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Yukon issues directive to preempt tailings storage overfill North of 60 Mining News – April 21, 2023
More than 1.4 million cubic meters of water was discharged in a safe and compliant manner in 2022, more than double what was discharged over the seven previous years combined.
Yukon Minister of Energy, Mines and Resources John Streicker April 18 announced that Minto Metals Corp. has been issued an inspector's direction to take action to prevent overfilling of the tailings storage facilities at its Minto copper mine during the spring snowmelt.
Located within the traditional territory of the Selkirk First Nation in the Minto Copper Belt of the Yukon, the Minto Mine has been in operation since 2007, with underground mining commencing in 2014. Over the 15 years thereafter, approximately 500 million pounds of copper have come from this Yukon operation.
Hoping to preemptively curb a potential overfilling of the tailings storage facilities at Minto, the Yukon government has directed Minto Metals to begin transferring water into one of the previously mined open pits if the available storage capacity in the tailings management facility drops below 300,000 cubic meters, which is about 79.25 million gallons.
"At that time, they must also temporarily cease the depositing of tailings during the spring snow melt to allow water storage levels to recover," Streicker wrote. "While transferring water to this pit is not part of the current water license, the risk is low as it was previously mined, and offers the best choice to protect the integrity of water and tailings storage facilities in advance of the spring snow melt."
The Yukon Energy, Mines and Resources minister said the directive aims to both mitigate potential short-term environmental risks and ensure longer-term operations at Minto.
"Our government supports responsible mining, and this decision was not taken lightly by the inspector. However, we must act in the face of growing evidence that additional precipitation and spring melt waters could put the environmental integrity of the mine site and downstream area at risk unless we direct action to take place now," he said.
Minto Metals, which has been working openly with the Yukon government and Selkirk First Nation in a trilateral forum since 2021, agrees that the inspector's directive is prudent and has already shown its willingness to curb operations to prevent any environmental mishaps.
"Minto is committed to strong environmental stewardship which we demonstrated last year by temporarily shutting our milling operation down for a total of six weeks to handle the excess water we received during spring freshet," said Minto Metals President and CEO Chris Stewart.
The company, however, believes that the operations increased water treatment capacity will ensure that the tailings storage capacity threshold is not reached.
In 2022, Minto Metals invested C$8 million (US$5.9 million) in a water treatment plant at the Yukon copper mine. This year, the company is allocating another C$12 million (US$8.9 million) for upgrading and operating the plant. In addition, Minto Metals is in the process of commissioning a second water treatment facility to double the output capacity as the spring thaw approaches.
Following a snowpack that was 417% above normal, more than 1.4 million cubic meters (370 million gallons) of water was discharged in a safe and compliant manner in 2022, which is more than double what was discharged over the seven previous years combined.
"With our investment into the water treatment plant over the past twelve months, we are in a much better position to treat and discharge larger volumes of water coming into spring freshet this year," said Stewart. "Although water treatment is very capital intensive, we are prepared to allocate the necessary resources to ensure any water events do not put the Company out of compliance with this order."
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