Hydraulic Barrier Research Articles

Computer Modeling Approach of Leachate Flow in Compacted Laterite Soil Liner

The use of hydraulic barriers in sanitary landfills has become an impeccable means of protecting the groundwater system from leachate. A question to be asked is, can these barriers continue to impede the migration of leachate over a long period? This paper investigates the phenomenon of leachate migration in compacted laterite soil used as liner in sanitary landfills. An experiment was carried out using laterite soil compacted at optimum moisture content using Standard Proctor energy. Leachate was poured on the compacted soil in an acrylic column and its migration was monitored using Digital Image Technique (DIT). The DIT capture photographic images at successive intervals of time which were fed through an image processing code to convert them to hue-saturation-intensity (HSI) format with the help of Surfer and Matlab computer softwares. Subsequently, PetraSim computer software was applied to predict the velocity behavior. The predicted velocity value shows that the laterite soil is compatible with the leachate and can be used as soil liner. The outcome of this study would enable designers to use non-destructive method to monitor and predict leachate migration in compacted soil liners to simulates leachate migration in waste containment applications.

Damage‐Based Time‐Dependent Modeling of Paraglacial to Postglacial Progressive Failure of Large Rock Slopes

AbstractLarge alpine rock slopes undergo long‐term evolution in paraglacial to postglacial environments. Rock mass weakening and increased permeability associated with the progressive failure of deglaciated slopes promote the development of potentially catastrophic rockslides. We captured the entire life cycle of alpine slopes in one damage‐based, time‐dependent 2‐D model of brittle creep, including deglaciation, damage‐dependent fluid occurrence, and rock mass property upscaling. We applied the model to the Spriana rock slope (Central Alps), affected by long‐term instability after Last Glacial Maximum and representing an active threat. We simulated the evolution of the slope from glaciated conditions to present day and calibrated the model using site investigation data and available temporal constraints. The model tracks the entire progressive failure path of the slope from deglaciation to rockslide development, without a priori assumptions on shear zone geometry and hydraulic conditions. Complete rockslide differentiation occurs through the transition from dilatant damage to a compacting basal shear zone, accounting for observed hydraulic barrier effects and perched aquifer formation. Our model investigates the mechanical role of deglaciation and damage‐controlled fluid distribution in the development of alpine rockslides. The absolute simulated timing of rock slope instability development supports a very long “paraglacial” period of subcritical rock mass damage. After initial damage localization during the Lateglacial, rockslide nucleation initiates soon after the onset of Holocene, whereas full mechanical and hydraulic rockslide differentiation occurs during Mid‐Holocene, supporting a key role of long‐term damage in the reported occurrence of widespread rockslide clusters of these ages.

Compound-Specific Isotope Analysis (CSIA) Application for Source Apportionment and Natural Attenuation Assessment of Chlorinated Benzenes

In light of the complex management of chlorobenzene (CB) contaminated sites, at which a hydraulic barrier (HB) for plumes containment is emplaced, compound-specific stable isotope analysis (CSIA) has been applied for source apportionment, for investigating the relation between the upgradient and downgradient of the HB, and to target potential CB biodegradation processes. The isotope signature of all the components potentially involved in the degradation processes has been expressed using the concentration-weighted average δ13C of CBs + benzene (δ13Csum). Upgradient of the HB, the average δ13Csum of −25.6‰ and −29.4‰ were measured for plumes within the eastern and western sectors, respectively. Similar values were observed for the potential sources, with δ13Csum values of −26.5‰ for contaminated soils and −29.8‰ for the processing water pipeline in the eastern and western sectors, respectively, allowing for apportioning of these potential sources to the respective contaminant plumes. For the downgradient of the HB, similar CB concentrations but enriched δ13Csum values between −24.5‰ and −25.9‰ were measured. Moreover, contaminated soils showed a similar δ13Csum signature of −24.5‰, thus suggesting that the plumes likely originate from past activities located in the downgradient of the HB. Within the industrial property, significant δ13C enrichments were measured for 1,2,4-trichlorobenzene (TCB), 1,2-dichlorobenzene (DCB), 1,3-DCB, and 1,4-DCBs, thus suggesting an important role for anaerobic biodegradation. Further degradation of monochlorobenzene (MCB) and benzene was also demonstrated. CSIA was confirmed to be an effective approach for site characterization, revealing the proper functioning of the HB and demonstrating the important role of natural attenuation processes in reducing the contamination upgradient of the HB.

Development of composting plant rock surrounding pollution. Case study – Točna in Příbor, The Czech Republic

Composting plant Točna utilize and modifies biologically biodegradable waste by aerobic fermentation method. After emergency leakage of leachate water in 2010 the quality of rock surrounding is being regularly monitored in the range of indicators: pH, conductivity, COD (chemical oxygen demand, Cr), HCO3–, Cl–, N-NH4+, N-NO3–, N-NO2– and humic substances. Technical adjustments of the interest area has been also made to prevent leakage of contaminated water. Locality monitoring system is ensured separately for shallow backfill aquifer and deeper quaternary aquifer. Protective hydraulic barrier is running at the same time to prevent effluent of shallow water to groundwater. Nitrogenous substances (above all ammonium ions) and humic substances belongs among main groundwater contaminants of the interest area. Peak concentration level of this substances is connected with shallow backfill aquifer, near south-east and east edge of the locality, not in general quaternary water direction. From long-term monitoring results follows that concentration of monitored substances is gradually decreasing, especially in water connected with backfill layer. Drier weather of last year helps to this development. Quality of quaternary aquifer is not influenced significantly, only locally in spots, in the places of both aquifers connection where increase of ammonium ions occurs as result of humic substance decomposition. In effect, monitored substances are not disseminated in quaternary aquifer.

Long-Term Permeability Characteristics of Soil-Geosynthetic Combination Used in Landfill Covers

Abstract Multilayered cover system (MLCS) forms an integral part of engineered landfills nearing closure. Geosynthetic materials find multiple applications in MLCS as hydraulic barrier, drainage, separation, and filtration layers. Performance of geosynthetics used as filters needs to be well understood to ascertain the stability of MLCS. The main objective of this study is to investigate the compatibility of the soil-geosynthetic combination by long-term permeability tests. The compatibility of five different types of geosynthetics was evaluated with respect to two different gradations of red soil (RS) and RS–fly ash (FA) 50:50 mix. The results of long-term permeability and clogging characteristics were used to judge the effect of soil type, soil gradation, and type of geosynthetics on soil-geosynthetic compatibility. The efficacy of geosynthetics as filters was established based on (1) permeability improvement factor, which is defined as the ratio of the permeability of soil-geosynthetic composition to the permeability of the soil, and (2) stabilization time, i.e., the time required by the soil-geosynthetic system to achieve hydraulic equilibrium. It was noted from this study that the soil type and gradation had significant effect on the long-term permeability variation. The effect of the geosynthetic on the soil-geosynthetic combination is governed by its pore-size characteristics and was found to be marginal in this study. The stabilization time of a soil-geosynthetic combination increases with increase in soil fines content. The cyclic variation in permeability with time for a particular soil was found to be similar when different geosynthetics were used. Irrespective of soil type, higher permeability improvement factor was observed in the case of a woven multifilament geosynthetic and less in the case of a geocomposite. The class F FA in conjunction with RS was found to be compatible with the geosynthetics used in this study.

Specific ion effects on surrogate compatibility indices of bentonite for hydraulic barrier applications

Bentonites are extensively used in waste containment facilities for controlling the migration of contaminants. The performance assessment of these facilities requires study on long-term hydraulic behaviour of proposed barrier material in the presence of different salts. Liquid limit water content and equilibrium sediment volume (ESV) of clays in the presence of different salt electrolytes are recognised to be the surrogate compatibility indices for understanding the long-term hydraulic behaviour of bentonites. The present paper provided a detailed analysis of influencing parameters on the behaviour of potential clay barrier through these two surrogate compatibility tests. The influence of different pore-fluid parameters, such as electrolyte concentration and specific ion effects on the behaviour of Indian bentonite was presented. The controlling mechanism of these two indices in the presence of different pore-fluid parameters was brought out. A relationship was obtained between the liquid limit water content and ESV data from the present study and the literature studies on different clays. Similarly, a good correlation was found between these indices and equilibrium hydraulic conductivity in the presence of different salt concentrations and different hydrated cation radii.

MICROSTRUCTURE AND MICROMECHANICS OF SHALE ROCKS: CASE STUDY OF MARCELLUS SHALE

Shale rocks play an essential role in petroleum exploration and production because they can occur either as source rocks or caprocks depending on their mineralogical composition and microstructures. More than 60% of effective seals for geologic hydrocarbon bearing formations as natural hydraulic barriers constitute of shale caprocks. The effectiveness of caprock depends on its ability to immobilize fluids, which include a low permeability and resilience to the in-situ formation of fractures as a result of pressurized injection. The alteration in sealing properties of shale rocks is directly related to the differences in their mineralogical composition and microstructure.Failure of the shale starts with deterioration at micro/nanoscale, the structural features and properties at the micro/nanoscale can significantly impact the durability performance of these materials at the macroscale, therefore, study at micro/nanoscale becomes necessary to get better understanding of the hydraulic barriers materials to prevent failure and enhance long-term geologic storage of fluids.Indentation tests were conducted at both micro and nanometer level on Marcellus shale samples to get the mechanical properties of bulk and individual phase of the multiphase materials. The mechanical properties map were created based on the nano indentation results and the properties of each individual phase can be correlated with bulk response in the multiphase composite; the effect of each component on the microstructure and bulk mechanical properties can be better understood.

Improved water resource management for a highly complex environment using three-dimensional groundwater modelling

A three-dimensional groundwater model was used to improve water resource management for a study area in north-west Switzerland, where drinking-water production is close to former landfills and industrial areas. To avoid drinking-water contamination, artificial groundwater recharge with surface water is used to create a hydraulic barrier between the contaminated sites and drinking-water extraction wells. The model was used for simulating existing and proposed water management strategies as a tool to ensure the utmost security for drinking water. A systematic evaluation of the flow direction between existing observation points using a developed three-point estimation method for a large number of scenarios was carried out. It is demonstrated that systematically applying the developed methodology helps to identify vulnerable locations which are sensitive to changing boundary conditions such as those arising from changes to artificial groundwater recharge rates. At these locations, additional investigations and protection are required. The presented integrated approach, using the groundwater flow direction between observation points, can be easily transferred to a variety of hydrological settings to systematically evaluate groundwater modelling scenarios.

An analytical model for the control of silica grout penetration in natural groundwater systems

Over the last three decades, colloidal silica has been investigated and more recently adopted as a low viscosity grouting technology (e.g. for grouting rock fractures within geological disposal facilities nuclear waste). The potential of colloidal silica as a favourable grouting material exists due to: its initial low viscosity; its low hydraulic conductivity after gelling (of the order of 10−7cm/s); the very low injection pressures required; its controllable set/gel times (from minutes to several days); the fact it is environmentally inert; its small particle size (less than hundreds of nanometres) and its cost-effectiveness. Despite the documented success of colloidal silica based grouts for hydraulic barrier formation, research has not translated into widespread industrial use. A key factor in this limited commercial uptake is the lack of a predictive model for grout gelling which controls grout penetration: whilst data are available to underpin design of a grouting campaign in laboratory conditions, little research has been done to underpin applications in natural environments. Here we develop and validate an analytical model of colloidal silica gelling in groundwaters with varying pH and background electrolyte concentrations. This paper presents an analytical model that accounts for changes in pH, electrolyte concentration, cation valency and molar mass, silica particle size and silica concentration giving predictive capability without the need for site-specific calibration. The model is validated against experimental observations for gel times of 32–766min, the model accurately predicts the log(gel time) with an average error of 4% which corresponds to an R2 value of 0.96.The model is then applied to a hypothetical case study to demonstrate its use in grout design, based on published in-situ groundwater data from the Olkiluoto area of Finland. The model successfully predicts the required accelerator concentration to achieve a grout gel time of approximately 50min, taking into account the cations already present within the synthetic groundwater.

Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover

Four geosynthetic clay liners (GCLs) serving as single liners were exhumed from below 0.7 m of silty sand on a 3:1 (horizontal:vertical) north-facing slope at the QUELTS site in Godfrey, Ontario, after 5 and 7 years. The 300 mm GCL overlaps with 0.4 kg/m supplemental bentonite were all physically intact. The exchangeable bound sodium was completely replaced with divalent cations. The GCL with the smallest needle-punched bundle size (average of 0.7 mm) and percentage area covered by bundles (4%) maintained low hydraulic conductivity (k) when tested under 0.07–1.2 m head with 10 mmol/L CaCl2solution as the permeant. For GCLs with larger bundles (1.1–1.6 mm) and higher percentage area covered by bundles (9%–14%), k was low when the head was low (0.07 m). Once the applied head increased, k increased by 1–4 orders of magnitude depending on the (i) hydraulic gradient, (ii) size and number of the needle-punched bundles, and (iii) structure and mass of the bentonite per unit area. The results suggest that the GCLs can perform effectively as a single hydraulic barrier in covers providing that the head above the GCL is kept low (e.g., by a suitable drainage layer above the GCL).

Water desorption and absorption isotherms of sodium montmorillonite: A QENS study

Understanding the adsorption, movement and release of water in bentonites under unsaturated conditions remains a critical factor in improving design of hydraulic barrier technologies to minimise transport of contaminants. In situ neutron scattering measurements during controlled exposure to water vapour partial pressures provide an opportunity to probe dynamics of adsorbed water over a large range of unsaturated conditions. The hydration state of a sodium montmorillonite (Na+-Mt) sample was monitored in situ by both the position of the (001) reflection and the elastic scattering signal amplitude to ensure that equilibrium was achieved at the chosen vapour pressures (p/po=0.85, 0.75, 0.55, 0.35 and 0.01 during dehydration and rehydration). Quantification of total adsorbed water, confirmed by separate gravimetric analyses on the same sample, was achieved by integrating the total scattering contribution between the limits ±2.0meV. A further integration between ±0.8meV allowed separating total adsorbed water into mobile and immobile fractions. Hysteresis was observed for the p/po=0.55 and 0.35 vapour pressures, but little or no hysteresis was observed for the p/po=0.85 and 0.75 states and these were representative of hydration intermediate between pseudo-monolayer and pseudo-bilayer hydrate states. Fitting of the quasielastic neutron scattering spectra to the water model resulted in rational changes in translational and rotational diffusion coefficients (Dt and Dr, respectively), mean residence time, τ0 and the mean relaxation time, τr, of the water with respect to experimental p/po. The behaviour of Dt and τ0 suggested that on rehydration at low p/po, water initially occupied the external surfaces before entering the interlayer spaces.

ASSESSMENT OF DIFFERENT MANAGEMENT SCENARIOS TO CONTROL SEAWATER INTRUSION IN UNCONFINED COASTAL AQUIFERS

The present study examines the capability of different hydraulic barriers to control seawater intrusion in coastal aquifer systems. Different management scenarios including abstraction of intruded saline water near the coast, artificial recharge of the aquifer with the good quality water, and combination of abstraction and recharge are simulated in unconfined aquifers and optimally analyzed using a simulation-optimization (S/O) approach. In each scenario of control, the trade-off between two objective functions: minimization of costs of management processes and minimization of total amounts of salinity in the aquifer, was obtained using the developed S/O framework. The recharge is implemented using a surface basin and therefore unsaturated flow theory is utilized in the simulation. Comparison of the developed management models suggests that the pumping of brackish water near the coast and its use for human and industrial consumption after desalination is an efficient method to control saltwater intrusion in deep aquifers. However, for aquifers with shallow hydrogeological settings, a new combined methodology is found to be the most cost-effective method in controlling saltwater intrusion. In this combined approach, the recharge by pond water is coupled with continuous pumping of intruded saline water near the coast followed by its desalination and use.

Estimating the spatial distribution of artificial groundwater recharge using multiple tracers

ABSTRACT Stable isotopes of water, organic micropollutants and hydrochemistry data are powerful tools for identifying different water types in areas where knowledge of the spatial distribution of different groundwater is critical for water resource management. An important question is how the assessments change if only one or a subset of these tracers is used. In this study, we estimate spatial artificial infiltration along an infiltration system with stage–discharge relationships and classify different water types based on the mentioned hydrochemistry data for a drinking water production area in Switzerland. Managed aquifer recharge via surface water that feeds into the aquifer creates a hydraulic barrier between contaminated groundwater and drinking water wells. We systematically compare the information from the aforementioned tracers and illustrate differences in distribution and mixing ratios. Despite uncertainties in the mixing ratios, we found that the overall spatial distribution of artificial infiltration is very similar for all the tracers. The highest infiltration occurred in the eastern part of the infiltration system, whereas infiltration in the western part was the lowest. More balanced infiltration within the infiltration system could cause the elevated groundwater mound to be distributed more evenly, preventing the natural inflow of contaminated groundwater. Dedicated to Professor Peter Fritz on the occasion of his 80th birthday

Managing the negative impacts of groundwater flow on electrothermal remediation

AbstractRapid groundwater fluxes often influence subsurface temperature distributions during in situ thermal remediation using electrothermal or conduction heating technologies. This study used a numerical approach to evaluate the impact of groundwater flow on electrothermal heating, as well as the effectiveness of several upgradient heat loss management strategies, in a hypothetical treatment volume. Design alternatives using upgradient (i) hydraulic barriers, (ii) physical barriers, and (iii) increased energy input are evaluated. Results indicate that target temperatures can be achieved, despite the presence of local groundwater flow velocities greater than 0.3 m/day, through the careful design and implementation of the alternatives evaluated. However, physical barriers need to be designed to prevent groundwater flow through the heated volume to be effective. Field data from an electrothermal application are also presented, where boiling temperatures were achieved after steam injection and upgradient pumping wells were implemented.

Measuring elastic modulus of bacterial biofilms in a liquid phase using atomic force microscopy

With the increasing interest in using bacterial biofilms in geo-engineering practices, such as soil improvement, sealing leakage in earth structures, and hydraulic barrier installation, understanding of the contribution of bacterial biofilm formation to mechanical and hydraulic behavior of soils is important. While mechanical properties of soft gel-like biofilms need to be identified for appropriate modeling and prediction of behaviors of biofilm-associated soils, elastic properties of biofilms remain poorly understood. Therefore, this study investigated the microscale Young's modulus of biofilms produced by Shewanella oneidensis MR-1 in a liquid phase. The indentation test was performed on a biofilm sample using the atomic force microscopy (AFM) with a spherical indentor, and the force-indentation responses were obtained during approach and retraction traces. Young's modulus of biofilms was estimated to be ~33-38 kPa from these force-indentation curves and Hertzian contact theory. It appears that the AFM indentation result captures the microscale local characteristics of biofilms and its stiffness is relatively large compared to the other methods, including rheometer and hydrodynamic shear tests, which reflect the average macro-scale behaviors. While modeling of mechanical behaviors of biofilm-associated soils requires the properties of each component, the obtained results provide information on the mechanical properties of biofilms that can be considered as cementing, gluing, or filling materials in soils.

Swelling prediction of bentonite-sand mixtures in the full range of sand content

The swelling prediction of bentonite–sand mixtures due to wetting is very important in evaluating the long term performance of the engineered barrier in the high level radioactive waste disposal system and the hydraulic barriers in geoenvironmental constructions. Sun et al. (2015) proposed the swelling prediction model of bentonite-sand mixtures due to full hydration, and predicted the swelling of different types of bentonite-sand mixtures, which was verified, to be consistent with the swelling test results. However, the predicted swelling results of bentonite-sand mixtures with extremely high sand content obtained by the original swelling prediction model have a large deviation from the test results. The reason is that the original model is based on an assumption that all the pores and available water are only associated with bentonite/montmorillonite fraction. However, for mixtures with extremely high sand content, the sand skeleton exists and resists the external stress from the very beginning. At the same time, the bentonite, dispersing in the sand skeleton, in contact with the pore fluid, swells freely to fully saturated state, however, still fails to fill the sand skeleton voids completely. In this research, the original swelling prediction model is extended by introducing the concept of critical filling sand content and critical contact stress. When sand content is more than the critical filling sand content, the deformation of the mixture is mainly due to the sand skeleton deformation. After the stress increases greater than the critical contact stress, the saturated bentonite fills the sand skeleton voids completely, and the swelling can still be predicted by the original swelling prediction model. In the extended model, the swelling prediction can be divided into three zones according to the two limit values of critical sand content and critical filling sand content. In different zones, the distribution ratio of the vertical stress that is borne by montmorillonite and sand skeleton is different. The extended swelling prediction model is applicable to predict the swelling due to full hydration for mixtures within the full range of sand content, and is verified by the swelling tests on bentonite–sand mixtures with various sand contents.

Slope stability and landform design in a coarse coal refuse reclamation.

Restoration of abandoned mine lands is on-going in Appalachia and across the United States. One potential technique to reclaim these areas is through the use of geomorphic landforming combined with paper mill residuals used as a soil amendment. The geomorphic approach attempts to approximate the long-term, steady state landform condition, leading to reduced erosional adjustment as compared to standard engineered fill designs. This study analyzed regraded mine refuse slopes for safety and erosion sustainability under a 100-year storm event for the Royal Scot refuse pile located near Anjean, WV. The project involved the design and evaluation of a cap and cover system composed of two layers. The first layer is a 60 cm. compacted barrier layer (hydraulic barrier) and second is a 30cm vegetative growth layer. The focus of the analysis was the effectiveness of the hydraulic barrier layer and the final slope stability of the system. A reclamation design was prepared and 3D finite element modeling was performed to assess ground surface terrain profiles considering weather and material strength. Results from the modeling indicate that for a 100-year storm event, the slope remains stable with a factor of safety ranging from 1.3 to 1.9 for different slope profiles. After the 100-year storm event, the hydraulic barrier reached a 20% degree of saturation proving its effectiveness with minimizing infiltration into the reclamation fill.

Prediction of curtain grouting efficiency based on ANFIS

As an important method for improving dam foundations, curtain grouting is designed to create a hydraulic barrier to decrease permeability, enhance strength, and reduce deformability of rock masses. To evaluate the improvement of rock masses, the Lugeon value (LU), rock quality designation (RQD), and fracture filled rate (FFR) after grouting are key evaluation indicators of grouting efficiency. A prediction method based on an adaptive neuro-fuzzy inference system is proposed to predict and evaluate curtain grouting efficiency in this study. Geological factors (fracture intensity, LU, and RQD before grouting), effective grouting operation factors (effective grouting pressure, effective grouting time, effective grout volume, and effective cement take), and tested interval depth are considered to be the critical factors that greatly influence the efficiency of curtain grouting and are selected as input parameters for prediction models. The grouting efficiency evaluation indicators (the LU value, RQD, and FFR after grouting) are selected as output parameters for evaluation of the efficiency. In addition, a formula for estimating the influence radius of grouting boreholes, which is used to determine the sphere of grouting influence, is proposed. To better reflect the influence of the position of grouting boreholes on the effects of grouting, this study suggests that the effective grouting operation factors can be calculated using an improved inverse distance weighting method. As a case study, this approach is used to predict the results of grouting and to evaluate the efficiency of curtain grouting in hydropower project A, located in the southwestern part of China. The approach shows considerable accuracy in predicting the results of grouting and evaluating grouting efficiency.

Reliability Analysis Applied on Land Subsidence Effects of Groundwater Remediation: Probabilistic vs. Deterministic Approach

The quantification of soil variability is one of the most important aspects in the geo-engineering context. The uncertainty analysis is the main part of the reliability assessment for which a quantitative evaluation was performed in this study. The Reliability Index and the Probability of Failure using the First-Order Reliability Method (FORM) represents both, an effective method which is easy to implement at the same time. This work analyzes possible effects of compaction induced into the aquifer of the Scarlino Plain, caused by the extension of the hydraulic barrier for groundwater remediation. The currently implemented vertical barrier is composed of 12 wells which reach the depth of 10 m. The improvement of the project involves the construction of a further 40 clusters, each consisting of a doublet which intercepts different depths (10 and 18 m). The models of the subsoil stratigraphy and of the groundwater were built using a numerical model. The groundwater flow and the piezometric surface in the current configuration of the barrier were studied and the project configuration was evaluated. Using the Aquitard drainage model, the land subsidence was estimated to calculate the maximum admissible displacement related to exhibited goods, the so called territorial vulnerability. The evaluation analysis was performed using a traditional deterministic approach, followed by a reliability method based on probabilistic models. Finally, the respective results were reported in a soil mapping with overlapping layers.

Enhanced removal of NAPL constituent from aquifer during surfactant flushing with aqueous hydraulic barriers of high viscosity

ABSTRACTThis study examines the effect of controlled groundwater flow paths induced by hydraulic barriers on the removal of NAPL constituent. An aqueous solution of thickener [0.05% (w/v) sodium carboxymethyl cellulose, SCMC] was continuously injected into a horizontally set two-dimensional physical model (sand-packed), forming aqueous plume(s) of high viscosity. The water flux at the down gradient of the model was measured using a flux tracer (n-octanol) and passive flux meter (PFM, packs of granular activated carbon). A non-reactive tracer (pentafluorobenzoic acid, PFBA) was used to identify the plume of high viscosity (hydraulic barrier) and ambient groundwater. When the barrier of high viscosity was formed, the plume was separated from the background water with little mixing, which was confirmed by the concentration profile of PFBA; whereas, the measured flux of ambient groundwater showed a distinctive distribution, due to the hydraulic barrier. When two barriers were set, the ambient water flux was enhanced in the middle, and the removal rate of PCE from the non-aqueous phase liquid (NAPL), measured by PFM, was found to improve by 26% during three hours of water flushing. When an aqueous solution of surfactant [0.37% (w/v), sodium dodecyl sulfate, SDS] was applied instead of water into the domain with two barriers set around the NAPL-contaminated spot, the removal of PCE from the NAPL increased by 101% for a three-hour time period. Based on the observations made in this study, hydraulic barriers formed by continuous injection of thickener solution change the flow direction of groundwater, and may increase the flux of groundwater (or aqueous solution of remediation agent) through a NAPL-contaminated region, improving the removal of NAPL.