Indian Geotechnical Conference (December 18-20, 2003) s5

Alternative Materials for Landfill Liners and Covers IGC 2009, Guntur, INDIA

ALTERNATIVE MATERIALS FOR LANDFILL LINERS AND COVERS

M.R. Patil Asst. Prof, Department of Civil Engg, BVBCET , Hubli–580 031, India. E-mail: [email protected] S.S. Quadri Professor, Department of Civil Engg., BVBCET, Hubli–580 031, India. E-mail: [email protected] Lakshmikantha H. Environmental Officer, Karnataka State Pollution Control Board, Bangalore–560 001, India. E-mail: [email protected]

ABSTRACT: An engineered landfill is a facility designed for the safe disposal of solid wastes. The bottom liner and a top cover, of the landfill are considered as the most critical components. These components are typically composite layers, made up of geomembrane overlying a compacted clay liner. Similarly landfill cover also consists of compacted clay layer to prevent the entry of surface water into the landfill. The main factor affecting the quality of compacted clay liners/covers is its permeability which should not be greater than 1.0 × 10–9 m/sec. Due to non-availability of suitable soil, it is necessary to develop alternative material for liners and covers. In the present study Kolar soil and Granite polish wastes are used as basic materials. The properties of these materials are altered by adding sodium bentonite to achieve the required properties of a competent material for landfill liners and covers. Also, the performance of these materials is tested under different physicochemical environments. The results of the study show that addition of sodium bentonite brings the permeability to the required range to use as an alternative material for landfill liners and covers.

1. INTRODUCTION In recent years, geomembrane and geosynthetic clay liners have been used to replace compacted clay liners. But these Solid wastes are the by products of human activities. Due to liners are vulnerable to accidental puncture and create a increase in population, change in life style, urbanization, potential problem with interface shear between their surfaces. advent of technology and industrialization, there has been Hence composite clay liners are preferred. radical change in quantity as well as quality of the solid waste produced. These wastes have become more hazardous The liners/covers of engineered landfill are multilayered systems consisting of hydraulic barrier layer as an important to human being and environment and demands careful component. The function of this layer is to minimize disposal practices. percolation of water through the cover system by directly Historically, landfill has been the most common practical blocking water and by indirectly promoting drainage or method for disposal of solid wastes. Hence an engineered storage of water in the overlying layers. Furthermore, landfill is a facility designed for the safe and environmental hydraulic barrier layer prevents landfill gasses from escaping friendly disposal of solid waste instead of open, un- into the atmosphere. Such gases are shown to be major sources of air pollution and ozone depletion. Also this layer engineered dumps. prevents the percolation of leachate into the ground and Engineering landfill basically consists of bottom liner and a reduces underground water pollution. top cover. These components play very important role in The hydraulic barrier layer for municipal solid waste landfills reducing the leachate quantity and minimizing the ground has consisted typically of a composite layer made up of a water pollution. Hence these are considered as the most geomembrane overlying a compacted clay layer having a critical components of an engineered landfill facility. Bottom hydraulic conductivity not greater than 1.0 × 10−9m/sec. liner and top covers are composite layers made up of (Danial, 1993). Compacted clay layers are of low cost, large geomembrane overlying a compacted clay liner of hydraulic leachate attenuation capacity and resistance to damage. Due conductivity not greater than 1.0 × 10–9 m/sec. These to non-availability of suitable soil at a site/to prevent the use composite layers woks as a hydraulic barrier layer in liner of fertile soil for these layers, it is sometimes necessary to and cover system. blend imported clay materials with local non-productive soils and industrial process wastes to achieve a suitable blended

45 Alternative Materials for Landfill Liners and Covers material. The most common blend is a combination of on site S. Properties Kolar soil Ilkal granite material/industrial process waste with sodium bentonite No polish waste which can lower hydraulic conductivity as much as several orders of magnitude. Compacted clay layers of liners and 1. Natural Moisture 3.50 0.42 covers are of low cost, large leachate attenuation capacity Content and resistance to damage. But strong acids and bases can 2. Atterberg Limits dissolve the solid materials in the soil, form channels and Liquid Limit (%) 28.30 Non-plastic increase the hydraulic conductivity. Hence lechate/pore fluid Plastic Limit (%) 20.06 Non-plastic with pH < 3 or >11 are usually of the most concern. Shrinkage Limit (%) 9.69 32.08 Plasticity Index (%) 8.24 Non-plastic 2. LITERATURE REVIEW 3. Grain size Analysis Blending of imported clay material with a local soil/ Gravel (%) 0.90 Nil industrial process waste to reduce the permeability is a popular practice in the construction of landfills. Many Sand (%) 54.40 1.00 researchers have worked on this approach and following are Silt (%) 43.20 93.00 few studies. Clay (%) 1.50 6.00 Sivapullaiah et. al. (2003) studied the geotechnical properties 4. Specific Gravity 2.58 2.5 of stabilized Indian red earth and reported that red earth 5. (a) OMC (%) 16.20 26 blended with bentonite, stabilized with lime can be used as (b) MDD (g/cc) 1.71 1.46 liner material. 6. Permeability 2.68 × 10–8 2.26 × Datta et al. (1999) studied the influence of additives on (m/sec) 10– 8 compaction characteristics and permeability. To achieve the low permeability in alluvial soils are blended with fly ash and clay. 4. RESULTS AND DISCUSSIONS Tiwari & Srivastava et al. (2000) studied the influence of 4.1 Kolar Soil and Effect of Sodium Bentonite additives such as fly ash and sodium bentonite and reported The properties of Kolar soil show that, it belongs to clayey that the compression index (Cc) increases with increase in fly –8 ash and bentonite and substantial decrease in permeability sands soil with permeability 2.68 × 10 m/sec. Addition of with both fly ash and bentonite additives. sodium bentonite shows that, there is a decrease in permeability as the percentage of sodium bentonite increases. However the decrease in permeability is marginal even with 3. EXPERIMENTAL PROGRAMME addition of 10% of sodium bentonite. The results of the tests Granite polish waste is the waste slurry, coming out from the are shown in Table 2. polishing process of natural granite slabs, to give them fine finish. As many industries are in operation in the granite Table 2: Kolar Soil and Effect of Sodium Bentonite available area throughout the world, considerably large Kolar Kolar soil + quantity of this waste is being generated and creating heaps Property soil % Sodium bentonite of this waste which faces disposal problem. Ilakal town in Bagalkot district is one such place which faces such problem. 1% 3% 5% 7% 10% Coeff. of 2.68 2.31 1.55 1.32 1.00 0.9 Similarly a natural soil from Kolar district which is a non- permeability × × × × × × fertile soil and has limited usage for many other works is (m/sec) 10–8 10–8 10–8 10–8 10–8 10– 9 identified for the study. Hence in the present study granite polish waste from Ilkal in Bagalkot District and natural soil called Kolar soil from Kolar district of Karnataka State, 4.2 Ilkal Granite Polish Waste and Effect of Sodium India, are used as basic materials for landfill liner and cover. Bentonite The geotechnical properties of these soils are determined and The properties of Ilkal granite polish waste show that, it reported in Table 1. belongs to silty soil having its permeability 2.26 × 10–8. Ilakl granite polish waste and Kolar soil are individually Similar to the Kolar soil, there is a decrease in permeability mixed with different percentages of sodium bentonite and as the percentage of sodium bentonite increases and addition their change in the permeability is observed with distilled of 4% bentonite decreases the permeability of the soil as per water. Also the effect of pH on the hydraulic conductivity of the desired limit. The results of the tests are shown in these materials is studied. Table 3.

Table 1: Geotechnical Properties of Study Materials

46 Alternative Materials for Landfill Liners and Covers

Table 3: Ilkal Granite Polish Waste and Effect of Sodium bentonite Bentonite Ilkal Ilkal granite polish waste + 5. CONCLUSIONS Property granite % Sodium bentonite added polish 1% 2% 3% 4% To safeguard ground water effectively and economically; the waste landfill liner and cover should be made with locally available Coeff. of 2.26 1.80 2.012 1.07 4.98 materials, which can attain low permeability and high permeability × 10–8 × 10–6 × 10–9 × 10–9 × 10–10 strength by addition of some additives. (m/sec) Following are the major conclusions drawn from the present investigations. 4.3 Effect of pH on Kolar Soil and Sodium Bentonite  Granite polish waste is fine grained non-plastic, light, Additive weight material with low permeability To study the performance of Kolar soil-sodium bentonite  Kolar soil is clayey sands with medium weight material mixture, leachate as a pore fluid, the permeability of this having low permeability. mixture is tested under different physico-chemical  It has been observed that the permeability of these environments. It is found that, permeability of the mixture is materials decreases with increase in sodium bentonite. increased under acidic and alkaline environments. However Ilkal granite polish waste with 4% sodium bentonite substantial change is observed in alkaline environment. It is added and Kolar soil with 10% of sodium bentonite will observed that addition of 4% bentonite will reduce the reduce the permeability of these soils to the desired permeability well within the desirable limit. The results of value to use as a material for landfill liner and cover the test are shown in Table 4. when water (pH = 7) is used as a pore fluid.  It has been observed that permeability changes with Table 4: Effect of pH Kolar Soil and Sodium Bentonite change in pH value. It is found that increase in Mixture permeability is high in alkaline medium for both the Coeff. of permeability study materials. But increase in the permeability of Ilkal Material In neutral In acidic In alkaline granite polish waste is marginal. It is due to inertness of condition environmen environnent the material to the change in pH. However the increase m/sec t m/sec m/sec in the permeability of Kolar soil is slightly more this Kolar soil + 10% 0.9 × 10–9 1.45 × 10–9 1.72 × 10–9 may be due to change in structure Recommended Sodium bentonite quantity of sodium bentonite to be added to Ilkal granite Kolar soil + 12% – 1.05 × 10–9 1.15 × 10–9 polish waste is 4% and that for Kolar soil is 14% to use Sodium bentonite them as a competent material for landfill liner and cover. Kolar soil +14% – 0.85 × 10–9 1.00 × 10–9 Sodium bentonite REFERENCES 4.4 Effect of Different Physicochemical Environment on Daniel David E. (1993). Geotechnical Practices for Waste Ilkal Granite Polish Waste and Sodium Bentonite Disposal, St. Edumundsdury Press Durystedmundds. Additive Dutta M., Parida B., Guha B. and Shreekrishnan T.K. (1999). It is found that, addition of 4% sodium bentonite will reduce “Industrial Solid Waste Management and Land Filling the permeability even under alkaline condition. The test Practice”, Narosa Publishers, Delhi. results of the study are shown in Table 5. Manual on Municipal Solid Waste Management (first edition), (2002). Govt. of India, Ministry of Urban Table 5: Effect of Physico-chemical Environments on Development. Permeability of Ilkal Granite Polish Waste and Sodium Sivapullaiah and Lakshmikantha H., et al. (2003). Bentonite Mixture “Geotechnical Properties of Stabilized Indian Red Earth”, Material Coeff. of Coeff. of Coeff. of Jr. of Geotechnical & Geological Engineering, 399–415. permeability permeability permeability Tiwari R.P. and Srivastava et al. (2000). “Utilization of in neutral in acidic in alkaline Industrial Waste (Fly ash) in Landfill Barrier”, IGC-2000, condition environment environment IIT Bombay, Mumbai: 207–210. in m/sec in m/sec in m/sec Ilkal granite polish waste 4.98 × 10–10 9.06 × 10–10 9.18 × 10–10 + 4% sodium