Remediation challenges in the Arctic – lessons from Alaska’s North Slope

Alaska’s North Slope comprises a 250,000 km2 broad plain extending from the Brooks mountain range in the south to the Arctic Ocean in the north, at a latitude that is well above the Arctic Circle. Despite a resident population of less than 10,000, the region has around 450 identified contaminated sites. The majority of these sites are associated with military installations, including DEW and former White Alice radar stations, oil exploration and production at Prudhoe Bay, and diesel releases from the storage and handling of fuel in remote villages. Historically, proper disposal of used oil and hazardous waste has been exacerbated by high transportation costs within a region that is largely road less and wholly dependent on air and ocean transport.
Characterisation of sites and the prediction of contaminant migration is complicated by the presence of continuous permafrost in the region. The active layer, which is the upper soil horizon that thaws, reaches a peak depth in August of around five feet, with suprapermafrost water flow restricted to this narrow zone. Within gravel pads placed to support infrastructure, groundwater flow is generally predictable, but within native tundra soil fracture flow dominates. Further, pockets of contaminated media can become isolated through differential ground melting if the thermal regime is disturbed.
Some case studies from Prudhoe Bay and Utqiagvik are presented to illustrate uncertainties in characterising Arctic sites. The remoteness and extreme climate of these sites places limitations on site remediation options. In-situ methods, including bioremediation and mycoremediation have some potential to reduce costs and limit the environmental impact of remediation.