NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, water quality, effluent, water treatment

Objective(s): To define the flow paths of effluent from the treatment lagoon to Great Slave Lake and thereby inform sampling design of the Great Slave Lake Monitoring Program and to assess the spatial extent, nature and degree of water quality impacts of the Fiddler’s Lake Treatment System discharge on Great Slave Lake

Project Description: This licence has been issued for the scientific research application No.5336. The purpose of the Wetland Delineation Study is to define the flow paths of effluent from the treatment lagoon to Great Slave Lake and thereby inform sampling design of the Great Slave Lake Monitoring Program. The objectives of the Wetland Delineation are varied and, based on available documentation, we understand them to include the following: 1) Identify any additional outflows and delineate drainage areas around the honey bag pit area; 2) Identify and delineate the flow paths that the Fiddler’s Lake Treatment System (FLTS) effluent takes to reach Great Slave Lake; 3) Delineate watershed boundaries of the areas that potentially drain into the effluent flow path (e.g., Fiddler’s Lake, Beta, Alpha, Mac, Kam Drainage Areas); 4) Identify potential flow connections to Beta Drainage; and 5) Produce maps that display the areas and the main outflow locations downstream of SNP 0032-F1 and 0032-F11. The purpose of the Great Slave Lake (GSL) Monitoring Program is to design and implement a water quality monitoring program and analysis of resulting data for a 4-year period (2023-2026). The main objectives of the GSL Monitoring Program are to assess the spatial extent, nature and degree of water quality impacts of the FLTS discharge on Great Slave Lake, and to provide a dataset that is suitable to develop action levels for future water quality monitoring efforts and, in the future, to compare monitoring results to these action levels and triggers. The wetland delineation study will start with evaluating the optimal method for determining the flow pathways from the Fiddler’s Lagoon to Great Slave Lake, including feasibility, cost and regulatory considerations, to be documented in a memo. The delineation will be completed based on the selected optimal method, and a final report will be prepared for the Mackenzie Valley Land and Water Board (MVLWB). The study design will be selected to ensure that the flow paths to Great Slave Lake are identified and thereby inform site selection for the Great Slave Lake Monitoring Program. Assessing the Optimal Method for Determining Flow Pathways - Background Information Review and Analysis: The research team will gather and review available background data including existing reports and relevant documents such as the Fiddler’s Lake Treatment System Plan and Great Slave Lake Nutrient Risk Assessment. The team will also review available geospatial data and mapping that contain information on topography, geology, hydrology, wetlands and flow paths. This information will be used to define any areas that could potentially be in contact with FLTS effluent, to help identify the area that will be visited during the site investigation. Site Investigation: The research team will visit the site and examine existing site conditions as required for both the lagoon system and the honey bag pit area. The team have assumed that the site visit for the lagoon system includes a helicopter survey of the areas that are to be mapped: Flow path through the Fiddler’s Lake Drainage Area; Fiddler’s Lake, Beta, Alpha, Mac and Kam Drainage Areas; Main outflow from the treatment system to Great Slave Lake; and areas south of the Fiddlers Lake Drainage path, such as Beta Drainage Area and any additional connected channels as identified during preparation from existing maps and during the survey. This site investigation will be used to collect valuable field information as input into the options development for wetland delineation. These may include, but not be limited to: Potential sampling locations for field investigations that are accessible by air, land or water; Collection of preliminary water quality samples from the lagoon and an unconnected lake or wetland to evaluate the presence of suitable tracers for a tracer analysis; Obstacles to boat access from GSL into the wetland system, such as beaver dams or log jams; and indications of effluent influence, such as different wetland vegetation densities or water colour. The research team will combine this site investigation with that for the Great Slave Lake Monitoring Program Design to pool resources for both study components. Development of Options for Wetland Delineation Study: The research team will identify and describe options for the wetland delineation study that will provide the information required. The team will use the existing background information, insights gathered during the site investigation, as well as the existing knowledge of wetland delineation and flow path analyses in this task. The team anticipate that there are two main approaches for a wetland delineation study: desktop approaches and field approaches. Desktop approaches mainly entail the development of a digital elevation model (DEM) and flow path analysis. There are several ways to obtain elevation information: 1) The team will investigate if there are existing topographic and hydrological data (e.g., DEMs) wet areas mapping and watershed boundaries. These may be in the public domain or available from academic sources; 2) The team will discuss the use of satellite imagery. Based on a quote obtained for the preparation of this proposal, this method may achieve 50 cm horizontal resolution but only 3 m vertical resolution. Given the flat topography of the study area, this data may be of limited benefit to the study; and 3) Acquire and analyze LiDAR data. The team have obtained a quote from a local subcontractor to do this work. This method may achieve 35 cm horizontal, 25 cm vertical resolution (expressed as Root mean square error of method). The research team will propose using the resultant digital elevation model in a flow path analysis using Geographic Information Systems (GIS). The GIS workflow would utilize the Arc Hydro toolset in ESRI’s ArcMap to perform DEM-based terrain analysis. This analysis will identify sinks and flow paths based on topographic variations and existing water body data and will assist in the delineation of drainage patterns. The GIS personnel and hydrologist will provide advice on the design of these options Field approaches include a sampling program of effluent tracers or addition and tracing of artificial tracers. The addition of artificial tracers, such as dyes or salts, and their tracing in the system may be time consuming, costly and subject to regulatory hurdles. Tracing effluent parameters that are already elevated over or different from natural/reference conditions is also commonly used. Conservative tracers, such as conductivity, chloride, and stable isotopes, are preferred in a slow flowing system like the FLTS. The ideal tracer can be informed by the initial field visit. The Wetland Delineation Lead and Technical Lead will apply their experience in hydrological tracer studies to design and evaluate these options. For each option, the team will describe the proposed methodology, including existing data that would be used, new data that would need to be collected, and expected results and deliverables. The team will discuss feasibility, logistics, approximate study timing, duration and sampling frequency for field studies. The team will evaluate the confidence in expected results by discussing potential sources of error and risk for each study option and to which degree these uncertainties can be mitigated through study design or contingency plans. Wetland Delineation Options Comparison Memo: Using the information obtained, the research team will compare the study options based on several criteria and recommend a preferred option. Main criteria for selecting a preferred option will be: Feasibility, including access and safety considerations; Confidence in the expected results and their suitability to fulfill conditions of the Water Licence to inform the Great Slave Lake Monitoring Program, and potentially to provide data for other future work required; Hydraulic retention time of the FLTS; Cost; and regulatory permitting and related scheduling risks. The research team will summarize the results of the options comparison and recommend top-rated options in a draft memo for discussion with the City. Once the City has chosen a preferred option, the team will attend a meeting with regulators to discuss the chosen delineation method. Feedback from that meeting, if any, will be incorporated into the study design, prior to proceeding with the work. Delineating Wetlands - Regulatory Permitting: Once the wetland delineation option has been selected, the team will initiate work on the study, starting with applying for any required permits. The team anticipate that the project description from the options comparison task can be used for permit applications, but that fieldwork details, such as schedule and locations, will need to be defined at this stage as well. The team will therefore engage any subcontractors at this stage and develop a field plan for the wetland delineation study. Alternatively, permit applications may be submitted early on with general wording to minimize risks to the project schedule. Site Monitoring: Once the required permits are issued, the team will complete all on-site requirements to proceed with the recommended delineation option. In the preparation of the proposal budget, the team have conservatively assumed that the following study components will be conducted: LiDAR acquisition and analysis; Desktop flow path analysis using LiDAR -based DEM; and field-verification of identified flow paths using conservative tracers already present in the effluent and that are not expensive to analyze (e.g., chloride, conductivity). The team have assumed that a maximum of 20 samples will be collected from the helicopter in different water bodies that are potentially connected to the FLTS, plus at least two reference sites (i.e., water bodies at higher elevation that cannot receive flow from the FLTS). Data Analysis and Modelling: The research team will analyze any topographic data obtained to develop a DEM and based on the DEM, identify watershed boundaries and flow direction. The team will tabulate and analyze any collected field data as required with the ultimate outcome to delineate the flow path of effluent through the FLTS. The team will prepare maps that display the required information. The research team will also review the interannual variability of precipitation and discuss its potential effect on flow paths. In addition, if the FLTS hydraulic flow paths might be affected in the future with climate change impacting the overall hydrology. The team will assess this possibility qualitatively as part of the Wetland Delineation Study report. The team will discuss with the City at the kick-off meeting if a quantitative assessment of climate change impacts on the drainage flows is desired as an additional part of this project. The GSL Monitoring Program needs to achieve its objectives as set by the Water Licence requirements while being feasible and repeatable over time by the City. The team will aim to design a scientifically defensible program that builds on existing knowledge, captures the local effluent mixing conditions in GSL, and properly documents impacts on the GSL aquatic ecosystem. At the same time, the team will consider feasibility and cost, and provide the City with opportunities for input and decisions on monitoring design. The approach will leverage the knowledge of the study area from the work on the Nutrient Risk Assessment, the understanding of regulator and City perspectives gained through the Water Licence Renewal, and additional information gathered through the Wetland Delineation Study and other recent studies. Background Information Analysis: The research team will review available background information including existing reports and relevant documents. This will entail: Review of MVLWB’s Guidelines for Effluent Mixing Zones; Review of historical sampling data from the City’s Surveillance Network Program (SNP) stations (0032-10, 0032-F3, 0032-F1) in the area, results of the Great Slave Lake Nutrient Risk Assessment and other studies conducted in the FLTS; Comparison of findings from the wetland delineation study to proposed sampling plan from the Fiddler’s Lake Treatment System Management Plan and previous sampling design of Great Slave Lake Nutrient Risk Assessment; and review of travel time of effluent from decant structure to GSL based on existing information. This review will inform the selection of parameters, potential sampling locations (reference areas and impacted areas), sampling depth, sampling timing and frequency and sampling media (e.g., water, sediment, biota). Site Investigation: The research team will conduct a field visit (likely in form of a fly-over) to determine accessibility of the identified ideal and other potential sampling locations. This will help in identifying landmarks and marking geographic coordinates of sampling locations and thereby facilitate return to those same locations during the monitoring program. The team will coordinate this field visit with the site investigation for the wetland delineation study to minimize related travel costs. Costing Analysis and Regulatory Requirement Investigation: The research team will prepare a monitoring program, with the intent to find the right balance of collecting as much data as possible, while recognizing the need to find cost efficiencies where possible. Program components will be evaluated for costs as well as the ability of the program designs to achieve the program objectives. Costs can vary significantly with varying sampling timing and frequency, number of locations, and media sampled. For example, water quality sampling is most cost-effective while including sediment and biota, such as benthic algae and invertebrates, is more costly. The team will determine regulatory approval requirements for the sampling program. These will be part of the City’s considerations in selecting a preferred Monitoring Program Design. Timing is not considered an issue for permitting for the GSL Monitoring Program since the fieldwork will not start until late spring/summer 2023. Program Design Review Meeting with City: The research team propose holding a meeting with the City to review the proposed monitoring program. The team will present optional items and results of the costing analysis and regulatory requirement investigation and provide a recommendation on the preferred program design for submission to the MVLWB. The team will discuss and confirm the path forward for the Program Design Report with the City. In addition, the team will discuss how the GSL Monitoring Program could be incorporated in the future into the Surveillance Network Program and how that affects the program design and future implementation. The team feel that having this meeting prior to drafting the Program Design Report will be highly beneficial for the project as it will: Provide an overview of monitoring program options and cost implications to the City early on; Allow sufficient time to review program objectives and discuss trade-offs between obtained results and required resources; Develop a solid rationale and strategy to work with regulators to develop long-term monitoring requirements through the SNP; and help focus Associated’s reporting efforts on the Program Design Report and reduce rework due to City comments. Detailed Program Design and Monitoring Program Design Report: Based on the outcome of the Program Design Review Meeting with the City, the team will finalize the Monitoring Program Design and document it in a Draft GSL Monitoring Program Design Plan for review by the City. This report will include the monitoring design, rationale and maps, reference to previous monitoring recommendations and incorporation into the SNP. The team will consider comments from the City and submit to the MVLWB. Following MVLWB review, the team will support the City in responding to regulator feedback received, and revisions to the design plan as necessary. Implementation of the Sampling Program - Sampling Program: The research team will implement the GSL Monitoring Program for four years (2023-2026) after approval by the MVLWB and the City. The services for the sampling portion of the project will include, but not be limited to: Provide schedule with expected sampling dates to the City at the beginning of each year; Work with the City’s preferred laboratory to receive the necessary bottles and coordinate sampling events; Perform all sampling as required over the four sampling seasons of the project, including safety planning, field data collection, sample collection and monthly progress reporting; and preliminary review and QA/QC check of the data received after each sampling event. Annual Data Report Memo to the City: The research team will provide annual data summaries in a memo to the City, which will include findings from each sampling season when sampling for the year has been completed. These memos will include minimal data analysis, e.g., comparison to applicable surface water quality guidelines and any unusual results. The team will present the results in annual data review meetings to allow discussions on program successes and challenges and any adjustments to the program. GSL Monitoring Program Report to MVLWB: After completing four seasons of sampling, the team will prepare the Great Slave Lake Monitoring Program Report in 2026 for submission to the MVLWB as part of the Adaptive Management Plan. The report will include all items listed: Description of monitoring activities and mapped locations; Data summaries and interpretation; Recommendations for future monitoring; and a plain language summary. Communication to the community and First Nations will be conducted by the City of Yellowknife The fieldwork for this study will be conducted from August 16, 2022 to December 31, 2022