Bottom Liner System Research Articles

Evaluation of per- and polyfluoroalkyl substances (PFAS) in landfill liquids from Pennsylvania, Colorado, and Wisconsin

Perand polyfluoroalkyl substances (PFAS) have been measured in aqueous components within landfills. To date, the majority of these studies have been conducted in Florida. This current study aimed to evaluate PFAS concentrations in aqueous components (leachate, gas condensate, stormwater, and groundwater) from four landfills located outside of Florida, in Pennsylvania, Colorado, and Wisconsin (2 landfills). The Pennsylvania landfill also provided the opportunity to assess a leachate treatment system. Sample analyses were consistent across studies including the measurements of 26 PFAS and physical-chemical parameters. For the four target landfills, average PFAS concentrations were 6,900, 22,000, 280, and 260 ng L−1 in the leachate, gas condensate, stormwater, and groundwater, respectively. These results were not significantly different than those observed for landfills in Florida except for the significantly higher PFAS concentrations in gas condensate compared to leachate. For on-site treatment at the Pennsylvania landfill, results suggest that the membrane biological bioreactor (MBBR) system performed similarly as aeration-based leachate treatment systems at Florida landfills resulting in no significant decreases in ∑26PFAS. Overall, results suggest a general consistency across US regions in PFAS concentrations within different landfill liquid types, with the few differences observed likely influenced by landfill design and local climate. Results confirm that leachate exposed to open air (e.g., in trenches or in treatment systems) have lower proportions of perfluoroalkyl acid precursors relative to leachate collected in enclosed pipe systems. Results also confirm that landfills without bottom liner systems may have relatively higher PFAS levels in adjacent groundwater and that landfills in wetter climates tend to have higher PFAS concentrations in leachate.

Analytical solutions for transport of organic solutes in multi-layered porous media

In this study, analytical solutions for one-dimensional transport of organic solutes in multilayered porous media are developed using the methods of matrix transfer and variable separation, where multiple factors such as advection, diffusion, mechanical dispersion, adsorption, degradation, boundary condition type and change in concentration are systematically incorporated for the first time. Compared with the existing analytical solutions solved by the techniques of integral transformation or Laplace transformation, the approaches adopted in this paper are simpler and have a quicker convergence speed. Also, the proposed analytical solutions are more practical with clear expressions and consideration of multiple factors, which can be applied to various engineering cases such as bottom liner systems at landfills, covering systems of contaminated sediments and vertical barrier systems in contaminated sites. Furthermore, the correctness of the derived analytical solutions is effectively validated by comparison with the experimental results, as well as with the existing analytical solution and a numerical method. Following this, the effects of different factors on the transport process of a single organic solute in a five-layered medium are investigated, and some novel and vital laws are obtained. Overall, this research contributes to appropriate evaluation of the transport behaviours in multilayered porous media.

Immobilizing lead using loess and nanoscale zerovalent iron (nZVI)-amended loess: Insights from macroscopic and microscopic tests

Lead (Pb) can accumulate in organisms causing damage to liver and kidney functions. Preventing Pb2+ migration to surrounding environments is considered of great necessity. This study explored the potential of applying the loess and nanoscale zerovalent iron-amended loess (nZVI-AL) to Pb immobilization. The static equilibrium adsorption analyses showed that the adsorption of Pb2+ by the loess and nZVI-AL was classed as homogeneous monolayer surface adsorption. The nZVI particles provided Pb2+ with more sites for their attachment and prevented their migration using Fe-O and Fe-O-H bonds. Their attachment encouraged the formation of cerussite precipitation, which not only caused the reduction in the diffraction peak of calcite mineral but shifted the peak of adsorption band from around 1430 cm−1 to a lower wavenumber. The unbonded electrons of the functional groups on the surface of quartz mineral coordinated with the empty orbit of Pb2+, leaving the diffraction peak at 3.3429 Å. Further, Ca2＋ distribution of the nZVI-AL sample was not as blurry as that of the loess sample because of the retardant of the depletion of calcite and quartz by the nZVI particles. Moreover, the hydroxyl groups bound via hydrogen bonds were formed by the nZVI amendment, displacing the peak of the adsorption band from 701 cm−1 to 698 cm−1. The hydroxyl groups of clay minerals coordinated with Pb2+ as well to form Pb(OH)+, corresponding to O-H stretching vibrations at 3616 cm−1 and 3430 cm−1 respectively. The nZVI-AL shows its potential in landfills as a bottom liner system.

Performances of the Soil–Bentonite Cutoff Wall Composited with Geosynthetic Clay Liners: Large-Scale Model Tests and Numerical Simulations

The geosynthetic clay liner (GCL) overlap plays a key role in maintaining hydraulic performance of the barrier systems, e.g., the bottom liner and cover systems. However, its influences on the behavior of the vertical barrier have been rarely investigated. This paper aims to address this issue using the large-scale model test and 3-dimensional finite element (FE) modeling. In the model test, the GCL overlap at the width of 500 mm was tested under a constant hydraulic head of 1 m and confining stress ranging from 10 to 150 kPa using a newly developed large-scale apparatus. Compared with the flexible wall permeameter, this apparatus could guarantee full field-scale GCL overlap to be tested. Results showed that the effective hydraulic conductivity of the GCL overlap decreased from 10−8 to 10−9 cm/s as the confining stress increased from 10 to 150 kPa. The addition of supplemental bentonite paste in between the overlap with a water-to-bentonite ratio of 19:1 contributed to reducing the effective hydraulic conductivity by 60% compared with that for a GCL overlap without bentonite paste. The breakthrough time for the soil-bentonite (SB) cutoff wall composited with GCLs was 64% longer in comparison with that for the single SB wall. Additionally, the breakthrough after 50 years is made for the entire depth of the single SB wall while at the depth no more than 0.9 m for the composite wall with bentonite paste at the GCL overlap. With consideration that the depth of the groundwater table is generally greater than 1 m, the GCL–SB composite cutoff wall will exhibit a good performance in containing groundwater contaminants in the field, especially when applying bentonite paste at the GCL overlap.

Analytical Solutions for General Two-Wedge Stability

A force-based limit equilibrium analysis is presented for the stability of a general two-dimensional, two-wedge sliding mass of soil, including a vertical or nonvertical wedge interface. The analysis is conducted using three failure planes and can accommodate variable conditions for wedge geometry, pore pressure, shear strength parameters, reinforcement, applied loads, and pseudostatic seismic coefficients. A constant factor of safety is assumed for each failure plane and reinforcement element, although this assumption can be relaxed through selection of strength parameters. The factor of safety is obtained analytically and requires solution for the roots of a polynomial equation. Verification checks show exact agreement with existing solutions for simplified conditions, including Mononobe–Okabe dynamic active force. Numeric examples are provided to demonstrate the method and illustrate the importance of several parameters for stability of a landfill bottom liner system and reinforced soil retaining wall. The analytical solutions take compact form, provide insight for the two-wedge method, and offer good capability to tailor conditions for applications that can be suitably characterized by wedge failure.

Temperature Effects on Stability and Integrity of Geomembrane–Geotextile Interface in Municipal Solid Waste Landfill

Review of the limited experimental studies available in the published literature that investigate the effects of temperature on the shear strength of typical geomembrane (GM) and geotextile (GTX) interface is performed. These studies suggest that the shear strength of GM–GTX interfaces generally increase with an increase in temperature. However, there is no study that examined the combined effect of the temperatures along the bottom liner and the large displacement induced by the waste settlement on the short-term and long-term stability and integrity of the GM–GTX interface in a composite bottom liner system in municipal solid waste (MSW) landfills. This paper presents the application of a thermal model to predict the evolution and distribution of temperatures within the waste and along the bottom liner system of a typical landfill cell model, while simultaneously evaluating the influence of the predicted temperatures on the shear response of GM–GTX interfaces in the composite bottom liner system. The predicted temperatures along the liner interface of the simulated landfill cell varied between 4 and 32 °C, which are well within the reported temperatures in and around the bottom liners in MSW landfills. The results also suggest that beginning the placement of waste in summer is favorable than in winter, since the high temperatures at the GM–GTX during summer mobilize higher shear strengths resulting in lower shear displacements. Further, if stability analysis using limit equilibrium method is performed, then the shear strength of GM–GTX interface corresponding to the low temperature ranges expected at the site should be used for conservative and reliable estimates of the stability of the bottom liner system.

Comprehensive coupled thermo-hydro-bio-mechanical model for holistic performance assessment of municipal solid waste landfills

A comprehensive coupled thermo-hydro-bio-mechanical (CTHBM) model is proposed to simulate the coupled interactions between the hydraulic, mechanical, biochemical, and thermal processes observed in municipal solid waste (MSW) and also assess their influence on the long-term performance of MSW landfills. The hydraulic model is based on two-phase fluid flow through unsaturated porous media. The biochemical model is based on a two-stage anaerobic biodegradation model. The thermal model is based on conductive heat transport with heat generation rates derived from the biodegradation model. The mechanical model uses the soft-soil-creep constitutive model to simulate the time-dependent creep behavior of the waste. The effect of biodegradation and subsequent mass loss on the waste settlement is also incorporated. Using the proposed CTHBM model, two numerical simulations were performed on a typical full-scale landfill cell geometry to determine the long-term spatial and temporal variations in the hydraulic, mechanical, biochemical, and thermal characteristics of waste under conventional and bioreactor landfill conditions. The influence of the dynamic changes in the waste characteristics on the shear behavior of a textured geomembrane-geotextile interface in the bottom liner and cover system of the simulated landfill cell was also examined.

Influence of Waste Temperatures on Long-Term Landfill Performance: Coupled Numerical Modeling

A coupled thermo-hydro-bio-mechanical (CTHBM) numerical model to simulate the long-term behavior of municipal solid waste in landfills is presented. Three numerical simulations—a conventional landfill simulation with no leachate injection (CONV) and two bioreactor landfill simulations involving leachate injection—were carried out by applying the CTHBM model to a typical two-dimensional (2D) landfill cell configuration to analyze the effect of temperature on the long-term performance characteristics of a landfill system. Of the two bioreactor landfill simulations, one (BIOR-T) incorporated temperature effects on the waste decomposition, while the other simulation (BIOR-NT) did not. For the waste conditions simulated, the CONV and BIOR-T had a maximum waste temperature of 54°C and 62°C, respectively. The temperatures at the bottom liner were determined to be in the range of 1°C–32°C and 1°C–39°C over the entire simulation time of the CONV case and BIOR-T case, respectively. The effect of waste temperatures on moisture distribution, methane gas production, and landfill surface settlement was also assessed. The surface settlement response for BIOR-T and BIOR-NT simulations suggests that incorporating the effect of waste temperatures on the waste decomposition is important for a realistic prediction of the waste settlement in landfills. The BIOR-T and BIOR-NT simulations had a similar interface shear response, suggesting that the changes in the stiffness and shear strength of waste, due to incorporating temperature effects on the biodegradation rate, have no noticeable impact on the interface shear response in the bottom liner system. Overall, the proposed CTHBM model can be used to predict long-term performance characteristics (e.g., moisture distribution, landfill gas production, settlement of waste, temperatures) relevant for effective design of bioreactor landfills.

Analytical model for coupled consolidation and diffusion of organic contaminant transport in triple landfill liners

A triple-layer composite liner consisting of a geomembrane liner (GMB), a geosynthetic clay liner (GCL) and a compacted clay liner (CCL) is commonly used at the landfill bottom liner system to isolate the contaminated leachates. In this paper, one-dimensional quasi-steady-state small deformation model (SDSS) was developed to investigate the behavior of organic chemicals transport in landfill composite liner system considering coupled effect of consolidation, diffusion and degradation. The first and second type bottom boundary conditions are used to derive the analytical solutions. The generalized integral transform technique (GITT) is adopted to derive the analytical solutions. The effect of consolidation on the performance of GMB/GCL/CCL with intact or leaking GMB is investigated. The triple liner under double drainage boundary condition (DDBC) has better performance compared to the case under single drainage boundary condition (SDBC). This is because the velocity induced by consolidation under DDBC is lower than that under SDBC. The effect of GCL consolidation shows an opposite trend compared to CCL consolidation. Considering GCL consolidation can increase the breakthrough time. The effective diffusion coefficient of GCL can be two magnitude orders smaller after consolidation, which provides a better diffusion barrier for the chemical transport. The effects of adsorption and degradation have been analyzed as well. Increasing the adsorption capacity of a deforming composite liner can increase the steady-state bottom flux, which shows the opposite tendency compared to the case without considering consolidation. This is due to the fact that for the case of a deforming composite liner, the advection induced by consolidation includes a new term due to the solid velocity. This velocity will result in the increase the mass of chemical migration through the composite liner.

From the design of bottom landfill liner systems to the impact assessment of contaminants on underlying aquifers

The most recent advancements of the research activity that has been carried out at the Polytechnic University of Turin since the 1990s are presented, with a focus on the design approaches which can be adopted for the optimisation of the engineered clay barriers that are used as a part of the composite liners of solid waste landfills. A particular attention is devoted to the characterisation of the geosynthetic clay liners (GCLs) in terms of their microstructural features and semipermeable properties, which affect both the liquid and contaminant transport and the swelling–shrinking behaviour upon a variation in the chemical and mechanical boundary conditions. In the first part of the paper, novel analytical solutions are derived in order to account for the influence of the chemico-osmotic counter-flow on the leakage rate through a lining system that consists of a geomembrane (GM) overlying a GCL, as well as for the effect of a variation in the GCL swelling pressure on the hydraulic transmissivity of the GM–GCL interface. In the second part of the paper, a steady-state analysis approach is proposed with the aim to include all the aforementioned phenomena in the assessment of the impact of contaminant migration through the landfill bottom liners on the groundwater quality, taking into account the presence of a natural attenuation layer between the GCL and the underlying aquifer.

Assessment of Consolidation-Induced Contaminant Transport for Compacted Clay Liner Systems

AbstractThis paper presents an investigation of the effect of clay consolidation on contaminant transport through compacted clay liner (CCL) and composite geomembrane liner (GML)/CCL landfill bottom liner systems. Numerical simulations were conducted using the CST2 model and consider coupled consolidation and contaminant transport with representative geometry, material properties, and applied stress conditions. Simulation results indicate that, depending on conditions, consolidation can have important effects on contaminant breakthrough time, mass flux, cumulative mass outflow, and concentration distribution within the CCL, not only during the course of the consolidation process but also long after consolidation has completed. In general, the effects of CCL consolidation increase with increasing CCL thickness, increasing magnitude of applied stress, decreasing loading time, increasing CCL organic carbon fraction, and increasing variation of effective diffusion coefficient. Traditional advective-dispersive...

On the current state of the Hydrologic Evaluation of Landfill Performance (HELP) model

The Hydrologic Evaluation of Landfill Performance (HELP) model is the most widely applied model to calculate the water balance of cover and bottom liner systems for landfills. The paper summarizes the 30year history of the model from HELP version 1 to HELP 3.95 D and includes references to the three current and simultaneously available versions (HELP 3.07, Visual HELP 2.2, and HELP 3.95 D). A sufficient validation is an essential precondition for the use of any model in planning. The paper summarizes validation approaches for HELP 3 focused on cover systems in the literature. Furthermore, measurement results are compared to simulation results of HELP 3.95 D for (1) a test field with a compacted clay liner in the final cover of the landfill Hamburg-Georgswerder from 1988 to 1995 and (2) a test field with a 2.3m thick so-called water balance layer on the landfill Deetz near Berlin from 2004 to 2011. On the Georgswerder site actual evapotranspiration was well reproduced by HELP on the yearly average as well as in the seasonal course if precipitation data with 10% systematic measurement errors were used. However, the increase of liner leakage due to the deterioration of the clayey soil liner was not considered by the model. On the landfill Deetz HELP overestimated largely the percolation through the water balance layer resulting from an extremely wet summer due to an underestimation of the water storage in the layer and presumably also due to an underestimation of the actual evapotranspiration. Finally based on validation results and requests from the practice, plans for improving the model to a future version HELP 4 D are described.

State-of-the-art report: GCL shear strength and its measurement – ten-year update

ABSTRACT: This paper presents an invited update to our 2004 state-of-the-art report and provides a comprehensive source of information on the shear strength and shear strength testing of geosynthetic clay liners (GCLs). Essential concepts of shear stress–displacement behavior and shear strength are presented, followed by detailed discussions on the laboratory measurement of the shear strength of GCLs and GCL interfaces. The paper also provides recommendations for the selection of design strength envelopes for stability analyses and checklists to assist users in the specification of GCL shear testing programs. North American practice is emphasized and discussions are focused primarily within the context of landfill bottom liner and cover systems. Conclusions and recommendations are provided with regard to GCL shear strength behavior and current GCL strength testing practice, improvements for GCL strength testing are suggested, and future research needs are identified.

Interface Shear Damage to a HDPE Geomembrane. I: Gravelly Compacted Clay Liner

AbstractAn experimental program of large-scale direct shear tests has indicated that shear displacement of a high-density polyethylene (HDPE) geomembrane (GM) over a gravelly compacted clay liner (CCL) under moderate to high normal stress conditions can cause much greater damage to the geomembrane than static pressure alone. Essentially, no damage was observed at low normal stress. The greatest geomembrane damage occurred at high normal stress (1,658 kPa) and yielded an average of 169 holes/m2, with a maximum hole size of 23 mm. Size, angularity, and hardness of the gravel particles are also important factors with regard to potential damage. Geomembrane damage was greatly reduced when a needle-punched geosynthetic clay liner (GCL) was placed between the geomembrane and gravelly CCL, including one test conducted at very high normal stress (4,145 kPa). The findings suggest that gravelly soils should be viewed with caution for the construction of GM/CCL composite liners for landfill bottom liner systems and ...

Leakage Performance of the GM + CCL Liner System for the MSW Landfill

The contaminants in the landfill leachate press pose a grave threat to environment of the soil and the groundwater beneath the landfill. Despite there being strict requirements in relevant provisions of both domestic and foreign countries for the design of the bottom liner system. Pollution of the soil and the groundwater still took place in a number of landfills because of the leakage. To investigate the leakage rate of the liner systems, the minimum design requirements of the liner systems are summarized according to the provisions of four countries, including China, USA, Germany, and Japan. Comparative analyses using one-dimensional transport model are conducted to study the leakage performance of these liner systems composed of geomembrance (GM) and compacted clay layer (CCL) meeting the relevant minimum design requirements. Then parametric analyses are conducted to study the effects of the hydraulic head, the thickness of GM, the hydraulic conductivity of CCL, and so forth on the leakage performance of the liner system. It is concluded that the liner system designed according to the minimum design requirements of Germany provide the best antileakage performance, while that of Japan performs the lowest. The key parameters affecting the failure time of the liner system are summarized. Finally, some suggestions for the design of the liner systems are made according to the analyses.

Hydraulic and chemical evolution of GCLs during filter press and oedopermeametric tests performed with real leachate

The solid waste decomposition inside a municipal solid waste (MSW) landfill may be enhanced by liquid addition in order to reach landfill stabilization in a reduced period of time as compared to dry-tomb landfills. This liquid addition provides an increased leachate volume and its specific chemical composition leads to fear a degradation of the hydraulic properties of the bottom liner system, especially the mineral part. In this study, the impact of four fluids on the chemical and hydraulic properties of three geosynthetic clay liners (GCLs) currently used in landfill bottom liner systems is evaluated using swelling tests, filter press tests and oedopermeameter tests. Each permeability test is associated to chemical analysis of the fluids before and after contact with the bentonites. The four fluids are two real leachates, a sewage slurry and a leachate from a green waste repository. The three GCLs contain either natural sodium bentonite or sodium-activated calcium bentonite.Filter press results and swell index tests reveal a larger impact on the permittivity of the bentonite of leachates as compared to the other fluids. Oedopermeameter tests lasted one year; they show a variable impact, either negative or positive, of the real leachate on the hydraulic conductivity of the GCLs. Specific conditions, such as pre-hydration, limit the impact of leachate on the hydraulic conductivity. Whatever the method used to determine the permittivity of bentonite or of the GCL, the natural sodium bentonite is less impacted by the fluids than the sodium-activated calcium bentonites.

Temperature effects on the swelling capacity and barrier performance of geosynthetic clay liners permeated with sodium chloride solutions

This paper examines the swelling capacity and hydraulic performance of geosynthetic clay liners (GCLs) at different temperatures against sodium chloride (NaCl) solutions. Free swell tests were conducted with deionized water and the NaCl solutions of 0.1–0.4 M. Permeating tests with the 0.4 M NaCl solutions were conducted using soil columns, which consisted of a GCL and underlying base layer soil similar to that in the bottom liner system in a landfill. The measured intrinsic permeabilities of the GCL to the 0.4 M NaCl solution are 5.9 × 10−18 m2 for 20 °C and 2.5 × 10−17 m2 for 60 °C, while the measured free swells to the solution are 8.5 mL/2 g for 20 °C and 11 mL/2 g for 60 °C and the free swells to other solutions tested also increase as the temperature increases. Even after accounting for the temperature dependence of the kinematic viscosity of the NaCl solutions, the intrinsic permeability increases with temperature because bentonite swelling depends on temperature. However, the free swell of bentonites in the GCLs increases as the temperature increases, and the relationship between free swelling and the permeability differs from the common notion that permeability decreases as the free swell increases. Consequently, the previous relationships obtained from free swell tests and hydraulic conductivity tests at room temperature are not applicable at elevated temperatures because at elevated temperatures, the increased intrinsic permeability is related to the decreased swelling pressure.

Geosynthetic Clay Liner Permeated with Acid Rock Drainage:The Role of Iron in Arsenic Immobilization

=Geosynthetic Clay Liners(GCLs) have the potential to immobilize cations present in solution. Due to this, GCLs have been considered suitable materials not only in landfill bottom liners, but also in rock containments eith the potential of acid rock drainage(ARD) generation.However,the bentonite inside GCLs dose not have affinity towards anions such as aresenic, which is one of the toxic components present in ARDs. Based on the authors' previous research on swelling, sorption, and hydraulic conductivity of GCL against ARD, through discussion on the role of Fe in As immobiliation was done in this paper.Swelling test showed that the presence of metals, especially a high concentration of Fe(4500 mg/L approximately) due to its high concentration, negatively impact the swelling of bentonite by increaing the hydraulic conductivity value. The hydraulic conductivity remained low during the test duration but was one order of magnitude higher in the ARD permeation case(5.0×10-10 m/s)than in the water permeation case(1.4×10-11 m/s)。Single metal sorption tests showed that Fe was sorbed by the betonite while As was As sorption.Considering that GCLs do not retain As, but Fe does, an additional Fe layer could be placed in the bottom liner system in order to immobilize it. However, if the ARD contains high Fe concentration, this additional layer would not be neccessary as the Fe in solution will prevent As mitigation.

Quantification of the adsorption of phenolic compounds on the geotextile and bentonite components of four geosynthetic clay liners

ABSTRACT: The aim of this paper is to present the experimental results obtained regarding the adsorption on various constitutive geotextiles and bentonites of geosynthetic clay liners of phenol, o-cresol, p-cresol, 2-chlorophenol, 4-chlorophenol, 2,4-dimethylphenol, 3,4-dimethylphenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, 2,3,5,6-tetrachlorophenol, pentachlorophenol, and bisphenol A. These contaminants, including certain derivatives of halogenated phenols, are known to be toxic even at very low concentrations. Geotextiles and bentonites were sampled from four geosynthetic clay liners (GCLs) representative of the GCLs commonly used in bottom liner systems in France. Adsorption was studied through batch adsorption tests. The effect of the nature of the bentonite (sodium versus calcium activated) was studied. Results obtained in this study show that, contrary to what has been observed for volatile organic compounds (VOCs), the adsorption isotherms are non-linear. For VOCs, linear adsorption isotherms are obtained both for geotextiles and for bentonites. The contrast between the adsorption on geotextiles and bentonites is smaller than for VOCs. Up to two orders of magnitude difference can be obtained between the low adsorption coefficient for bentonite as compared with the large adsorption coefficient for geotextiles when adsorption of VOCs is considered. For phenolic compounds, the adsorption coefficients are of the same order of magnitude for bentonite and geotextiles. Two different trends were observed for woven and nonwoven needle-punched geotextiles as regards the adsorption parameters measured. For chlorophenols, polarity appears to affect adsorption: the adsorption coefficients increased with increasing number of chlorine atoms.

Contaminant mitigating performance of Chinese standard municipal solid waste landfill liner systems

In 2004, Chinese Government prescribed standard municipal solid waste (MSW) landfill bottom liners. However, very limited research has been conducted to evaluate the performance of the standard MSW landfill bottom liners prescribed by the Chinese Government. In this paper, the performance of the two types of Chinese MSW landfill bottom liner systems was evaluated based on: (1) the maximum leachate head; (2) leakage rate; (3) peak concentration of the target contaminant in an aquifer which was underlain the assumed landfill, and (4) total mass per unit area of the target contaminant discharged into the aquifer. The performance of the German standard MSW landfill bottom liner system was evaluated and compared with that of Chinese ones. It is found that the calculated maximum leachate head for the Chinese landfill liner systems was much higher than that for the German one. The calculated leakage rate, peak concentration and the maximum total mass per unit area in the aquifer of the target contaminant show that the performance of the Chinese standard landfill liner Type 2 is practically the same as that of the German standard landfill liner with holed geomembrane wrinkles, while the Chinese standard liner Type 1 is less effective, with regarding the mitigation of the impact of landfills to the groundwater quality. It is concluded that the overall performance of the Chinese standard landfill liner systems is less strict than that of the German standard landfill liner system.