Spring meltwater has been causing trouble at the Faro Mine Remediation Project.
After last week’s warm weather, water levels in a reservoir known as Moose Pond nearly rose to capacity.
To prevent the pond from overflowing, cleanup crews breached a ditch that ran to the pond, sending the water over the hillside, down through the forest and into Vangorda Creek.
The breach was made on the night of May 17 and kept open for two days.
The runoff had a high level of sediment but was otherwise safe and sanctioned by a water inspector, according to Deborah Pitt, the senior project manager of the Faro project execution team.
But two days later water monitors found rising levels of zinc in the water.
“As soon as we saw zinc levels increasing we shut off the tap,” said Pitt.
The problem arose in the Vangorda/Grum area of the mine, where a large amount of remediation work was done last summer.
To prevent lead and zinc leaching from toxic waste rock, the rock was resloped, covered in a heavy-duty plastic liner and covered in topsoil.
The covered pile of waste rock was called the Grum Sulphide Cell, and Pelly Construction was paid $11.5 million dollars to construct it.
The cell was arranged in a series of terraces, with drainage to allow water to flow off, causing erosion.
But the drainage worked a little too well, filling Moose Pond far more quickly than anticipated.
“It could’ve been an issue,” said Pitt.
“If it continued in that way, it would have overtopped the pond, and you don’t want to have the water spilling out uncontrolled like that.”
Instead, the water spilled out from the breached ditch.
It’s unclear why zinc levels began to rise last Thursday, said Pitt.
“It’s a mine site, so there are sources of metals in a number of areas and we’re trying to pinpoint where this might have come from.”
On Saturday, a new pond was dug on the site as a temporary solution to the high amounts of water.
The new pond is not currently in use and, because most of the snow in the area has already melted, has only been built in case of a heavy rainfall.
It’s still not clear whether this temporary measure will be made permanent to deal with spring run-off next year.
Despite the two-day breach, there’s still too much water in Moose Pond.
Yesterday afternoon, clean water from the top of the pond was being released into a forested area below, eventually making its way to Vangorda Creek.
This method of managing the water levels in the pond was also approved by the water inspector, said Pitt.
Zinc is not harmful to people but, at certain levels, it can be harmful to fish.
“The section of Vangorda Creek where the water was draining is not fish bearing,” said Pitt.
“Several kilometres downstream of there is a natural waterfall that prevents fish passage to this section of the creek.”
Contact Chris Oke at