NWT RESEARCH DATABASE

Regions: North Slave Region, South Slave Region

Tags: mining, hydrology, environmental baseline, groundwater

Objective(s): To provide additional data that describes the existing surface water conditions at the site. The six monitoring wells are situated within the project footprint and will provide additional information to refine the spatial and temporal variability of groundwater chemistry.

Project Description: SURFACE WATER HYDROLOGY: The goal of the 2010 research program is to provide additional data that describes the existing surface water conditions at the site. This information is required for environmental assessments and water management plans for the area. Data obtained will help determine a quantitative description of the annual temporal and spatial distribution of stream flow conditions, precipitation, runoff processes, and lake levels at Thor Lake and its vicinity. GROUNDWATER: The six monitoring wells are situated within the project footprint and will provide additional information to refine the spatial and temporal variability of groundwater chemistry. The data will also help predict mine dewatering chemistry; potential challenges in using mine water for process needs, and better establish baseline groundwater chemistry. SURFACE WATER HYDROLOGY: Thor Lake hydrology data are collected at a series of water level and flow gauging sites located in the vicinity. Specifically, lake level monitoring is being conducted on Thor Lake and Long Lake. Stream flow and water levels are being monitored at the outlet of Thor Lake, the outlet of Fred Lake, the outlet of Long Lake, and at inflow sites to Thor Lake and Long Lake. Stream flow gauging will be completed at several streams connected to Thor and Long Lakes that have marginal autumn flows but expected high spring and summer flows. Water levels are monitored at each location using a HOBO pressure transducer that has been secured to the lake/stream bed. These devices are small, self-contained, non-obtrusive data loggers that are benign to the environment. Flow measurements at channels entering or leaving Thor and Long Lakes are derived by standard area-velocity, or volume measurements using a Swoffer flow meter and standard stream gauging techniques. These techniques have no impact on the water environment. Stantec will also train Avalon staff, or other personnel designated by Avalon, in the installation and removal of the equipment, manual measurement techniques and data retrieval. Two site visits are proposed by the Stantec hydrologist: one in late May during freshet to record flows during high flow conditions and install hydrometric equipment; and, in October to conduct further measurements and remove continuous monitoring equipment. GROUNDWATER: Five of the aforementioned monitoring wells will be examined for water level and groundwater quality; the sixth well (MWL08-134) has a thermistor installed and will continue to be checked throughout 2010 in conjunction with other Discipline field programs. Methodology for the 2010 program will include standard field methods and collection protocols, identical to those used in the 2008 and 2009 programs. Instantaneous groundwater levels will be recorded at the five monitoring wells using a water level meter. Groundwater samples will be collected from all five monitoring wells if they are accessible (i.e., not frozen). Groundwater samples will be taken using disposable bailers and 0.45 µm in-line filters (for dissolved metals samples). Sample bottles will be provided by ALS Laboratories. Groundwater samples will be analyzed for physical parameters, nutrients, total and dissolved metals and total organic carbon. The information may provide locals with a more thorough scientific overview of the local surface water hydrology which can be used for various purposes (e.g., land use planning, economic development). As the Thor Lake Project proceeds further into the regulatory process, regulatory review and environmental assessment processes will provide information to affected Aboriginal communities and First Nations. Plain language information and summaries on the proposed research program will also be provided to interested and affected Aboriginal communities, First Nations and other stakeholders. The fieldwork for this study will be conducted from June 2, 2010 to October 8, 2010.