2019 SMART Remediation Toronto – January 24, 2019

Norman Rankin, MECP
Communicating Effectively with the MECP
Bio | Abstract | Presentation

Jacquelyn Stevens, Willms & Shier Environmental Lawyers LLP
Court Upholds MECP’s EPA No‐Fault Order Requiring Off‐Site Soil Vapour, Groundwater and Surface Water Investigation
Bio | Abstract | Presentation

Carl Spensieri, Berkley Canada
Managing Real Estate (re)Development Risk & Environmental Insurance
Bio | Abstract | Presentation

Bithun Sarkar, Jacobs
“Where is the NAPL” – Understanding NAPL Mobility for Risk Management Decision‐Making
Bio | Abstract | Presentation

“Where is the NAPL” – Understanding NAPL Mobility for Risk Management Decision‐Making

Background/Objectives: Full-scale remediation of NAPL impacted sites to regulatory standards can often be technically prohibitive, costly, and provides marginal increases in protection to human health and the environment. With the advancement of NAPL investigation techniques, modeling, and mobility understanding, in many cases, NAPL can be managed in place allowing sites to be reused without costly remediation. Such an approach is being evaluated for the Toronto Port Lands Flood Protection and Enabling Infrastructure Project (PLFP) led by Waterfront Toronto. NAPL mobility is an important metric that should be included in the development of remedial and risk management strategies. Unlike many risk-based criteria which represent a defined toxicity and relatively easily measured value, metrics for NAPL mobility remain nebulous. NAPL mobility and stability are best understood using multiple lines of evidence including historical site data such as depth to NAPL, presence of NAPL in wells, spatial plume stability, and site-specific laboratory data such as total petroleum hydrocarbon (TPH) concentrations and NAPL saturation from undisturbed soil cores. This study provides an example of how these multiple lines of evidence can be combined to develop NAPL mobility criteria, which can then be used to manage NAPL in place in different areas of the PLFP site. Approach/Activities: This presentation will demonstrate how existing geological, TPH, and laser-induced fluorescence (LIF) data can be used to provide a relatively high spatial data density for NAPL analysis. Two distinct LIF methods (UVOST and TarGOST) were utilized to distinguish between areas with different NAPL types, which typically have varying degrees of mobility. Due to inconclusive results from a previously completed NAPL transmissivity test, an undisturbed soil core study was conducted for further mobility assessment. NAPL information from existing site data were correlated with results from undisturbed soil core analysis. NAPL saturation data obtained from undisturbed soil cores were used to provide interpretation of NAPL mobility specific to soil and NAPL types. It is important to distinguish between mobile and stable NAPL, as it ultimately affects the selection of risk management measures. In particular, NAPL mobility was explored under typical groundwater gradients (via water drive test), conservative centrifuge testing, and spontaneous imbibition testing. By combining these data sets, NAPL mobility metrics (i.e., concentrations and soil types), above which NAPL may migratewere developed. Results/Lessons Learned: Corollary analysis of undisturbed soil core results to other NAPL site characterization data was important for establishing a relationship between large historical data sets describing the NAPL distribution across the site and where those NAPL distributions may pose potential NAPL mobility risks. The NAPL mobility thresholds defined through this analysis provides a technical basis for remedy selection.

Jim Depa, St. John-Mittelhauser & Associates
How Do 3D Conceptual Site Models Reduce The Costs of Environmental Remediation?
Bio | Abstract | Presentation

Mohamedarif M. Jagani, AiMS Environmental
Vapour Intrusion: Diffusion - the Often Overlooked Pathway
Bio | Abstract | Presentation

Vapour Intrusion: Diffusion - the Often Overlooked Pathway

Intrusion of volatile contaminant vapour into buildings has been closely studied and regulated more over the past two decades as the science of vapour intrusion has become more understood and the allowable levels of airborne contaminants have become more restricted. Mitigation methods include engineered vapour barrier membranes in conjunction with a venting system. In this presentation, we share the experience of a spray applied membrane our Client commissioned during construction of a commercial slab-on-grade building on a contaminated property in Guelph that had undergone a risk assessment and was approved for redevelopment subject to installation of the vapour barrier as one of the risk management measures. The site hosted a former electronic circuit board manufacturer who used trichloroethylene in their cleaning process, which had resulted in groundwater contamination by TCE and its degradation compounds. One of the assumptions in using vapour barriers is that the barriers are largely impermeable to the contaminant vapour or have negligible gas permeance. While this may be true, our experience at a long-term project over the last five years suggests that measurable amounts of the contaminant can make it past the barrier regardless of how air-tight the barrier is made and installed. Even after ensuring installation of the barrier has been done correctly with all quality control checks such as visual inspections, coupon samples collected for verifying the thickness of the membrane meets or exceeds specifications, one still cannot completely guarantee that no vapour intrusion is occurring. We found this out the hard way when our Client imposed some special requirements for monitoring of the sub-slab air quality. Laboratory reports showed the sub-slab air samples collected from the air space above the membrane consistently had levels of trichloroethylene in excess of the Ministry of the Environment draft health-based indoor air quality criteria. The contractor performing the installation was understandably perplexed as the Client and their own consultant suggested there might be a breach in the membrane. We performed some calculations which supported the theory that diffusion was playing a role in allowing small amounts of the contaminant vapour making it past the vapour barrier. The presentation will demonstrate the findings of this project together with the math behind the diffusion pathway as the likely explanation for the observed contaminant vapour levels. It will also provide insight into whether the diffusion pathway should be a cause for concern and should be considered at other sites.

Phil Dennis, SiREM
Advances in Anaerobic Bioremediation of Benzene
Bio | Abstract | Presentation

Advances in Anaerobic Bioremediation of Benzene

Widespread use of petroleum products has resulted in contamination with BTEX compounds at numerous sites. BTEX compounds, which are the most soluble of petroleum hydrocarbons, can readily biodegrade under aerobic conditions, however where anaerobic conditions prevail, natural attenuation of BTEX has also been observed. Most often, under anaerobic conditions, benzene is observed to persist, due to its recalcitrance to degradation and can become a regulatory driver for remediation. Several benzene degrading cultures have been identified including a methanogenic benzene enrichment culture (DGG-B), developed at the University of Toronto. DGG-B transforms benzene and produces methane and the key benzene degrader, Deltaproteobacteria ORM-2, has been identified. This culture also degrades benzene under sulfate reducing conditions. Recent research efforts have been undertaken to determine 1) whether bioaugmentation with the DGG-B culture is an effective remedy for benzene contaminated sites; 2) if the presence of benzene degrading biomarkers can be correlated to in situ biodegradation activity and 3) if scale up of the culture to volumes sufficient for field pilot testing application is feasible. Numerous anaerobic treatability studies have been conducted using site materials impacted with petroleum hydrocarbons. The time frame for these treatability studies ranged from 8 to 14 months. Degradation of BTEX was monitored with and without DGG-B bioaugmentation and under various electron acceptor conditions. The results to date indicate that bioaugmentation with the DGG-B culture was able to accelerate benzene degradation under methanogenic or sulfate-reducing conditions, while in one case, no benzene degradation was observed despite bioaugmentation. Results from ongoing treatability studies will be presented to provide insights into the performance of the DGG-B bioaugmentation culture at a range of petroleum hydrocarbon contaminated sites, as well as into the correlation between the presence of benzene degradation molecular biomarkers and in situ biodegradation.

John Valkenburg, PeroxyChem
Evaluation of ISCR PRB Longevity under High Sulfate and High Flux
Bio | Abstract | Presentation

Evaluation of ISCR PRB Longevity under High Sulfate and High Flux

Background/Objective. Historical grain storage facility fumigation operations resulted in groundwater Carbon Tetrachloride (CT) impacts in a small Kansas farming community. High site groundwater flow velocity (estimated at ~700 ft year) has resulted in the CT plume extending approximately 2,500 feet downgradient where it discharges into a small creek; the highest concentrations of CT (approximately 1,500 ug/L) are located near the source area. To limit further plume migration, a Permeable Reactive Barrier (PRB) was installed across the plume width to passively treat CT. The PRB was constructed by injecting EHC® slurry in to a line of direct push injection points. EHC is composed of slow-release plant-derived organic carbon plus micro-scale ZVI particles. Inflowing groundwater is sulfate rich (~120 mg/L), potentially affecting substrate consumption rates and treatment zone reactive life. This presentation reviews geochemical parameter response and CT removal rates over time downgradient of the PRB and compares them with theoretical calculations on ZVI consumption rates using site specific data. These calculations are then discussed relative to the > 10 year PRB longevity and apparent mechanisms for the extended life. Approach/Activities. 48,000 lbs of EHC was injected into an area measuring approximately 270 ft long x 10 ft wide x 9 ft thick on average. The PRB was installed along a road and extended across the width of the plume to limit further plume migration. PRB effectiveness is measured at two compliance wells located 70 and 140 ft downgradient from the PRB. Monitoring is performed on a bi-yearly basis and includes CVOCs and geochemical parameters. Total Organic Carbon (TOC) is monitored as an EHC reagent indicator while ORP, Dissolved Oxygen (DO), nitrate and sulfate are monitored to assess redox conditions in the downgradient zone. Direct measurements of iron have not been performed, but iron consumption rates have been estimated based on inflowing concentrations of terminal electron acceptors. Results/Lessons Learned. CT removal rates peaked 16 months after installation at >99 percent removal. Two years after installation these rates decreased slightly to approximately 95 percent removal and have stabilized around that level for over ten years continuously supporting inflowing groundwater treatment. A significant increase in TOC was measured 70 ft downgradient from the PRB during the first two years. Since then, TOC levels have returned closer to background levels, suggesting that the more readily degradable carbon component (cellulose) had been consumed. During this initial phase redox conditions also reached their lowest point concurrently with significant reductions in inflowing nitrate and sulfate. After TOC levels returned closer to background, sulfate levels also moved closer to inflowing concentrations while ORP remained significantly below background. Theoretical ZVI consumption calculations suggest the ZVI may be consumed after 2.7 years if reacting Stoichiometrically with inflowing sulfate. However, geochemical data suggest that ZVI by itself is not supporting significant sulfate reduction. The probable explanation for the long PRB reactive life is the formation of an iron sulfide mineral based reactive zone created downgradient of the PRB during the initial sulfate reduction phase and since acting as an electron reservoir. This zone may also be continuously rejuvenated by low levels of TOC in inflowing groundwater (~2 mg/L) and from the hydrogen produced from ongoing ZVI corrosion.

Taras (Terry) Obal, Bureau Veritas
PFAS Replacement Compounds: “The Next Generation”
Bio | Abstract | Presentation

PFAS Replacement Compounds: “The Next Generation”

Industries in the United States have phased out production of PFOA and PFOS because of potential health risks to humans. As global production of PFOS and PFOA is eliminated, manufacturers have been and continue developing PFAS replacement technologies to reformulate or substitute longer chain PFAS (e.g. PFOS and PFOA) with shorter-chain perfluoroalkyl or polyfluorinated substances. These processes result in: fluorotelomer alcohols (FTOH); perfluorobutane sulfonyl fluoride (PBSF)-based derivatives (e.g., perfluorobutane sulfonate (PFBS) as a substitute for PFOS); and polyfluoroethers (e.g. GenX, ADONA and F53B used in the manufacture of fluoropolymers) among others. While there is a substantial body of knowledge for managing risk from PFOS and PFOA, much less is known about replacement PFAS. Although published toxicological data is limited, studies are suggesting that some of the lower molecular weight PFAS replacement compounds may be more hazardous than their long-chain predecessors. Information on the type and extent of environmental contamination by replacement PFAS is also limited, as most are currently not reported as part of the routine suite of PFAS commonly analysed by commercial analytical laboratories. Three key PFAS replacements currently being studied are commonly referred to as GenX, ADONA and F53B. PFAS rreplacement chemicals like these tend to have fewer carbon atoms in the chain, but have many similar physical and chemical properties as their predecessors PFOS and PFOA (e.g. they repel oil and water). Because of an increased interest in PFAS replacement compounds and the potential for their regulation in some jurisdictions, Maxxam has validated methods for the determination of GenX, ADONA and F53B by isotope dilution liquid chromatography coupled with tandem mass spectrometry. This presentation will describe: the history and environmental impact of these compounds; required sample collection protocols; analytical performance considerations; and site remediation challenges.

Daniel Bouchard, Sanexen
What Additional Value Can Compound Specific Isotope Analysis (CSIA) Bring to the Assessment of Organic Contaminants in Groundwater?
Bio | Abstract | Presentation

What Additional Value Can Compound Specific Isotope Analysis (CSIA) Bring to the Assessment of Organic Contaminants in Groundwater?

Over the last three decades, compound-specific isotope analysis (CSIA) has evolved from the state of laboratory studies to a recognized, highly-sensitive field assessment tool. For this reason, the tool has been deployed on numerous contaminated sites to gain key information on released organic compounds (such as petroleum hydrocarbons and chlorinated solvents) that traditional concentration measurements are unable to reveal. For instance, CSIA has proven its reliability and robustness in demonstrating the biological destruction of organic compounds in groundwater, thus becoming an indicated tool for use in the framework of a Monitored Natural Attenuation program. CSIA greatly enhances the quality of information derived from the dataset collected over time, strengthens the conclusions drawn on the fate of organic contaminants in groundwater, and reinforces the Regulator’s decision to approve on-site application of the natural attenuation remedial strategy. Furthermore, the tool has been used to differentiate sources of the same contaminant present in the subsurface for forensic purposes, or to better understand source architecture on complex sites having the potential for multiple release episodes. More recently, the application of the tool has reached another milestone, when it was applied in the framework of in situ remediation treatments to assess whether the intended contaminant mass reduction was initiated as anticipated. More specifically, CSIA was proven reliable in determining whether the contaminant mass reduction observed was attributed to dilution or destruction, or which co-occurring physical, chemical or biological process was the dominant mass-reduction process. In such cases, application of CSIA supports field practitioner’s decision to modify the treatment in real time, which leads to cost-effective remediation treatments. This talk aims to briefly explain the fundamentals of the CSIA method, followed by examples of field applications.