Potential Cost Impacts for Adaptation of Building Foundations in the Northwest Territories

The Northwest Territories (NWT) is within the zone of permafrost. Many buildings, particularly in the northern NWT, are founded on permafrost. The last 30 years have exhibited increased warming trends. Continued warming will result in increased ground temperatures and thaw of permafrost, in turn resulting in ground settlement and increased seasonal freeze-thaw effects. For buildings founded on or in permafrost, this can be expected to bring about foundation distress. This paper describes the development of cost estimates to adapt existing building foundation infrastructure in the NWT to climate change impacts. Building foundation inventories were compiled for six communities in the NWT. The communities were selected to represent a range of sensitivities, geographic regions and populations. Unit costs to adapt different foundation types were developed, based on building size. The unit costs were applied to the inventories to determine a potential cost to adapt the foundations in each community. The findings from each community were upscaled to the entire NWT by considering community size and estimated distributions of foundation type. The estimated "worst case" cost, assuming all foundations on permafrost would require adaptation, totals about $420 million. A "best guess" adaptation cost, considering the thermal and physical sensitivity of each community, is in the range of $200 to $250 million.