Toronto

The presentation will cover basic site geology and hydrogeology and the initial distribution of contaminants at the site. The focus will be on the initial remedial injection process and the challenges that occurred due to structural and geotechnical issues that were not readily apparent during the planning stages and the steps that were taken to overcome these issues. At this time the presentation will cover how we were able to keep progressing towards the remediation goals with making modifications to the in-situ program. The analytical results from the performance groundwater monitoring and sampling will also be presented pending the amount of time allowed for the presentation.

Background. In situ chemical oxidation (ISCO) has been used to treat organic contaminants of concern (COCs) at thousands of sites around the world. This technology originated in the 1980’s with the application of unstabilized hydrogen peroxide. Over time ISCO has evolved to include chemistries based on ozone, sodium and potassium permanganate and sodium and potassium persulfate. Each ISCO technology supplies a thermodynamically powerful electron acceptor which results in the oxidation of many organic contaminants. Approach. The evolution has been driving by both the identification of new effective chemistries, adjustments based on lessons learned and site-specific requirements. Current best practices consider key site characteristics and objectives and how those interact with the selection of the proper ISCO chemistry and application method and have matured beyond only chemical efficacy but also evaluate proper dose, rate of release of the oxidant, application method and monitoring programs. Key points of evolution include: • Development of multiple oxidative technologies typically based on hydrogen peroxide, permanganate, ozone and persulfate. • Identification of reductive pathway with activated persulfate and hydrogen peroxide chemistries that were attributed to the superoxide radical allowing ISCO technologies to be used to treat even completely oxidized compounds such as carbon tetrachloride. • The use of low solubility oxidants for extended release allowing for treatment over a longer period of time (extended release). • Updates in injection strategies including injecting into a larger percentage of an effective pore volume. • The use of solid slurry emplacement to inject the extended release oxidants. • The use of soil mixing to overcome issues with site heterogeneity issues including site geology and contaminant distribution.

Sites with Dense Non-Aqueous Phase Liquid (DNAPL) are notoriously difficult to remediate. Advances with in-situ remediation methods and products in recent years has resulted in DNAPL remediation success. This presentation will provide a review of a new product, CAT 100 and its applications on chlorinated solvent sites with suspected or measured DNAPL. CAT 100, a biologically enhanced version of the Trap and Treat® BOS 100® technology, combines activated carbon impregnated with metallic iron, a complex carbohydrate (time release substrate), a consortia designed to degrade chlorinated solvents and a second consortia designed to breakdown the polymeric carbohydrate to monomeric fragments. These smaller substrate fragments are then efficiently used by the CVOC degraders. The science behind CAT 100 and project summaries with supporting lines of evidence for the degradation processes (e.g. dissolved gases and microbiological diagnostics) will be covered. Site 1. A former dry cleaning facility in Northern Europe, where a large PCE plume was impacting groundwater on and off-site. In 2017, CAT 100 and BOS 100® were applied as part of a large-scale remediation program after a large scale Remedial Design Characterization (RDC) was performed. Currently, a 95% average reduction in PCE concentrations has been observed in the monitoring wells located in the areas targeted by the remediation. Site 2. CAT 100 was successfully implemented as part of a combined remedies (BOS 100® and Sodium Permanganate were also applied) strategy to treat elevated levels of Trichloroethylene in a shallow fine grained aquifer at a former large industrial facility. Total chlorinated ethene (TCE, cis-1,2 DCE, and VC) concentrations in the source area have been reduced by over 97% in less than 12 months. Site 3. A former chemical plant that stored hydrogen peroxide, MIBC, PCE, acetone, ethanol, and diesel fuel was remediated using a phased combined remedies approach. The interim corrective action was completed in 2013-14 and included 1) an off-site in-situ permeable reactive barrier utilizing BOS 100® to capture dissolved impacts leaving the facility and 2) shallow soil mixing activated persulfate (lime activation) to mitigate unsaturated soil impacts adjacent to source media. In addition, five phases of CAT 100 injections have been completed at the site since 2016. Total solvent concentrations have been reduced 96-99% in the CAT 100 treatment areas to date.

Located in the southwest corner of Hamilton Harbour, in the Port of Hamilton, the Randle Reef site is approximately 60 hectares (120 football fields) in size. The site contains approximately 695,000 cubic metres of sediment contaminated with polycyclic aromatic hydrocarbons (PAH) and other toxic chemicals – the largest PAH-contaminated sediment site on the Canadian Great Lakes. Impacted by historic operations this site has a legacy of a variety of past industrial processes dating back to the 1800s. There were multiple sources of contamination including coal gasification, petroleum refining, steel making, municipal waste, sewage and overland drainage. Environment and Climate Change Canada (ECCC) serves as the project lead and Public Services Procurement Canada (PSPC) provides technical and construction management, and procurement services. Setting: Active port; average total PAH concentration near 5,000 ppm with peaks over 73,000 ppm; Depth of Water: ranges from ~4 m to ~ 12 m; Sediment Depth: ranges from ~0.1 m to >3 m. This project included the design of a remediation plan that included constructing a 6.2 hectare Engineered Containment Facility (ECF) over the highly contaminated sediment (Stage 1) and using a combination of hydraulic and mechanical dredging to remove approximately 445,000 m3 of contaminated sediment and placing within the ECF (Stage 2). The ECF is made of double steel sheet pile walls with the outer walls driven to depths of up to 24 metres into the underlying sediment. The inner wall is sealed creating an impermeable barrier. The dredging of the contaminated sediments also involved the treating and dewatering the ECF to balance the water input into the ECF. This involved the design/build of a water treatment plant that would match the input of the dredging and balance the water level within the ECF. Dredging was followed by Thin Layer Capping of marginally contaminated sediment and Isolation Capping of the Stelco Intake/outfall channel sediments. Following the dredging the ECF will then be covered by a multi-layered environmental cap accompanied with consolidation and dewatering of the sediments (Stage 3). This presentation reviews the unique considerations and challenges faced following the discovery of contamination in a previously unidentified wetland that served as a key source of traditional medicine for the community. The problems within the wetland were further aggravated by high water levels and species at risk which introduced additional constraints to a final remedy. A phased approach was adopted that included source removal of impacts adjacent to the wetland from targeted areas and the completion of a risk evaluation and functional assessment of the wetland for successful management of the remaining impacted areas of the wetland. Further field data collection was necessary to address data gaps and included soil/sediment sampling and analysis of medicinal plants located in the wetland. Stakeholder collaboration (MBQ and Indigenous Services Canada) and the implementation of an environmental monitoring program during construction was critical to the success of the phased approach for the remediation and risk management of the wetland. In addition, in collaboration with MBQ, the planned excavation of impacted soil in heavily forested area was curtailed as risks were evaluated and a mitigation plan was incorporated into the design.

Located in the southwest corner of Hamilton Harbour, in the Port of Hamilton, the Randle Reef site is approximately 60 hectares (120 football fields) in size. The site contains approximately 695,000 cubic metres of sediment contaminated with polycyclic aromatic hydrocarbons (PAH) and other toxic chemicals – the largest PAH-contaminated sediment site on the Canadian Great Lakes. Impacted by historic operations this site has a legacy of a variety of past industrial processes dating back to the 1800s. There were multiple sources of contamination including coal gasification, petroleum refining, steel making, municipal waste, sewage and overland drainage. Environment and Climate Change Canada (ECCC) serves as the project lead and Public Services Procurement Canada (PSPC) provides technical and construction management, and procurement services. Setting: Active port; average total PAH concentration near 5,000 ppm with peaks over 73,000 ppm; Depth of Water: ranges from ~4 m to ~ 12 m; Sediment Depth: ranges from ~0.1 m to >3 m. This project included the design of a remediation plan that included constructing a 6.2 hectare Engineered Containment Facility (ECF) over the highly contaminated sediment (Stage 1) and using a combination of hydraulic and mechanical dredging to remove approximately 445,000 m3 of contaminated sediment and placing within the ECF (Stage 2). The ECF is made of double steel sheet pile walls with the outer walls driven to depths of up to 24 metres into the underlying sediment. The inner wall is sealed creating an impermeable barrier. The dredging of the contaminated sediments also involved the treating and dewatering the ECF to balance the water input into the ECF. This involved the design/build of a water treatment plant that would match the input of the dredging and balance the water level within the ECF. Dredging was followed by Thin Layer Capping of marginally contaminated sediment and Isolation Capping of the Stelco Intake/outfall channel sediments. Following the dredging the ECF will then be covered by a multi-layered environmental cap accompanied with consolidation and dewatering of the sediments (Stage 3).

Permeable Reactive Barrier’s (PRB’s) using transitional metals such as Zero Valent Iron (ZVI) to target organic and inorganic contaminants in-situ have been in use since the mid-1990s. This approach for groundwater treatment has seen tremendous growth since its inception due to its reliability and cost-effectiveness. Reactive Barrier technologies have also expanded to include novel installation and deployment techniques as well as novel amendments to improve performance and target a wider range of contaminants. Even with all this growth, ZVI and the “traditional” approach remains a staple of the PRB marketplace. With an increasing demand for cost-effective groundwater management solutions, a growing number of professionals and stakeholders are turning to PRB-based solutions to meet their site goals. Fueled by the many success stories and abundance of available information, many consultants and their clients are tackling program design and installation from the comfort of their chairs. But are we looking at the installation of PRB’s through rose coloured glasses? What does it actually take to translate conceptual design into a successful solution in the field? The purpose of this talk is to share some of the lessons learned from the installation of one of the largest “traditional” ZVI PRBs completed in North America. The site is a former industrial facility with legacy chlorinated solvent issues (mainly TCE and daughter products). The management of off-site migration was a critical part of the CPU to facilitate site redevelopment. A critical RMM included the installation of a 400 m, ZVI based permeable reactive barrier system to control plume migration. The site conditions necessitated the creative use of multiple installation procedures; the wall was installed via a blended approach utilizing direct push injection and trenching techniques, to address the complex plume structure. In total, over 400,000 kgs of ZVI was installed across 335 m of linear injection points and 65 m of trenching to complete the PRB installation to depths of up to 9 meters. Our focus in sharing this case study will be down-to-earth and practical. How does a contractor actually install a PRB? What techniques are being used in the field and why? How can you creatively problem solve to address technical and logistical challenges? And most importantly, how do we balance these challenges while completing a project on time, on budget, and with the ultimate goal of an effective PRB installation.

In the midst of a booming construction industry comes new legal requirements to manage excess soil. As of January 1, 2022, Ontario’s excess soil laws were in full legal force and effect. Quebec regulates contaminated excess soil and has recently published new regulations about electronic tracking of same. British Columbia is considering changes to its soil relocation laws. As these new and emerging excess soil regimes come into legal force, projects that generate excess soil will impose obligations on construction and waste management industries, consultants, contractors, municipalities, land owners, and developers. These various parties now face or will soon face new legal risks and requirements. Join Willms & Shier lawyers as they review: what is excess soil, who can be liable under new excess soil laws, and tips for managing the legal risks.

In the midst of a booming construction industry comes new legal requirements to manage excess soil. As of January 1, 2022, Ontario’s excess soil laws were in full legal force and effect. Quebec regulates contaminated excess soil and has recently published new regulations about electronic tracking of same. British Columbia is considering changes to its soil relocation laws. As these new and emerging excess soil regimes come into legal force, projects that generate excess soil will impose obligations on construction and waste management industries, consultants, contractors, municipalities, land owners, and developers. These various parties now face or will soon face new legal risks and requirements. Join Willms & Shier lawyers as they review: what is excess soil, who can be liable under new excess soil laws, and tips for managing the legal risks.

The environmental industry has experienced steady evolution since the “good old days” of “dig and dump” as advances in science, technology, regulation and broader societal trends, like sustainability, have taken place. Since the early days when remediation was only driven by heavy metal contamination in soil and only addressed via excavation, environmental remediation technology has evolved dramatically. Remedial designs now consider hundreds of contaminants in soil, groundwater and soil vapour and at concentrations as low as parts per trillion. Additionally, our greater understanding of the subsurface now requires us to consider complex processes such as vapour intrusion and diffusion-controlled contaminant migration to increase the effectiveness and certainty of in-situ remediation approaches. The author’s experience from over 30 years of environmental consulting and remediation contracting will provide insights into the dramatic evolution that has occurred over this period by discussing advances in the understanding and characterization of site conditions; better-engineered remedial amendments; advances in application technologies; and the use of detailed interim data collection to assist in optimizing remedial programs and outcomes. Upon review of the past, it is hoped environmental practitioners and stakeholders will gain a more thorough understanding of the current state of remediation in Canada, what is possible, what is not, and potentially what the future of our essential sector may hold.