In
October 2012 Vista Gold implemented an innovative plan to change the pH of more
than ten gigalitres of contaminated water stored in the mine site’s open cut
pit.
More than
six months later, Vista Gold General Manager,Brent Murdoch said that the
program has delivered results at the top end of their expectations.
“Without
a doubt we have proven that the water treatment program is a viable solution,”
he said.
“The
results speak for themselves. The pH level of water in Batman Pit has changed
from an acidic 3.3 to a neutral 7.9 and 99.8% of all the metals contained in
the top 15 metres of water have been taken out.”
Vista
Gold’s water treatment program entailed 10,000 tonnes of finely ground
limestone and 2,000 tonnes of quicklime added to the water in Batman Pit
causing a chemical reaction which increased the pH level and caused the metals
to precipitate to the bottom of the pit.
After the
water is released the metals will be pumped into the existing Tailings Dam and
encapsulated there.
“This
process was based on extensive independent scientific research and testing
which now sets a benchmark for environmental mine management beyond Mt Todd," Mr Murdoch said.
“While
Vista Gold will continue to pursue other water treatment programs, we now have
a proven method for managing the volume of water on site until Mt Todd goes
into production.”
The Mt
Todd mine site still holds a total volume of more than 16 gigalitres of water
which will need to be treated and removed from site before the mine goes into
production.
Water
collection and storage is the biggest environmental issue facing the Mt Todd
site. Since the mine ceased operations in 2000 mine affected water has been
collected in the Tailing Storage facility (RP7) and the Waste Rock Dump Dam
(RP1). This water is then been pumped and stored in the Batman Pit (RP3) as
required.
Regardless of the whether the mine goes ahead, this water requires treatment and release from site as historically the Mt Todd mine site receives a net positive of 1.5 gigalitres of water each year.
Vista
Gold is also currently looking at evaporation techniques such as land apping
for reducing the volume of water.
The release
of water from site is governed under licence from the Northern Territory
Government and strict environmental controls.
Vista
Gold is yet to make a final investment decision on reopening the mine. A
positive decision will require a workforce of around 450 people during construction
and 350 for the operation of the site.
Vista Gold aims to recruit workers who live in Katherine or Pine Creek, boosting demand for goods and services from local businesses and will continue to show preference for doing business with local companies.
“In
addition to local employment and services, long term benefits from Mt Todd
reopening include rehabilitation of the site and sound environmental
stewardship,” Mr Murdoch said.
-ends-
Vista Gold General Manager, Brent
Murdoch will be available to meet with media on site at 2pm on Thursday, 9 May
for a site inspection.
Due to
security requirements please register your interest in attending by 5.30pm
Wednesday, 8 May.
Protective
clothing and a brief site induction will be required.
To
register for the site inspection or for further information please contact
Jeannette Button on 8941 9169 or 0407 727 080.
