WC134 JanFeb 2024 - Magazine - Page 24
FEATURE
lake landscape and that mine engineers failed to account for silt
underneath the tailings containment pond, resulting in structural
insufficiencies. In 2018, Imperial Metals settled a lawsuit against
two engineering firms for $108 million. As well, three engineers
who worked on the facility were found in breach of their professional association’s codes of conduct, and sanctioned.
MPMC has claimed project success, citing renewed spawning
of rainbow trout in Hazeltine Creek and the declaration by the
region’s medical health officer that fish from Polley and Quesnel
lakes are safe to consume. However, with one of Canada’s worst
non-lethal mining disasters now a decade into the past, there’s
disagreement over ongoing and longer-term impacts. In research
reported in 2022, University of Northern British Columbia
geography professor Ellen Petticrew and environmental science
professor Phil Owens found that, when Quesnel Lake water columns turn over seasonally, copper-rich sediment is re-suspended
in the water column and reintroduced into local waterways, with
metal concentrations identified in phytoplankton and zooplankton, which fish consume. UNBC researchers have also reported
significantly elevated levels of dissolved metals and nutrients such
as phosphorus.
wsp.com
24
WATER C AN ADA • JANUARY/ FEBRUARY 2024
Community concerns
Doug Watt lives along the Quesnel Lake shoreline in the
community of Likely, seven kilometres from the mine’s effluent
release pipes, and he says the lake water meets Canadian drinking
water standards but he doesn’t trust its potability. “I’ve been here
26 years and I know people who have been here 50 to 60 years,
and we’ve noticed the deterioration of the quality of the water.
The rocks along the shore are slimy, we have algae blooms which
never occurred before, and the water is cloudy whereas it used to
be an ultra-pure oligotrophic lake.”
Area residents have persistently challenged the mine’s environmental record through an ad-hoc organization, Concerned Citizens of Quesnel Lake. Watt, a member, singles out the treatment
system’s emphasis on solids and its reliance on a 100-metre-radius initial dilution zone (IDZ) in Quesnel Lake as particularly
troubling. “They don’t have to meet B.C. water quality guidelines
until outside that IDZ, so they dump the water into Quesnel
Lake, which dilutes it, and then they sample outside that radius.”
MPMC and Imperial Metals acknowledged but didn’t follow
up on Water Canada’s request for comment. However, the company was planning a public meeting on company premises in
December to provide details on current permitting activities and
application submissions on various aspects of the mine. “This
meeting is intended to convey information on mine site status
with a tour of the concentrator building focusing on concentrator processes such as grinding and floating, material sciences and
engineering that support metallurgical practice at Mount Polley
Mine,” one circular read.
Any unforeseen changes in direction notwithstanding, time
may ultimately determine whether or not the remediation
work is sufficient in scope and depth, and how the lake’s health
parameters pan out. Watt says as long as mines continue to rely
on wet tailings ponds like the one at Mount Polley, and as long
as dilution-based approaches are permitted, he lacks confidence
in the regulatory regime. While Mount Polley continues to rely
on its storage pond, wet-based tailings storage may be on its way
out in mining circles, generally. Bas Vriens points to gradual industry movement to dewatered and dry stacking methods, where
tailings contain considerably less water than those housed in
conventional ponds, and are therefore less prone to widespread
release. “It doesn’t stop the reactions but it does stop the water
from flowing out of those waste storage facilities,” he adds.
The tailings spill at Mount Polley might not, on its own, be
responsible for movement away from wet storage, however Vriens
says the incident does show what can happen when protective
systems fail. And, in the longer term, it illustrates the complicated ‘friend and foe’ role water plays throughout a mine’s entire
lifecycle. “The images of the Mount Polley tailings spill going
across the country really reverberated in the industry as well,”
Vriens says. “Mount Polley did a lot for making the company
and the industry well aware that they don’t just need a government license to operate, but also a social license.”
WAT E R C A N A D A . N E T
