Lake, Craig
Permanent URI for this collectionhttps://hdl.handle.net/10222/39724
Craig Lake
Associate Professor
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Item Open Access Biodegradation kinetics of individual and mixture non-steroidal anti-inflammatory drugs in an agricultural soil receiving alkaline treated biosolids(Elsevier, 2021) Shu, W; Price, G; Jamieson, R; Lake, C.BLand application of biosolids is one potential source of pharmaceuticals and personal care products (PPCPs) into agricultural soils. Degradation is an important natural attenuation pathway that affects the fate and transport of PPCPs in soil system and could be altered upon biosolids application. The present study was performed to assess the degradation kinetics of three commonly used non-steroidal anti-inflammatory drugs (NSAIDs), including naproxen (NPX), ibuprofen (IBU), and ketoprofen (KTF), in a sandy loam soil amended with alkaline treated biosolids (ATB) introduced either as individual compounds or as a multi-compound mixture. Results of this study indicated the disappearance of studied NSAIDs in all treatments were mainly attributed to biodegradation and followed the first-order exponential decay response. In soil receiving ATB amendment, degradation of NPX and IBF in all treatments, as well as KTF in individual treatment was inhibited over the 14 day incubation study. Inhibition effect from ATB amendment was also observed in sterilized treatment. The presence of NSAIDs in mixture treatment reduced the degradation rate of NPX and KTF in soil, while the opposite results were observed in ATB amended soil. Ibuprofen exhibited the inhibition of degradation in both soil and ATB amended soil. Inversely, mixture compound environment stimulated the disappearance of all studied NSAIDs in sterilized treatment, except NPX in soil. Results of this study demonstrated the complex degradation behavior of NSAIDs in the presence of ATB and chemical mixtures, which warrants future investigation that incorporates a broader range of biosolids, soil type, and pharmaceutical mixtures to better understand the fate of pharmaceuticals in the environment.Item Open Access Characterizaing sediment physical property variability for bench scale dewatering purposes(Thomas Telford Ltd, 2020) Alimohammadi, MA field sampling program was undertaken to assess the variability of physical characteristics of contaminated sediments in a large (160 ha) effluent stabilization lagoon. The objective of this paper is to use this “field lab” as a basis for comparing different sampling techniques (i.e. discrete and composite) for remediation-based evaluations (i.e. sediment volume estimates and bench scale dewatering studies). The distribution of sediment thickness measured throughout the lagoon by gravity core sampling is presented for context. Selected gravity core sediment samples are evaluated with respect to physical property (water/solids content, bulk density, and particle size) variability in both the vertical (i.e. within a single gravity core) and spatial directions (between among gravity cores). Composite samples created via homogenization of a single entire gravity core is performed to compare to the discrete and average physical properties of a nearby gravity core. Vacuum-based samples are also compared to gravity core samples in terms of particle size. It is demonstrated that by understanding sediment variability, composite samples can be shown to be an efficient method of obtaining representative samples. When large samples for dewatering trials are required, vacuum sampling can produce samples with similar mean particles size to discrete and composite samples.Item Open Access Particle Size Effects on Breakage of ACT Aggregates Under Physical and Environmental Loadings(American Society of Civil Engineers, 2020) Choi, H.; Lake, C.B.; Hills, C.D.Aggregates manufactured from fine-grained thermal waste residues using accelerated carbonation technology (ACT) represent a potential sustainable alternative to natural aggregates. However, for these manufactured products to compete with virgin stone in geotechnical applications, their durability under mechanical and environmental loadings must be assessed. This paper describes particle breakage that occurs for different grain sizes (entire sample, 5mm-2.5mm, and 2.5mm-1.25 mm) of a cement kiln dust accelerated carbonated manufactured aggregate after undergoing triaxial compression, triaxial shear and freeze/thaw (f/t) testing. It is shown that the particle breakage of the aggregate is dominated by the larger (5mm-2.5mm) size fraction of the sample under all loading conditions. Particle breakage results from f/t testing showed that the 5mm-2.5mm size corresponded to similar or slightly less particle breakage than that under triaxial shear, while the particle breakage of the 2.5mm-1.25mm aggregate after 20 cycles of freeze-thaw was relatively small. The performance of the carbonated aggregate in terms of relative breakage was similar or slightly better than natural calcareous sand results in the literature.Item Open Access Development of a leaching procedure to asses the risk of uranium leaching due to construction and demolition waste(Elsevier, 2018) Letman, M.M.; Drage, J.; Ryan, A.M.; Lake, C.B.; Jamieson, R.Naturally-occurring uranium can be found at elevated concentrations in groundwater throughout the world, with the potential to cause kidney damage in chronically exposed individuals. Empirical evidence shows that uranium mobilization can be enhanced in the presence of ions that are associated with leachate from construction and demolition (C&D) disposal sites. There is need for a simple and effective procedure to evaluate soil and rock formations for uranium mobility prior to the permitting of waste disposal facilities which could alter groundwater chemistry. A series of leachate extractions were performed to represent the impact of C&D leachate on uranium-bearing rocks, focusing on the impact of calcium, sodium, chloride, sulphate, and bicarbonate concentrations on uranium mobilization. Based on these observations a uranium leaching procedure (ULP) was developed and compared to the synthetic precipitation leaching procedure (SPLP). The ULP was capable of mobilizing an order of magnitude more uranium than the SPLP from six rock samples and shows promise as a tool for assessing the risk of groundwater contamination by C&D waste through uranium mobilization.Item Open Access Using a geotextile with flocculated filter backwash water and its impact on aluminium concentrations(Elsevier, 2018) Jahan, I.; Wood, M.; Lake, C.B.; Gagnon, G.A.The use of geotextiles (i.e. geotextile tubes) in wastewater treatment applications is ever increasing. This paper examines the potential of using a geotextile to improve upon the treatment of aluminium present in a filter backwash water that is generated from a water treatment plant in Halifax, Canada. A field investigation to ascertain the distribution of aluminium in the filter backwash water treatment process is provided and compared to regulatory guidelines at the environmental compliance point. It is shown that aluminium is undergoing incomplete treatment at various times throughout the year. To examine a potential corrective action, the results of bench scale studies are presented in which cationic additives (i.e. CaO, MgO, and Fe3O4) are combined with a polymer to remove aluminium from solution and flocculate particulate matter from the filter backwash water. A geotextile is utilized to retain particulate matter generated from this process. It is shown that the combined use of the cationic additive with polymer can successfully reduce aluminium concentrations in the filter backwash water and that filtration via a geotextile can retain the aluminium particulate in the filter backwash water to levels close to regulatory requirements. Further optimization with the flocculation process is recommended prior to pilot testing.Item Open Access The effect of different dewatering techniques on resulting effluent particle size.(Canadian Science Publishing, 2020) Alimohammadi, M.; Tackley, H.; Lake, C.B.; Spooner, I.S.; Walker, T.R.; Jamieson, R.C.; Gan, C.; Bossy, K.A paucity of literature has compared geotextile dewatering methods to more conventional dewatering methods (i.e. centrifuge, sedimentation) in the context of how geotextile dewatering performs at reducing particulate matter in dewatering effluent. Particulate matter is the primary source of inorganic and organic contaminants (i.e. dioxins and furans) in an unconsolidated sediment (estimated 577,000 m3) that has accumulated in a wastewater stabilization basin in Nova Scotia, Canada. Physical and chemical properties of contaminated sediment were initially characterized, and subsequent laboratory experiments were carried out for three common dewatering methods: sedimentation, centrifugation, and geotextile filtration. Filtrate quality of suspended solids (number, particle size distribution of particles) was examined for differences based on three dewatering techniques assessed. All three methods provided effective removal of particulate matter during dewatering, but geotextile dewatering could be a more cost-effective and practical solution for dewatering of these sediments.Item Open Access Quantifying hydraulic conductivity spatial variability for a cement-based solidification/stabilization (S/S) remediation project: a case study.(Canadian Science Publishing, 2021) Fenton, G.A.; Lake, C.B.; Liza, R.K.This paper presents statistical analyses of hydraulic conductivity data collected from an existing cement-based solidification/stabilization (S/S) system. The goal is to characterize the spatial variability of hydraulic conductivity and to examine sampling recommendations for the quality control (QC) program of that system in order to achieve target decision error probabilities regarding the acceptance or rejection of the system with respect to hydraulic conductivity. Over 2000 quality control hydraulic conductivity samples, taken over an area of 300,000 m2, are used as a basis for these analyses. The hydraulic conductivity spatial variability is described by a marginal log-normal distribution with correlation function parameterized by directional correlation lengths, which are estimated by best fitting an exponentially decaying correlation model to sample correlation functions. The spatial variability associated with hydraulic conductivity of the studied S/S system is then utilized to assess sampling requirements for the QC program of that system. Considering the “worst case” correlation length and the hydraulic conductivity mean and variance, hypothesis test error probabilities are used to provide recommendations for conservative sampling requirements. It is believed that the analysis of this large construction project represents a unique opportunity to review the current practice of S/S field sampling requirements.Item Open Access Examining the Ultraviolet Optical Screening Tool as a Viable Means for Delineating a Contaminated Organic Sediment(Elsevier, 2021) Davidson, K.B.; Lake, C.B.; Sweet, B.; Spooner, I.S.Rapid and accurate delineation of contaminated sediments in marine environments is critical for the effective assessment of site risks and the development of appropriate remedial action plans. In this study, a new application of the ultraviolet optical screening tool (UVOST) equipped with electrical conductivity measurement (UVOST-EC) is proposed to delineate a water-covered sediment contaminated with dioxins and furans in a decommissioned pulp and paper wastewater stabilization basin. Bench scale experiments are presented that were used to develop a UVOST-EC interpretation method for delineating between two different sediment types present in the basin: an anthropogenically derived organic rich contaminated sediment (“black sediment”) and a naturally occurring grey organic silt sediment with marine provenance (“grey sediment”). The method involves comparative analysis of fluorescence and electrical conductivity signatures between the two sediments. Results indicate that each sediment type presents unique “signatures” related to fluorescence and electrical signals which corresponds to variability in their physio-chemical structure. Almost 100 UVOST-EC tests performed at the study site were paired with ex situ physical gravity core measurements of the black sediment to test the accuracy of the UVOST-EC-based method. A statistical analysis at seven sample “cluster” sites (i.e. multiple sub-samples within a defined area) indicated that the mean of sediment thickness obtained by the UVOST-EC measurement technique at a given site were not significantly different (p=0.05) from measurements derived from sediment gravity core measurements. The UVOST-EC-based sediment thickness delineation method reliably determined the thickness of the dioxin and furan contaminated sediments as compared to gravity core determination for the sediment in this study. Application of this approach to other studies should be assessed in a similar manner. The UVOST-EC method offers health and safety, cost, logistics, and data interpretation benefits.Item Open Access Fate and transport of particle matter during geotube dewatering of a dioxin and furan (PCDD/F) contaminated sediment.(Elsevier, 2022) Alimohammadi, M.; Lake, C.B.Geotextile tube dewatering is a pre-treatment method utilized in the remediation of high-water content materials (i.e. sediments and slurries). However, given the association some contaminants (e.g. dioxins and furans, (i.e. PCDD/F)) have with particulate matter in these contaminated sediments, understanding the fate and transport of this particle matter in the dewatered effluent is essential. In this paper, pressure filtration tests (PFTs) were conducted to investigate the effect of pressure and filter cake formation on both geotextile filtration efficiency and effluent quality. Transport tests were then performed to evaluate the particle transport through the developed filter cake, as well as the hydraulic characteristics of the medium during dewatering. HYDRUS, a one-dimensional model contaminant transport model was then employed to simulate the experimental particle transport test results. Three different mechanisms of particle transport (i.e. attachment only, detachment only, both attachment and detachment) through saturated porous media were examined to identify the possible mechanisms of observed effluent particle concentration. HYDRUS modeling outputs suggest that both attachment and detachment mechanisms are involved in a given particle’s fate and transport during geotextile dewatering. In addition, parameters such as confining pressure and filter cake properties affect the particle concentration in the effluent.Item Open Access Evaluating the movement of dissolved porewater species through a marine sediment 51 years after establishment of a pulp and paper effluent stabilization basin(Canadian Science Publishing, 2022)Over 50 years ago, a marine estuary was converted to a wastewater stabilization basin for treatment of primarily pulp and paper effluent. As a result, the basin was immediately converted to a “freshwater” environment and subsequently accumulated a thin layer of black, organic-rich sediment containing varying amounts of dioxins and furans, metals, polycyclic aromatic hydrocarbons and petroleum hydrocarbons. Previous studies on the site have shown that the majority of this contamination in the basin appears to have been contained within this black sediment layer and not migrated to any significant extent into the original underlying marine sediments. The purpose of this study is to examine sediment porewater chemistry changes that have occurred over 51 years of operation of the stabilization basin with the intent of better understanding why contamination has been minimal into the underlying natural marine sediments. Field and laboratory testing is presented to characterize the physical, chemical and mineralogical sediments in the basin. Porewater chemistry profiles obtained from this work are then used in combination with a one-dimensional contaminant transport model to examine the role of diffusion, sorption and upward groundwater flux in the porewater profiles found for the sediments.Item Open Access Low impact development effects on aquifer recharge using coupled surface and groundwater models(ASCE, 2018) Mooers, E.W.; Jamieson, R.C.; Hayward, J.; Drage, J.; Lake, C.B.Low impact development (LID) is promoted as a sustainable management practice for stormwater in urbanized catchments. While the positive effects of LID features on surface water hydrology and water quality have been investigated, less is known regarding their effects on aquifer recharge. The hydrologic model PCSWMM was coupled with the groundwater model MODFLOW, to assess the influence of LID on aquifer recharge in a study area undergoing residential development. The coupled models were calibrated and validated with pre-development stream flows and groundwater levels from a predominately forested catchment. PCSWMM was used to quantify net infiltration rates for conventional and LID stormwater practices for the development. Net infiltration rates were then coupled with MODFLOW, to determine aquifer recharge, and the potential effects on groundwater availability for the development. Results suggested that LID practices would help restore pre-development aquifer recharge conditions. This study demonstrated a novel approach for assessing the effects of LID stormwater practices on aquifer recharge and groundwater availability in new residential developments.Item Open Access Spatiotemporal assessment (quarter century) of pulp mill metal(loid) contaminated sediment to inform remediation decisions(Springer, 2017) Hoffman, E.; Lyons, J.; Boxall, J.; Robertson, C.; Lake, C.B.; Walker, T.R.A bleached kraft pulp mill in Nova Scotia has discharged effluent wastewater into Boat Harbour, a former tidal estuary within Pictou Landing First Nation since 1967. Fifty years of effluent discharge into Boat Harbour has created >170,000 m3 of unconsolidated sediment, impacted by inorganic and organic contaminants, including metal[loid]s, polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans. This study aimed to characterize metal(loid)-impacted sediments to inform decisions for a $89 million CAD sediment remediation program. The remediation goals are to return this impacted aquatic site to pre-mill tidal conditions. To understand historical sediment characteristics, spatiotemporal variation covering ~quarter century, of metal(loid) sediment concentrations across 103 Boat Harbour samples from 81 stations and four reference locations, were assessed by reviewing secondary data from 1992 to 2015. Metal(loid) sediment concentrations were compared to current Canadian freshwater and marine sediment quality guidelines (SQGs). Seven metal(loid)s, As, Cd, Cr, Cu, Pb, Hg, and Zn, exceeded low effect freshwater and marine SQGs; six, As, Cd, Cr, Pb, Hg, and Zn, exceeded severe effect freshwater SQGs; and four, Cd, Cu, Hg, and Zn, exceeded severe effect marine SQGs. Metal(loid) concentrations varied widely across three distinct temporal periods. Significantly higherCd, Cu, Pb, Hg, and Zn concentrations were measured between 1998 and 2000, compared to earlier, 1992–1996 and more recent 2003–2015 data. Most samples, 69%, were shallow (0–15 cm), leaving deeper horizons under-characterized. Geographic information system (GIS) techniques also revealed inadequate spatial coverage, presenting challenges for remedy decisions regarding vertical and horizontal delineation of contaminants. Review of historical monitoring data revealed that gaps still exist in our understanding of sediment characteristics in Boat Harbour, including spatial, vertical and horizontal, and temporal variation of sediment contamination. To help return Boat Harbour to a tidal estuary, more detailed sampling is required to better characterize these sediments and to establish appropriate reference (background) concentrations to help develop costeffective remediation approaches for this decades-old problem.Item Open Access Particle size effects on breakage of ACT aggregates under physical and environmental loadings(ASCE, 2020) Choi, H.; Lake, C.B.; Hills, C.D.Aggregates manufactured from fine-grained thermal waste residues using accelerated carbonation technology (ACT) represent a potential sustainable alternative to natural aggregates. However, for these manufactured products to compete with virgin stone in geotechnical applications, their durability under mechanical and environmental loadings must be assessed. This paper describes particle breakage that occurs for different grain sizes (entire sample, 5mm-2.5mm, and 2.5mm-1.25 mm) of a cement kiln dust accelerated carbonated manufactured aggregate after undergoing triaxial compression, triaxial shear and freeze/thaw (f/t) testing. It is shown that the particle breakage of the aggregate is dominated by the larger (5mm-2.5mm) size fraction of the sample under all loading conditions. Particle breakage results from f/t testing showed that the 5mm-2.5mm size corresponded to similar or slightly less particle breakage than that under triaxial shear, while the particle breakage of the 2.5mm-1.25mm aggregate after 20 cycles of freeze-thaw was relatively small. The performance of the carbonated aggregate in terms of relative breakage was similar or slightly better than natural calcareous sand results in the literature.Item Open Access Examining metal migration through geotextiles during dewatering(Elsevier, 2020) Tackley, H.; Alimohammadi, M.; Lake, C.B.This paper presents a study conducted to assess the influence that a filter cake deposited on the surface of the geotextile has on the mobility of three metals (Cu, Pb, Zn) during filtration of a contaminated sediment. Two chemical additives (cationic coagulant and cationic polymer) were introduced to the sediment to increase the particle size and improve the filtration efficiency. Bench scale experimentation was conducted to identify contaminant reduction using a small volume of sediment. A field test was applied to observe what effect three-dimensional filtration and a larger filter cake had on metal mobility. Analysis of the effluent was conducted to determine total and dissolved metal contaminants, as well as particulate matter. Effluent chemical properties (pH, Eh, and zeta potential) were analyzed to identify a possible rationale for variations in concentration during filtration. The results of the study show that as an increasing buildup of filter cake on the surface of a geotextile developed, filtrate quality was improved with respect to the metal and particulate contaminants considered. In addition, the metals detected in the effluent were primarily in the solid state, suggesting further reduction could be achieved through subsequent filtration (if desired).Item Open Access Historical characterization and spatial distribution of organic contaminated sediment derived from kraft pulp mill effluent.(Springer, 2019) Hoffman, E.; Alimohammadi, M.; Lyons, J.; Davis, E.; Walker, T.R.; Lake, C.B.Organic sediment contaminants [polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and polycyclic aromatic hydrocarbons (PAHs)] were assessed using secondary monitoring data from a former tidal estuary (Boat Harbour) impacted by historical industrial effluents. Spatiotemporal characterization of PCDD/Fs and PAHs in sedimentswas conducted to inform a sediment remediation program designed to return this contaminated aquatic site back to a tidal lagoon. Spatiotemporal variations of sediment PCDD/F and PAH concentrations across Boat Harbour and off-site reference locations were assessed using secondary monitoring data collected between 1992 and 2015. Sediment PCDD/F toxic equivalency (TEQ) and PAH concentrations were compared to sediment quality guidelines. Sediment PCDD/F concentrations exceeded the highest effect thresholds posing severe ecological health risks. High sediment PCDD/F concentrations have persisted in Boat Harbour despite implementation of Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans Regulations in 1992. PAH concentrations varied greatly. Five individual PAH compounds frequently exceeded severe effect thresholds, in contrast to total PAHs, which were below severe effect thresholds. Forensic analysis using PAH diagnostic ratios suggests pyrogenic PAHs derived from wood processes or coal combustion were likely sources. Twenty-five years of monitoring data revealed large data gaps inour understanding of sediment characteristics in Boat Harbour. Gaps included spatial (vertical and horizontal) and temporal variations, presenting challenges for remediation to accurately delineate sediment contaminants. Deeper horizons were poorly characterized compared to shallow sediments (0–15 cm). Historical secondary monitoring data showed that spatial coverage across Boat Harbour was inadequate. Due to severe ecological health risks associated with high sediment PCDD/F concentrations, remediation of the entire sediment inventory is recommended. Detailed vertical and horizontal sampling within Boat Harbour, establishment of local baseline concentrations, and additional sampling in down-gradient-receiving environments for a suite of contaminants are required to better characterize sediments prior to remediation.Item Open Access Lateral sand filters are effective for removal of antibiotic resistance genes from domestic wastewater(Elsevier, 2019) Hayward, J.L.; Huang, Y.; Yost, C.K.; Truelstrup Hansen, L.; Lake, C.B.; Tong, A.; Jamieson, R.The ability of lateral flow sand filters, used as on-site wastewater treatment systems (OWTS), to remove antibiotic resistance genes (ARGs), antibiotic resistant bacteria (ARB), and other relevant genetic markers (HF183, 16S rRNA, and int1) was assessed. Municipal wastewater was settled in a septic tank prior to loading into six pilot-scale lateral flow sand filters comprised of three different sand media types, at 5 and 30% slopes. The sand filters were sampled bi-weekly for: 9 ARGs and 3 other complimentary gene markers (sul1, sul2, qnrS, tetO, ermB, blaTEM, blaCTX-M, mecA, vanA, int1, HF183, 16S rRNA), and conventional microbial and water quality indicators, from July to November in 2017, and four times in the summer of 2018. The sand filters were observed to attenuate 7 of the ARGs to mostly below 2 log gene copies per mL. Log reductions ranging from 2.9 to 5.4 log were observed for the removal of absolute abundances of ARGs from septic tank effluent in 5 of the 6 sand filters. The fine-grained filter on the 5% slope did not perform as well for ARG attenuation due to hydraulic failure. The apportionment of cell-associated versus cell-free DNA was determined for the gene markers and this indicated that the genes were primarily carried intracellularly. Average log reductions of ARB with resistance to either sulfamethoxazole, erythromycin, or tetracycline were approximately 2.3 log CFU per mL within the filters compared to the septic tank effluent. This field study provides in-depth insights into the attenuation of ARB, ARGs, and their genetic compartmentalization in variably saturated sand OWTS. Overall, this type of OWTS was found to pose little risk of antimicrobial resistance contamination spread into surrounding environments when proper hydraulic function was maintained.Item Open Access Examining freeze/thaw cycling and its impact on the hydrualic conductivity of cement-treated silty sand(American Society of Civil Engineering, 2015) Jamshidi, R.J.; Lake, C. B.; Barnes, C.L.Cement-based solidification/stabilization (s/s) is a remediation technology that has been widely used for treatment of a range of contaminants. Currently there is limited published data on changes in hydraulic performance of cement-treated materials subjected to cycles of freezing/thawing (f/t). Fourteen sets of tests were performed to examine the influence of factors such as number of f/t cycles, freezing temperature, curing time, and mix design on hydraulic conductivity and unconfined compressive strength (UCS) of a cement-treated silty sand. Results showed an increase of up to three orders of magnitude in hydraulic conductivity as well as decreases in UCS values after exposure to four to twelve f/t cycles. Analysis of variance (ANOVA) performed on the results of a factorial experiment considering the effect of freezing temperature, curing time, and number 22 of f/t cycles showed that all of these factors are significant in affecting the measured changes in the hydraulic conductivity and UCS values. Monitoring of damage using the impact resonance method showed that changes in the resonant frequency of specimens was consistent with changes in hydraulic conductivity and UCS after f/t exposure and also allowed monitoring of damage for intermediate cycles with minimal effort.Item Open Access Manufactured aggregate from cement kiln dust(Institute of Civil Engineers Publishing, 2016) Lake, Craig B; Choi, Hun; Hills, Colin D.; Gunning, Peter; Manaqibwala, IdrisThis paper presents the results of a laboratory study that evaluated the geotechnical and geoenvironmental properties of a manufactured aggregate derived from cement kiln dust (CKD). The aggregate manufacturing process involves accelerated carbonation technology (ACT), has been used to treat contaminated soils at trial scale. The process operates at commercial scale in the UK, producing aggregates from thermal residues. The ACT process relies on the accelerated reaction of carbon dioxide with the calcium oxide in the CKD material in the presence of water. No additional binder was used in this study, relying solely instead on the formation of carbonate to form the aggregate. In this paper, the aggregate manufacturing process is briefly described. To explore future potential construction applications of the aggregate, several geotechnical test results are used to assess strength and durability (i.e. individual particle strength, internal shear strength of the particle assemblage, wet–dry testing, freeze–thaw testing). Screening tests on the aggregate’s geoenvironmental characteristics are discussed (metal leaching, dissolved heavy metal adsorption and hydraulic conductivity) to assess potential uses further. It is shown that the aggregate studied has adequate properties for a variety of construction applications, but is unsuitable for use in freezing and thawing environments.Item Open Access An Analytical Approach to Assess Quality Control Sample Sizes of Cement-Based Solidification/Stabilization(NRC Research Press, 2017) Liza, Rukhsana; Fenton, Gordon A; Lake, Craig B; Griffiths, D.V.This paper presents an analytical approach to selecting the sample size required to achieve acceptable quality control in a cement-based solidification/stabilization construction cell program intended for the treatment/containment of contaminated soils. The proposed approach is based on the hypothesis test that the cell does not have an acceptably low hydraulic conductivity (the null hypothesis), versus the alternative hypothesis that it does. Analytical solutions are developed to compute the probabilities of both type I (mistakenly rejecting the null hypothesis) and type II (mistakenly failing to reject the null hypothesis) errors as functions of the number of samples and the statistics of the hydraulic conductivity field. The analytical results are validated by Monte Carlo simulations and are then used to develop rational sampling requirements. An example is presented to illustrate how the proposed approach can be used in practice to assess the required sample size for the quality control program of cement-based S/S construction cells.Item Open Access Geotextile biofiltration of primary treated municipal wastewater under simulated artic summer conditions.(Elsevier, 2016-12) Bridson-Pateman, Evan; Jamieson, Rob; Lake, Craig BWastewater stabilization ponds (WSPs) are common for wastewater treatment in remote Canadian Arctic communities. In this paper, two geotextiles of different mass/unit areas are examined as a potential biofiltration upgrade to existing WSPs in arctic summer conditions. The intended role of the geotextile is to provide additional treatment of municipal wastewater seeping from these WSPs. Column filtration experiments were performed using municipal wastewater in a controlled laboratory environment at either 10 C or 2 C. The columns contained one of two different nonwoven geotextiles over 10 cm of gravel, simulating a WSP berm in contact with exfiltrating wastewater.Weekly wastewater samples were taken upstream and downstream of the geotextile/gravel filter and were analyzed for a suite of water quality parameters; the hydraulic conductivity of the columns was also measured weekly. Results showed that it is possible to accumulate biomass on geotextile material over a 3 month period at these temperatures, which corresponded with 1e2 log reductions in hydraulic conductivity. Significant removal of total suspended solids, 5-day biochemical oxygen demand, total nitrogen, and total phosphorus was observed; however, removal efficiencies for most parameters were reduced at the lower temperature. This study demonstrates that geotextiles could be used to enhance the performance of WSP systems operating in arctic climates.