Mandalay Resources wants to expand its operations and says it has does not have the permission to deal with with all of the water-mixes it expects over the mine's remaining six years of life.

"There could be an increase in the quantity of mine water requiring disposal," miners have written in a submission to the City of Greater Bendigo's planning department.

"During the process of underground mining, it is necessary to pump out groundwater that enters the mine workings from the surrounding water table to ensure safe access to ... workings."

Mandalay would like permission to pump water laden with a brine into its evaporation pond. The water is a byproduct coming out of a reverse osmosis facility.

The water would then evaporate over summer as required.

It comes after Mandalay submitted a separate planning application in August to sink a new shaft in Costerfield.

More: Miners seek green light to keep striking gold after 2020

It wants to start digging into an underground ore body discovered in 2017, operations manager Adam Place said in August.

"It's a continuation of a structure that the old-timers mined from the late 1800s," he said.

"The Costerfield mine was really quite big at that stage. I think it was nearly 1000 feet (304 metres) deep, which would be reasonably-sized by today's standards."

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