NWT RESEARCH DATABASE

Regions: Sahtu Settlement Area, Dehcho Region

Tags: contaminants, hydrology, groundwater, wastewater treatment, geophysical survey

Objective(s): To improve understanding of wastewater effluent transport within permafrost environments in the NWT.

Project Description: This licence has been issued for the scientific research application No.5413. The overall objective of this study is improved understanding of wastewater effluent transport within permafrost environments in the NWT. The proposed study aims to answer the following questions: 1) What is the potential for contamination of groundwater and receiving waters through active layer transport of effluent from passive wastewater treatment systems in the NWT? 2) How does the presence of permafrost and subsequent permafrost thaw influence wastewater effluent transport within the subsurface? 3) How should design guidelines for subsurface wastewater treatment systems be adapted for permafrost environments? This research will quantify the present and future environmental and human health risks related to the contamination of groundwater and surface water resources as a result of the subsurface disposal of wastewater effluent. Preliminary groundwater modelling studies been conducted by the Canadian Water Research Society (CWRS) for the active infiltration lagoon wastewater treatment systems used by the communities of Enterprise and Fort Good Hope. Results from this preliminary groundwater modelling exercise have identified that infiltration systems represent a viable option for wastewater management for other small communities in NWT. However, as the performance of an infiltration lagoon is dependent on several site-specific factors, further research is required in order to validate initial model predictions, and to develop specific guidelines for the design and operation of infiltration lagoons in the north. As such, this research project will focus on further characterizing site conditions within the vicinity of the active infiltration lagoon for the communities of Enterprise and Fort Good Hope to validate initial model results. The research team will summarize the results of each project phase and provide recommendations for the development of passive wastewater treatment guidelines within NWT. To summarize, the proposed project phases are as follows: Phase 1: Data Acquisition and Analysis for Enterprise Field Site (Year 1, May 2022 – December 2022). In this phase, we will conduct preliminary investigations at the Enterprise field site. Additional hydrogeologic information that will be assessed includes, but is not limited to, digital elevation models, soil characterization, borehole logs, groundwater table elevations and hydraulic conductivity estimates, ground temperatures, and permafrost distribution. The research team will also establish community contacts and engagement mechanisms to ensure local knowledge is incorporated into the study findings. Phase 2: Characterization and Monitoring of Enterprise and Fort Good Hope Systems (Year 2-3, May 2023 – September 2024): In years 2 and 3 each research site will be monitored. These trips will align with annual spring thaw in order to capture the development of the active layer where permafrost is present. The research team will use a combination of frost-probing, installation of thermistors and/or water monitoring data loggers, and geophysical surveys to characterize the subsurface along potential flow paths from wastewater treatment facilities to potential ecological receptors. Moderate ground disturbance may be required depending on the necessity for the installation of shallow boreholes or monitoring wells. Water samples will be collected from monitoring wells and analyzed for chemical and microbial contaminants/. The data will be used to calibrate and validate groundwater models for each research site. The research team will present preliminary results at the 2023 ArcticNet meeting and the NTWWA 2023 conference, and will also use the conference as an opportunity to touch base with NWT partners. Phase 3: Reporting and Dissemination. (Year 3, September 2024 – December 2024) Following the completion of the characterization and monitoring phase, the research team will focus on reporting and dissemination of findings. Data will be made accessible online through the NWT Discovery Portal and Mackenzie DataStream. Results will be communicated with community members throughout the study during site visits and through conference calls and email correspondence. The project team has established partnerships with the NWT Departments of Environment and Natural Resources Department, and Municipal and Community Affairs, and the Mackenzie Valley Land and Water Board. The scope and objectives of this project were informed with support from the NWT Government contacts, and the research team will continue to consult with these Departments throughout the duration of the project including advice regarding communications and reporting. Findings will also be reported back through in-person meetings with community stakeholders during each visit, and on an on-going basis through conference calls and email correspondence. The fieldwork for this study will be conducted from May 1, 2023 to December 31, 2023.