Browsing by Author "Scalia, Joseph, IV, advisor"

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Open Access
Assessing irrigation canal seepage reduction using polymer sealants
(Colorado State University. Libraries, 2024) Lund, Ahmad Abdur Rehman, author; Scalia, Joseph, IV, advisor; Gates, Timothy K., advisor; Venayagamoorthy, S. Karan, committee member; Andales, Allan A., committee member
Irrigation canals around the world experience varying degrees of seepage losses, with several potential adverse consequences and influenced by numerous factors. A synthesis and interpretation of field seepage data from peer-reviewed literature (impact factor >1.5) on seepage measurement and control reveals several key insights: (i) seepage rates differ significantly due to diverse field conditions; (ii) the inflow-outflow method is the most reliable for measuring canal seepage in the field; and (iii) polymer sealants (PSs) offer a cost-effective alternative for reducing seepage in irrigation canals. Compared to conventional liners (CLs) such as concrete, geomembranes, or masonry, PSs are not only more affordable but also can be applied selectively, allowing for seepage when the surface water supply is sufficient and groundwater recharge is desirable. Studies show PSs can reduce seepage by 64% to 88%, while CLs achieve reductions of 53% to 95%, highlighting the potential of PSs for further research and application. However, best field application techniques for PSs, the uncertainty in evaluating effectiveness, and ambiguity in potential environmental impacts require more comprehensive investigation. The most widely researched PS for reducing canal seepage is linear anionic polyacrylamide (LAPAM), a synthetic polymer sealant (SPS). When applied to canal water, LAPAM forms flocs through cation bridging with divalent cations (Mg2+ and Ca2+) commonly found in canal water, which settle along the canal perimeter and reduce hydraulic conductivity. Observed seepage reduction from field trials of LAPAM that had been conducted prior to this study on three mid-sized canals (two in Colorado, USA and one in Sindh, Pakistan) using the recommended inflow-outflow method for seepage testing were analyzed. The average pre-LAPAM seepage rate was approximately 0.32 m/day, while the post-LAPAM rate dropped to 0.04 m/day, with results demonstrating seepage reductions between 69% and 100%. An uncertainty analysis of the pre- and post-LAPAM tests indicated an 85% probability that the seepage reductions were due to the LAPAM treatment. While LAPAM has proven effective, the long-term environmental impact of LAPAM treatment remains uncertain, underscoring the need to explore natural alternatives to synthetic polymer sealants. Biopolymer sealants (BPSs) were identified and evaluated through both laboratory and field experiments, designed to mirror the approach used with LAPAM. These experiments were conducted in triplicate (lab) and duplicate (field) to enhance confidence. In the lab, constant head saturated hydraulic conductivity (KSAT) tests simulated irrigation canal perimeter conditions. Five BPSs—pectin citrus (PC), cellulose hydroxyethyl ether (CHE), pullulan desalinated (PD), sodium alginate low viscosity (SALV), and xanthan gum (XG)—were initially tested and compared against LAPAM. The pre-and post-polymer KSAT values revealed that PC, PD, and XG achieved average reductions exceeding 40%, which was used as the threshold for further exploration. Subsequent testing under conditions more representative of irrigation canals identified XG as the most effective BPS. Alternative application rates were assessed, with 20 mg/L identified as the preferred concentration, as higher concentrations did not significantly enhance KSAT reduction. Long-term performance tests in the lab showed that XG, at 40 mg/L, can reduce hydraulic conductivity by over 90% for 9–10 months and by 60–70% over 1.5 months at 20 mg/L. These findings were validated using seepage tests in the field, where XG applied to a 3-km earthen canal reach at 20 mg/L reduced seepage by up to 63% over a month (at which time the canal was taken out of service). While the use of SPSs may still be justified for controlling canal seepage, this research shows that BPSs such as XG, have the potential to replace SPSs for canal sealing. However, further work is needed to optimize application methods and dosage rates, to better understand working mechanisms, to demonstrate long-term effectiveness, and to assess scalability across diverse field conditions.
Open Access
Characterizing tailings professional labor demand
(Colorado State University. Libraries, 2021) Spencer, Louise, author; Scalia, Joseph, IV, advisor; Bareither, Christopher, advisor; Sanford, William, committee member
A low-carbon future necessitates increased extraction of critical minerals via mining. The act of mining includes not only extraction of commodities, but also management of tremendous volumes of waste. Despite the need for mining to support green technologies, mining is experiencing a credibility crisis due to historic legacies of environmental damage and recent catastrophic failures of tailings (mine waste) facilities. To regain social trust and environmental credibility, the mining industry must do better at managing tailings. The recently issued Global Industry Standard on Tailings Management (GISTM) places significant demand on tailings professionals worldwide. Given these pressures, this study addresses the question: is the current tailings professional labor pool sufficient to provide the specialized labor needed to meet new guidance designed to make tailings facilities safer, and if not, how can this shortage be rectified? To address this question, a coupled qualitative-quantitative approach was undertaken. Research was conducted to characterize the current (Spring 2021) industry practitioner perspectives on the state of tailings labor resources. Then, future tailings labor demand under the GISTM was calculated quantitatively by estimating professional labor demand based on guidelines presented in the GSITM and applied to the estimated number of tailings facilities worldwide. Finally, opportunities to address current and future tailings labor demand were identified through tailing practitioner perspectives. According to current practitioners, there is shortage of qualified tailings professionals, related to increased labor needs, difficulties of recruitment into and retention within the industry, as well as senior-level professionals retiring. Managing the minimum estimated 16,000 tailings facilities worldwide was estimated to require as many as 17,800 full-time equivalent, qualified and trained personnel. Finally, current actions to train future tailings professionals are provided, as well as recommendations for actions via collaboration between academia, industry, consultants, regulators, and non-governmental organizations (NGOs) to fortify tailings recruitment activities, training programs, and educational opportunities.
Open Access
Effectiveness of polymer for mitigation of expansive soils
(Colorado State University. Libraries, 2017) Taher, Zana, author; Scalia, Joseph, IV, advisor; Bareither, Christopher A., advisor; Valdes-Vasquez, Rodolfo, committee member
The objective of this study was to determine the effectiveness of commercially available polymer treatment as a mitigation technique for expansive soils in transportation applications. Four commercially available polymers were used in this research. A survey of state departments of transportation within the mountain-plains region (Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming) was conducted to define the state-of-the-practice in expansive soil mitigation. A literature review on expansive soil treatments, with a focus on polymer mitigation, was also performed to establish the state-of-the-art in expansive soil mitigation. The soil tested was composed of expansive soil from Fort Collins, Colorado, that classified as low swelling, amended with 15% (high swelling) sodium bentonite. Fifteen percent bentonite was selected to meet the Federal Highway Administration (FHWA) classification for highly expansive soil. Treated and untreated soils were classified, and tested for swelling, strength, and hydraulic conductivity. Four commercially available polymers were tested; lime and fly ash, two common techniques used in treatment of expansive soils, were tested for comparison. Preliminary swell tests were performed on four commercially available polymers, P1, P2, P3, and P4, to analyze the relative effectiveness of the polymers. P4 was selected for this study based on the high effectiveness of P4 from the swell test results. P4 reduced expansive soil swelling and increased strength, but was less effective than lime or fly ash. Based on reduced swelling, and increased strength, lime was the most effective treatment for stabilizing and strengthening the expansive soil tested. Swell test data do not support use of P4 (or P1, P2, P3) over traditional treatments for swell mitigation of the expansive soil tested in this study. However, lime and fly ash treatments resulted in multiple orders-of-magnitude increases in hydraulic conductivity, while P4 did not. Since water ingress is required for soil swelling, future testing that couples the effects of hydraulic conductivity and swelling is recommended. In addition, testing of other commercially available polymers, and additional soils (such as sulfate rich soils) is recommended.
Open Access
Enhancing oleophilic biobarriers for non-tidal sediments impacted with petroleum hydrocarbons
(Colorado State University. Libraries, 2021) DeBiasi, Marina Ann, author; Scalia, Joseph, IV, advisor; Sale, Tom, advisor; Sutton, Sally, committee member
The objective of this study is to develop tools to prevent petroleum hydrocarbons trapped in non-tidal sediments from causing detrimental effects such as sheens. Oleophilic biobarriers (OBBs) provide a robust, low-cost solution for managing petroleum hydrocarbon contamination at groundwater-surface water interfaces in tidal zones but are untested in non-tidal zones. This study evaluates enhanced OBB remedies for petroleum hydrocarbon contamination in non-tidal zones by incorporating amendments within the OBB. The amended OBB is intended to serve as an engineered bioremediation tool to enhance microbial growth and degradation of petroleum hydrocarbons by supplying the system with a resource of electron donors and nutrients while simultaneously mitigating petroleum hydrocarbon releases to surface water. Complementary laboratory and field studies were conducted to test non-tidal OBBs (NOBBs) with six amendment types: (1) hematite (H), (2) greensand (GS), (3) greensand + hematite (GS+H), (4) gypsum (GYP), (5) hematite + greensand + gypsum (ALL), and (6) blank (B). The laboratory study was constructed as a series of chemostats using sediment and water samples from the field site. This study observed the productivity of petroleum hydrocarbon degradation through biweekly headwater extractions analyzing alkalinity, dissolved inorganic carbon (DIC), and pH as well as continuously monitored oxidation reduction potential (ORP). Results from these tests indicated that the GYP amendment was most effective in degrading petroleum hydrocarbons while the B and ALL amendments were least effective. However, all systems exhibited increased effluent DIC characteristic of enhanced petroleum hydrocarbon degradation. The field study was constructed as a series of OBB disks deployed atop petroleum hydrocarbon impacted sediments in a non-tidal setting. Results from the laboratory and field study illustrated abundant microbial growth after six months. The NOBBs with the top three highest numbers of microbial abundance were found in the field (F): F-GS+H, F-B, and F-GS. The overall results of both lab and field studies suggest that NOBBs, whether amended or not, provide effective media for petroleum hydrocarbon-degrading microorganisms. This study illustrates the promise of the non-tidal OBB as a bioreactive barrier for petroleum hydrocarbon impacted sediments. Further study is needed to evaluate the rate of petroleum hydrocarbon degradation in a non-tidal OBB relative to the rate of loading.
Open Access
Exploration of passive desaturation of in place tailings using wicking geosynthetics
(Colorado State University. Libraries, 2024) Monley, Kendall O., author; Scalia, Joseph, IV, advisor; Bareither, Christopher, committee member; Ross, Matthew, committee member
As global demand for metals and critical minerals increases, so too does the production of tailings. Tailings are what is left behind after extraction of valuable metals and minerals from ore, and consist of finely ground rock, water, unrecoverable metals, chemicals, and organic matter. These residuals are managed in engineered facilities that function to both dewater and store tailings, known as tailings storage facilities (TSF). A common assumption is that the water initially contained in TSFs will drain down to an unsaturated condition after deposition of new tailings ceases. However, a review of literature on geotechnical and hydrotechnical conditions of legacy TSFs (TSFs that have stopped receiving tailings) in arid environments illustrates that achievement of unsaturated conditions in internal fine-grained layers may not always occur. As the tailings are deposited, layers of finer and coarser particles are interbedded. This causes the formation of capillary barriers and may ultimately result in finer-grained layers held at near saturation after drain down. These fine-grained layers are more susceptible to liquefaction concerns and can require costly remedial actions to ensure geotechnical stability. Dewatering is the process of removing water from whole tailings and offers benefits including increasing geotechnical stability and recovering stored water. Tailings dewatering may occur prior to or after deposition into a TSF. In this study, I explore in-situ dewatering via use of capillary (wicking) geotextiles, and the effectiveness of the wicking geotextiles. Beaker and column experiments were created to emulate stratigraphy seen in legacy TSFs. Additionally, shrinkage testing was conducted to compare the final densities and void ratios of samples with and without wicking geotextiles. Column testing reveals the wicking geotextiles accelerated dewatering by 2.8 times the rate of natural drying processes. At the conclusion of testing, the wicking geotextile experiments had reached similar densities and void ratios to control experiments. This novel approach to passively dewatering tailings warrants additional testing.
Open Access
Influence of geochemical processes on geotechnical stability of tailings storage facilities
(Colorado State University. Libraries, 2023) Orcutt, Heath Marie, author; Scalia, Joseph, IV, advisor; Bareither, Christopher, advisor; Ridley, John, committee member
Incorporation of geochemically induced material changes and weathering patterns into geotechnical design and long-term stability analyses of tailings storage facilities has yet to be implemented widely or consistently. Tailings are deposited in disequilibrium with the surrounding environment and must undergo physical, chemical, and biological weathering to reach their most stable form. As a result, the geotechnical properties of the tailings (i.e., particle size, water retention capacity, shear strength, etc.) change over time. Herein, an in-depth review of published literature is provided, ranging across multiple disciplines (geochemistry, geotechnical engineering, hydrogeology, environmental engineering, mining engineering), and focusing on studies that document or allude to material property changes of weathered sulfidic base metal tailings. Synthesized visual aids are provided as a framework for beginning interdisciplinary conversation that couples geochemistry and geotechnical engineering. By drawing attention to potential geochemically induced failure modes, I hope to draw connections between geochemistry and geotechnical engineering that are fundamental to developing robust designs and advanced monitoring plans that ensure long-term tailings storage facility stability. A "proof of concept" laboratory design is presented which analyzes changes to the physical material properties (compressibility, permeability, and shear strength) of saturated fine-synthetic tailings mixed with calcite at different pH values. Overall, this report seeks to lay the foundation for future study and advance communication between experts.
Open Access
Investigation of mineral bentonite barriers optimized for hydraulic compatibility and shear strength
(Colorado State University. Libraries, 2024) Jacob, Samuel Robert, author; Scalia, Joseph, IV, advisor; Bareither, Christopher, committee member; Sanford, William, committee member
Liners are a foundation tool of environmental geotechnics. Modern liners are constructed using natural and polymeric materials with low hydraulic conductivity (k), often at the expense of having low shear strength. These liners are often subject to high stresses on the order of hundreds to thousands of kPa which can lead to decreased performance over time and failure of the liner in shear. This research investigates mineral-bentonite mixtures in the context of high-stress liner applications. Mixtures containing varying amounts of sand, bentonite, and rock flour were created in the laboratory. Hydraulic conductivity of specimens was measured using flexible wall permeameters in accordance with ASTM D7100 using either de-ionized (DI) water, 10 mM, or 500 mM CaCl2 solutions. Specimens were removed from permeameters once k termination criteria were met and subsequently tested in direct shear at either 35 kPa or 825 kPa effective stress to obtain peak (φ´peak) and ultimate (φ´u) friction angles. Mixtures generally achieved a final k of 10- 9 m/s with bentonite contents of 4.5% and 8% when permeated with DI water and 10 mM CaCl2 solutions, respectively. Adding rock flour to mixtures containing bentonite lowered final equilibrium k but rock flour was not suitable as a complete replacement for bentonite. At 35 kPa effective stress, shear strength increased until approximately 15% equivalent fines, whereas shear strength was relatively constant at 825 kPa with increasing equivalent fines from 0-15%. At 825 kPa, shear strength substantially dropped at equivalent fines greater than 15%, which is the approximate percentage of fines that the sand matrix began to lose grain-grain contact due to the displacement by fines. The results from this study highlight that while low k and high φ´ can be achieved, even at high effective stresses, care and precision during design and construction of a mineral-bentonite barrier is required to ensure that all design criteria are met.
Open Access
Limiting membrane and diffusion behavior of a compacted sand-bentonite mixture for hydraulic and chemical containment
(Colorado State University. Libraries, 2017) Fritz, Cameron John, author; Scalia, Joseph, IV, advisor; Shackelford, Charles D., advisor; Ronayne, Michael J., committee member
Sodium-bentonite (Na-bentonite) commonly is used either as an additive component or as the sole component of engineered barriers used for waste containment applications, because the tendency of Na-bentonite to exhibit high swell can result in the restriction of advective and diffusive contaminant transport. Additionally, compacted mixtures of Na-bentonite and sand can be an effective and economical alternative to barrier materials consisting only of natural clay (e.g., compacted clay liners) if the use of natural clay is not logistically or economically feasible. The existence of membrane behavior, i.e., the ability of a porous material to exhibit selective restriction of migrating chemical species from the clay pores, previously has been shown for typical engineered bentonite-based barriers commonly used in hydraulic and chemical containment applications, including compacted sand-bentonite (SB) mixtures. However, the extent to which clay membrane behavior may persist in the presence of highly concentrated chemical solutions, which have been shown to have an adverse effect on the magnitude of membrane behavior in clays, remains largely unknown, with few studies having quantified the limiting membrane and diffusion behavior of bentonite-based barrier materials. Moreover, the limiting membrane and diffusion behavior of compacted SB mixtures has not yet been evaluated. Based on these considerations, the purpose of this study was to quantify the limiting membrane and diffusion behavior of two specimens of a compacted SB mixture comprising 15 % Na-bentonite (by dry weight) by determining the threshold salt concentration at which measurable membrane behavior was eliminated. The specimens were exposed to a series of boundary monovalent salt solutions with increasingly higher source concentrations, Cot, until measured values of the membrane efficiency coefficient, ω (0 ≤ ω ≤ 1), were effectively nil (i.e., 0.000), representing the limiting condition at which measurable membrane behavior was eliminated. Overall, ω decreased from an average of 0.032 to 0.000 as Cot increased from 160 mM KCl to 3.27 M NaCl, resulting in a threshold concentration between 1.63 M and 3.27 M NaCl for both specimens that was much higher than the range of salt concentrations for which measurable membrane behavior previously was thought to exist. Effective diffusion coefficients, D*, for nonreactive chloride (Cl-) also were measured during membrane testing to evaluate possible changes in diffusion behavior corresponding to the progressive destruction of membrane behavior. However, D* was relatively constant throughout all testing stages (2.1 x 10-10 m2/s ≤ D* ≤ 3.0 x 10-10 m2/s), indicating that the corresponding decrease in ω from 0.032 to 0.000 had little to no effect on the diffusion of Cl-.
Open Access
Procedure for measurement of surficial soil strength via bevameter
(Colorado State University. Libraries, 2020) Bindner, Joseph R., author; Scalia, Joseph, IV, advisor; Niemann, Jeffrey D., advisor; Butters, Gregory, committee member; Green, Timothy R., committee member
Spatial prediction of moisture-variable soil strength is critical for forecasting the trafficability of vehicles across terrain. The Strength of Surface Soils (STRESS) model calculates soil strength properties as a function of soil texture from SSURGO data (or locally available data) and soil moisture from the Equilibrium Moisture from Topography, Vegetation, and Soil (EMT+VS) model. The STRESS model yields soil strength properties (friction angle and moisture-variable cohesion) that vary with soil texture and moisture conditions. However, the STRESS model is hindered by a lack of surficial soil strength data linked directly to soil texture. The objective of this study is to develop and validate a bevameter procedure to improve measurement of near-surface moisture-variable soil strength. The bevameter is a test apparatus that measures in-situ surficial soil strength properties by rotational shearing of a shear annulus under a constant normal force at a constant rate. The bevameter allows for lab or field determination of Mohr-Coulomb surficial soil strength properties at a given moisture content in a manner that approximates how vehicles interact with surficial soils. Experimental variables evaluated include the shearing surface (grousers, sandpaper, or bonded angular sand) and the use of interior and exterior annular surcharge weights to minimize slip sinkage of the shear annulus. Based on the results of this study, a bevameter procedure is recommended that uses a coarse sandpaper as the shear interface with an internal and external surcharge of 2 kPa during shear testing. Using the revised bevameter procedure for field testing, the performance of predicted moisture-variable soil strength by the STRESS model is evaluated. Field validation illustrates the need to develop surficial-soil specific pedotransfer functions for use in the STRESS model.
Open Access
Selected factors affecting measurement of the hydraulic conductivity of geosynthethic clay liners
(Colorado State University. Libraries, 2018) Popang, Monika Aprianti, author; Scalia, Joseph, IV, advisor; Shackelford, Charles D., advisor; Ronayne, Michael J., committee member
Geosynthetic clay liners (GCLs) are thin (~7 to 10 mm), factory manufactured hydraulic barriers typically comprising a layer of sodium bentonite sandwiched between two geotextiles. Upon hydration and permeation with water at low effective stress (σ´) (e.g., typically ≤ ~30 kPa [4 psi]), the bentonite in GCLs, which typically is initially in an air-dried condition, swells to form a low hydraulic conductivity (k) layer (i.e., k of ~2-3×10-11 m/s) that is suitable for use as a barrier in hydraulic and chemical containment applications. However, adverse physico-chemical interactions between the bentonite in GCLs and both the hydrating and permeating liquids may yield substantially higher k than what is typically acceptable for design (i.e., k ≤ 1×10-9 m/s). Accordingly, this study pertained to evaluating the effects of the type of permeant liquid and the magnitude of σ´ on the measurement of k of two GCLs, a higher grade needle-punched (HGN) GCL and a lower grade needle-punched (LGN) GCL. The permeant liquids included tap water (TW), conservative water (CW), and several calcium chloride (CaCl2) solutions, and the σ´ included 27.3 kPa (4 psi) and 61.7 kPa (9 psi). The resulting measured ratios of final k for the HGN GCL relative to the LGN GCL (kf HGN/kf LGN) at ~24-27 kPa (4 psi) were ~28 (1.5 orders of magnitude), ~194 (2.3 orders of magnitude), and ~1975 (3.3 orders of magnitude) based on permeation with 5, 10, and 20 mM CaCl2, respectively. Thus, an increase in the fiber bundles density of the needle-punched fibers of the GCL adversely impacted the k of this GCL. Tests using dyed permeant liquids revealed that the high k was attributable to preferential flow along the fiber bundles of the GCL. Also, an increase in σ´ from 27.3 kPa (4 psi) to 61.7 kPa (9 psi) did not appreciably impact the measured k. Finally, permeation of the HGN GCL with the more dilute liquids (TW, CW, 1 and 2.5 mM CaCl2) resulted in consistently low k of ~2×10-11 m/s. The results of this study also illustrate the importance of achieving not only hydraulic equilibrium but also chemical equilibrium before terminating the k tests, as the measured k at hydraulic equilibrium based on the higher ionic strength solutions (i.e., 5, 10, and 20 mM CaCl2) typically were lower and, therefore, more unconservative than the measured k at chemical equilibrium. This study also evaluated the use of different methods to measure the k of the HGN GCL, including the falling headwater, constant tailwater method and the constant rate-of-flow method using a flow pump with pressure transducers. The results indicated that neither method proved substantially effective at achieving chemical equilibrium faster, although employing higher hydraulic gradient (i) was shown to expedite the attainment of chemical equilibrium. This result is associated with flushing action in the intergranular pore spaces that effectively maintaining higher concentration gradient between within and outside the bentonite granules. Also, prehydrating the specimens with the permeant liquid tended to enhance the osmotic swell of the bentonite resulting in a lower k at lower pore volumes of flow. Finally, diffusion of solutes from interlayer to intergranular pore spaces within the GCL specimens permeated with CW was shown to be the rate-limiting mechanism for attaining chemical equilibrium.
Open Access
Unsaturated fluid flow and volume change behavior of filtered tailings
(Colorado State University. Libraries, 2022) Aghazamani, Neelufar, author; Scalia, Joseph, IV, advisor; Bareither, Christopher A., committee member; Shackelford, Charles D., committee member; Ham, Jay M., committee member
As the global demand for minerals continues to increase so does the generation of mine waste. Tremendous volumes of mine waste, viz. tailings and waste rock, are generated and placed in impoundments and piles. Improved methodologies are needed to enhance the sustainability of mine waste management. Tailings are typically discharged as a slurry of finely ground rock within water to a settling facility contained by an embankment. These facilities often necessitate long-term management of inherently weak materials. Tailings dewatered via filtration yields enhanced water stewardship and greater geotechnical stability; filtered tailings are readily amenable to progressive closure and environmental restoration. But, the high cost of tailings filtration, and the potential for acid rock drainage (ARD) due to oxygen ingress and internal unsaturated flow of water have limited the adoption of filtered tailings by the mining industry. The goal of this study is to advance the state of knowledge of filtered tailings. To this end, this dissertation consists of three components; (1) assessing the influence of filtered tailings placement conditions on filtered tailings unsaturated characteristics, (2) assessing excess pore pressure generation during compression of unsaturated filtered tailings, and (3) exploring hydrologic paths to minimize ARD and improve geochemical stability of filtered tailings stacks. Pressure plate, chilled mirror, and shrinkage curve tests were performed to produce soil water characteristic curves (SWCCs) for two precious metal mine tailings with varying initial water contents and dry densities. The resultant SWCCs illustrate that the placement water content and dry density have a significant influence on the unsaturated characteristics of the filtered tailings. Generation of excess pore water pressure was assessed via undrained compression tests. Unsaturated filtered tailings started generating appreciable excess porewater pressure (> 10% of the incrementally applied total vertical stress) when the saturation of the tailings was at the range of 80 to 90%; this appreciable excess pore pressure did not fully dissipate after 24 h. Filtered tailings in this study followed a stress path with void ratios below the critical state line (i.e., dilative during undrained shear) unless placed initially loose and wet. The SWCCs produced were used to model the hydrology of filtered tailings and comingled filtered tailings columns via HYDRUS-2D in example wet, hemiboreal, and dry climates. Results of this study illustrate that for the filtered tailings evaluated in this study, ARD is anticipated to be minimized via varying climate-dependent mechanisms. In the arid climate, filtered tailings functioned as a water balance layer, storing, and releasing precipitation as evaporation not percolation. In the wet climate, filtered tailings became rapidly saturated and maintained a saturated surficial layer preventing inward movement of oxygen and potentially minimizing generation of ARD. In the hemiboreal and wet climates percolation was minimal due to the low hydraulic conductivity of the filtered tailings, and inclusion of a commingled capillary barrier layer further reduced percolation (further reducing the potential flux of ARD). Results from this study illustrate the potential efficacy of filtered tailings to maintain both geotechnical stability and limit ARD.