire Council, major industry and highway user groups.

The San Antonio and Roswell deposits would become a single open-cut mine stretching for about 1.7 kilometres.