The Infiltration Performance of Practically Operating Landfill Liners - Literature review Example

 Landfill counts to a major share with reference to the total quantum of global waste management. However the permeability of the leachate into the surrounding soil system and into the water bodies causes serious environmental concern. The methodology followed globally to reduce the detrimental effects of infiltration of landfill leachate into the surrounding systems is to make impermeable linings to the landfill walls. A number of components has been effectively tested and incorporated in the landfill linings so as they restrict the flow of leachate. Researches had been continuously evaluating and testing the efficacy of different lining materials and their combinations in serving as landfill liners. The gradual development of landfill linings and the relevance of the same in ensuring environmental sustainability have been reviewed in a lot number of studies. Bentonite has been found as resourceful in limiting the leachate flow from the landfills. A number of literatures have been identified supporting this property of bentonite. The increased performance of this component in comparison with normal clay has also been studied by a number of researches. Literatures are also available in the context of performance of various materials in serving as effective landfill liners. Landfill leachate and its effect on the landfill liners have also received scientific attention. Policy decisions on the designing part of landfills also have been reviewed by analysts. In this review of literature, works pertaining to different aspects of landfill liners and the role of bentonite as landfill liners is being reviewed. The review of literature supports the research on the properties of landfill liner made of crushed slate waste and bentonite clay while serving as the scientific background for the study. 2. The background history to landfill liners and geological barriers used in landfill site and why they are required. As per the Landfill Regulation 2002, “landfills include any site which is used for more than a year for the temporary storage of waste; and any internal waste disposal site, that is to say a site where a producer of waste is carrying out its own waste disposal at the place of production” (Crown, 2002) The leachate emissions which occur from the non lined traditional landfills cause serious environmental concerns. This can cause higher concentration of ammonium and create anaerobic conditions around the landfills. The danger increases as the concentration of ammonium can remain significantly high for considerably long time. This results because the low level of pH does not promote the degeneration and volatisation process (Pivato & Raga, 2006,123-132). Pivato and Raga (2006,123-132) has confirmed the increasing importance of landfill technology in order to nullify the uncontrolled emissions from the landfills. The study suggests and explains the development that the history has seen with regard to bottom lining systems. Legislations have also asserted the importance of landfill liners and geographical barriers in association with landfills and other waste management systems. Landfill Regulation 2002 has strictly confirmed that “Soil, groundwater and surface water is to be protected by the use of a geological barrier combined with a bottom liner during the operational phase of the landfill; and a top liner following closure and during the after-care phase” (Crown, 2002). 3. Comparison between natural clay liner and Bentonite Enhanced Soil (BES) liner. There are a number of studies which deals with the comparison of natural clay liner and Bentonite Enhanced Soil (BES) liner. Several studies have indicated that the inclusion of Bentonite improves the lining properties of natural clay. Shi, Jao and Hong (2003, 355-359) have conducted experiments in similar lines. The study suggests the limitation of the natural clayey liner in the prevention of leachate infiltration occurring in the landfills. The paper further confirms the effectiveness of the improved soil liner comprising of clayey soil, lime and bentonite. The results of the study indicated that the permeability of the improved liner can be decreased from 10 super(-8)-10 super(-7) cm/s to 10 super(-9)-10 super(-8) cm/s in comparison with the natural clayey liner (Shi, Jao & Hong 2003, 355-359). The holding capacity of the liner with reference to COD, nitrogen and iron also improved considerably in the case of the improved liner Shi, Jao & Hong 2003, 355-359). The reverse osmosis properties of Bentonite Enhanced Soil (BES) liner has been confirmed by Salingdon and Whitworth (2006, 90-95). The study had compared the performance of Clay and different mixes of Bentonite and glass beads as effective landfill liners. The study tested the membrane properties of different mixes included in the experimental model. The results suggested that all the mixtures of Bentonite and glass beads exhibit measurable membrane properties. The reflection coefficient values from the study showed a low percentage of 0.07 for 12% Bentonite and 0.26 for 100% clay (Salingdon & Whitworth ,2006, 90-95). The study also indicated clear cut comparison of the properties of clay and Bentonite Enhanced Soil (BES) and other mixes of Bentonite as liners. The amount of solute rejection was found to be less as 12.6% for natural clay whereas the solute rejection was found to be increasing with the increase in percentage of clay in the samples. The percentage of solute rejection was found to be more than 40% for 50% and 100% clay samples (Salingdon &Whitworth 2006, 90-95). On the other side the glass beads represented fine-grained sand and showed no membrane properties. The solute rejection property directly refers to the quality of a material as a landfill liner. Mohamedzein et.al (2005, 271-281) has analysed the efficacy of crushed shale as landfill liners. The study investigated the hydraulic conductivity, compaction, swelling, consolidation, X-ray diffraction (XRD), and the chemical properties. The results indicated positive results on the hydraulic conductivity and X-ray diffraction qualifying the material as a landfill liner. The study also averted the danger of post-construction settlement as the compressibility of the material was low. The shear strength of the compacted shale was also confirmed by the study and the same confirmed with the standards of liners Mohamedzein et.al (2005, 271-281). Sezer, Turkmenoglu & Gokturk (2003, 711-717) has analysed the mineralogical and sorption capacity of Ankara Clay so that it can be used as a landfill liner. The results indicate that the mineralogical and sorption capacity along with the known engineering capacity of Ankara Clay makes it an ideal landfill liner (Sezer, Turkmenoglu & Gokturk ,2003, 711-717). The geotechnical properties and the compaction permeability characteristics of Ankara clay with reference to the efficacy as landfill liner were further assessed by Akguen and Wallace (2005, 193-197). The results pertaining to geotechnical tests and leakage rate calculations indicated that Ankara clay is an effective compacted clay landfill liner material Akguen and Wallace (2005, 193-197). 4. Investigate other types of landfill liners using bentonite and other soil materials (use journals, published papers, books etc) Bartelt et.al (2005, 848-856) evaluated the sorptive capacities of granular activated carbon (GAC), shale, benzyltriethylammonium-bentonite (BTEA-bentonite), and hexadecyltrimethylammonium-bentonite (HDTMA-bentonite) when used in combination with compacted clay landfill liners. The experiment was based on laboratory based sorption and permeability experiments. The results indicated that all the four materials tested had high sorptive capacity for benzene, trichloroethylene, and 1,2-dichlorobenzene. In a study conducted by Gueney and Oezdemir (2005, 561-569) sepiolite and natural soil-added sepiolite mixtures were tested for their utility as compacted landfill liner. The economic feasibility of the material was also anlaysed by the study. The hydraulic conductivity, leachate analysis, unconfined compression strength, consolidation, volumetric shrinkage and swelling tests were done to analyze the geotechnical and physico-chemical properties of the samples (Gueney and Oezdemir 2005, 561-569). The observations of the experiment indicated that the permeability and swelling properties were lower in the case of compacted natural soil-added sepiolite mixtures in comparison with pure sepiolite, whereas in the case of compressive strength the result was vice versa. The study concluded that in general the natural soil-added sepiolite performed well as a landfill liner as it showed high contaminant absorption capacity (Gueney and Oezdemir 2005, 561-569). Guney and Koparel (2005, 449-459) tested the possible use of kaolinite/zeolite mixtures as alternative landfill liner mixtures. The experiment examined the geotechnical and physicochemical properties of the mixtures. Compaction test was used to evaluate the optimum moisture content which provides the best field level compression. Extensive experiments pertaining to the specific gravity, liquid and plastic limits, unconfined compression strength, consolidation, pH, and electrical conductivity were conducted to formulate the optimal mixture using kaolinite and zeolite to be used as landfill liner mixtures (Guney and Koparel, 2005, 449-459). Tuncan et. al (2003, 54-61) further investigated the role of natural zeolite as an impervious landfill liner. Different combinations and ratios of bentonites and zeolites compacted using optimal moisture content was tested for strength parameters, permeability, pH, heavy metals and other properties (Tuncan et. al ,2003, 54-61). The most effective ratio found as per the study was 0.10 (B/Z) with regard to the low hydraulic conductivity and high cation exchange capacity. This would futher help in the reduction of the thickness of the base liner of the landfills (Tuncan et. al ,2003, 54-61). Roberts and Shimaoka (2008, 2635-2644) in their study checked the feasibility of Bentonite coated gravel (BCG) as lining material for landfill. The study was conducted with the assumption that BCG is an effective capping material for correcting the contaminant sedimentation in aquatic environments (Roberts and Shimaoka 2008, 2635-2644). The study evaluated the permeability and the strength of the lining material. It also considered the factors of X-ray diffraction, methylene blue absorption, compaction, free swelling, permeability, 1D consolidation, triaxial compression and cone penetration (Roberts and Shimaoka 2008, 2635-2644).The observation made by the study was the reduction of permeability with higher compactive efforts. However excess compaction was found to create fractures in the aggregate structure of BCG. This would however result in the increase of permeability (Roberts and Shimaoka 2008, 2635-2644). Another impact of higher compactive efforts as observed by the study is the increase in swelling pressures which would resultantly hinder the performance of BCG as a landfill liner (Roberts and Shimaoka 2008, 2635-2644). This paper published by Kockar, Akguen and Aktuerk (2005, 187-192) tested the effectiveness of a liner mixture constituting of compacted bentonite and sand liner material in 10:90 proportion. The study was conducted using flow tests for the isolation of refuse in sanitary landfills. The study put forward effective recommendations for further research to be done in the subject. (Kockar, Akguen and Aktuerk 2005, 187-192). Chalermyanont, Arrykul and Charoenthaisong (2009, 117-127) has identified the scope of a lateritic soil and a marine clay as potential landfill liners. The peculiarity of the liner constituents included in the study is that these simulate natural conditions typical to the situations found in hot and humid climatic regions. Physical and chemical, batch adsorption, column, hydraulic conductivity tests were conducted to assess the heavy metal sorption capacity, chemical compatibility of hydraulic conductivity, and transport parameters of the materials (Chalermyanont, Arrykul and Charoenthaisong 2009, 117-127). The results of the experiments indicated that marine clay had increased absorption capacity than lateritic soil materials (Chalermyanont, Arrykul and Charoenthaisong 2009, 117-127). As far as the hydraulic conductivity is concerned, marine clay was found to have increased retardation factors and lower diffusion coefficients. The general conclusion of the study was that marine clay showed better properties as a landfill liner in comparison with lateritic soil materials (Chalermyanont, Arrykul and Charoenthaisong 2009, 117-127). Bozbey and Guler (2006, 1277-1286) investigated the feasibility of silty soil excavated in highway construction for being used as landfill liner. The effectiveness of the study is that it included both laboratory and in situ scales. Moreover the samples were tested both in pre and lime treated forms. Compaction energy was another variable in the study. (Bozbey and Guler 2006, 1277-1286).The tests revealed that the treatment with lime helped in improving the shear strength of the liner resultantly increasing the higher hydraulic conductivity values in comparison with normal soil. However the field experiments exhibited results of different nature (Bozbey and Guler 2006, 1277-1286). 5. Landfill leachate and its effect on landfill liners. One key problem with landfills is the uncontrolled leachate emissions. This is considered to cause serious environmental impacts. Landfill leachate causes an increased concentration of ammonium due to landfill leachate. This ammonium presence is susceptible to have longer persistence in the environment due to the decreased possibility of degeneration and volatisation process (Pivato & Raga, 2006,123-132).The pH level decreases in the soil system around the landfill area due to leachate. Bartelt et.al (2005, 848-856) using synthetic leachate had evaluated the effect of leachate on four different constituents of landfill liners. The results indicated that granular activated carbon (GAC) and BTEA-bentonite did not show competitive sorption of leachate constituents (Bartelt et.al, 2005, 848-856). In this study, shale exhibited some competitive sorption effects between benzene and trichloroethylene and the leachate constituents (Bartelt et.al, 2005, 848-856). Further in the study, all the tested materials retarded the movement of benzene. The sustainability of the amendments made to the liners using the tested materials was also studied. The elimination of benzene flux through the liner amended with 3 or 9% GAC or 3 or 9% BTEA-bentonite sustained for over hundred year period (Bartelt et.al, 2005, 848-856). 6. Identify and evaluate the main landfill site design and landfill liner design concepts used today, use government standards such as Landfill Regulation 2002, The Landfill Directive, The Groundwater regulations 1998 etc. Several studies have reviewed the effectiveness of various landfill designs and concepts. Favaretti and Previatello (2005, 51-62) have described the methodology to test the linear system effectiveness of mechanically pretreated municipal solid wastes landfill. Government has had continuous interventions pertaining to the policies regarding landfill designs and other waste management policies. The landfill regulations 2002, issued by the secretary of state act as an extra as machinery in carrying out the environmental protection act of 1999. The regulations have strictly suggested the acceptance procedures for landfills, control and monitoring measures for landfills and regulations on the after care of landfills (Crown, 2002). The regulations have suggested strict waste acceptance criteria and has classified and catalogued European wastes. The general requirements for landfills in terms of location, design, lining and geographical barriers, leachate monitoring and transitional provisions has been explained by landfill regulations 2002 (Crown, 2002). "The Landfill Directive represents a step change in the way of ware disposal within the country and helps in driving waste up the hierarchy through waste minimisation and increased levels of recycling and recovery” (DEFRA, 1999). This governmental document has incorporated particular changes in the management practices of landfills helping in the reduction of environmental impacts. In general certain wastes were banned from being disposed in landfills, classification of wastes being disposed in the landfills and strict guidelines on the requirement of pre-treatment of wastes before disposing it in the landfill were suggested by the landfill directive (DEFRA, 1999). The guidelines on the groundwater regulations 1998 issued by the Department of environment, transport and regions also has imposed strict control over the landfill designs in ensuring to control the detrimental effects of leachage from landfills. (DETR, 2001) 7. Permeability requirement of a landfill liner. Bartelt et.al, (2005, 848-856) has conducted permeability tests on different specimens of landfill liners including Ottawa sand and untreated bentonite. It was observed that the samples had conductivity less than or equal to 1X10 (super -7) cm/s. However, the specimen with 3% GAC measured conductivity value of 2X10 (super -7) cm/s (Bartelt et.al, 2005, 848-856). The paper by Moo Young et al (2004, 283-311) analysed a number of literatures pertaining to the infiltration rates from landfill liners and characterized them. The paper compiled the results of studies which described the infiltration performance of practically operating landfill liners. It reviewed the studies on 149 cites with compacted clay liner (CCL) and one cite with geosynthetic clay liner (GCL) (Moo Young et al ,2004, 283-311). Further it characterized the infiltration rates through geomembrane (GM) liners and composite liners for 259 sites. One of the salient features of the observations of the paper was that composite liners studied by the paper had an average infiltration ranging from 0-32 lphd for geomembrane and GCL systems to 0 to 1410 lphd for geomembrane and CCL systems (Moo Young et al ,2004, 283-311). The research by Foose, Benson and Edil (2002, 391-403) compared the solute transport through three composite landfill liners. Out of the three liners studied, the composite liner having a GCL had lowest infiltration. 8. Identify if the new BES liner mixtures capability and its effectiveness in containing leachate mainly in terms of their puncturing and leaking potential to current standards. There are a number of natural materials used as landfill liners. Pivato & Raga (2006, 123-132) has confirmed the effectiveness of Bentonite and various mixes of bentonite including Bentonite Enabled Soils (BES) in controlling leachate. Bentonite is usually coupled with other materials basically through two different methods. The first among them is in addition with in situ soil. The second methodology is to use Bentonite in geocomposite clay liner (GCL). Pivato & Raga (2006, 123-132) conducted a laboratory based test to evaluate the effect of bentonite on the attenuation of ammonium in leachate penetrating through the liner of the landfill. This study included standardized batch test with pulverized bentonite and also tested the effectiveness of compacted bentonite through another batch test. Both the tests indicated that bentonite had better impact on containing leachate with emphasis on the attenuation of ammonium than other natural landfill liners (Pivato & Raga ,2006, 123-132). Both the tests resulted with higher values for the partition coefficient (Kd) than the average values pertaining to other natural materials usually used as constituents of landfill liners. (Pivato & Raga ,2006, 123-132). Though the results of both the tests were similar the study suggests the test with compacted bentonite as more simulative with original conditions. There is studies available pertaining to the enquiry into the limitations of bentonite-enhanced sand mixtures (BES) as landfill liners. Tay, Stewart and Cousens (2001, 263-274) has reported the possibilities of shrinkage desiccation cracking of bentonite-enhanced sand mixtures (BES) after drying on exposure to air. This study confirmed the volumetric shrinkage of bentonite-enhanced sand mixtures after air drying and the event increasing with increased moisture content during compaction. It was concluded that cracking occurs in the liner when undergoes more than about 4% volumetric shrinkage (Tay, Stewart & Cousens, 2001, 263-274). Chemical amendments have been confirmed by various literatures as instrumental in improving the capacity of BES liners to contain leachate. The work done by Voudrias (2002, 251-258) has explained the idea of a sorption chemical barrier in order to increase the performance of landfill liners. It suggested the formulation of sorption chemical barrier through the addition of organoclay hexadecyltrimethylammonium-montmorillonite (HDTMA-montmorillonite) to a fine sand-bentonite liner (Voudrias , 2002, 251-258). The study with reference to previous studies and using mathematical simulations confirmed that the sorption chemical barrier enhances the property of the liner in retarding the infiltration of landfill leachate components. In the cases analysed by the study, the life of the liner was increased by a factor of 5 to 10 using the suggested amendment (Voudrias , 2002, 251-258). This performance was found to be maintained even after the sorption extent was significantly decreased. One another major suggestion by the study was that the increased life of the liner makes possible the reduction of the liner thickness which is ideally required to provide optimal barrier properties (Voudrias , 2002, 251-258). Thus in comparison with liner containing no organoclay, the required thickness of the suggested liner was ideally low. References Akguen, H; Wallace, RB, 2005,Utilization of ankara clay for sanitary landfill bottom liners, Turkey , Journal of Solid Waste Technology and Management ,Vol. 31, no. 4, pp. 193-197. Bozbey, Ilknur; Guler, Erol, 2006, Laboratory and field testing for utilization of an excavated soil as landfill liner material, Waste Management Vol. 26, no. 11, pp. 1277-1286 Bartelt-Hunt, Shannon L; Smith, James A; Burns, Susan E; Rabideau, Alan J, 2005, ‘Evaluation of granular activated carbon, shale, and two organoclays for use as sorptive amendments In clay landfill liners’, Journal of Geotechnical and Geoenvironmental Engineering, vol.131, no.7, pp.848-856. Chalermyanont, T; Arrykul, S; Charoenthaisong, N, 2009, Potential use of lateritic and marine clay soils as landfill liners to retain heavy metals , Waste Management, Vol. 29, no. 1, pp. 117-127 Crown, 2002, The Landfill (England and Wales) Regulations 2002, Queen's Printer of Acts of Parliament, viewed 13 February, 2009, http://www.opsi.gov.uk/si/si2002/20021559.htm DEFRA, 1999, Landfill Directive, DEFRA, viewed 13 February, 2009, http://www.defra.gov.uk/Environment/waste/topics/landfill-dir/pdf/landfilldir.pdf Department of environment, transport and regions, 2001, Guidance on the groundwater Regulations 1998, Department of environment, transport and regions, viewed 13 February, 2009, http://www.defra.gov.uk/ENVIRONMENT/water/ground/pdf/groundwater- guidance.pdf Favaretti, Marco; Previatello, Paolo, 2005, ‘Effectiveness testing of MSW landfill liners system--Collaudo funzionale del sistema di impermeabilizzazione di una discarica controllata di RSU’ ,Geologia Tecnica & Ambientale, vol. 2005, no. 2, pp.51-62. Foose, Gary J; Benson, Craig H; Edil, Tuncer B, 2002, ‘Comparison of solute transport in three composite liners’, Journal of Geotechnical and Geoenvironmental Engineering, vol.128, no.5, pp.391-403. Gueney, Y & Oezdemir, HV,2005, ‘The utilization of sepiolite in landfill liners’ , Environmental Technology [Environ. Technol.], Vol. 26, no. 5, pp. 561-569. Guney, Yucel; Koparel, Savas, 2005, ‘The use of kaolinite/zeolite mixtures for landfill liners’, International Journal of Environment and Pollution ,Vol. 23, no. 4, pp. 449-459. Kockar, MK; Akguen, H; Aktuerk, Oe, 2005, ‘Preliminary evaluation of a compacted bentonite/sand mixture as a landfill liner material’ , Journal of Solid Waste Technology and Management ,Vol. 31, no. 4, pp. 187-192 Mohamedzein, Yahia E A; Al-Rawas, Amer A; Al-Aghbari, Mohammed Y; Qatan, Ahmed; Al-Rawas, Abdul-Hamid, 2005, ‘Assessment of crushed shales for use as compacted landfill liners’, Engineering Geology, vol.80, no.3-4, pp.271-281. Moo-Young, H; Johnson, B; Johnson, A; Carson, D; Lew, C; Liu, S; Hancock, K, 2004, ‘Characterization of Infiltration Rates from Landfills: Supporting Groundwater Modeling Efforts’, Environmental Monitoring and Assessment , Vol. 96, no. 1-3, pp. 283-311 Pivato, A & Raga, R , 2006, ‘Tests for the evaluation of ammonium attenuation in MSW landfill leachate by adsorption into bentonite in a landfill liner’, Waste Management [Waste Manage.]. Vol. 26, no. 2, pp. 123-132. Roberts, AA; Shimaoka, T, 2008, ‘Analytical study on the suitability of using bentonite coated gravel as a landfill liner material’, Nuclear and Chemical Waste Management Vol. 28, no. 12, pp. 2635-2644 Saindon, R & Whitworth, T M , 2006, ‘Reverse osmosis properties of bentonite/glass bead mixtures at low compaction pressures’, Applied Clay Science, vol.31, no.1-2, pp.90-95 Sezer, G A; Turkmenoglu, A G; Gokturk, E H,2003,‘Mineralogical and sorption characteristics of Ankara Clay as a landfill liner’, Applied Geochemistry, vol.18, no.5, pp.711- 717. Shi, Jing-hua; Zhao, Yong-sheng; Hong, Mei, 2003, ‘A study on modification of clayey soil as landfill liner material’, Journal of Jilin University (Earth Science Edition) ,Vol. 33, no. 3, pp. 355-359 Tay, Y Y; Stewart, D I; Cousens, T W, 2001, ‘Shrinkage and desiccation cracking in bentonite-sand landfill liners’, Engineering Geology, vol.60, no.1-4, pp.263-274 Tuncan, A; Tuncan, M; Koyuncu, H; Guney, Y, 2003, Use of natural zeolites as a landfill liner , Waste Management & Research ,Vol. 21, no. 1, pp. 54-61. Voudrias, Evangelos A, 2002, ‘The concept of a sorption chemical barrier for improving effectiveness of landfill liners’, Waste management & research: the journal of the International Solid Wastes and Public Cleansing Association, vol. 20, no. 3, pp.251-258 Read More