NEWS 2010

Posted April 14, 2010

Event: April 21, 2010

CGS/U of A: Cross Canada Lecture Tour, Mr. Don Hayley, P.Eng., FEIC - Design, Construction and Operations of Dams in Permafrost Regions

Location: NREF 1-001, U of A Campus

Time: 5:30pm - 6:30pm

The CCLT is organized by the Canadian Geotechnical Society, with funding through the Canadian Foundation for Geotechnique.

Sponsorship provided by:

• AMEC Earth & Environmental
• BGC Engineering
• Golder Associates
• Reinforced Earth Company

Mining in the Canadian north has taken on new importance with discovery of diamonds and increased prices for both precious metals and base metals. Diamond mining in the Northwest Territories began in 1998 with the opening of Ekati Diamond Mine and has expanded to include two additional producing mines. Mining in regions of permafrost has focused attention on the challenges of building dams for water management and waste containment. This presentation focuses on the unique characteristics that frozen ground and ground ice present when planning, designing and constructing earth and rockfill dams on a permafrost foundation.

The presentation examines the attributes of three common dam types that are currently in use in the Canadian arctic:

• frozen core dams on a permafrost foundation,
• rockfill dams on a permafrost foundation with internal geosynthetic liner,
• embankment dams with a membrane cut-off wall through the permafrost foundation to frozen bedrock.

The first two types require comprehensive geothermal analyses to ensure that frozen soils integral to the design for both strength and seepage prevention will function as intended throughout the life of the structure. In many cases supplementary cooling must be provided using passive devices such as thermosyphons to enhance heat extraction from the foundation. Other passive methods for extending the useful life of permafrost within the foundation soils are also reviewed. The design and construction process is illustrated with case history examples from project files.

All new mines proposed for arctic environments must include reclamation objectives and preliminary plans that will be critically reviewed by regulators and their consultants. The designer must be prepared to address long-term issues pertaining to climate change and permafrost response following site abandonment. The desirable objective is always to decommission dams on permafrost foundations but there are exceptional cases where this is not practical. In these cases, modification of the structure coupled with long term monitoring will usually be required to reduce future environmental risks to acceptable levels.

Don Hayley, P.Eng., FEIC is a founding partner of EBA Engineering Consultants Ltd. where he has been a consulting engineer for 41 years. His focus throughout this period has been developing design and construction practice for northern regions where permafrost, snow and ice are particular challenges. His work has focused on northern infrastructure, oil and gas exploration and mining. He has applied his technical knowledge across the entire northern hemisphere by active participation in major projects including mining at Svalbard, Norway, oil fields in Siberia and exploration platforms in the Beaufort Sea.

Don received his B.Eng. (Civil) from Carleton University in 1966, followed by an M.Sc. (Civil-Geotechnical) in 1968 from University of Alberta. He was appointed as a Fellow of the Engineering Institute of Canada in 2002 and received the Julian C. Smith Medal from the EIC for contributions to the development of Canada in 2005. He has played an active role in support of permafrost research in Canada as Chairman of the Canadian National Committee for the International Permafrost Association and subsequently was a member of the Executive of the International Permafrost Association from 2003 to 2008. He has presented keynote papers on northern engineering at a number of international and national conferences. He spent five years as a Director of the Canadian Geotechnical Society and assisted with organizing the Cold Regions Division. He received the Roger Brown Memorial Award from CGS for contributions to permafrost science and engineering in 1991, and delivered the R.M. Hardy lecture at the annual conference in 1998.

More recently, Don has developed recognized expertise in design and construction of winter roads and roads over floating ice. He is frequently called upon to develop improved procedures for managing the hazard of working on ice and directed the technical content for a new guideline published in Alberta in 2009. He has contributed his expertise to improving worker safety on floating ice by assessing the causes of ice failure incidents in Manitoba, Alberta and Northwest Territories.