RFP 2023-0029 - Collection of Airborne Geophysical Data

The goal is to apply new developments in geophysical imaging to understand the 3D distribution of permafrost in areas where it impacts highway construction. Subsurface measurements that can determine the thickness of the frozen layer are central to this type of permafrost research. This information can be determined in a number of ways. Drilling provides the most
direct measurement of the thickness and properties. However, drilling cannot cover large areas in an efficient manner. Geophysical methods can address this issue and measure subsurface properties using surface measurements. Various geophysical techniques are available, and the choice depends on the
property of the Earth to be measured. In studies of permafrost, measurements of electrical resistivity are very useful. Frozen ground has an electrical resistivity that is typically greater than 1000 Ωm. In contrast unfrozen ground has a resistivity in the range 10-1000 Ωm. The subsurface electrical resistivity can be measured by a range of electrical and electromagnetic techniques, depending on the depth of interest. For local scale, near surface studies, the DC resistivity method and be used, and the University of Alberta
has extensive experience with this method. Typical studies with this method have been able to image to a depth of 20-30 m. For deeper exploration, and coverage of a larger area, airborne methods are the most effective electromagnetic method. These systems use a transmitter and receiver system carried beneath a helicopter or fixed wing aircraft.

The University is inviting firms with sufficient capacity and demonstrated experience, in providing the collection of airborne geophysical data in the Northwest Territories for the study of permafrost along two highway corridors to submit a Proposal for these Services.