The remediation and revegetation of the abandoned Bralorne Takla Mine in northern B.C. by British Columbia and the Takla Nation (TN) shows how government and a First Nation can work together to develop and implement a successful clean-up of complex environmental contamination.
The five-hectare Bralorne Takla site is a former mercury mine that operated for nine months during the Second World War.
It is located within the traditional territory of the TN, formerly the Takla Lake First Nation, approximately 180 km north of Fort St. James.
Mercury ore was mined underground and then crushed and roasted onsite. The heat of the roaster vaporized the mercury, which was collected and cooled in condensing tubes until it formed liquid mercury. The mercury was collected in steel flasks and then used in the war effort.
After the war, the mine wastes, processing equipment and other materials were abandoned and remained unremediated until B.C.’s Crown Contaminated Sites Program (CCSP), which identifies contaminated properties that need to be remediated, began investigating the site in 2005.
Methyl mercury was detected in ground water and surface water samples at concentrations approaching or exceeding dangerous levels for aquatic life. And liquid mercury was found on some of the mill equipment and in soil on the site.
The Crown Contaminated Sites Program temporarily ceased its investigations in 2009 in order to develop a solid working relationship with TN.
Trevor McConkey, Takla Nation’s environmental operations manager, said the province hired engineering, procurement and construction company SNC-Lavalin to develop an engagement strategy with TN.
“Takla Nation became a partner with SNC-Lavalin on behalf of the province,” he said.
Since 2012, every field visit has included at least one TN member.
After extensive investigations to characterize the type, location, and extent of contaminated material on site, a remedial planning process was developed with TN.
The remediation plan that was implemented was chosen jointly by the First Nation and the province.
“The conceptual design for the project was done in 2013-14,” said McConkey. “SNC-Lavalin acted as owner’s rep and assisted the province with procurement and the hiring of Envirocon and CH2M Hill to perform the detailed engineering and construction.”
The remediation work, which took place between 2015 and 2016, was extensive and ambitious and combined physical remediation and risk management.
It included the following:
- Capping mine openings with concrete covers and planting with native species;
- Abatement and demolition of structures containing mercury and asbestos;
- Off-site disposal of hazardous waste at prescribed sites in Alberta and northeastern B.C.;
- Consolidation of non-hazardous waste (soil, mine waste, demolition debris) into two landfills constructed on-site;
- Re-contouring the site to manage surface water and shallow groundwater; Re-vegetation of the site and landfill covers; and
- Putting in place land use risk controls to protect future site users.
Today, the site undergoes ongoing monitoring, such as regular inspections of the cover, checking vegetation growth and sampling surface and groundwater.
Revegetation of the site with native species – including two native seed mixtures, Arctic lupine, black gooseberry, thimbleberry, willow, lodgepole pine, hybrid white spruce, and subalpine fir – was completed in spring 2017.
“The objective of the project was to make the former mine site disappear,” said McConkey. “We wanted to construct something that fit in with the existing natural environment.”
The landfill design included a biotic barrier composed of coarse rock that was free-draining and that acted as a barrier for burrowing animals, with a protected polyethylene liner underneath.
“Over the barrier we placed a thick layer of soil to protect the liner and for trees to grow on,” said McConkey. “We wanted to create an environment for trees to grow without harming the integrity of the liner system.”
TN was a key partner during the implementation of the remediation site work.
“Through Sasuchan Development Corporation, the economic development arm of Takla Nation, it provided equipment and the local work force,” said McConkey.
Established in 2003, the CCSP manages the remediation of contaminated sites on Crown land for which there is no existing responsible party. In most cases, these are long-abandoned mine sites.
“To date, 87 contaminated sites are either under investigation, or, like Bralorne Takla, have been remediated,” said Joanna Runnells, acting senior contaminated sites expert in B.C.’s Ministry of Forests, Lands, Natural Resource Operations and Rural Development.
Most of the clean-up sites are in remote parts of the province.
In addition to the Bralorne Takla mine, other mine remediation projects under CCSP auspices include the Atlin Ruffner mill and tailings site and the ongoing investigation and remediation work towards closing the Britannia mine.