The 869 km Norman Wells oil pipeline runs from Norman Wells, N.W.T. south through the Mackenzie Valley and Alberta plateau to Zama , Alberta. The route provides a north- south transect through the discontinuous permafrost zone, beginning in widespread permafrost in the north (underlying 60-80% of the terrain) and ending in sporadic permafrost in the south (20-30%). The small diameter pipeline is buried in unconsolidated Quaternary deposits, with lacustrine and moraine terrain units dominant in the north, and organic and moraine terrain in the south. Peatlands occur in small pockets in the north covering 10-20% of the terrain, while in the south they cover 25-75% of the terrain, mainly in the form of peat plateaus (which are perennially frozen) and fens (unfrozen).
Research sites were established in the mid 1980s along the pipeline route to document and understand the impact of the pipeline project on permafrost and terrain conditions, and to compare observed behaviour with predicted response. Several of the instrumented study sites, are located in peatlands south of Fort Simpson. Drilling and instrumentation of deep boreholes (up to 20 m) provided baseline data on peat and permafrost thickness at each site, and on ground temperatures. Measurements of soil and ground temperatures, air temperature, thaw depth, and surface settlement have been regularly obtained, either manually or via data loggers, over the last 12 years, both on and off the pipeline right-of- way. In addition visual observations have been made at the sites as well as along the remainder of the route. These data have allowed an assessment of the environmental changes resulting from pipeline construction (e.g. effects of construction techniques, right- of-way clearance, trenching), from operation of a warm pipeline (mean annual temperature >0oC), and from natural changes (eg. fires, climate change). A comparison between different peatland types has also been possible. Thermal effects, such as magnitude and rate of change in thaw depth and active layer, permafrost degradation and thaw settlement, have been documented. Little environmental change occurred in fen type of peatlands. However, disturbance to bog type has been greater, including scraping, exposure and erosion of the peat surface, very slow recovery of vegetation, pronounced thermal degradation (3 to 5 m) and surface settlement (up to 1.5 m in the trench area). Accelerated thermal erosion occurred at peat plateau collapse scars.
Margo M. Burgess Terrain Sciences Division Geological Survey of Canada 601 Booth St. Ottawa, Ontario, K1A 0E8 CANADA Telephone: 613-996-9317 Fax: 613-992-2468 E-mail: burgess@gsc.emr.ca C. Tarnocai Centre for Land and Biological Resources Research Agriculture Canada Ottawa, Canada, K1A 0C6 CANADA Phone: 613-759-1857 K.L. MacInnes Lands Administration Department of Indian and Northern Affairs, Canada P.O. Box 1500 Yellowknife, N.W.T., X1A 2R3 Phone: 403-669-2680