Proceedings of the Canadian Society for Civil Engineering Annual Conference 2024, Volume 5

Life cycle assessment (LCA) is a powerful tool established by the International Organization for Standardization (ISO) that can be used to assess the environmental impacts of a product or process from cradle-to-grave. Many studies utilize the LCA methodology within the site remediation field to compare various decontamination methods, including bioremediation, thermal remediation and excavation for off-site treatment and disposal. However, limited information is available in the literature on a sustainability tool that can be used to help assess and select the optimal remediation technology at any given site. Accordingly, this project was undertaken to develop a tool to assist with the selection of the most sustainable technology with the focus of contaminated gasoline sites. Preliminary LCA results show decreased environmental impacts for the remediation of a contaminated gasoline site for each technology when compared to a no remediation alternative. Sensitivity analyses are now being completed on site parameters to determine how environmental impacts fluctuate at other contaminated locations based on parameters such as transportation distances or soil type. Additionally, the social and economic impacts associated with the technology are being reviewed to complete a full sustainability assessment. Utilizing the environmental, economic and social results, a sustainability tool will be developed to help to assist in the selection of the best remediation option.

This study investigated the influence of high levels of dissolved oxygen (DO) on the matured aerobic granular sludge (AGS) treating high-strength ammonium wastewater. AGS was cultivated and matured through a SBR after long-term treatment of synthetic influents having the same characteristics (COD = 1250 ± 70, TN = 165 ± 36, and TP = 54 ± 11 mg/L) under limited DO (≤ 2 mg/L). Two identical SBRs were operated for 208 days. In stage I (77 days), DO was 5 - 6 mg/L, while in stage II (days 78 - 146) DO jumped to 7.5 mg/L, and finally, in stage III, DO was ≥ 8.5 mg/L. Initial results indicated that SBRs achieved simultaneous COD/NH₄-N/PO₄⁻³-P removal efficiencies of 94/89/91%. Ammonium oxidation rate of 15.4 ± 1.4 mg-NH₄/g-MLVSS·h, and simultaneous nitrification–denitrification (SND) has been recorded. Phosphorus release/uptake rates of 58/14 mg-P/g-MLVSS·h, respectively, and efficient physical properties (size ≥ 2.7 mm and sludge volume indexes were ≤ 31 mL/g) were detected. On day 75, ammonium oxidation rate jumped to 16.1 ± 1.1 mg-NH₄/g-MLVSS·h and PO₄⁻³-P effluent concentrations were reduced to 1.3 mg/L. However, results obtained during the following stages did not show any significant development in reactors’ performance. Effluent ammonium and nitrate concentrations on day 146 were 8.2 and 1.8 mg/L, while on day 208 they were 7.7 and 3.8 mg/L, respectively. PO₄⁻³-P was increased to 1.4 mg/L on day 208, and deterioration of AGS accompanied with reduction in the secretions of extracellular polymeric substances occurred after applying DO ≥ 8.5 mg/L.

Small water systems serve ~ 15% of the Canadian population and face unique challenges; however, small systems are often overlooked in terms of research, resources, and support. This project aims to better understand the experiences, challenges, and needs of small water systems operators and develop a co-training program to assist in capacity building. This pilot program introduces co-training between engineering students and water and wastewater (W&WW) operators, facilitating the exchange of knowledge and strengthening the skills and resources available to both parties. This project is a collaboration between Carleton University and Yukon University’s Water and Wastewater Operator Program (YWWOP). Interviews and surveys of W&WW operators are used as a tool to collect information around their experiences, challenges, support needed, feedback on current training programs, and thoughts about co-training with engineering students. Through co-training, the goal is for engineering and operator students to develop a more comprehensive understanding of water treatment through exchanging knowledge, gaining hands-on skills, and experiential learning. Preliminary results have been positive, with data collection ongoing. This project has the potential to enhance the capacity building of small systems operators in the Yukon and engineering students at Carleton University and other southern institutions by strengthening the skills, knowledge, and resources available to both parties.

The accidental release of Hazardous and Noxious Substances (HNS) can negatively affect the environment and human health. Biofuels are promising alternatives to fossil fuels as they are produced from renewable sources (i.e., vegetable oils or animal fats). However, biofuels are considered one of the HNS categories that are frequently transported and will impact the ecosystem if spilled on water. Although studies support the biodegradation of some commercially available biodiesels in water, the non-volatile nature of newly developed alternative biofuels (ABFs), such as biomass-derived pyrolysis oils, and their unique physicochemical properties suggest that these oils may behave differently if spilled in water. This study aimed to determine the fate and transformation (chemical or biological) of pyrolysis oils in Canadian marine waters through bench-scale biodegradation experiments. The biodegradation experiments were performed by spilling pyrolysis oils (100 µL), obtained from two different suppliers, in 200 mL of water, collected from the Canadian East Coast, Pacific Ocean, and the Arctic Ocean, under aerobic conditions (200 rpm) at 4 °C water for 21 days. Samples were collected at T3 (three hours post-spill) and the end of the test and analysed for total organic carbon content (TOC) and microbial community analysis by 16S rRNA gene sequencing. Visual observation of the bio-oil showed that the oil sank to the bottom of the water, but the wood oil floated first and sank after a short period of time. Both oils experienced limited biodegradation (<20%) in the marine waters. Further analysis of oil properties in waters will unfold the factors that led to the low biodegradation of the tested oils in cooler water.

Law contributes to climate change adaption in the infrastructure sector by reducing exposure to climate hazards, increasing the adaptive capacity of individuals, households and communities, and creating incentives for climate-adaptive behavior (Berrang-Ford et al., Clim Change 124:441–450, 2014). The present paper concerns the normative lifecycle of public infrastructure projects by focusing on Quebec’s legal framework and aims to answer the following research question: «How do laws, regulations and other normative sources interact and contribute to climate change adaptation in the infrastructure sector?». From forbidding construction, through the obtention of authorizations and public tendering, to demolition and reuse of materials regulations, this paper focuses on the diversity of sources of law, people and organizations with the power to influence the adaptation of infrastructure projects to climate change. Law notably finds its sources in participatory democracy and also emerges from collaborative governance between private and public. But classic hierarchical power structures also punctuate Quebec’s normative framework, such as large discretionary powers vested to ministers. This paper aims to offer a conceptual framework illustrating the fragmentation of Quebec’s legal framework and the difficulty of implementing coherent and cohesive action, while also offering a roadmap for practitioners from the private and public sector interested and willing to address climate change adaptation in infrastructure projects.

This paper investigates the optimization of iron electrolysis-catalysed ozonation (ECO) as a candidate for micropollutant abatement. Charged iron ions are produced to catalyse the degradation of dissolved ozone and form hydroxyl radicals. Hydroxyl radicals can reduce practically any contaminant that might resist treatment by conventional wastewater processes. Tert-butyl Alcohol (TBA) was used to measure performance, due to its resistance to ozonation but ready oxidation by hydroxyl radicals. A Headspace—SPME GC–MS method was used to accurately quantify the removal of TBA. Comparison of the ECO experiments to separate electrolysis and ozonation trials suggested that the proportion of non-catalytic removal of TBA is ~9% over the reaction duration. A comparison of ECO operating at a targeted dissolved ozone concentration was made to operation at a fixed ozone supply. Catalytic removal fractions between 5 and 60% of TBA were observed, suggesting strong removal potential for ozone-resistant compounds. Optimal operation of this ECO system occurred around 4 mg/L dissolved ozone and 14–33 mg/L total iron.

The global mining industry is essential for resource supply but faces significant environmental hurdles, especially in managing wastewater. Moreover, the industry’s reliance on fossil fuels worsens environmental issues due to greenhouse gas emissions. Pressure retarded osmosis technology (PRO) offers promise in addressing these challenges by utilizing salinity gradients for wastewater treatment and renewable energy generation. While existing research focuses mainly on PRO’s application in wastewater treatment, its integration into mining remains largely unexplored. This study aims to investigate the potential of PRO for treating mine water and generating energy, with a focus on pretreatment methods’ impact on system efficiency. Physicochemical analyses of effluents from various processes of a gold mining company revealed prevalent anions and cations. Various pretreatment techniques, including microbubble ozonation, ultrafiltration, and nanofiltration, were evaluated to determine the most effective and cost-efficient method for achieving stable power density. Results showed that mine water holds promise as a PRO feed solution, offering both electricity generation and wastewater treatment benefits. Particularly noteworthy is the higher power density observed in the effluent sample obtained from the explosive leaching process treated with microbubble ozonation, attributed to its elevated salinity and significant osmotic pressure potential. Moreover, combining microbubble ozonation with nanofiltration proved highly effective in reducing fouling, leading to increased water recovery rates and satisfactory permeate flux levels. This resulted in a notable power density of up to 18 W/m², comparable to other commonly used feed solutions in PRO applications.

Excessive global petroleum consumption continues to be a primary cause of soil contamination, primarily due to the introduction of toxic fuel components such as benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) into the environment. Bioremediation techniques can play a crucial role in mitigating this contamination by optimizing microbial activity through alterations in physical and chemical conditions in subsurface environments. This study delves into various strategies aimed at enhancing soil remediation. BTEX-degrading microorganisms were isolated from wastewater treatment plant sludge and subsequently employed as inoculants. These microorganisms underwent an acclimation process within granular activated carbon (GAC) columns, where aromatic hydrocarbons served as their sole source of carbon and energy. Batch experiments were conducted to investigate the augmentation of BTEX biodegradation through the addition of inoculum, nutrients, and oxygen, with parallel control experiments to account for abiotic losses. The findings revealed that, under natural conditions, the degradation of all aromatic hydrocarbons was around 95%; the duration was 45 days and the initial BTEX concentration was 10 mg/L. BTEX utilization rates were calculated and compared across different conditions. The introduction of supplemental nutrients significantly improved the rate of biodegradation, and when hydrogen peroxide was added alongside nutrients, utilization rates increased by 50%. The combined addition of nutrients and microorganisms boosted the rates by over 100% for toluene, ethylbenzene, and xylene. Optimal conditions for the biodegradation of all BTEX compounds were achieved when supplemental oxygen, nutrients, and inoculum were introduced, leading to a more than twofold increase in the rate constants of utilization. Notably, the addition of nitrate proved highly effective in enhancing the degradation rates of toluene, ethylbenzene, and xylene, allowing the degraders to shift to an anaerobic pathway when oxygen was depleted. It was observed that the addition of inoculum expedited the onset of measurable biodegradation. Over time, the indigenous population developed the necessary catabolic abilities and reached a density at which the disparity in degradation abilities between indigenous and preselected biomass was no longer discernible.

This study delves into the intricate interplay between chemical volatility and soil moisture content within the context of soil vapor extraction (SVE) for industrial pollutant remediation, investigating the key determinants of SVE’s efficiency in eliminating contaminants. Concerning chemical volatility, our research reveals a direct correlation between chemical vapor pressures and mass flow rates, demonstrating that chemicals with higher vapor pressures exhibit increased mass flow rates under consistent air flow conditions. Notably, toluene displayed a more pronounced decline in mass flow rate compared to xylene and ethylbenzene, suggesting potential column depletion, possibly arising from an experimental leak. These findings align with prior research highlighting SVE’s challenges in removing low-volatility chemicals, thus advocating for alternative bioremediation approaches. Additionally, regarding total petroleum hydrocarbons (TPH), SVE proved effective for low molecular weight compounds with high volatility but faced limitations with high molecular weight compounds possessing low volatility. Soil temperature reductions were observed to reduce contaminant volatility, thereby diminishing remediation efficiency. However, benzene, with its high vapor pressure, was efficiently extracted by SVE, followed by toluene, ethylbenzene, and o-xylene. Concerning moisture content, our study explored its impact on exhaust concentrations in both organic and sandy soils. Organic soils, with higher moisture content, exhibited elevated exhaust concentrations of toluene and xylene compared to sandy soils. Conversely, benzene displayed higher exhaust concentrations in sandy soil, indicating that higher vapor pressures can overcome moisture-related constraints. In this study, dry sandy soil outperformed soil with 7.6% moisture content at a specific air flow rate, with exhaust concentration decreasing as moisture content increased. The study also reaffirmed earlier findings of a reduction in the mass transfer coefficient due to declining non-aqueous phase liquid (NAPL) saturation, primarily driven by evaporation-induced reduction in interfacial area. This study underscores the intricate relationship between chemical properties, moisture content, and SVE efficacy in pollutant remediation, offering valuable insights for shaping environmentally sound and effective remediation strategies.

With the escalating focus on the global environmental concerns, cement industry is highlighted as one of the largest sources of carbon dioxide (CO₂) emissions worldwide. There is a need for exploring mitigation measures to systematically identify, asses, and modify the cement production process CO₂ emissions. For that, a framework is designed for the available assessment measures which is inspired by the common literature. The aim of this paper is to evaluate the different performance measures and polices focusing on reducing the carbon footprint of the cement plants. With a comprehensive review of the existing CO₂ emission levels globally and focusing on Egypt, this study evaluates the implementation of these mitigation measures for a more environmentally friendly cement industry in Egypt. The study focuses on some technological advancements, fuel and electricity efficient cement plants, and greener alternatives for the reduction. Cement plant in Alexandria is taken as a case study to calculate and compare the results of various combined modifications done on the CO₂ emission levels. The essential data were collected from the sustainability reports and the literature with the guidance of the Intergovernmental Panel of Experts on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. Moreover, this study can be used for deeper knowledge of the challenges, best practices, and policies that face the reduction of CO₂ emissions from cement plants in Egypt. It also projects the findings to see its alignment with the 2030 Net Zero emissions and 2050 climate goals. By applying the reduction measures, the cement plant could reach the 2030 goal as strategically planned. There is a potential of total CO₂ emissions reduction of the plant by 22.1% reaching the goal.

Water quality monitoring of distribution systems has traditionally relied on infrequent grab sampling and laboratory analysis, lacking spatiotemporal resolution to capture contamination events across complex water networks. However, emerging sensor technologies integrated into wireless sensor networks (WSNs) enable real-time continuous monitoring to revolutionize water security. This paper explores the development of affordable in-situ optical sensors leveraging UV–vis absorption and fluorescence measurement techniques for improved water quality monitoring in distribution systems. Critical considerations for designing a low-cost UV absorbance/fluorescence sensor are examined, including strategic photodetector selection using the technique for order of preference by similarity to ideal solution (TOPSIS) analysis and optimizing components through design of experiments. The impact of sample holder material, air gap, and water type are quantified, informing the prototyping process. Calibration with humic acid solutions demonstrates the sensor’s sensitivity across a wide concentration range. While challenges persist around sensor miniaturization, power management, data transmission, and cost-effective mass production, the outlined innovations illuminate opportunities for deploying spatially dense WSNs for real-time water quality monitoring. Continuous high-resolution data can revolutionize contamination detection, process control, and watershed management when coupled with analytics and decision support systems, fostering intelligent and responsive urban water infrastructure.

To mitigate greenhouse gas (GHG) emissions within the constraints of a limited government budget, efficient and effective energy system planning is crucial. While extensive research has been conducted on regional energy systems planning, there is a growing focus on community-scale planning due to its closer connection to end-users. In this study, a community-scale energy system planning model is developed for the City of St. Catharines in Ontario, Canada. This model aims to minimize energy system costs while meeting municipal emission and budget goals and properly allocating conventional and renewable energy sources to the end-users. It addresses the generation, expansion, and emissions costs of five energy sources (i.e., grid electricity, pipeline gas, community solar, community wind, and gas recovery) over a 30-year planning horizon. Uncertainties associated with the community-scale energy system planning process are addressed using the Fuzzy Flexible Programming (FFP) technique through the imposition of tolerance intervals and penalties. Optimized solutions will be generated for both the planning of conventional energy, as well as the expansion of renewable. The results will not only formulate cost-effective allocation and expansion strategies for the city’s energy system but also provide valuable insights for municipal decision-makers, assisting them in more effectively planning and managing energy systems under uncertainties.

While aircraft engines are efficient at high thrust modes, they are notably less efficient at low-power settings during idling and taxiing. Recognizing the need to address environmental and economic concerns, the civil aviation industry is increasingly exploring sustainable solutions with a view to minimize fuel consumption during ground movements. As the Royal Canadian Air Force (RCAF) advances toward its federal mandate of achieving net-zero emissions in aviation, an essential requirement is to determine potential solutions by conducting a comprehensive review of best and/or relevant practices. As such, within this context, this paper examines experiences and insights derived from the global and domestic civil aviation industry and allied air force/military counterparts that could potentially be implemented and incorporated within RCAF operations. The analysis accounts for the specific requirements, constraints, and security considerations faced by military aviation, illustrating how these factors may impact the effective adoption of pertinent sustainable initiatives. Using 8 Wing Trenton as a case study, this research study assesses the carbon emissions associated with the transport fleet and their related ground support equipment. The study also includes the feasibility and anticipated fuel savings resulting from the staging of infrastructure (i.e. organizing the location of the various task-tailored buildings that service the aircraft within the air force base) and ground operations optimizations (i.e. taxiing). This comprehensive examination offers practical insights and strategies to enhance sustainability within military aviation. The results of this research study will guide relevant managers within the RCAF and the wider military aviation sector, aiding them in making informed decisions regarding fuel efficiency, carbon emission reduction, and the integration of sustainable practices. This paper represents yet another step by the Department of National Defence (DND) and the RCAF to continue to be a leader amongst federal agencies concerning sustainability and their efforts to combat climate change while preserving national security and operational effectiveness.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of notoriously persistent and water-soluble chemical compounds that can be found worldwide. Most PFAS are highly toxic and can bioaccumulate via food chains. PFAS enter the environment through point and non-point sources. Point sources include manufacturing plants and areas with regular use of aqueous fire fighting foams (AFFF), such as airports, military bases, and fire halls. Non-point sources involve water runoffs from agriculture, industry, or wastewater treatment plants (WWTPs), as well as atmospheric deposition. Firefighting wastewater in effluent from WWTPs is considered one of the main sources of PFAS in the environment. The pervasive presence of PFAS in aquatic environments poses a substantial concern for military installations across Canada. This research focuses on identifying the pathways that PFAS follow as a result of military activities, and how they can impact drinking water sources. Related sampling methodologies are investigated to optimize PFAS monitoring; seasonal training schedules and patterns of dominant PFAS types (short chain or long chain) are also part of this study. A mixed-method research methodology is employed for this purpose, with integration of quantitative and qualitative data. Quantitative data have been collected during environmental monitoring programs, while qualitative data are used to interpret measurable parameters. The overall expected outcome is to inform PFAS management and associated monitoring practices, with a view to optimizing the protection of drinking water sources from these “forever chemicals.” The recommendations from this investigation could be extrapolated to support the military as well as manufacturing sectors and municipal facilities requiring PFAS contamination management.

The recovery of valuable components from dairy processing waste products is an approach that creates an economic opportunity for producers while reducing the environmental burden of treating and disposing of this waste. For this purpose, bentonite clay has been investigated as an adsorbent material to recover protein from cheese whey. In this process, powdered bentonite clay is mixed with whey to adsorb and physically separate whey proteins from the bulk liquid. This approach presents several potential advantages compared to traditional membrane filtration, as it can be achieved using minimal equipment and operator experience, allowing for easier application at the source of production. The removal of major whey proteins has been monitored using HPLC following contact with bentonite clay while operating under varying bentonite dosages and temperature conditions. Complete removal of major whey proteins was observed using a bentonite dosage of 35 g/L after 6 h of contact at a pH of 4.7. When considering the removal of individual whey proteins, it was found that alpha-lactalbumin (α-LA) displayed a higher adsorptive affinity towards bentonite than beta-lactoglobulin (β-LG) under these conditions. Modification of temperature using a fixed adsorbent concentration of 20 g/L revealed that the overall removal of major whey proteins was diminished at 4 °C but remained relatively constant between 20 and 40 °C. In particular, the removal α-LA was significantly affected by changes in temperature, with removal increasing from 54.27 to 91.49% as the temperature during adsorption was raised from 4 to 40 °C.

What happens if you run a filter for ~ 35 years without regular check-ups? Even when filters consistently meet effluent water quality standards, there can be performance issues lurking beneath the surface. The City of Ottawa’s Britannia and Lemieux Island Water Purification Plants operate 18 dual-media anthracite/sand biofilters for treating water from the Ottawa River. Traditionally, filter backwashing is the primary operational parameter for maintaining the proper function of filters. Filters were backwashed with velocities ranging from 43 to 47 m/h; in addition, backwash techniques varied between surface sweep agitators and air scouring methods. Floc retention analysis revealed that one filter struggled to meet the < 60 NTU clean media standard post backwash. Further examination of the filter media showed significant size degradation. Findings provide insights into key operational and design parameters, aiding in the identification of filter recovery strategies and proactive maintenance measures. This full-scale research emphasizes the use of floc retention data for evaluating filtration system health and aims to optimize biofilter performance.

Ceramic membranes are becoming increasingly popular in water treatment due to their remarkable tolerance for intense cleaning options with severely fouled membranes in comparison to their polymeric membrane counterparts. Despite their robust capacity, there is a lack of research on the mitigation of ceramic membrane fouling with chemically enhanced backwash (CEB) methods. CEB uses a low-concentration chemical solution to dislodge and remove foulants in place of, or in addition to, a conventional backwash procedure which enables a longer membrane filtration duration before a more in-depth clean-in-place step is required. This research examined the use of Tween 80, a non-ionic surfactant, with NaOH + NaOCl and carbon dioxide (CO₂) as novel CEB solutions for foulant removal. While the carbon dioxide clean was not effective, Tween 80 (polysorbate 80), which is a versatile emulsifier produced encouraging outcomes. This study found that the transmembrane pressure (TMP) of Tween 80 + NaOH + NaOCl compared to hydraulic backwash after multiple filtration cycles was 84.46 kPa over 129.73 kPa. Resistance-in-series (RIS) evaluation showed that Tween 80 in conjunction with NaOH + NaOCl reduced irreversible fouling from 2.30E+12 m⁻¹ to 1.12E+12 m⁻¹ compared to a hydraulic backwash. This study emphasizes surfactant selection in CEB, examining its effects on zeta potential and water quality parameters. It also shows how surfactant-driven techniques might improve ceramic membrane filtration and promote sustainable water treatment.

The purpose of this research study is to investigate the applicability of deep learning, and more especially the long-short-term memory (LSTM) model, to the prediction of droughts, one of the extreme weather events caused by global warming. The research considered the standardized precipitation index (SPI), a drought index that is commonly used in the scientific community to estimate the drought severity. The study was conducted using one of the global climate models from the six-phase coupled model intercomparison project (CMIP6), the latest version of the CMIP models, namely the Canadian Earth System Model version 5 (CanESM5-1). The data were collected using historical and future simulations. The shared socio-economic pathway (SSP5-8.5), which represents the worst-case scenario for future climate change forecasts, is the foundation for the future data. The CanESM5-1data were utilized throughout the nineteenth, twentieth, and twenty-first centuries (1850–2100). The location of this study is the Canadian prairies which include Alberta, Saskatchewan, and Manitoba. To train and test the LSTM machine learning algorithm, the data were split between 70% training, 15% validation, and 15% testing sets. Seventy percent of the data were used for training the LSTM machine learning algorithm, fifteen percent for validation, and fifteen percent for testing. The outputs of the LSTM model were compared with the drought indices calculated from numerical methods. The statistical analysis was conducted using two statistical metrics: the mean-square error (MSE) as a loss function and R-squared (R²) to evaluate the performance of the model. The LSTM model demonstrated remarkable predictive accuracy, with a MSE value of 0.0035, 0.004, and 0.004 and R² of 0.87, 0.78, and 0.74 for Saskatchewan, Alberta, and Manitoba, respectively.

Eutrophication due to excessive phosphorus (P) loads to inland waters is a major challenge worldwide. While quantification and management of P loads from agricultural areas has been well studied over the past decades, non-point source P loading from urban areas is less well understood. It remains unclear how P exports vary between different urban land use types and between seasons. The objective of this study is to evaluate P exports from a cold climate urban watershed, including the effects of land use and seasonal variability. The objective was addressed by event-based field monitoring during summer and fall seasons over a 29-month period within a 5.8-km² watershed in London, Ontario. This was combined with load estimations calculated using LOADEST, and the development and calibration of a hydrologic and water quality (SWMM) model. Water quantity and quality data, including total suspended solids (TSS) and total P (TP) were collected at two watershed outlets representing different land use areas. Field data indicate that TP concentrations at the watershed outlets consistently exceeded the eutrophic threshold of 30 µg/L during baseflow and event flow conditions. LOADEST estimations highlight the large contribution of individual extreme precipitation events to total annual P loads. The calibrated SWMM model simulated monthly TSS and TP loads that were consistent with the LOADEST estimations. This SWMM model can now be used as a valuable tool for simulating the impact of future land use, stormwater management and climate change scenarios.

There has been a shift in the paradigm of geotechnical engineering design from the working or allowable stress design (WSD/ASD) to limit state design (LSD) to better tackle the uncertainties in design and soil parameters. Using reliability-based design (RBD) methods, designers can quantify the risk of designs and make informed decisions to avoid the designs being excessively conservative. Thus, RBD can help reduce environmental impacts indirectly through the optimization of risk and performance of geotechnical structures. To incorporate environmental impact considerations in the design process, a strong understanding of the trade-offs between the engineering reliability and environmental sustainability of geotechnical structures is needed. This study aims to provide a comprehensive analysis of the relationship between reliability and global warming impact of drilled shaft designs. The impact of global warming is evidenced by the rise in Earth’s surface temperature resulting from the emissions of carbon dioxide and other greenhouse gases. In this study, the first-order reliability method (FORM) and life-cycle assessment (LCA) are used to investigate the relationship between reliability and global warming impact of drilled shaft designs, considering uncertainties in (i) soil properties, (ii) applied load, (iii) design equations, and (iv) pile dimension. Charts are developed for quick estimation of the global warming impact of drilled shaft designs that have different safety requirements, applied load, and design dimensions. The charts are useful for designers who do not have access to specialized software packages for conducting FORM and LCA and can be helpful for achieving a balance in the reliability, cost, and environmental sustainability of drilled shaft designs.

Characterization of first flush behaviour is important for urban stormwater management design. While mass-based definitions for first flush are common, current first flush definitions were developed considering tropical and temperate climates rather than continental climates. This study aims to investigate first flush behaviour in two urban and mixed land use subcatchments in London, Ontario, Canada, which is located in a continental climate. Data was analysed using four first flush definitions. The results revealed first flush was moderate for total suspended solids (TSS), total phosphorus (TP), and soluble reactive phosphorus (SRP). As expected, particulate pollutants (TSS) showed a stronger first flush as compared to mixed (TP) and dissolved pollutants (SRP). No significant correlation was found between the strength of the first flush definition and rainfall characteristics likely due to first flush occurring only during the initial runoff period. None of the monitored events satisfied FF₃₀ criteria, suggesting this definition may be unsuitable for continental climates. Significant differences in first flush strength between definitions suggest further research is needed to identify suitable definitions for continental climates.

The primary goal of water distribution systems is to ensure the delivery of high-quality drinking water at adequate pressure. However, the operational efficiency could be impacted by aleatory uncertainties stemming from random variables like water demand and pipe roughness, as well as epistemic uncertainties due to incomplete data and complex system interactions. Water demand at nodes is influenced by these uncertainties, being random, due to variable customer behavior, and fuzzy, because of the difficulty in specifying exact demand values. This research aims to represent water demand as a fuzzy random variable to quantify both uncertainties in a unified modeling framework. Previous works that utilized a fuzzy random approach assumed a normal distribution with a fuzzy mean and a standard deviation set as a fixed percentage of demand, using triangular or trapezoidal functions to represent uncertainty. Such a fixed percentage for variation assumes uniform uncertainty across all nodes and conditions, which is not realistic in practice. This research intends to avoid simplifying assumptions and implement unsupervised soft clustering methods to define fuzzy membership functions. Uncertainty in water demand limits the value and use of current distribution system modeling. Due to this uncertainty, models are too inaccurate and rigidly defined to use for setting day-to-day operational thresholds. This research presents a water demand modeling methodology that better captures uncertainty and can be used to identify realistic ranges of conditions expected in water distribution systems.

Froth treatment tailings (FTT) are a waste product of the bitumen extraction process from Alberta oil sands. FTT contains residual bitumen, diluents (naphtha or paraffinic), water, and sand containing the sulphide mineral pyrite (FeS2). FTT is deposited in tailings ponds and there is a risk that the pyrite in tailings undergo weathering when exposed to oxygen, producing acidic drainage. A key area of research is to understand the effects of material overlying FTT in acid generation. This will allow us to predict post-closure acid rock drainage (ARD) generation and/or GHG emissions from the FTT. In this study, two scenarios under which covering materials may contribute to ARD were assessed. These include: (1) FTT capped with peat and (2) FTT capped with quartz sand. Columns with quartz sand capped with peat were used as controls. Columns were water-saturated, and water was added every week from the top of each column, while water samples were collected from a port at the base of the columns. Samples were analysed weekly for water chemistry, and monthly for microbial analysis. In the columns where FTT was capped with quartz sand, changes in physicochemical parameters (i.e., decreases in solution pH, or increases in dissolved iron and sulphate concentrations) were observed. This suggests acid generation at the late stage of the tests, while other columns show a lesser degree of acid rock drainage. Analysis of the microbial community structure with 16S rRNA gene amplicon sequencing in the leachate from the columns was started when the geochemistry changes were observed in the columns. Results showed that peat or peat-covered FTT was dominated by methanogens (mainly Methanolobus zinderi, Methanosaeta pelagica (Aceticlastic methanogens) and Methanomicrobium mobile (hydrogenotrophs methanogens. On the contrary, quartz sands-capped FTT was dominated by acidophiles (members of sulphur-oxidizing or iron-oxidizing bacteria). Methanogens were abundant in the early (days 277–354) stage of the sampling period, while acidophiles were abundant in the late stage (days 354–644) of the sampling period. Overall, the changes in physicochemical parameters and microbial communities in these columns suggest the weathering of sulphide minerals in the columns.