A smothering effect caused by the lack to oxygen to their roots is the reason why some trees which have tailings covering the forest floor from the Mt. Polley breach have been appearing to be stressed this spring.
UBC Professor of Forest Ecology, Dr. Suzanne Simard as well as associates with Golder, recently completed a study on forest conditions and die back in areas of thicker tailings deposit.
Imperial Metals Vice President of Corporate Affairs, Steve Robertson spoke with us about the study and says Simard was able to determine that copper toxicity had no role.
“She (Simard) was able to conclude that is not the case, that the effects on the trees simply are this physical smothering effect. It wasn’t of evident for the first little while because after the incident in August (2014) the materials deposited in the fall and the trees still looked good going into winter and became relatively dormant…it was this spring that there was a sudden change,” he said.
“In this case, we’ve had a bunch of materials deposited on top that is blocking the access of oxygen to the roots so the effect is that the trees are being physically smothered. As a matter of fact, the cover has actually restricted the oxygen levels that it creates a reducing environment.”
Robertson says Imperial will be further discussing the study’s results with experts to come up with steps to move forward now that they have concluded what the cause of concern is.
He says they have started to fall trees that have been killed in areas where the tailings deposit have been the deepest.
An application of no more than two years, meanwhile in which treated mine effluent would be discharged into Quesnel Lake continues to be reviewed by government officials including the Ministry of Environment.
Robertson says they will be submitting an application for a full-time restart of the mine in early November.