Along the eastern shoreline of Great Slave Lake, only a small automated weather station operated by Environment and Climate Change Canada (ECCC) remains in operation at the remote Fort Reliance Weather Station. However, the property has historically served as a base of operations for numerous federal organizations, including an RCMP detachment (starting in 1927), a Department of National Defence Aviation Weather Station (1948-1970), and the weather service (originally the Atmospheric Environment Service) who operated a fully manned facility between 1959 and 1991. Public Services and Procurement Canada, on behalf of ECCC, retained Tetra Tech Canada in 2017 to conduct an initial gap assessment. The program has continued since, and the team has now completed an archaeological assessment, borrow material assessment, hazardous materials assessment, remedial options analysis and action plan, detailed design and cost estimates, stakeholder engagement, tendering and remediation implementation in short succession.

The site’s location and varied history resulted in numerous challenges related to site operations, timing, and access during the investigation, remediation and decommissioning of this remote site, including:

• No road access to the site, and the lack of an airstrip meant that staff and heavy equipment access is only available by fixed wing aircraft on floats or skis, helicopter, or barge (if timing aligns with scheduled community servicing routes), all of which are highly weather-dependent.
• The short field season due to the site’s northern location limited the ability to conduct multiple field programs in a year, resulting in a higher degree of preparation required.
• Accommodations near the site are limited, and at various times required combinations of daily boat trips, rotating assessment teams, and daily helicopter mobilization from the nearest community, LutselK’e.
• The risk of delays due to bird nesting required an early season trip to site prior to site remediation in order to restrict access to potential nesting sites.
• Presence of poor condition, designated heritage buildings on-site necessitated a pre-season site visit to allow for the required pre-demolition surveys.
• The short season, combined with the desired remediation schedule and federal government tendering requirements, resulted in an accelerated design and tendering process.

Nick Oke, Senior Vice President, Environment and Water Practice, Tetra Tech Canada
Nick Oke, M.Sc., P.Chem., is the Senior Vice President for Tetra Tech Canada's Environment and Water Practice, based in Edmonton, Alberta. He has 24 years of experience in consulting, research and industry positions. His areas of expertise include arctic site remediation, project and program management, contaminated site assessments, industrial facility decommissioning and environmental compliance auditing. During the past twelve years he has focused almost entirely on project management for remote, arctic projects for federal government clients. These projects have included the site investigations and remedial designs at abandoned military facilities (DEW Line and navigational sites) and high arctic weather stations, which have resulted in strong understanding of the unique challenges posed by working at remote sites in the Canadian Arctic. Additional experience managing a multitude of multidisciplinary engineering and environmental projects related to the Giant Mine Remediation Project has resulted in strong understanding of the requirements of working with federal government clients.

In March 2008, an estimated 14,000 litre diesel spill occurred from a transport truck roll over at Portage 32 of the Tibbitt to Contwoyto Winter Road, approximately 100 metres (m) upgradient of a freshwater lake. Emergency response included excavation and removal of most highly impacted snow and soils (based on visual staining) over an area approximately 10 m by 5 m by 1 m deep, where excavation was halted due to frozen ground conditions.

Due to the remote location, access is by winter road from January to March and helicopter during summer. Natural drainage is southeast, towards the nearby lake. The bedrock geology is consistently granitoid with small scale quartz lined fractures. No major faults or intrusions were mapped at the site and the bedrock surface has undergone glacial scouring. Surface sediments consist of boulders and organic soils to a depth of 1.0 to 1.5 m where bedrock does not outcrop. The spill site is in a low-lying bedrock area, surrounded by granitoid ridges.

From 2008 to 2011, 37 monitoring wells and four well points were installed to assess and delineate groundwater impacted with hydrocarbons. In 2011, a risk assessment indicated potential receptors include freshwater aquatic life via surface water/groundwater and wildlife via soil contact. A remediation options evaluation was conducted that suggested in-situ chemical oxidation would be a viable option given the remote location. An evaluation of candidate chemical oxidants suggested PermeOx® Plus calcium peroxide oxygen releasing compound was suitable and was subsequently injected in 2012 and 2013 into wells containing detectable concentrations of hydrocarbons.

Prior to the injection of PermeOx® in July 2012, a total of 12 wells contained concentrations of hydrocarbons (benzene, toluene, and ethylbenzene) exceeding guidelines in the July or September sampling that was conducted each season. Following the injection, hydrocarbon concentrations significantly reduced in the wells. In September 2013, only six wells contained concentrations of toluene, naphthalene, and/or pyrene which slightly exceeded guidelines.

The remediation performance was evaluated by comparing the theoretical decrease (decay) of hydrocarbons (toluene and ethylbenzene) based upon natural processes to the observed concentrations after the application of PermeOx®. The observed concentrations were significantly less than theoretical concentrations suggesting the addition of PermeOx® was effective at reducing hydrocarbon concentrations.

An assessment was conducted to estimate the concentration of toluene that could potentially be reached at the nearby lake based upon the residual concentrations measured in 2013. The assessment was conducted using Alberta Environment’s steady state model for contaminant migration. This model is used for the development of site-specific guidelines for the protection of groundwater resources under Alberta’s Tier 1 and 2 frameworks, accounting for the processes of dispersion and biodegradation. The results of the assessment indicated that concentrations of toluene could reach the lake on the order of 10 orders of magnitude less than guidelines.

The remediation program was anticipated to reduce concentrations to below guidelines in the next year or two. Effective in-situ remediation of hydrocarbons can be achieved in remote northern areas.

Steve Mailath, Principal Hydrogeologist, Trace Associates Inc.
Steve Mailath is a Principal Hydrogeologist at Trace Associates Inc., with over 36 years of experience in the environmental consulting field for a variety of industries. His specialties are the assessment of soil and groundwater contamination, migration processes, contaminant fate, groundwater remediation and management, groundwater resource evaluation, management and licensing, analytic and numeric groundwater modelling, remediation technology development regulatory liaison, surface and groundwater interaction, and expert testimony. His expertise includes municipal and industrial waste contaminant fate, impact evaluation, and risk assessment. He has prepared industry guidelines and has been an instructor at courses and workshops for contaminant assessment, remediation, and environmental impact assessment.

Cleanup of Abandoned Northern Sites (CLEANS) is a multi-year project to assess and reclaim 37 abandoned uranium mines/mills in northern Saskatchewan. The sites were used for uranium exploration and extraction in the early 1950s and were mostly abandoned by the mid-60s with little or no remediation. The overall purpose of Project CLEANS is to eliminate or significantly reduce on-site environmental and public hazards using the best available practices for mine site closure. The Saskatchewan Research Council (SRC) manages the project on behalf of the governments of Saskatchewan. The final stage of site remediation includes revegetation of all disturbed areas using passive and active techniques.

There are a lot of limitations for vegetation recovery on the remediated sites, such as poor growth media, limited soil depth, and complex topography with many steep slopes prone to erosion. SRC is committed to use only native plant species for revegetation, which is associated with many challenges, such as limited knowledge of native plant species suitable for revegetation under harsh local conditions, lack of propagation material in the Canadian market, and need for special seeding equipment capable of operating on stony substrates and uneven terrain.

Since 2011, SRC has been conducting extensive research to identify native plant species suitable for growing on poor soil conditions in a northern environment and the most efficient soil treatments to promote the plant growth. The research included a desktop review of applicable guidelines and scientific literature, observation of early stages of natural succession in this region, greenhouse and field trials with different plant species and soil treatments, and sustainability assessment for selection of a revegetation option with the best balance of environmental, social and economic aspects. It also included a traditional knowledge component including indoor and outdoor workshops with local Indigenous community representatives to get their feedback regarding proposed revegetation plans and advice on which plants they would like used for revegetation. Based on the research outcome, over 50 ha of disturbed sites were revegetated with the application of various techniques. The presentation will provide an overview of the revegetation research with a focus on how it benefited the revegetation planning and contributed to overall project success. Alexey Klyashtorin, Senior Environmental Scientist, Saskatchewan Research Council

Working in remote areas of the Northwest Territories can present a multitude of challenges, both for the engineering aspects of remediation and the necessary engagement with impacted communities and other stakeholders. The Bullmoose-Ruth Remediation Project was a complex undertaking. The project involves seven Indigenous partner communities and non-Indigenous stakeholders ranging from mineral lease holders to remote lodge owners to the Canadian Armed Forces. The project consisted of seven abandoned mines in a remote part of the North Slave Region and required the construction of 270 km of winter access roads and unique remedial engineering approaches designed for extreme climatic conditions. This presentation will explain the socio-economic adaptive approaches, as well as the engineering adaptive approaches, that were used to successfully complete the remediation between 2016-18.

Adaptive decision-making was used to create solutions to emerging problems that fit the structural constraints in the human and biophysical environment. Adaptive engineering approaches were used to solve the remote, northern and site-specific challenges. The seven sites within the Bullmoose-Ruth Remediation project were all abandoned gold mines or explorations sites: Bullmoose Mine, Ruth Mine, Spectrum Mine, Beaulieu Mine, Joon Mine and the Chipp and Storm exploration sites. These sites were active between the 1940s and 1980s and are located 80-95 km east of Yellowknife, NT. Between September 2016 and July 2018, the following remedial measures were undertaken: closure of 13 mine openings; removal of 11,618 m3 of metal impacted soils, sediments and tailings; treatment of 7,082 m3 hydrocarbon-impacted soils; and, off-site disposal of 2,231 m3 of non-hazardous waste and 433 m3 of hazardous waste. The project included the winter construction of engineered landfills; reconstruction of a length of the Bullmoose Creek; installation of monitoring infrastructure and instrumentation; and, construction of engineered hydrological controls.

The remediation phase of the project is complete; however, monitoring will continue for an initial five-year period, at which time site conditions and monitoring approaches will be reassessed. The use of adaptive decision-making throughout the project allowed for changes, modifications and solutions based on field conditions, available resources and close collaboration with team members and stakeholders. The project team was able to find both engineering solutions and engagement solutions that benefitted the project with a completion date a full year ahead of schedule. This presentation will discuss these optimizations, and how the close collaboration with Indigenous partners allowed for a more efficient and successful project completion.

Ron Breadmore, Project Manager, Contaminated Sites and Remediation Division, Crown-Indigenous Relations and Northern Affairs Canada
Ron Breadmore has been a Project Manager with CIRNAC-Contaminated Sites and Remediation Division since 2007 and has successfully closed out a number of contaminated sites projects including Colomac, Axe Point, Great Slave Lake and Bullmoose-Ruth.

The Marwell Tar Pit, located in the heart of the City of Whitehorse, was the Yukon Territory’s largest single-source hydrocarbon contaminated site. The Tar Pit’s origins date back to the mid 1940’s when hydrocarbon waste stemming from post-World War II refinery decommissioning was dumped into a former large-scale tank berm at the site. Over the years the site became an unlicensed dump site for local residents and businesses to dispose of liquid waste. The liquid waste remained exposed until the early 1960’s when the Tar Pit was capped with gravel for safety reasons.

Ongoing environmental assessment of the Marwell Tar Pit began in 1990, and in 2011, the governments of Canada and Yukon commissioned a multi‐phase remediation project of the tar pit with the federal government providing 70% of the funding for the remedial activities. Milestone and technical partner Iron Creek were retained in the spring of 2018 by the Yukon Government for the clean-up of this complex and interesting legacy contaminated site. The remediation of the Marwell Tar Pit was successfully completed in the fall of 2019.

A sustainable and innovative approach was selected for the management of tar saturated contaminated soils by treating the soils on site using an enhanced thermal conduction (ETC) technology. Using this unique thermal process, Milestone and Iron Creek were able to work throughout the unpredictable climate extremes of the north and effectively break down the recalcitrant hydrocarbons associated with tar. Remediation activities were seamlessly completed through all four seasons. Soils were successfully treated by the ETC process to a standard that allowed for soils to be used as backfill in the excavations, avoiding the need for offsite disposal of soils.

Many challenges were encountered during the remedial program, including technical issues, logistics challenges and extreme northern weather events. This presentation will highlight the creative approach used to manage the project along with the successes and lessons learned during the remediation of this challenging northern site.

Eric Pringle, Regional Manager, Western Region, Milestone Environmental Contracting Inc.
Eric Pringle, Regional Manager, Western Region, Milestone Environmental Contracting Inc., based in Langley, BC. Eric has over 30 years of experience in the environmental and remediation industry. As a Partner and Regional Manager with Milestone, he leads a team of engineers, scientist, and major project and technical specialist in the fields of environmental remediation and specialized contracting. As a Regional Manager, he is responsible of several private and public accounts for environmental remediation projects and initiatives for various industries, indigenous communities, all levels of government and agencies throughout Canada. As a professional engineer, Eric is well known for his extensive experience in brownfield redevelopment and environmental contracting. Eric also serves as a senior technical peer reviewer for the entire project team. Under his leadership, Milestone has experienced exponential growth, and has led to Milestone being ranked and listed as one of Canada’s 500 fastest growing company in 2019, by the Canadian Business and Maclean Magazines GROWTH 500.

Before joining Milestone, Eric was a Principle and VP at Hemmera Envirochem Inc. from 2000-2014, Manager Pacific Region with Conor Pacific ET from 1997-2000, and was an Environmental Engineer with Gartner Lee Limited from 1988-1996.

Earthmaster Environmental Strategies Inc. has successfully developed and implemented plant growth promoting rhizobacteria (PGPR) enhanced phytoremediation systems (PEPSystems®) for cost effective removal of petroleum hydrocarbons (PHCs), polycyclic aromatic hydrocarbons, and salt from soils. PEPSystems facilitates the production of abundant root biomass and the exponential growth of rhizobacteria which facilitates degradation of PHCs and sequestering of salt into plant foliage. It has been successfully deployed on many sites across seven Canadian provinces and territories to remediate PHC and salt contamination in soil and has provided significant cost savings and has proven to be very effective in remediating soils in remote/northern areas, where harsh conditions and permafrost exist, and access to landfill facilities is not practical.

This presentation will detail phytoremediation activities, field results and final site closure requirements associated with remediation of PHC and salt contaminated soil at a remote Northwest Territories well site. PEPSystems was first deployed at the Nota Creek C-17 site near Norman Wells in 2008 to treat historical oil and gas related contamination. Between 2008 and 2010, the surface soil containing elevated salt levels was successfully phytoremediated. In 2011, PHC contaminated soil from the on-site sumps and pits was partially excavated and placed upon the on-site treatment area or stockpiled for future treatment. This excavated soil was successfully phytoremediated between 2011 and 2016. In the winter of 2017, the remaining in-situ PHC impacted soil was excavated from the pits and sumps, was placed onto the treatment area and was successfully phytoremediated. Backfilling the excavations and recontouring the site using the treated soil plus re-vegetation of the site was completed in 2018 to comply with Northwest Territories reclamation requirements. Overall remediation costs were significantly less than if offsite landfill disposal or other non-passive remedial technologies would have been utilized. Kinetic modeling of PEPSystems performance will also be discussed as the basis for predicting the length of time required to remediate PHC contaminated sites.

Elizabeth W. Murray, Senior Scientist, Earthmaster Environmental Strategies Inc.
Elizabeth W. Murray, Ph.D., P.Biol., R.P.Bio., is a senior scientist with Earthmaster Environmental Strategies Inc. in Calgary, Alberta. Her background is in human genetics and she has worked for more than 20 years in medical related research and in plant-based biotechnology, developing biologics as treatments for human diseases. Elizabeth has worked in environmental sciences for over seven years and plays a lead role in PEPSystems® research and development as well as the analysis and reporting of phytoremediation research and results.