Heavy rains and flooding have prompted environmental authorities to assess a series of evaporation ponds outside Bendigo built to store groundwater pumped from the city’s gold mines – water which is laced with arsenic, hydrogen sulphide and heavy metals.
Earth Resources Regulation and Environment Protection Authority inspectors visited the Woodvale evaporation ponds this week following concerns from community members that water was flowing from the ponds into Myers Creek.
Both state regulators moved to reassure residents, saying the ponds were not overflowing into waterways, while a spokesperson for the mining company partially responsible for the site’s rehabilitation said it could withstand a one-in-a-100-year flood.
“Our inspector found no evidence of water being discharged outside the ponds,” an ERR spokesperson said.
“Additionally, the inspector observed all ponds have available storage capacity to allow for further rain.”
In August, the state government directed the company responsible for the rehabilitation of evaporation ponds at Woodvale to submit a closure plan for the site by the end of the year.
GBM Gold – which acquired the Bendigo Goldfield in May – said its staff visit to the Woodvale site three times weekly – and more often during periods of site activity and/or extreme weather.
The spokesperson said the Woodvale ponds had sufficient holding capacity to accommodate further sustained rainfall.
“The ponds were designed and built to withstand the effects of “one-in- one- hundred-year” flood events,” the spokesperson said.
“The ponds easily accommodated the influence of the 2011 rain event at a time when they were receiving groundwater from the underground mining operation based at Kangaroo Flat.”
Rising groundwater is no longer pumped into the evaporation ponds – currently it is being pumped into the disused New Chum mine.
Related: State orders pond closure
Coliban Water is working on a ‘transitional solution’ to the problem of rising groundwater – which would otherwise spill into Bendigo’s waterways – under a funding agreement with Department of Environment, Land, Water and Planning.
A DELWP spokesperson said works, approvals and the tender processes was “well underway”.
“The ‘permanent solution’ is also being developed and will be informed by the ‘transitional solution’ once it is in place early next year,” the spokesperson said.
The GBM Gold spokesperson said rising water levels in the ponds was due to rainfall on their immediate catchment area and said they did not accumulate run-off water from the surrounding areas.
“Storm water run-off is diverted around the site by means of a system of diversion drains,” the spokesperson said.
“This system was inspected during the recent rain event and found to be operating efficiently.”
The ERR spokesperson said GBM Gold was required to have controls in place to prevent the release of water from the Woodvale ponds.
“ERR regularly monitors these compliance and licensing requirements to ensure local communities and the environment are not adversely impacted by mining operations,”
“As a condition of the recent licence transfer for the site in July 2016, GBM is required to develop and submit a closure plan for the Woodvale evaporation ponds.
“This is currently being developed and must be provided to ERR by 16 December 2016.
“As part of this closure plan Ponds 6 and 7 – 80 hectares or two-thirds of the ponds – must be rehabilitated by 9 May 2018.
“Earth Resources Regulation will continue to monitor the situation and keep the local community informed through open dialogue with local representatives.”
The EPA said it urged members of the public to continue reporting suspected pollution to the EPA on 1300 372 842 (1300 EPA VIC) or at www.epa.vic.gov.au