Report from June 1995
Permafrost and National Defence in Northern Canada
Engineers with the Canadian Department of National Defence (DND) have had an interest in permafrost and the special problems it presents ever since their experience with it during World War II. During the war, American army engineers and civilian contractors built the Alaska Highway and CANOL road and pipeline system across northwestern Canada, to ensure a secure supply of fuel and other materiel for Alaska. Canadian military officers were attached to the construction effort, and many got their first exposure to the problems of thaw settlement in disturbed, ice-rich, fine-grained soils at that time (S. Thompson, personal communication, 1973). T. Lloyd provides a description of the problems encountered at the first site of Camp CANOL, across the Mackenzie River, just downstream of Norman Wells (Oil in the Mackenzie. Geographical Review, 34(2): 275-307, 1944). The camp signals area, which was enclosed by a fence and so remained undisturbed, soon developed into an island several feet higher than the surrounding sea of mud (T. Lloyd, personal communication, 1972).
After the end of the war, the Cold War and Canadian commitments to NATO resulted in the construction of a number of facilities and installations for the defence and security of North America. Most were constructed and operated jointly with the United States. In recent years, many have been decommissioned, as a result of obsolescence and the lessening of international tension. Given Canada's northern location, and the Cold War preoccupation with Asia, many of these facilities were built in the permafrost region. The problems faced by the military engineers responsible for their construction were the same as those that face all engineering projects in permafrost areas. These included questions of location (controlled by the purpose of the specific facility), site selection, foundation conditions, sources of construction materials, water supply and waste disposal. In the early years, however, they were exacerbated by a poorly developed supply and transportation system. Each of the major facilities had to include an airstrip in addition to the living quarters and operational structures.
These defence installations in the north comprised four main components: 1) Joint Arctic Weather Stations, built in the 1950s; 2) Distant Early Warning (DEW) Line radar stations, also built in the 1950s; 3) Short Range Radar Stations, built in the 1980s; and 4) the current Forward Operating Locations program, of upgrading selected arctic airstrips for potential military use.
When the Arctic Weather Stations and the DEW Line sites were being designed and built, it was thought urgent to get them completed quickly. Thus the approach to their design and construction planning was one of "overdesign and overbuild" as a way of coping with the possible foundation problems presented by permafrost. Thus more piles than may have been necessary were placed under the buildings and thick pads of gravel were laid down for the airstrips and roadways.
In the 1980s, when the Short Range Radar Sites were being built, however, there was less pressure for a quick completion and much more was known about design and construction in permafrost terrain. Like the original DEW Line construction, much of the work on site selection and investigation, design and construction was done by civilian contractors. More attention was therefore paid to optimizing pile design, for example, and research on pile design for specific permafrost conditions was undertaken (K.W. Biggar and D.C. Sego, Field pile load tests in saline permafrost. I. Test procedures and results. II. Analysis of results. Canadian Geotechnical Journal, 30(1): 34-59, 1993).
The current program of airstrip upgrading began in the late 1980s. A major concern is the possible effects of global warming on permafrost stability and on the performance of the airstrips and associated buildings and, in particular, the possible effects of differential thaw settlement of runways on the safety of jet aircraft. Jets land and take off at relatively high speeds and differential settlements of as little as 5-10 an over a horizontal distance of 60 m are considered excessive by aircraft manufacturers. Thus research into the extent of permafrost and of ground ice and their seasonal variation in the soils beneath runways has been undertaken, principally at Inuvik and Rankin Inlet, NWT (A.S. Judge, C.M. Tucker, J.A. Pilon and B.J. Moorman, Remote sensing of permafrost by ground-penetrating radar at two airports in Arctic Canada. Arctic, 44(1): 40-48, 1991). At Rankin Inlet, because of the high costs associated with mobilization and construction at this relatively inaccessible location, the runway and building foundations have been deliberately overdesigned, so as to accommodate a potential warming of the permafrost by 1-2°C over the next few decades.
Prepared by J.A. Heginbottom
with the assistance of C.M. Tucker, June 1995
Report from December 1995
The Canadian National Committee (CNC) for the IPA held its annual meeting in Ottawa, at the Geological Survey of Canada (GSC), on 24 June 1995. The business of the meeting was devoted largely to the planning of the 7th International
Conference on Permafrost, to be held in Canada in June 1998. In particular, the committee completed a thorough review of the decision to hold the conference in Yellowknife, NWT. Concern had been expressed over the high cost of travel to Yellowknife and over the implications of cutbacks in the federal and territorial governments for the success of this conference. The CNC heard strong statements of support from the GSC and from the representative of the Science Institute of the NWT/Aurora College. In conclusion, the CNC confirmed that Yellowknife is indeed an appropriate place to hold the conference, and that there is a strong local commitment to its success, by all sectors of the community. In response to institutional changes within the federal public service, the Science Institute of the NWT has resumed the lead role in supporting the conference Local Arrangements Committee, replacing the Yellowknife office of the GSC (scheduled to close in December 1995). The Technical Program Committee is now in place and the Field Trips Plan is well on its way to completion.
The Canadian Geotechnical Society's 48th annual conference, held in Vancouver in September, included a session on Permafrost/Engineering Geology, organized by the Cold Regions Division. The papers presented addressed such diverse topics as natural piping failures in permafrost; effects of forest fires on ice-rich, fine-grained permafrost slopes; use of georadar for geotechnid study of insulated permafrost slopes; modeling of diesel he1 leaks in permafrost; and creep deformation of massive ground ice. Dr. Elisabeth Hivon, of EBA Engineering Consultants Ltd, Edmonton, will take over the
chair of the Cold Regions Division in January 1996; the three other members of the division's executive will be chosen in due course. The 1995 Roger J.E. Brown Award is being shared by A.J. Hanna, J.M. Oswell, E.C. McRoberts, J.D. Smith and T.W. Fridel for authoring a paper entitled "Initial Performance of Slopes: Norman Wells Pipeline Project, Canada," presented at the 7th International Cold Regions Engineering conference in Edmonton in March 1994. The 49th Canadian Geotechnical Conference will be in St. John's, Newfoundland, in September 1996 (see p. 25).
Submitted by J.A. Heginbottom, Secretary, CNC-IPA