January 2006 ISSUE
backgrounder
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Coming Through |
Permafrost, Pipes and People
All three coexist in Inuvik, a northern town with a well-pondered genesis. And thanks to forethought and sound engineering, the challenges of the north are well met in a community Diefenbaker said would bring ‘new opportunity to the people of the western Arctic.’
BY KEN JOHNSON, P.ENG.
PEGG Contributor
The Town of Inuvik, Canada's largest community north of the Arctic Circle, has a unique history as the first completely engineered northern community. According to some, there has never been a Canadian town so “pondered, proposed, projected, planned, prepared and plotted” as East-3, which was its original site identification back in the 1950s
Inuvik was planned and engineered by the Canadian Government in the late 1950s to replace the flood-prone Aklavik, 50 kilometres to the west, as the region's administrative centre. Canadian Prime Minister John Diefenbaker dedicated Inuvik as “the first community north of the Arctic Circle built to provide the facilities of a southern Canadian town. It was designed not only as a base for development and administration, but as a centre to bring education, medical care and new opportunity to the people of the western Arctic.”
The site was chosen for its elevation above the Mackenzie River flood zone, abundant gravel deposits, ample space for an airport, freshwater lakes and navigable waters. The community sits on a broad terrace between the East Channel of the Mackenzie River and the upland that forms the present-day Mackenzie Delta's eastern boundary.
The Mackenzie Delta is the largest delta in Canada; it is 210 kilometres long, has an average width of 62 kilometres, and occupies 13,000 square kilometres.
The Challenges
Preconceived and engineered though Inuvik may be, the townsite continues to challenge
engineers. Notable among these challenges are long, very cold winters, permafrost,
and the great distance from supply sources.
Diefenbaker likened Inuvik to a southern town, but in actuality it depends on southern sources for materials of all sorts, with the exception of drinking water.
The built environment of Inuvik must also cope with the permafrost and the extreme cold for buildings, water, sewer, roads and drainage; each of these elements requires unique design and construction considerations.
The problem with permafrost is that it never completely melts. However, in the summer the top metre or “active layer” may melt with the warm temperatures. The permafrost ground below Inuvik is also ice rich, which means that when the ice partially melts, the ground may settle by hundreds of millimetres to fill the voids left by the melting ice.
This magnitude of settlement can cause major structural damage to buildings and pipes. The heat from houses, and water and sewer pipes may also melt permafrost. Therefore all of the buildings and pipes in Inuvik are built on piles to provide a thermal break between the building and the ground.
The water and sewer mains, and power poles that service each building run along a dedicated right-of-way along the back of each lot; the cost of these services is about $50,000 per lot.
Service connections exit above ground from each building and create a large metal centipede as they connect to the water and sewer mains. Road crossings of the utilidor create another challenge, because the road must literally bridge the utilidor — at another cost of nearly $50,000.
Taking the High Road
Inuvik's methods of development access and site preparation have also adapted
to the extreme conditions. Roads are built above the natural grade, with embankments
thick enough to provide an insulating layer to minimize permafrost melting. Road
grades and building lots are never excavated for pre-grading purposes; this is
to avoid the effects of continuing thaw settlement, which can go on for several
years in developed or disturbed areas.
Building lots are often filled to provide grading for drainage and access for construction vehicles, as well as to reduce thaw settlement. Drainage runs on the surface in ditches, except where it passes through culverts under roads.
Inuvik originally developed with a reasonably compact and efficient downtown business core, just east of the East Channel. Primary and secondary schools were located on large blocks of land between the core and surrounding residential areas. A large regional hospital was sited at the south end of the townsite.
The residential areas radiate outward from the central core, and there is a considerable amount of undeveloped space between the current margins of developed residential districts and a perimeter collector road.
Inuvik acts as its own developer of serviced land for townsite expansion, undertaking both financing and administrative work itself in order to supply serviced lots at the lowest cost reasonably achievable.
New residential housing in Inuvik has taken on a southern look, but the odd new house maintains a very northern flair.
Population Patterns
Inuvik grew steadily from 1961 to 1986, from 1,200 people to 3,570 people. The
population increased significantly in the mid-1970s, along with the gas and oil
exploration at the time. When the exploration activity declined in the late ’70s,
the population also declined a bit from about 3,100 people to 2,900.
In the period of 1986 to 2004, the population of Inuvik dipped to around 3,400, with minor fluctuations until returning to the 1986 population of nearly 3,600.
The residents of Inuvik, and northern people in general, have a variety of lifestyles that usually revolve around a lot of outdoor activity. Therefore quick and easy access to the natural environment is expected.
Inuvik’s outdoor activities are maintained on many fronts, including a strong cross country ski club, which produced athletes for the Canadian Olympic team in the 1970s. Indoor recreation in Inuvik is also strong, supported by a new multiplex facility.
The Town of Inuvik experienced a severe housing shortage in 2002 because of the economic growth of the coming Mackenzie Gas Pipeline; since 2000 there has essentially been a zero per cent vacancy rate.
The pipeline has opened another chapter for the community and presents some very interesting challenges for engineers. These will be on the pipeline itself — and in a unique Canadian community that must continue to make sure pipes, people and permafrost can coexist.
Mr. Johnson, is a senior planner and engineer with Earth Tech Canada in Edmonton. In addition to be being a nationally recognized expert on northern community infrastructure, Mr. Johnson is an avid writer and the technical editor for the Journal of the Northern Territories Water and Waste Association (www.ntwwa.com).