NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, water quality, hydrology, sediment quality, environmental baseline, groundwater, soil chemistry

Objective(s): The objective is to conduct monitoring to ensure that the project is overall compliant with the environmental permit and approval conditions and requirements.

Project Description: This licence has been issued for the scientific research application No.4710. The objective is to conduct monitoring to ensure that the project is overall compliant with the environmental permit and approval conditions and requirements. Water monitoring at water crossing locations will be required for any in-water construction and where there is potential for entrainment of sediments. This includes locations where there may be construction below the high-water mark and where flows are present (i.e., the water is not frozen to bed or dry at the time of construction). Monitoring of turbidity levels may be initiated on non-permanent water bodies when there is a construction related incident resulting in potential entrainment of sediments. Prior to initiation of a monitoring program, the monitoring crew will survey the study area at each crossing location. The crew will set up sampling (cross-sectional) transects relative to the work area per crossing (one upstream and three downstream transects); the positioning of downstream transects will depend on the size of the water body. All transect locations will be marked with a Global Positioning System (GPS) in addition to any other site marking methods used (e.g., flagging tape). Total Suspended Solid (TSS) is a composite of suspended inorganic and organic solids and cannot be immediately or directly measured in the field. Measurements of TSS (milligrams per litre [mg/L]) require specialized equipment and considerable time, making the required analytical procedure impractical for use in field settings. For this reason, measurements of turbidity (Nephelometric Turbidity Units [NTU]) have been proposed for the Tli?cho as a surrogate measurement for TSS. TSS (mg/L)-turbidity (NTU) relationships can vary between water bodies, and in larger systems, can vary between sites. Prior to construction, a representative sediment sample will be collected from instream and exposed portions of river bed substrate adjacent to each crossing. A representative water sample will also be collected near each crossing at this time. For each water body, the crossing-specific sediment and water samples will be combined to produce approximately 20 surrogate suspended sediment samples, creating a range of turbidity values that might be encountered during construction. The TSS samples may be collected up to one month in advance of construction; collecting TSS samples during periods with increased suspended solids (i.e., during freshet, following heavy rains) should be avoided to ensure that samples with low levels of suspended solids are included when calculating the TSS turbidity relationship. Upon receipt of results, TSS and turbidity data will be plotted graphically and analyzed. The development of the TSS-turbidity relationship described in a table format per permanent crossing will allow for quick calculation of TSS concentrations based on the turbidity measurements collected during instream construction activities. As a result, it will be possible based on the relationship to determine when TSS levels exceed the CCME TSS guideline in the field and provide notification to the NSI Environmental Manager to apply the appropriate mitigation measures during construction. The TSS correlation will be updated monthly to validate / calibrate the TSS turbidity relationship, using weekly TSS samples that are concurrent with the turbidity readings. All transects and sample stations will be sampled at a minimum frequency of two times daily during any works taking place below the high-water mark, but more frequent monitoring may be triggered based on monitoring results. No less than six hours should pass between the start of the first sample collection and the start of the last sample collection for each day, and at least one set of samples should be collected immediately prior to work starting below the high-water mark to identify any baseline variations in TSS/turbidity between sampling sites. Photos upstream, downstream, and of the left and right downstream banks at each transect must also be taken during a sampling event. Information for every photo taken must be recorded in a “Photo Log” datasheet. The field crew will also be responsible for maintaining the construction activity log and will be the initial point of contact for reporting any plumes or elevated levels of turbidity/TSS to the NSI Environmental Manager. The start and end of any significant activities that have the potential release sediment must be documented in a “Construction Log”. Any conversations with the construction crew or NSI should also be recorded with names, dates, times, and a description of the conversation. Water throughout the water column will be collected for each sample, with the crew lowering and raising a bottle attached to a pole through the water column at a steady rate to collect the sample. For sites where depths are shallower than 0.5 m, samples can be collected by hand at the mid-column depth. Collection of samples to be upstream of the sampler to avoid Turbidity will be measured using a portable turbidity meter. Prior to measuring turbidity, each sample collection container will be gently agitated to re-suspend settled solids. Samples will be disposed of on site or archived for TSS analysis, if needed. For periods of prolonged in-water work, work during timing windows or when manual sampling is not practical (due to high flows or river width), NSI will utilize the use of in-water sondes and dataloggers that collect data on a real-time basis. The data-loggers are connected to a radio antenna which transmit to a shore mounted receiver for download. Weekly TSS water samples will be collected and sent to a certified lab for analysis. The Canadian Water Quality Guidelines for the Protection of Aquatic Life (Total Particulate Matter; CCME 2002) outline guidelines for turbidity and TSS. If materials are encountered during the course of construction that could be either archaeological, heritage resources, such as burial site and place naming or sensitive cultural heritage sites, careful steps will be taken to ensure to not disturb or collect the artifacts. Monthly and annual report will be generated and provide to the community organization. The project also has a working group that consists of personnel from Department of Fishers and Ocean, Government of Northwest Territories, GWNT Environmental Natural Resources, Environment and Climate Change Canada, Tlicho Government, Wek’eezhii Land and Water Board as well as elders and community members from Whati, North Slave Region and Bechoko, which meet every 6 months to discuss different topic or any project concerns. The project also has an engagement management plan that is followed and documents all engagement that has take place for the project. The fieldwork for this study will be conducted from February 5, 2020 to December 31, 2020.