NWT RESEARCH DATABASE

Regions: Gwich'in Settlement Area

Tags: physical sciences, soil, groundwater, landslides, slope failure

Project Description: Year 2 of this four-year project involves detailed mapping of landslides and collection of soil samples. Soil sampling will be carried out by digging shallow test pits with hand tools or by using a small hand-held, gas-operated coring machine. It is estimated that up to six test pits of about 1.5m diameter and about 1.5m deep will be excavated at a site; however, the total number of test pits to be excavated over the course of the year is unknown at this time. The purpose of the test pits is to inspect the subsurface soil conditions for evidence related to slope failure. Soil testing will be carried out using hand-held geotechnical instruments, for example a vane shear tester and a thermal conductivity probe. In addition, some tree dating might be carried out, which involves taking a small cored sample from a tree. This process leaves a small hole but does not otherwise harm the tree. Some test plots might be set up by removing a small area of surface organics and mineral soil adjacent to an existing landslide to monitor the impact on ground temperature and other condition changes. It is anticipated that up to six 4m by 4m test plots would be set up at a site. Some geotechnical test holes will be drilled within and around the test plots using a heli-portable drill rig weighing less than 2,500kg, as allowed under a Class B land use permit obtained from the Gwich’in Land and Water Board. The drill holes will be about 4 to 6 inches in diameter and to a depth of around 15m. The drill holes will be used for subsurface soil sampling and installation of instruments to monitor ground temperature, soil moisture, groundwater pressure and ground settlement. Additionally, mini weather stations might be set up. These stations would monitor precipitation, air temperature and humidity, wind speed and direction, and solar radiation. Data loggers will collect information between site visits. All instruments will be monitored until March 2009. It is estimated that project work will involve one to two weeks in the field several times per year, normally in the summer but possibly in winter, as well. Travel will be by helicopter from Inuvik. A team of up to six people will be working in the field. Overnight camping might be required for up to two weeks at a time at each site during detailed mapping and instrumentation installation. Subsequent instrument monitoring will require several short site visits. The study will be conducted from February 10 to September 30, 2006 around a landslide on a small lake (N67°40.0’ W131°31.8’) located southeast of Travaillant Lake. Other areas in this vicinity might also be investigated. The fieldwork locations have been reviewed and approved by the Gwich’in Tribal Council (Type II Research Authorization #G05R06) and the Gwich’in Land and Water Board (Class B Land Use Permit #G05S006).