"I am frightened for the life and safety of those I love. I am frightened for myself, too," says Ms French, who is fighting gold miner Unity Mining's attempt to use cyanide to process ore upstream at Majors Creek.

A bulldozer arrived at Mrs Clubb's stone fruit orchard on Monday to push over 25,000 trees because she cannot risk a spillage upstream, where the mine's sediment dams failed in heavy rain in 2013.

Ms French says if NSW Planning and Environment allows Unity to modify its activities, they will use cyanide to separate gold from ore. "Instead of the heavy metals lead, zinc, cadmium, uranium and other potentially deadly heavy metals being trucked [off site], these heavy metals will sit in a tailings dam on the steep site at the top of the Majors Creek/Deua/Moruya catchment, above Eurobodalla's water supply, farms, businesses and households.

"If – or when – there is an overflow, this tailings dam is only 10 minutes away from us as the water rushes down the slope below the mine site and over the escarpment. One major cyanide spill could be deadly to us, our near neighbours and the endangered wildlife of the valley."

Unity Mining chief executive Andrew McIlwain said that, under the proposal, cyanide would be in dedicated tanks, deep within concrete walls.

Sludge from cyanide processing would be pumped to the tailings dam, which exceeded government guidelines, and surface water would be channelled around it, not captured by it.

"In a highly unlikely event such as a one in 1000 year downpour, water will overflow via a spillway and not compromise the tailings storage facility," Mr McIlwain said.

"Given low initial concentrations and influx of high water volume, outflow in Spring Creek would have a cyanide concentration of 0.0007 milligrams per litre. Drinking water standards in Australia can have a concentration of 0.08 mg/L – over 100 times above this level," he said.

Mrs Clubb said for a host of reasons she put her orchard on the market last September. She could not afford spraying and pruning over winter given the proximity of the mine. "I'm not prepared to take the risk; there is no 100 per cent guarantee a spill won't happen.

"It is hard enough without the threat of mining. We have had not one offer [to buy the orchard] and now we are subdividing, and 25,000 trees will have to be pushed out."

Mrs Clubb said Unity would need to raise $70 million to begin the mine, had to pay redundancies at its Tasmania operation and was being asked to rehabilitate sites at Bendigo. "So there is no chance of them being able to clean up any spill," Mrs Clubb said.

She said that planning approval relied on technical data which was flawed because no one, aside from the Environmental Protection Authority, looked behind the application at the proponent's business.

"What happens if the company goes bankrupt and walks away?" Mrs Clubb said.

Mr McIlwain said Unity had $60 million insurance to cover an unlikely spillage, and the project approval required a $3.1 million bond dedicated to remediate the site, which would be reviewed if the mine's proposed modification was approved.

A Unity spokesman said a tirade on Facebook, which included accusing Mrs Clubb and Ms French of being environmental vandals, was from a former Unity employee, and was not instigated by the miner.

Mrs Clubb said the abuse had included a false claim she was pumping water from the creek. "I just find it destructive and upsetting," she said.