Kwong, YTJ 2010, 'Tailings decommissioning options at Mount Nansen, Yukon, Canada ©', in R Jewell & AB Fourie (eds), Proceedings of the First International Seminar on the Reduction of Risk in the Management of Tailings and Mine Waste
, Australian Centre for Geomechanics, Perth, pp. 91-101.
A total of 250,000 t of tailings enriched in arsenic and cyanide impounded behind an earth dam of suspect
physical integrity constitute the greatest environmental liability at an abandoned gold mine on Mount
Nansen, Yukon Territory, Canada. The primary cause of dam deterioration can be traced back to improper
initial tailings placement, resulting in gradual melting of frozen ground into which the dam was keyed. Field
investigation and sampling revealed that permafrost still underlay most of the impoundment. Subsequent
comprehensive mineralogical and geochemical characterisation of the collected samples indicated that the
tailings remained relatively stable chemically with low potential for metal leaching. Given that cyanide and
related compounds continued to degrade naturally, rendering the tailings increasingly benign with time, and
that the containment dam is unlikely to collapse catastrophically except perhaps under extreme seismic
stress, it is suggested that the impounded tailings need not be relocated for permanent site decommissioning.
A viable long-term alternative could involve downstream reinforcement of the dam structure, dewatering the
existing shallow pond and covering the tailings with a layer of benign waste rock to arrest erosion and
prevent direct access by roaming animals.
AGRA Simons Ltd. (2000) Memorandum: Reclaim Water Treatment System Upgrade, Mount Nansen Mine, prepared
for Indian and Northern Affairs Canada, February 18, 2000.
Carlson, G.C. (1987) Bedrock geology of the Mount Nansen and Stoddart Creek map areas (115I/03 and 115I/06),
Exploration and Geological Services Division, Yukon, Indian and Northern Affairs Canada, Open File 1987-2.
Conor Pacific Environmental Technologies Inc. (2000) Mt. Nansen Minesite Historical Review, Site Assessment and
Field Sampling Program, prepared for Indian and Northern Affairs Canada, February 2000.
EBA Engineering Consultant Ltd. (1999) Geotechnical Data Review Report, Mount Nansen Tailings Dam Safety
Evaluation, prepared for Indian and Northern Affairs Canada, December 1999.
Filipek, L.H. (1999) Determination of the source and pathway of cyanide-bearing mine water seepage, in The
Environmental Geochemistry of Mineral deposits, Part B: Case Studies and Research Topics, L.H. Filipek and
G.S. Plumlee (eds), reviews in Economic Geology, Vol. 6B, pp. 549–565.
Gartner Lee Limited (2004) Mt. Nansen Mine Site – Brown McDade Pit Hydrological and Hydrogeological
Investigation, prepared in association with Northwest Hydraulic Consultants Ltd. and Lorax Environmental
Services Ltd. for Yukon Energy, Mines and Resources, Abandoned Mines Project Office, June 2004.
Government of Canada (2005) Taking action on federal contaminated sites: An environmental and economic priority,
Environment Canada, Gatineau, July 2005, 20 p.
Landforms and Decommissioning
Mine Waste 2010, Perth, Australia 101
Hall, G.E.M., Gauthier, G., Pelchat, J-C., Pelchat, P. and Vaive, J.E. (1996) Application of a sequential extraction
scheme to ten geological certified reference materials for the determination of 20 elements, Journal of Analytical
Atomic Spectrometry, Vol. 11, pp. 787–796.
Hart, C.J.R. and Langdon, M. (1997) Geology and mineral deposits of the Mount Nansen camp, Yukon, Yukon
Exploration and Geology 1997, Exploration and Geological Services Division, Yukon, Indian and Northern
Affairs Canada, pp. 129–138.
Klohn Crippen Consultants Ltd. (1995) Tailings Impoundment – Final Design Report, prepared for BYG Resources
Inc., August 1995.
Klohn Crippen Consultants Ltd. (2000) BYG Tailings Dam, Mount Nansen, YT, Project Data Review Report, prepared
for Indian and Northern Affairs Canada, January 2000.
Kwong, Y.T.J., Kapoor, A., Fiset, J-F. and McAlpine, B. (2003) Assessment of chemical stability of the impounded
tailings at Mount Nansen, Yukon Territory, in Proceedings 7th International Symposium on Mining in the
Arctic, J.E. Udd and G. Bekkers (eds), March 30 – April 1, Iqaluit, Canada, Canadian Institute of Mining,
Metallurgy and Petroleum, Montreal, pp. 355–367.
Strathcona Mineral Services Limited (2000) A Review of the Mt. Nansen Property, Yukon Territory, prepared for
Department of Indian Affairs and Northern Development, December 2000.
Tailings decommissioning options at Mount Nansen, Yukon, Canada © Y.T.J. Kwong
102 Mine Waste 2010, Perth, Australia