Fate of heavy metals in lagoon and wetland wastewater treatment systems and quantification of relative impacts to downstream aquatic systems
Principal Investigator: Jamieson, Rob (1)
Licence Number: 16610
Organization: Centre for Water Resources Studies (CWRS), Dalhousie Univerity
Licensed Year(s): 2019
Issued: Aug 08, 2019
Project Team: Dr. Leah Boutilier; Jenny Hayward

Objective(s): To understand the levels and treatment of heavy metals in Sewage Disposal Facilities and Solid Waste Disposal Facilities in the NWT.

Project Description: This licence has been issued for the scientific research application No.4511.

The overall objective of this study is improved understanding of heavy metals in Sewage Disposal Facilities (SDFs) and Solid Waste Disposal Facilities (SWDFs) in the NWT. The proposed study aims to answer the following questions: 1) What is the existing treatment capacity of SDFs in NWT for heavy metals? 2) Are SDFs “hot spots” for heavy metals and legacy metal contamination or are they effective at treatment of heavy metals? 3) Are wetland treatment areas a natural geological source for some heavy metals (e.g. Arsenic)? And, 4) What are the cumulative impacts of these potential heavy metal “hot spots” on receiving water environments?

This research will assess the cumulative impacts of heavy metals in SDFs and SWDF leachate on receiving water bodies, and characterize their relative contribution to environmental and human health risks.

Phase 1: Desktop data mining and analysis will be conducted for 5 to 7 sites identified by NWT decision-makers and the Cumulative Impacts Monitoring Program (CIMP) steering committee. Data mining and analysis will include water quality data, with focus on heavy metals in SDFs and SWDF leachate and downstream aquatic systems, using existing compliance monitoring and community-based monitoring data available through the Surveillance Network Program (SNP) monitoring database. CCME Water Quality Guidelines for the Protection of Aquatic Life (PAL) will be used as a comparison and an indicator of relative impact on the environment (including treatment wetland areas) to highlight parameters of potential concern. Statistical analysis will also be used to compare sites against one another and CCME Water Quality Guidelines. Based on the outcomes of the desktop analysis, two priority sites will be selected for monitoring during Phase 2; decisions will be finalized in consultation with NWT decision-makers and the CIMP steering committee. Other factors that will be considered will include degree of legacy contamination, SDF type, SWDF leachate management, climate, latitude, logistics, and value to decision makers.

Initial site and community reconnaissance will be carried out after phase 1 is complete. Establishing community contacts and engagement mechanisms will be the primary focus of this first visit to ensure local knowledge is incorporated into the detailed monitoring plan. Examples of important information associated with this study will include timing of freeze/thaw cycles, presence and timing of animal traffic in wetland treatment areas and receiving water bodies, potential locations of control sites (un-disturbed water body), and popular locations for local food harvesting (especially fish). Members of the research team will visit the two priority sites during this trip and gather information that will help inform and finalize the detailed monitoring plan. During this time, key community members who may be interested in working as part of the monitoring team will be identified.

For each sampling event water levels and wetland flow rates will be measured at wetland treatment area inlets and outlets as a minimum, and at locations of other potential surface water inputs (e.g., SWDF leachate). Water samples will be collected from each study site from the following locations: source drinking water; control site; raw sewage; SWDF leachate; non-sewage effluent (if applicable), at least 3 locations within the lagoon; 6 locations in treatment wetland areas; and upgradient and downgradient of the effluent discharge in the receiving environment (~6 locations). Sediment/soil samples will be collected from lagoon sludge; wetlands; and receiving water benthic environments; for a total of approximately 30-35 samples per study site, including duplicates (10%). The community member partners will be consulted to inform the siting of sample locations. Water samples will be analyzed for basic water quality indicators including total suspended solids (TSS), alkalinity, major cations/anions, oxidation-reduction potential (ORP), pH, turbidity, specific conductance, temperature and ph. Water velocities and channel morphology will be characterized throughout the wetland systems to identify areas of resuspension and deposition. Collected water and sediment samples will be preserved accordingly and transported back to Dalhousie University labs for analysis including metal concentrations (total and dissolved in water and soil), total and dissolved organic matter (water), organic matter (soil), cation exchange capacity (soil), and grain size analysis (soil). A comprehensive suite of metal parameters of interest will be included in the detailed monitoring plan and approved by the CIMP steering committee.

After the monitoring plan is complete, the research team will focus on reporting and dissemination of findings. Data will be made accessible online through the NWT Discovery Portal, Mackenzie DataStream, and NWT CIMP. Results will be communicated with community members throughout the study during site visits and through conference calls and email correspondence. All written communication with the community, such as plain language reports, will be translated into the local language.

The project team has established partnerships with the NWT Government Departments of Health, Environment and Natural Resources, Community and Government Affairs, and 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.

The fieldwork for this study will be conducted from August 23, 2019 to August 31, 2019.