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.