Several large, recent Canadian remediation projects have relied on excavating blocks of soils pre-classified on the basis of in-situ data. The approach has significant advantages when done well, including an exceptional level of cost estimate detail for the owner prior to tender. When done poorly, however, the approach can be misleading and difficult to execute. This presentation highlights a contractor’s experience with 3-dimensional pre-characterization at three large-scale Canadian sites (completed in 2016, in 2019 and in-progress).

In Case 1 (2016) is a large manufactured gas plant excavation extending into Victoria Harbour in Victoria, BC. 2-dimensional (2-D) “slice” plans were provided to the contractor for each metre of geodetic elevation, with up to four material classifications per slice. Each slice was loaded into a survey rover operating relative to a local base station, which was used for stakeout and verification. The use of geodetic elevation created irregular “blocks” at the surface and on slopes, but greatly simplified layout and logistics. A local construction laser could be used temporarily when multiple fronts were open or the rover would not work (for example, in deep shoring boxes).

In Case 2 (2019) is a former paint factory on Victoria Harbour. Slice plans were also provided in 2-D, one-metre-thick “slices”, but relative to original grade, which was sloped. This approach eliminated irregular shallow layers, but then left the contractor trying to maintain an irregularly-shaped bottom. Conversion to geodetic proved difficult as it would have required re-defining every waste “block”. The excavation was carried out with extensive in-pit survey, although deeper excavations along the foreshore used a global navigation satellite system (GNSS)-controlled (i.e., “grade control”) excavator. While the irregular bottom (relative to level geodectic) added complexity, the GNSS-controlled machine was able to adapt.

For Case 3, an on-going project in the Toronto Port Lands, lessons learned with respect to technology and machine control have been used to improve outcomes:

1. An owner-supplied 3-D model relative to geodectic was virtually “pre-excavated” well in advance of contractor mobilization to identify potential problem areas;
2. Separate 3-D analyses of the geologic model, groundwater model and inferred non-aqueous phase liquids (NAPL) distribution were assessed for zones of compressible materials, potential debris and the potential effects of dewatering; and,
3. GNSS (a.k.a., GPS) controlled equipment is being used to excavate to the limits of designated blocks (and/or to log the actual “as-dug” limits when chasing a given material type past the original block boundary). Machine positional information is uploaded to the cloud on a near-real-time basis, allowing visualization of progress and providing the first datapoint (position of origin) for cloud-based multi-mode soil tracking systems.

The use of machine-control technology and a 3-D model that can easily be translated into 2-D slices allows good tracking to the intended model, good documentation of necessary deviation from the model and reasonable excavation productivity. It also significantly improves site hazard management by largely excluding vulnerable survey crews from work within the excavator’s swing radius and/or close to steep slopes and wet pits.

The use of each various methods has strengths and weaknesses, and the aim of this presentation is to highlight these attributes and the potential for innovation with GNSS-controlled equipment. 

Nicholas Doucette, National Manager for Special Projects, QM Environmental

Nicholas Doucette, QM Environmental's National Manager for Special Projects, is a passionate advocate for innovation in the pursuit of safer, more sustainable environmental remediation projects. He has applied his civil engineering education from the University of Waterloo and the Swiss Federal Institute of Technology at some of Canada's most important and challenging environmental projects, literally coast-to-coast from the Sydney Tar Ponds in Nova Scotia to the Rock Bay site in Victoria, B.C. Nick’s areas of expertise include: large scale multi-disciplinary projects, water treatment, project documentation and project controls, design-build delivery and project management. He is fluent in both English and French.

At an acid rock drainage (ARD) remediation site in Northern Canada, Arcadis Canada Inc. manages seasonal water treatment operations to meet provincial water quality discharge requirements. In doing so, a vast quantity of data is generated within various categories: health and safety; operational; hydrologic; and, chemical. Historically, data was collected on paper forms, sometimes digitized on a spreadsheet, filed and rarely indexed. Spreadsheet tabulation involved manual data re-entry, and the data was presented for single-use cases and was generally siloed. Data analytics and visualization tools were used to implement more advanced data management protocols. The long-term strategic objectives involved:

1. Leveraging existing and incoming data to generate insights that improve site visibility, diagnostics, predictions, and the development of action plans;
2. Improving efficiency by standardizing and automating workflows; and,
3. Empowering stakeholders by developing self-serve analytics tools that can be used by individuals without a background in data science.

To accomplish these goals, the digital team prepared the existing data in a standard database schema. Existing data included historical operational data, historical chemical data and historical field measurements (e.g., sludge thickness). The data described above was then uploaded to a structured query language (SQL) server database (EQuiS by Earthsoft). For field-collected data, the digital team developed custom applications (that synchronized with the SQL server) on the field data collection platform, Fulcrum. For laboratory-provided data, database specialists were tasked with intercepting and loading laboratory electronic data deliverable (EDD) files to the enterprise EQuiS databases. Field personnel were given tablets and credentials to use Fulcrum. Additionally, field personnel were encouraged to install Fulcrum on their smartphones and were trained on its use. This raw data was automatically processed (if necessary) to produce useful information. Fields from SQL server databases were linked to paginated reporting structures on Microsoft’s SQL Server Reporting Service (SSRS). These SSRS reports allowed users to specify certain parameters and obtain a report showing project data and information within the search parameters.

The digital team developed self-serve dashboards for health and safety as well as operational data that allowed users to monitor site status and performance. The digital team worked with the project management team and subject matter experts to define thresholds and limits within the reports and dashboards that would act as triggers to alerts. For example, discharge pH values that fall outside of a certain range initiate such a trigger.

As a result of these activities, data management became far more streamlined at the site. Data is now only entered once for all modified processes, improving efficiency onsite. Data integrity was therefore also preserved since QA/QC activities need only be performed once and the most current data is always in the correct storage location. In addition, automated reporting allows users to quickly generate custom reports as needed in a variety of formats from any location. Furthermore, dashboards provide improved visibility by empowering the project team with statistical interpretations for the data as well as a platform to generate custom insights on-demand using intuitive and straightforward controls. In summary, digital technologies improved the technical performance, safety, and accessibility for stakeholders at this remote, northern project.

Omar Nawara, Environmental Engineer and Certified Project Manager, Arcadis Canada Inc.

Omar Nawara (PMP) is part of the Arcadis Canada Inc. team as an environmental consultant and Arcadis Certified Project Manager, providing project management, technical, and in-field support for a variety of Arcadis projects. With a Bachelor of Science in Environmental Engineering from the University of Saskatchewan, Omar works on a variety of initiatives, including digital transformation, water and soil quality monitoring programs, environmental remediation, project management, data interpretation, and water treatment. Omar is heavily involved in Arcadis' digital transformation and leads digital transformation initiatives in the Prairies.

The benefits of flux-based conceptual models derived from high-resolution site characterization are well understood for chlorinated solvents (CVOCs) and hydrocarbons – results indicate that more than 80 percent of contaminant mass flux is typically focused in less than 20 percent of the aquifer volume (Guilbeault, 2004). However, most practitioners are not aware that the approach can be used for emerging contaminants like per- and polyfluoroalkyl substances (PFAS). As a result, many are reverting to the use of monitoring wells and fixed laboratory analysis for investigating PFAS sites, rather than taking advantage of the latest developments in real-time, high-resolution site characterization. A mobile laboratory capable of producing reliable PFAS results for soil and groundwater in hours instead of weeks has enabled us to conduct adaptive characterization at PFAS sites for the first time. When combined with high resolution injection logging methods like the hydraulic profiling tool (HPT), the stratigraphic flux approach can map PFAS impacts within a mass flux framework to identify key transport pathways that help focus extraction-based remedies; currently the most likely option for PFAS risk management.

An adaptive approach for PFAS sites, can streamline site evaluation and reduce the expensive stepwise process of planning, investigating and reporting. A mobile PFAS laboratory, developed by Pace Analytical Services, Inc., has enabled real-time analysis of PFAS including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). The laboratory uses a solid phase extraction sample prep technique followed by liquid chromatography with tandem mass spectrometry (LC-MS-MS) analyses that are based on the Environmental Protection Agency (EPA) Method 537 (modified). The mobile lab is Department of Defense Environmental Laboratory Accreditation Program (DoD ELAP) (QSM 5.1) compliant and National Environmental Laboratory Accreditation Program (NELAP) certified and can provide fully defensible and cost-effective soil and groundwater data within a day of sample collection.

To date, we have deployed the PFAS mobile laboratory at two sites in the US with excellent results. Comparison of the mobile lab data to fixed laboratory results shows good correlation. The mobile lab was able to process up to 20 groundwater samples per day, which was sufficient to guide two drilling rigs and eliminate wasted borings and samples. The ability to evaluate PFAS sites in real-time and at high-resolution enhances our ability to efficiently characterize these sites and allows stakeholders to quickly understand the risk associated with this emerging issue, and to evaluate focused, efficient remedies – particularly important given the challenges associated with PFAS remediation.

John Vogan, Service Line Director, Arcadis Canada Inc.

John Vogan has 30 years’ experience in groundwater and soil investigation and remediation and is part of Arcadis Canada Inc.’s PFAS leadership team. He has been involved in many hydrogeologic assessments involving the sub-surface transport and remediation of PFAS, chlorinated solvents (VOCs), trace metals, and agricultural contaminants. Prior to joining Arcadis, John led a pioneering in-situ remediation company which established permeable reactive barrier groundwater treatment technology in the marketplace. John has co-authored over 30 technical publications and taught several short courses in collaboration with the US EPA and the Interstate Technology Regulatory Council (ITRC). He currently sits on the Advisory Committee of the Ontario Water Consortium.

The Rogers Pass site, located along the Trans-Canada Highway (TCH1) in Glacier National Park, BC, and the highest elevation point between Golden and Revelstoke, was historically owned and operated by the Canadian Pacific Railway (CPR) circa 1880s to 1919. During CPR ownership, a rail station and rail yard occupied the site. Parks Canada Agency (PCA) purchased the site in 1919 at which time the CPR rail yard had been abandoned and the remaining structures had burned down or were removed. Circa 1964, the site was developed to include the Glacier Park Lodge, Rogers Pass Discovery Centre and a service station on the west side of the TCH1, and a federally operated maintenance compound east of the TCH1. This site is currently listed under the Federal Contaminated Site Inventory (Site Number 18752001).

Due to historical site activities, both soil and groundwater contamination was identified extensively throughout the site. The Glacier Park Lodge and service station buildings were vacated in 2011, and in 2018, both buildings were abated and demolished. Following demolition, approximately 7,000 m³ of impacted soil was removed from multiple locations within the service station and Glacier Park Lodge footprints. The excavation was limited by the high groundwater table (~1m to surface), the location of existing underground and aboveground infrastructure and archeology considerations. Soil contaminants included benzene, toluene, ethylbenzene and xylene (BTEX); petroleum hydrocarbons (PHC) fractions; polycyclic aromatic hydrocarbons (PAHs); and, metals.

Groundwater at the site was historically impacted east and west of the TCH1. Contaminants include anions, BTEX, PAHs and dissolved metals. In addition, a thick layer of non-aqueous phase liquids (NAPL) was identified in the centre of the site that extends underneath the TCH1. Due to the following, groundwater remediation at the site proves challenging:

• Remote location;
• Short field season (site is snow covered up to eight months of the year);
• Constant public use and presence;
• Large fluctuation of groundwater levels across the site and seasonally (varies up to 8m across the site and up to 2m seasonally);
• Proximity of surface water receptors (within 5m of known groundwater impacts in some areas);
• Competing construction projects; and,
• Pre-existing high concentrations of sodium and chloride (background concentrations).

In order to effectively remediate groundwater to reduce the risk to human health and the environment and move the site towards closure, an in-situ chemical oxidation (ISCO) program was completed in October 2019 on the east side of the TCH1. Eight injection wells were installed and three existing groundwater monitoring wells were used for injection of remediation chemicals over a 10-day period. Results of the ISCO program are pending.

The identified NAPL covers an area of approximately 5,800m². Soil impacts range from approximately 3 to 15 metres below ground surface (mbgs). Groundwater impacts range from 3 to greater than 12 mbgs, with free product in some wells up to 2m thick. Based on the location and physical characteristics of the NAPL plume, innovative remedial solutions are being considered in order to reduce the risk to human health and the environment. The NAPL investigation is ongoing and results pending. 

The final objective of remedial activities at Rogers Pass is an accepted detailed quantitative human health and ecological risk assessment, site closure, removal from the Federal Contaminated Site Inventory and redevelopment of portions of the site to include various public uses.

Katelyn Zinz, Team Lead – BC Interior/North, Environment, WSP

Katelyn Zinz has over 10 years of environmental experience and is based in Kelowna, British Columbia. She currently manages the environmental team for WSP within the interior and northern BC and specializes in environmental assessments and contaminated sites. Katelyn also acts as the provincial lead for designated substances and hazardous materials and appreciates the challenges that multi-disciplinary projects present. Katelyn focuses on providing a client driven approach on projects and enjoys integrating and working with various stakeholder groups. She has managed and conducted numerous Phase I, II and III environmental site assessments and remediation programs. She is also skilled in environmental management, regulatory approvals, soil assessments, groundwater sampling programs, and soil profiling and mapping. Katelyn has hands-on knowledge of regulatory framework in Western Canada and she has managed projects involving federal governments, municipal governments, private developers and industrial clients.

Natural source zone depletion (NSZD) is increasingly being considered as a longer-term management strategy at sites impacted with light non-aqueous phase liquid (LNAPL) petroleum hydrocarbons (PHCs). Relatively significant NSZD rates of PHCs have been demonstrated at sites indicating passive processes for PHC depletion should be considered in site remediation as a complementary or alternative remedy to active remediation methods. While NSZD processes are conceptually well understood, there are limited field trials of methods and published case studies on estimation of NSZD rates and remediation timeframes.

A comprehensive applied research and development program has been conducted at a former refinery and terminal site from 2015−2019 on technologies for the measurement of NSZD rates of PHC source zones. The program included field trials where the following non-intrusive methods for measurement of surface CO₂ efflux above a shallow LNAPL source zone were compared: 1) E-FLUX static trap; 2) LI-COR dynamic closed chamber; and, 3) Eosense forced diffusion (eos_FD) chamber. The NSZD rates were estimated from CO₂ efflux measurements using radiocarbon (¹⁴C) corrections for natural soil respiration. Continuous thermal monitoring of the source zone using five multi-level RST digital thermarray strings (0.2- 5.6 m below ground surface) was additionally used to estimate NSZD rates from heat generated from biodegradation reactions.

The field trial at the former refinery and terminal site provides useful data on multiple methods for estimation of NSZD rates and the observed temporal and spatial variability in rates. The monitoring showed that seasonal conditions (primarily soil moisture) influenced temporal NSZD estimates that ranged from approximately 110 – 1300 US gal C₁₀H₂₂/acre/year (1030−12160 L/hectares/year). Estimates of hydrocarbon NSZD rates in the unsaturated zone from continuous subsurface temperature monitoring were of similar magnitude.

The broader application and use of NSZD rates in making decisions for evaluating remediation progress and evaluating transitions from active to passive remediation as part of the site management process is also discussed.

Anne Wozney, Junior Environmental Geoscientist, Golder Associates Ltd.

Anne Wozney is an environmental consultant of Golder Associates Ltd. located in Vancouver, BC, with a BSc. in Geology and a Masters in Earth Science from the University of Ottawa. Her graduate studies work focused on development of radiocarbon isotope correction methods for tracing hydrocarbon contamination in soil gas overlying hydrocarbon source zones and evaluating NSZD rates. Anne has been involved in implementing field trials at hydrocarbon impacted sites for assessment of NSZD since 2015. 

In the past ten years there has been a steady increase in the incorporation of metallic nanomaterials into commercial products with manufacturers seeking to take advantage of the unique properties these nanomaterials exhibit. Silver nanomaterials hold one of the largest market shares of nanomaterial-containing products for their use in textiles, food packaging materials, medical devices, and surface coatings. Active use of these products can result in the release of weathered silver nanomaterials into the environment with a potential for impacts. Research into impact and treatment of nanomaterial-contaminated waters currently use pristine spherical nanomaterials which fail to represent what is realistically released into environmental systems.

A Natural Sciences and Engineering Research Council of Canada Strategic Partnership Grant project was funded with partners from industry, government and international organisations to examine the practicality of generating and using of realistic nanoparticles in environmental transport, fate and effects studies. First, a simulated human weathering of commercial products method was developed and validated against human experiments. This allowed for in-depth characterization and large-scale generation of the released weathered nanomaterials. Second, the transport and fate of these weathered nanomaterials were investigated in subsurface, terrestrial and wetland systems. Finally, the use of constructed wetlands was investigated for their ability for long term sequestering of weathered silver nanomaterials.

The conclusion of this research identified that environmentally relevant weathered silver nanomaterials are characteristically different than what is commonly studied, and the incorporation of these materials is a necessity for proper investigation into realistic fate, transport and effects in environmental systems. It was also determined that both soils and wetlands can be effective at sequestering weathered silver nanomaterials, with no short-term detrimental effects. This research allowed for the development of a commercial product screening technique to be used to identify the contaminant release potential of imported products, as well as the development of a water treatment technology capable of effective removal of nanomaterials and other emerging contaminants.

David Patch, Research Assistant, Environmental Sciences Group, Royal Military College of Canada

David Patch is a PhD student under supervisors Dr. Kela Weber and Iris Koch under the Royal Military College of Canada. David investigates emerging contaminants in the environment including metallic nanoparticles and, more recently, PFAS. Alongside his PhD role he is also the analytical technician for the Environmental Sciences Group, a research group at the Royal Military College of Canada. His analytical technician work is also focused on PFAS, with David providing technical and analytical assistance on over fifteen different PFAS projects across the areas of source characterization, fate/transport, and remediation.