A proposal from a mining company to fill two disused gold pits at Nagambie with waste from Melbourne has raised a few questions for farmers about the possible impacts on the environment.
Nagambie Resources has plans to use the two mine sites to safely store large amounts of waste — about 6million tonnes, possibly 100000 to 200000 tonnes per year — created by the Melbourne Metro Rail Tunnel and other developments.
The Nagambie site's east pit is 915 m long and up to 154 m wide, with the water up to 50 m deep. The west pit is 560 m long and up to 220 m wide, with the water up to 40 m deep.
A proposal from a mining company to fill two disused gold pits at Nagambie with waste from Melbourne has raised a few questions for farmers about the possible impacts on the environment.
Nagambie Resources has plans to use the two mine sites to safely store large amounts of waste — about 6million tonnes, possibly 100000 to 200000 tonnes per year — created by the Melbourne Metro Rail Tunnel and other developments.
The waste is known as PASS — potential acid sulfate soil — and is harmless when stored underground. However, it risks becoming sulphuric acid when exposed to air.
While Nagambie Resources said placing PASS under water, maintaining its anaerobic state, was the best environmental solution, some farmers are not convinced.
Nagambie cropping farmer Peter Robinson was seeking more information about the plan but said he did not like the sound of it.
‘‘It doesn’t sound good to be putting this waste into a disused gold mine — there is possible contamination of the watertable,’’ Mr Robinson said.
Wahring farmer Lindsay Essex echoed this sentiment and said if the waste seeped into the groundwater, it could create issues for bore water users downstream.
‘‘If someone has a bore, they’ve got water that has been in the mine coming into it at some stage, so if there’s contaminated water in there, someone downstream with the bore will get contaminated water,’’ Mr Essex said.
However, Nagambie Resources chairman Mike Trumbull reiterated that PASS was clean fill, not toxic.
PASS is only a problem if you expose it to air. (This way) it will be put under water and it won’t oxidise once under water,’’ Mr Trumbull said.
The plan has Environment Protection Authority approval and Mr Trumbull said the company would adhere to strict guidelines including weekly testing of the pH levels in the water and ensuring pH levels in PASS material were appropriate with no signs of acidification before being added to the pit.
Mr Trumbull said the EPA was excited that Nagambie had two large water-filled tips that were naturally alkaline.
‘‘I think it’s the first time anyone in Victoria has ever rehabilitated old mining pits into farming land.’’
Mr Robinson was also apprehensive about the traffic that would be created and the subsequent danger to the local road system.
For the two years the EPA has approved the plan, Nagambie Resources has estimated about 12 to 24 trucks per day travelling to the 258ha Zanelli Rd site.
Once the pits have been filled, the plan is to cover them with clay and return the former mine to its original use as farming land.
Aside from his environmental concerns, Mr Essex questioned the mining company’s motives saying the plan might have been a commercial move to try to make money through the Australian Stock Exchange.
‘‘I just see this as they’re trying to make money from disallowed ... they’re a mining company but they don’t do any mining.’’
Mr Essex said it was odd for a company to be tipping rubbish on top of a gold site and also wondered why the company could not find an appropriate site closer to Melbourne as it would save transport costs.
Strathbogie Shire’s deputy chief executive officer and sustainable development director Phil Howard said Nagambie Resources had not lodged an application so council’s decision on the proposal was pending.
Mr Howard said this was first the council had heard of using old mining pits in Nagambie to store PASS.
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