NWT RESEARCH DATABASE

Regions: Sahtu Settlement Area

Tags: discontinuous permafrost, community based monitoring, waste sump, Mackenzie Valley

Objective(s): To evaluate the integrity and containment of contaminants of a selection of Sahtu region drilling sumps and to create a database of pertinent environmental sump information including ground ice content, permafrost terrain conditions and recommendations for long-term management of sumps in the central Mackenzie Valley.

Project Description: This licence has been issued for the scientific research application No. 5763. This proposed research will build on the previous years’ studies completed in the Mackenzie River valley by researchers at the Permafrost Archives Laboratory at the University of Alberta. The objective of fieldwork being completed in 2023 are as follows: 1) An evaluation of the integrity and containment of contaminants of a selection of Sahtu region drilling sumps and 2) Creation of a database of pertinent environmental sump information including ground ice content, permafrost terrain conditions and recommendations for long-term management of sumps in the central Mackenzie Valley. Objective 1: In the Central Mackenzie Valley, more than 180 drilling sumps have been created over the past 80 years with the goal of encapsulating waste in warm, discontinuous permafrost terrain. At present, none of these sites have undergone complete remediation efforts. Over 270 drilling sumps exist in the Mackenzie Delta Region, in cold, continuous permafrost. Thermal modeling has inferred that in a warming climate, drilling fluids (3.5m depth) in warm permafrost thawed within a few decades, but in cold permafrost, the drilling fluids remained frozen after four decades. We have identified a selection of drilling sump sites of community concern, and sumps which have expressed climate-induced thaw such as thermokarst ponds, resulting in further warming of sump areas. We will measure and test the specific environmental site conditions, including surficial conditions (topography, vegetation, soil conditions) and sump stability (subsidence, sloughing, cracking, erosion, surficial ponding and further permafrost degradation) through collecting shallow permafrost cores and conducting shallow geophysical surveys to determine permafrost thickness and distribution. In addition, high-resolution digital elevation models (DEM) using aerial videos from rapid helicopter surveys will test for evidence of subsidence of sumps. Together, these data will provide a comprehensive assessment of the overall waste containment capacity of the drilling sumps constructed in warm permafrost in the Sahtu region. Objective 2. A protocol to evaluate the design, construction and abandonment practices of Mackenzie Delta sumps was developed as the 2006 Protocol for the Monitoring of Drilling-waste disposal sumps, with sumps monitoring occurring on a semi-annual basis. With future climate change, the Mackenzie Valley sumps are increasingly at risk for thaw, requiring a similar protocol to be established for this region. The results from these fieldwork and lab analyses will be compiled in a database to visually illustrate the distribution of Sahtu region sumps requiring further management. A set of recommendations for the eventual remediation of sumps will be presented, highlighting the need for long-term monitoring plans and a commitment from the responsible authorities for long-term site maintenance. During the 2023 fieldwork, empirical evidence will be collected to: 1) establish whether permafrost is present within the sumps or whether through-going talks (thawed ground) penetrate the sumps; 2) determine the physical properties of the sediments and permafrost (if present); and 3) Establish if elevated trace metals or other contaminants are present at sump sites. To do so, our team will employ non-destructive geophysical survey methods, collect shallow permafrost cores, and collect surface water samples from ponds above sumps. Information from shallow geophysical surveys and electromagnetic geonics will be collected using electrical resistivity tomography (ERT) and conductivity meters (EM-31) in the field, allowing us to determine the thickness and distribution of permafrost, and whether through-going taliks are present. This non-invasive method involves inducing an electrical current through a string of small electrodes at the surface and measuring the resistivity of the ground, allowing areas of high resistivity (permafrost) to be imaged, thus determining permafrost thickness. Permafrost cores up to 5m of depth will be collected using a two-person Talon drill system, with the uppermost removed soil layer being used for capping following extraction of the core, mitigating disturbance. (*Thermistors sentence*). These cores will be shipped frozen to perform sample analysis at the Permafrost Archives Science Laboratory at the University of Alberta. The research team will utilize the micro X-ray computed tomography (Core CT scanner) to determine the physical properties of the sediments by grain size and dissolved organic carbon analysis (DOC), and determine whether they are frozen. Further, surface water samples will be collected to determine whether elevated trace metals and other contaminants are present at each site. Using technology such as an isotope and gas concentration analyzer (Picarro), and an inductively coupled plasma mass spectrometer (ICP-MS), the team will test for major cations and anions, and test the electrical conductivity and pH. Lastly, we will test for overall subsidence of the drilling sumps, which indicates degradation of permafrost, through the use of DEM surveys. The research team is working with the SSRB's Petroleum Histories Project to create a summary guidance document (2025) on the state of the four studied sumps and subsequently a database to be worked on during the project to further our understanding of the wells and sumps which exist in the Sahtu. In 2023, the team co-facilitated a permafrost monitoring workshop with the K'ahsho Got'ine Foundation in Fort Good Hope and presented our research on sumps while also focusing on community-based monitoring techniques of installing ground temperature stations in Tuyeta. In September 2022, the Sahtu Secretariat Inc (SSI) invited Dr. Duane Froese and graduate students to facilitate a workshop in permafrost and climate change adaptations in two Sahtu communities, Tulit’a and Déline. We used this opportunity to engage community members in permafrost research in the Mackenzie Valley area. Dr. Froese and the SSI invited community members of Tulit'a and Déline respectively to an event to discuss the changes within Sahtu region permafrost and inquire about regions of most community concern. With the funding from the GeoNorth Gems program, mature students and community members will be involved in helicopter site visits around the communities to permafrost drilling sumps, gaining training in specific issues related to permafrost; stability, monitoring, sampling and the fate of contaminants. All information resulting will be provided to the Aurora Research Institute and the Indigenous communities of the Sahtu region. The fieldwork for this study will be conducted from: June 28 - July 13, 2024