Brent Murdoch, Vista Gold General Manager said that the in-situ water treatment program had produced an outstanding improvement on the quality of the water in Batman Pit.
“Vista Gold has invested $9 million into this water treatment program. We have added 10,000 tonnes of finely ground limestone and 2,000 tonnes of quicklime to the water and it is paying off.”
“Just as the scientists said it would, the limestone has caused a chemical reaction in the water, increased the pH level and caused the metals to precipitate to the bottom.”
Since October last year the pH level in Batman Pit has increased from an acidic 3.3 to a pH level of 7.5.
Recent reports have raised concerns about the level of cadmium in the water, which Mr Murdoch says is one of the slowest metals to drop out.
“79% of the cadmium has already gone from the top 15 metres, or pumping zone, and we expect it to continue to reduce as the metal responds to the treatment,” he said.
Vista Gold was recently issued a Waste Discharge Licence by the Northern Territory Government for the release of water from the mine site into the Edith River. It has not however, discharged any water from Batman Pit this wet season.
Batman Pit currently holds 10.3 gigalitres of treated water. Vista Gold will only release the water when the quality of the water and the flow of the Edith River meet specific environmental protection levels.
Under the terms of the Waste Discharge Licence, Vista Gold is required to publish water monitoring results on its website when it discharges water. The company has made a commitment to the community beyond this and is already publishing weekly water treatment results on www.mttodd.com.au.
A table showing all of the metal values in Batman Pit is also now available on the website.
“Vista Gold is committed to ensuring that the water in the Edith River meets the Australia Drinking Water Guidelines for Health,” he said. “This is our commitment to the community.”
For more information on the RP3 Water Treatment Metal Reductions go to: http://mttodd.com.au/environment