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September 2000 - present
Publications
Publications (722)
Field experiments are conducted to quantify the leakage through an 11-mm-diameter hole in the liner on slopes with and without a bench under waste cover conditions. Over 14 months, with a total precipitation of 947 mm, a 0.68 m bench on a 4H: 1V slope results in a 43-fold increase in leakage (from 6.5 L to 282 L) compared to the reference section w...
The effect of backfilling of a surface differential settlement trough to reduce leakage is explored both experimentally and numerically. The field experiment examined two lined sections each with an 11 mm-diameter hole in the liner on a nominally 4 horizontal:1 vertical slope. A 2 m by 3 m, 0.3 m deep depression was filled with a
50-50 sand-snow mi...
The degradation of a HDPE geomembrane in heap leaching environments is evaluated using immersion tests at five temperatures. The incubation solutions had a pH of 9.5, 11.5, and 13.5, relevant to gold and silver pregnant liquor solutions. After 9.3 years, the geomembrane's mechanical properties had reached nominal failure at 95, 85, and 75 • C in al...
The transport of perfluorooctanoic acid (PFOA) through the base of a municipal solid waste landfill lined by a single or double composite liner system underlain by an aquifer is examined. Experiments conducted to obtain permeation coefficients for PFOA (and other PFAS) through HDPE and a GCL at different stress levels are described and the results...
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals formed by carbon chains where fluorine atoms replace one or more hydrogen atoms. These bonds are extremely stable and PFAS components are known to be persistent environmental contaminants. The impact of these contaminants on two geomembranes is studied. Specifically, the short-term...
Twenty-one transmissivity tests were performed in a double composite liner contaminant barrier for landfills. The secondary drainage system was tested with three geocomposite drains with different geonet core structures, biplanar, triplanar, and triaxial. Half of the tests were conducted under normal applied load of 250 kPa and varying temperatures...
This paper reports on an investigation into the failure of a double HDPE geomembrane lined retention reservoir constructed in 2018 that failed in 2021, only 3 years after construction. Several technical and non-technical factors contributed to the failure, and these are examined systematically. The primary failure occurred at the outlet pipe penetr...
This study evaluates the impact of differential settlement on leakage through geomembrane holes in landfill and mine tailings covers. Conducted at the Queen’s University Experimental Liner Test Site, the research spanned two sections with 4H:1V slopes over 13 months. Section B, featuring a 3 m x 2 m depression (0.12 - 0.17 m deep), exhibited a 51-...
The finite element (FE) method is used to identify limitations and extend the applicability of an analytical solution for leakage through holed wrinkles in composite liners. The limiting assumption in the analytical model is relaxed based on FE results, providing a means of obtaining good agreement through the two methods over a wide spectrum of ca...
The depletion of antioxidants from a 2 mm high-density polyethylene geomembrane immersed in brine at seven temperatures (95, 85, 75, 65, 55, 40, and 25°C) for 28 months is reported. An Arrhenius model is used to predict the performance of the geomembrane at low site-specific temperatures. The antioxidant depletion times are reported for temperature...
This paper is a summary of many of the key findings on the application of geosynthetics in tailings storage facilities. Topics include the compressibility and permeability of tailings, the equations predicting leakage through circular and non-circular geomembrane holes, the effect of the subgrade permeability, and the effect of a lateral drainage s...
Low-permeability liners are required at the base of municipal solid waste (MSW) landfills to minimize leachate leakage and contaminant migration into groundwater. This paper uses a two-dimensional coupled groundwater flow and contaminant transport model to examine the performance of three types of low-permeability liners specified by the current Ch...
The tensile shear strength, break location, and constant tensile load failure times are examined for seams made from one 4 mm-thick bituminous geomembrane (BGM) product, with corresponding observations specific to that material. In short-term tests, failure is observed within the sheet material once the seam strength exceeded 0.8 times that of the...
The effect of applied stress (20, 60, and 150 kPa) on the diffusion of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) through a geosynthetic clay liner (GCL) is examined. The diffusion coefficients deduced from GCL diffusion tests for PFOA and PFOS decrease linearly with decreasing final bulk GCL void ratio (increasing applied s...
The effect of blown-film co-extrusion texturing (using entrained nitrogen gas) on the long-term performance of high-density polyethylene geomembranes (GMBs) immersed in synthetic municipal solid waste leachate is examined over an approximately 8-year period. Antioxidant depletion of the textured part is shown to be much faster than that of the smoo...
The correlation between the single-point notched constant tensile load-stress crack resistance (SP-NCTL SCR) Test (ASTM D5397; Appendix) of smooth high density polyethylene (HDPE) geomembranes and their strain hardening modulus is investigated for both unaged and aged specimens. The strain hardening modulus was calculated based on the (force-elonga...
The effect of ageing at 85°C of extrusion welds of 1.5 mm-thick high-density polyethylene (HDPE) geomembrane, immersed in synthetic municipal solid waste leachate, is investigated with respect to its standard oxidative induction time (Std-OIT) and stress crack resistance (SCR). Results show that the heat-affected zones (HAZ) adjacent to the squeeze...
To quantify the effects of differential settlement on leakage through a geomembrane (GMB) hole in waste (landfill/mine tailings) covers, field experiments were conducted at Queen's University Experimental Liner Test Site on two sections, each with a 4H:1V slope. Over 13 months, measurements showed that a 3 m x 2 m x 0.12 - 0.17 m depression in Sect...
The stress crack resistance (SCR) of high-density polyethylene (HDPE) geomembrane extrusion welds is examined for a 1.5 mm HDPE geomembrane and three different welding parameter combinations (denoted as “Cool”, “Good”, and “Overheated”). Results are reported for unnotched welds, unnotched sheet, and notched sheet. The average SCR for a Good extrusi...
Three hundred and twenty-four data points on the saturated hydraulic conductivity (k) of various hard rock mine tailings are collected from previous publications. The applicability of existing empirical equations for hard rock mine tailings is assessed based on this database collected. Results show that with a greater exponent of d10, the correlati...
The stress crack resistance (SCR) of different multilayered textured geomembranes (GMBs) immersed in synthetic municipal solid waste leachate at 55 and 85 o C for 50 months is assessed using their smooth edge or smooth equivalent GMBs made from the same formulation of the textured GMBs. The difference between the actual thickness of the smooth edge...
High-density (HDPE) and linear low-density polyethylene (LLDPE) geomembranes are used in barrier systems in various containment applications. The former is known for its better chemical resistance, while the latter is known for its higher stress-crack resistance (SCR). The SCR of high-density polyethylene is well defined in the literature, but the...
The paper develops an analytical model based on the force equilibrium for the design of steep slope geosynthetic liner systems to overcome downdrag loads from waste settlement. This analytical model calculates the required tensile stiffness for a high strength/stiffness geotextile (HS-GTX) reinforcement over the GMB to limit the maximum HS-GTX tens...
The antioxidant-stabilizer depletion of four 1.5-mm HDPE geomembranes from the same manufacturer each with a different resin and additive package is examined in air and a synthetic municipal solid waste leachate at a range of temperatures (40-95°C) for 7.5 years. Two were formulated for high-temperatures and used polyethylene of raised temperature...
Field observed shrinkage was quantified and compared for one geosynthetic clay liner (GCL) type left covered only by a black geomembrane, a white geomembrane, and 0.3 m of gravel cover. Shrinkage is reported for up to 28 months field exposure of an additional four GCLs beneath a black geomembrane. All GCLs were needle-punched geotextile encased: on...
The degradation behaviour of five multilayered textured white geomembranes (GMBs) is investigated when immersed in two synthetic low-level waste (LLW) leachates with pH 7 and 9 at a range of temperatures (40–85 °C) for 48–55 months. Results are compared to the performance of the GMBs in synthetic municipal solid waste (MSW) leachate. Increasing pH...
Experiments are conducted to investigate leakage through circular GMB holes overlain and underlain by both tailings with various hole diameters and GMB thicknesses. Finite element analyses are performed to explore the effect of hydraulic conductivities (k) of subgrade (underliner) and tailings above the GMB (overliner) on water head contours dissip...
This study offers an analytical solution for radial consolidation that captures the biogeochemical clogging effect in acid sulfate soils. Field sites and personal communication with industry practitioners have provided evidence of piezometers exhibiting retarded pore pressure readings that do not follow conventional soil consolidation and seepage p...
The durability of five 1.5-mm thick geomembranes (GMBs) is investigated in pH 0.5 and 13.5 synthetic mining solutions using immersion tests. Two high density polyethylene (HDPE), two linear low density polyethylene (LLDPE), and one blended polyethylene (BPO) GMBs are investigated at 85 • C for incubation durations of 4.5-6.5 years. It is shown that...
Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorobutane sulfonic acid (PFBS), 6:2 fluorotelomer sulfonic acid (6:2 FTS), and GenX are tested for diffusion and sorption through thermoplastic polyurethane (TPU) and three ethylene interpolymer alloy (PVC-EIA) liners (EIA1, EIA2, and EIA3) with decreasing ketone ethylene ester...
The longevity of two white multilayered textured geomembranes, manufactured with a smooth edge for welding, is examined when immersed in synthetic municipal solid waste leachate at five temperatures (40, 55, 65, 75, and 85°C) for 50 months. The textured and smooth parts of the geomembranes had similar initial chemical and physical properties, but t...
The long-term performance of a geosynthetic clay liner (GCL) above a drainage layer and a geocomposite drain (GCD) are investigated. Full-scale tests are used to: (i) assess the integrity of GCL and GCD in a double composite liner below a defect in the primary geomembrane with ageing, and (ii) establish the head at which there was internal erosion...
Leakage and erosion of a soluble subgrade overlain by a geomembrane with a 70-mm-long slit defect is examined. The subgrade (gypsum) solubility and its rate of dissolution from a solid state in contact with various solutions are investigated. In the absence of flow, the rate of dissolution is negligible. However, when there is flow there is dissolu...
The degradation in physical and mechanical properties of a 1.5 mm thick HDPE geomembrane immersed in seven different low pH and three high pH simulated mining solutions is examined at temperatures between 95 and 40 °C for 3 years. The solutions with pH between 0.5 and 13.5 encompass solutions found in copper, nickel, uranium, gold, and silver heap...
To safely contain Per-and Polyfluoroalkyl substances (PFAS) in municipal solid waste landfills and contaminated soil monofills, it is necessary to understand how these substances interact with components of engineered systems designed to contain them. This paper examines the interaction between one of the most critical components of the system: a h...
Tailings dams and heap leach pads projects are among the mining applications that extensively use polyethylene geomembranes to prevent the migration of fluids to the surrounding environments. The pH of acidic heap leaching solutions are typically at or below 2.0, while tailings pore waters from pre-filtered or unsaturated tailings may range between...
In landfill covers, geomembranes are mainly used to control the infiltration of moisture from rainfall and snow melt. Unlike the base liners, cover geomembranes are on a slope and are more vulnerable to differential settlement due to the non-uniform degradation and thawing of waste. Also, in the long term, some holes in cover geomembranes are inevi...
The difference in seam squeeze-out antioxidant loss (in terms of standard oxidative induction time, Std-OIT loss) and thickness reduction are evaluated for three different 1.5 mm-thick high density polyethylene (HDPE) geomembranes (GMBs) seamed using a variety of welding parameters and two different wedge welders. Partial squeeze-out antioxidant lo...
An experimental study of the effect of closed system and a limited study of open system freeze-thaw cycles on the interface transmissivity at applied stresses between 10 and 150 kPa is described. The effect of closed system freeze-thaw is most apparent after 100 freeze-thaw cycles and permeation at a stress ≤25 kPa. The effect of permeating fluid c...
The stress crack resistance (SCR) and standard oxidative induction time (Std-OIT) reduction of high- density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for a 12-year old 1.5 mm HDPE GMB when welded using nine welding parameter combinations. The GMB experienced a decrease in Std-OIT from 135 to 87 min between manufacturing and we...
The state-of-the-art for barriers systems control of pollution migration and hydraulic structures including liner systems for landfills, mine waste, and dams/lagoons are discussed along with some comments on current significant environmental issues.
Experiments were conducted to quantify short-term tensile strains induced in a 1.5 mm thick high-density polyethylene geomembrane overlain by tailings. Four subgrades, a poorly graded angular to subangular gravel (GP), a well-graded angular to subangular gravel (GW), a poorly subrounded graded sand (SP), and silty sand (SM), and two nonwoven geotex...
This study demonstrates the change in porosity of permeable reactive barrier (PRB) material when it reacts with acidic flow. The laboratory column test data obtained over 9 months prove that the porosity of a granular limestone assembly decreases significantly due to bio-geochemical clogging caused by a continuous flow of acidic groundwater. The va...
The state-of-the-art for barriers systems control of pollution migration and hydraulic structures including liner systems for landfills, mine waste, and dams/lagoons are discussed along with some comments on current significant environmental issues.
Waste disposal facilities commonly have a composite liner (e.g., a geomembrane, GMB, over a geosynthetic clay liner, GCL) in both the cover and bottom liner. The performance of a composite liner primarily depends on the size, number, and location of holes in the geomembrane together with the hydraulic conductivity, k, of the GCL, and the interface...
Performance indicators of geosynthetic clay liners (GCLs) exposed to the Antarctic environment were assessed using field and laboratory methods. Barrier properties of the GCLs were not impacted by the field conditions and exhumed hydraulic conductivities with respect to tap water ranged from 0.4 × 10⁻¹¹ to 12 × 10⁻¹¹ m/s, compared to 5 × 10⁻¹¹ m/s...
Time and method dependencies, lack of sufficient capillary connections, and wetting-drying hysteresis may cause inaccurate results from filter paper tests (FPTs) when used for suction measurements of geosynthetic clay liners (GCLs). These limitations of the filter paper method for suction measurements of GCLs were investigated using initially dry c...
Experimental data is presented for leakage through slits, square, and rectangular geomembrane defects overlain by silty sand tailings and underlain by a well-graded gravel. The rectangular GMB defects have a range of widths, B, lengths, L, and aspect ratios (L/B), and ratios of defect length to thickness of tailings above the geomembrane (L/T). A b...
Two GCLs with sodium bentonite and three GCLs with polymer amended bentonite were subjected to wet-dry cycles selected to simulate the conditions to which a GCL on an 18 o slope might be subjected: for a GCL below an exposed geomembrane wrinkle with a hole. The wetting involved water flowing over the GCL for 8 hours each cycle. Three drying cycles...
The effect on GCL hydration and dehydration, when subject to thermal cycles, of (1) GCL bentonite granularity (powdered vs. granular), (2) GCL geotextile type (scrim-reinforced nonwoven vs. woven), (3) subgrade macrostructure due to fines aggregation, and (4) subgrade density and fines content is examined. Results of 17 hydration tests were assesse...
The stress crack resistance (SCR) of high density polyethylene (HDPE) geomembrane (GMB) fusion seams is examined for two 1.5mm HDPE GMBs and a range of welding parameters. Results are reported for both unnotched and notched seams as well as their corresponding sheet material. Unnotched seam SCR specimens are shown to preferentially initiate craze f...
The self-healing of five geosynthetic clay liners (GCLs) with laboratory simulated down-slope erosion defects (quasi-circular holes and linear slits where there is little or no bentonite) upon hydration from Godfrey silty sand subgrade with w fdn = 16% under an overburden stress σ v = 20 and 100 kPa is examined. While there was an up to 9.6 mm redu...
Microstructure showing the involvement of the fine and coarse grains in the soil skeleton is evaluated. Incremental loading tests using a stress-dependent permeameter are conducted on the mixtures of poorly graded sand and nonplastic fines originating from tailings. The results are compared with the published data of various tailings. It is shown t...
ABSTRACT
Over a period of 40 years, fuels spills and leaks have occurred at Canadian sub-Arctic and Arctic Distant Early Warning Line (DEW Line) sites. The Canadian Department of National Defence has initiated cleanup program of these sites estimated to cost $320 million (Cdn). Access to these sites is often limited and the environmental conditions...
The impact of time-dependent unsaturated behaviour of virgin and the impact of cation self-diffusion on the time-dependent unsaturated behaviour of exhumed Geosynthetic Clay Liner (GCL) specimens were investigated using a chilled mirror hygrometer. Total suction values (after 7 weeks water homogenization) are reported for ten virgin (six different...
A laboratory investigation was conducted on two different conventional GCLs (one with fine granular and another one with powdered bentonite) to explore the effect of prehydration and permeant fluid; GCL desiccation on the interface transmissivity, θ, between the interfaces of a 1.5 mm-thick high-density polyethylene (HDPE) geomembrane (GMB) and a G...
Experiments are conducted to study leakage and piping through circular geomembrane holes from the overlying silty sand tailings. Three subgrades, a poorly graded gravel, a well-graded gravel, and a poorly graded sand are studied. Test results show that leakage through the geomembrane hole is not proportional to the surface area of the hole. A 5-fol...
The design of saturated tailings impoundments often relies on geomembrane liners at the base and upstream face of the storage facility to prevent the movement of tailings-derived water into the adjacent groundwater flow system. The geomembrane must be chemically compatible with the tailings pore water to ensure its long-term performance in protecti...
The observation of failure surfaces within column-supported embankments is critical to understanding how the embankment stresses are transferred towards the column heads. In this study, finite element simulations utilising a strain-softening constitutive model, nonlocal regularisation, and the Arbitrary Lagrangian–Eulerian formulation are used to e...
Waste disposal facilities commonly have a composite liner (e.g., a geomembrane, GMB, over a geosynthetic clay liner,
GCL) in both the cover and bottom liner. The performance of a composite liner primarily depends on the size, number, and location
of holes in the geomembrane together with the hydraulic conductivity, k, of the GCL, and the interface...
The contaminant transport of perfluorooctane sulfonate (PFOS) through the base of a municipal solid waste landfill lined by a single composite liner comprised of a geomembrane over a geosynthetic clay liner (GCL) and a 3.75 m-thick attenuation layer underlain by an aquifer is examined. Both pure diffusive transport and advective transport through h...
Experiments are conducted to quantify leakage through holes in a geomembrane (GMB) overlain by tailings with 30% fines and underlain by a well-graded gravel. Analytical and empirical equations for predicting leakage through a circular hole are used to analyze the data. Test results show that changing the hole shape from circular to noncircular incr...
Experiments are conducted to quantify leakage through a circular geomembrane (GMB) hole using two subgrades (underliners) not meeting modern filter criteria. Test results show that a 1.9- and 5.0-fold increase in hole diameter causes a 1.8- and 6.2-fold increase in leakage, respectively, whereas a 2-fold increase in GMB thickness results in an appr...
CSCE's Engineering Mechanics and Materials (EMM) division is organizing a panel session titled: Transitioning from Graduate Studies to Securing Faculty Positions, to be held on Wed, May 26, 12-1 pm (EST), as a part of the CSCE annual conference (https://csce2021.ca/). All CSCE graduate student members are welcome to join.
Leakage through a 10 mm diameter circular hole in a geomembrane beneath fine-grained tailings is examined for a range of pore pressures and effective stresses. Leakage was measured in an experiment with coupled physical and hydraulic conditions to simulate the effective stresses and flow conditions near the hole. The leakage rate was as little as 0...
The self-healing of a GCL with a circular hole is examined in experiments where the GCL, overlain by geomembrane, is hydrated from a silica sand subgrade (SSS) having three different pore water chemistries. Factors considered included: hole size, subgrade initial moisture content wfdn, GCL mass per unit area, and overburden stress (20–100 kPa). GCL...
The performance of five different GCLs (two GCLs with standard sodium bentonite and three GCLs with polymer enhanced bentonite) subjected to three different climatic modes of wet-dry cycles simulating conditions to which a GCL might expose in cover systems over a prolonged time is reported. The wetting cycles lasted for 8 h, while the drying cycles...
Swelling characteristics of compacted bentonite when hydrated with a hypersaline pore fluid (332 g/L total dissolved solids; 6.6 mol/L ionic strength) are reported. The pore fluid mimics the multiple constituents and their concentrations found for the Cobourg limestone of the Michigan Basin and is dominated by sodium (25% mole fraction) with some p...
This lecture examines the progress made in the last few decades concerning the use of geosynthetics for aiding in the construction on soft soils. Consideration is given to different soft soils ranging from peat to rate-sensitive soft clay and silt. Both relatively elastic and rate-sensitive reinforcements are examined. Consideration is given to bas...
A series of laboratory tests were conducted to investigate the interface transmissivity, θ between a 1.5 mm thick high-density polyethylene geomembrane (GMB) and a multicomponent geosynthetic clay liner (MC_GCL) when permeated with a simulated municipal solid waste landfill leachate under a range of applied stresses (10-150 kPa). The effect of thre...
Diffusion of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) through 0.1 mm and 0.75 mm LLDPE and 0.1 mm and 0.75 mm LLDPE coextruded with ethyl vinyl alcohol (denoted as CoEx) at room temperature (23 °C), 35 °C, and 50 °C is examined. These tests had negligible source depletion throughout the monitoring period, indicating limited co...
This paper examines the hydration/dehydration behaviour of geosynthetic clay liner (GCL) under polar conditions for four simulated conditions experienced at Australia's Casey Station in Antarctica: (a) hydration during summer, (b) dehydration during a winter-summer cycle, (c) hydration through a fine Antarctic soil, and (d) hydration through a coar...
The interface transmissivity (θ) of two multicomponent geosynthetic clay liners (GCLs) is investigated upon hydration and permeation with a highly saline solution (TDS ≈ 260,000 mg/l; Na⁺ ~ 95,000 mg/l; K⁺~12,000 mg/l) at two stress levels (10 kPa and 150 kPa). One GCL had a smooth 0.2 mm-thick coating whereas the second GCL had a textured 1 mm-thi...
The longevity of textured geomembranes (GMB) widely used as base and slope liners is rarely studied. The variability of the thickness and defects on the surface of co-extruded textured GMBs result in non-uniform mechanical properties across the GMB roll. Therefore, the effect of texturing on the stress crack resistance (SCR) of unaged and aged high...
The paper examines the effects of settlement-induced downdrag on geosynthetic liner systems for a waste containment facility with steep side slopes for different design scenarios, and conducts the stability analysis of the waste mass during waste filling operations. Without the presence of a reinforcing layer above a geomembrane (GMB) liner, the li...
Geosynthetic reinforced column supported embankments predominantly utilise two mechanisms to transfer embankment loads towards column heads, soil arching and membrane actions. When undertaking the design of column supported embankments, it is common practice to perform a two-step design, whereby the arching actions are estimated independently of th...
Recently, there has been increased interest in the use of geosynthetic clay liners (GCL) in composite liners in harsh environments like the Arctic and Antarctic regions. The primary role of a GCL in the composite liner is to minimize the advective flow of contaminants if there are any holes in the geomembrane (GMB). The two parameters controlling t...
