Faro Mine

Since 2007, climate change projections have been incorporated into the remediation of the Faro mine in response to threats from flooding, permafrost thawing and erosion. The derelict Faro mine, located some 200 km north east of Whitehorse, was one of the world’s largest zinc mines. It operated from 1970 until 1997, and in 1998 its owner, Curragh Resources declared bankruptcy. The Federal and Territorial Governments were obliged to assume responsibility for the mine, which can best be described as an environmental mess with a large quantity of waste, comprising crushed rock/ore, and tailings made up of lead, zinc, copper in various forms and other minerals such as metal sulphides which are potentially harmful to the environment. Ultimately, water on the site will have to be processed to remove toxins and metals before release into the broader environment. Clean up of detritus at Faro, a formidable task in a stable environment, is especially challenging because remediation will be taking place in the context of current and long term long climate change. In the summer of 2008 the region experienced intense rainfall that caused erosion at the mine-site, in 2012 spring melt-water threatened to overwhelm the site and given the prognosis for increased precipitation and accelerated spring run-off in the central Yukon this problem could potentially worsen. Management of site hydrology and ensuring that mine-site water doesn’t contaminate the larger context watershed is a major concern. Additionally, accelerated permafrost melt could increase slope instability and increase the potential for leeching. The bacteria that contribute to the production of Acid Rock Drainage (ARD) are active at the mine-site, and it is expected that metals released in ARD will continue to increase for hundreds of years. it is anticipated that clean up of the Faro mine-site could take well over a century, and the climate unknowns over that time period are considerable. Climate forecasting and assessment of terrain conditions have long been important components of mine-site remediation planning, but it is now recognised that a more dynamic approach is required. Instead of looking at recent past climate trends, modelling and projections are now employed incorporating climate change scenarios to anticipate future climate and weather trends post-closure.

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Understanding and Assessing Impacts

Historically problems associated with mine closure in the Yukon were due to underfunding of remediation, mine abandonment and the incidence of “orphan” mines. However, over recent years there is accumulating evidence that a changing climate, manifest in permafrost degradation and changes in precipitation patterns, have negatively impacted abandoned mine-sites. In Faro, increased summer precipitation and spring runoff led to increased run-off, creating problems for drainage management. These experiences, combined with experiences from elsewhere in the Yukon, including precipitation changes and suspected permafrost degradation at Minto and the post closure review of the Brewery Creek mine have served to inform decision makers.

Clean up of detritus at Faro, a formidable task in a stable environment, is especially challenging because remediation will be taking place in the context of current and long term long climate change. Acknowledgement that climate change would be an issue affecting the site took some time. It was not clearly and overtly identified as an issue until 2007 when an independent peer assessment of remediation provided an overview of progress to date and the prognosis for the future. Reference to climate change appeared some 23 times in the summary document, and it was concluded that not enough attention had been played to the issue in the remediation process and more needed to be known about it. The long term and uncertain nature of climate change was acknowledged and the panel advocated adaptive management but provided little substantive detail on possible responses. In the summer of 2008 the region experienced intense rainfall that caused erosion at the mine-site, in 2012 spring melt-water threatened to overwhelm the site and given the prognosis for increased precipitation and accelerated spring run-off in the central Yukon this problem could potentially worsen. Management of site hydrology and ensuring that mine-site water doesn’t contaminate the larger context watershed is a major concern. Additionally, accelerated permafrost melt could increase slope instability and increase the potential for leeching. The bacteria that contribute to the production of Acid Rock Drainage (ARD) are active at the mine-site, and it is expected that metals released in ARD will continue to increase for hundreds of years.

Identifying Actions

There is an evolving culture of incorporating climate change prognoses into mine-site remediation planning, with both the Yukon Environmental and Socio-economic Assessment Board (YESAB) and the Water Board addressing the issue by increasingly requiring climate change assessments in proposal submissions. However, while it is recognised that the natural environment is shifting, dealing with the possible consequences of such shifts is problematic. For example, it is anticipated that clean up of the Faro mine-site could take well over a century, and the climate unknowns over that time period are considerable. Climate forecasting and assessment of terrain conditions have long been important components of mine-site remediation planning, but it is now recognised that a more dynamic approach is required.

Instead of looking at recent past climate trends, modelling and projections are now employed incorporating climate change scenarios to anticipate future climate and weather trends post-closure. Building on this, ideally, are expectations about permafrost and groundwater behaviour. Long-term local level historical meteorological data are basic to both conventional climate projections and adjusting downscaled climate modeling; however, a scan of data for Yukon reveals that such data are inconsistent and spatially and temporally “spotty”. Site remediation will be a centuries long process, and while it is some sixteen years since the mine ceased operation there is, as yet, no detailed remediation plan in place. Site activity is best described as “care and maintenance”, with the objective of neutralizing the site to ascertain that detritus and possible contamination are contained while a full remediation plan is being developed. Key components of this are a ground water interception system, monitoring to anticipate acidification by checking for sulphate levels in water, and managing the interaction between climate and the mine landscape so that site conditions don’t deteriorate.

Implementation

The broad components of the long term Faro closure and remediation plan involve stabilizing the site by upgrading dams containing tailings to ensure they can withstand natural events such as earthquakes and floods. All waste rock will be re-sloped to improve long-term stability and covered with soil, and a “state of the art” water treatment plant installed to clean water at the site. All these components require evaluation of future climate events or their impact, including precipitation and run-off forecasts and permafrost evaluation. Climate change projections play an important role in these evaluations.

Outcomes and Monitoring Progress

While formidable challenges are faced in remediating mines abandoned before climate change was recognised as an issue and consequently was not factored into long term planning, experience over the last several years has served to inform emerging approaches to remediation. For mines in development, such as Victoria Gold expectations about climate change can be built into full life-cycle planning including closure. Remediation plans are posted when a mine is developed, and modified through its life as operations change or new information becomes available. Remediation at Faro would have been costly to Governments even if climate change were not a consideration because the financial provisions made by the mine’s owners for post operation clean-up were grossly inadequate. Although the Faro mine was developed and abandoned before climate change emerged as a substantive issue, it demonstrates the capacity of unanticipated climate related events to exacerbate costs. Lessons that have been learned from the Faro experience are the necessity of rigorous “cradle to grave” mine planning that incorporates climate change considerations, and ensuring that companies realistically factor the costs of remediation into their operations.

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