Tetra Tech was part of a team that helped the Gwich’in community of Tsiigehtchic in the Northwest Territories prepare to deal with future degradation of the permafrost on which the community’s infrastructure is built.

In northern Canadian communities like Tsiigehtchic, buildings are on permafrost, which can degrade due to warming temperatures, affecting foundations. Infrastructure critical to Tsiigehtchic’s well-being is exhibiting symptoms of the negative impacts of climate change on permafrost.

Assessment of Building Foundation Sensitivity to Climate Change in the Northwest Territories (Revision 1, January 2005) ranked Tsiigehtchic fourth or fifth highest of 32 communities in sensitivity to climate change. Tetra Tech worked with Natural Resources Canada on that report and created the assessment methodology that improved the understanding of future permafrost degradation, the vulnerability of community buildings, and the time frame for informed adaptation.

Tetra Tech worked with Ecology North to develop proposed adaptations to climate change in Tsiigehtchic that require geotechnical engineering expertise. The team developed a desktop-level community permafrost map to inform future land use and development, to determine preferred areas for building, and to provide a baseline for monitoring potential future changes in the permafrost.

Tetra Tech identified problems that appear to be widespread in Tsiigehtchic’s residential foundations, as well as some practical solutions for the most common problems. Tetra Tech evaluated stabilization options for Church Hill that examine in detail the stability of the hill slope and the potential risks to the church and cemetery should further slope failures occur. The team also identified potential remediation options and Class D cost estimates.