The Concept of Landfilling Processes - Term Paper Example

LANDFILL ENGINEERING (Student Name) (Institution) (Instructor) (Course No) (Date) 1. Introduction One of the most debated topics in the field of environmental management today is the safe disposal of wastes. Several provisions have been established in different countries, and internationally that enhance the safe disposal of wastes with the aim of reducing their adverse effects on the environment. One such convention is the Basel Convention on the control of the transboundary movement of hazardous wastes and their disposal, commissioned by the United Nations Environment Program (UNEP). Many countries around the globe employ the use of landfills in the disposal of waste materials. A landfill is a structure built on the ground and secluded from the surrounding environment with the main aim of disposing waste materials by burying them. This form of waste disposal has been used over the years because of its long-term storage capability. However, following the increase in environmental and health problems emanating from abandoned waste disposal sites and the high clean -up costs, there was the need for the introduction of landfill engineering to ensure total isolation of the wastes from the environment. Landfill engineering is defined as the application of engineering methods and processes in the improvement of the human hygiene through the removal and disposal of wastes as well as the supply of safe water. Landfill engineering concept is important since it reduces environmental and health risks and captures both recyclable and reusable materials that would otherwise be wasted through the normal landfilling processes. This paper give a detailed assessment of the concept of landfill engineering and the processes involved as well as its role in ensuring environmental health and safety. History of Landfill Engineering The concept of landfilling has long been used in the disposal of wastes with little attention being paid to the landfill structures. The disposal of wastes was initially done on the earth’s crust and was deemed the best method. However, with the increased urbanization and increase in population growth as well as industrialization, massive changes have occurred in landfilling. This is because of the environmental and health problems that have long been caused by the uncontrolled landfills such as environmental pollution and increased accidents. Consequently, there has been the need to impose regulations on various aspects of the landfills such as their location, preparation, design, and maintenance. Methods of building landfills Although the construction of landfills vary from place to place, there are three basic methods that are used in the building of the landfills namely; the area method, the trench method, and the ramp method. The area method is commonly used in areas with gentle slopes and can be applied to the quarries, ravines and old surface mines. In the area method, the wastes are arranged in layers, compacted and covered (Velinni, 2007, p. 39). During the subsequent days, the incoming wastes are placed above the material covering the previous day’s wastes, arranged into layers, compressed and covered at the end of each day. The spreading and flattening of the layers of wastes is aided by machines such as the landfill compactors or the track-type tractors. The material used in covering the wastes in this method is the soil and is acquired from burrow sites. The other method used in the construction of landfills is the trench method. This method of landfill construction is mainly used in flat or gently sloping surfaces where the ground water table is deep seated. The effective application of the trench method requires that the selected area soil is easy to dig and has the ability to provide suitable cover (Nemerow, 2009, p. 246). One major advantage of the trench method is the availability of cover. This is because the soil removed when digging the trenches is used in covering the wastes after disposal. Its disadvantages include; the drainage problems, as well as the additional costs of stockpiling and moving the soil in cases where the amount of soil removed, is more than the amount required. The final method of constructing landfills is the ramp method which differs from the other methods. This method of landfill construction involves the spreading and compaction of waste materials on an existing slope (Das, 2011, p. 23). The excavation of the soil for covering the waste material takes place right in front of the waste. The soil is spread on the waste and compacted and the excavated area acts as part of the cell for the next day’s work. The method portrays a similar advantage to the trench method in that there are no additional costs incurred for the transportation of the cover material. Additionally, this method provides a perfect way of starting landfills with minimum equipment use since the land does not need to be prepared in advance. 2. Landfill Siting The excellent functioning of a landfill depends on several factors hence the need for a rigorous process in the identification of the site for landfill construction. The areas identified for the construction of the landfills must satisfy the required government regulations. Additionally, the sites selected must have ways of minimizing the adverse impacts of the landfill on the environment and health as well as the additional economic costs of maintenance (Steiner and Butler, 2007, p. 306). Different regions have different criteria governing the selection of sites for the construction of landfills. The factors influencing the choice of landfill sites can be categorized into different groups such as the geomorphological factors. Hydrologic factors, humanistic factors and land use factors. Geomorphological Criteria The geomorphological criteria deals with the existence of physical features that influence the construction of landfills in a given area. One such factor is the soil water permeability which deals mainly with the texture of the soil. Soils that are highly permeable such as the district cambisols are not fit for the construction of landfills due to high leaching rates. Conversely, soils with low permeability such as the clayey soils provide perfect grounds for the construction of landfills. Another geomorphological factor that influences the selection of a landfill is the slope of the land. The slope of the land is described as the degree of inclination of the land. Areas that have very high values of the slope (steep slopes) are unsuitable for the construction of landfills. This is primarily because the steep slopes allow the leaching of materials to the other areas downhill this resulting in adverse environmental and health effects downhill (Chang and Pires, 2015, p. 714). Hydrologic Criteria The other criteria used in the selection of the sites for the construction of landfills is the hydrologic criteria which defines the location of the landfill in relation to the surrounding water bodies. One factor under this criterion is the distance from the rivers. The areas that are located far away from open water bodies such as rivers, lakes and oceans are preferred to those that are nearer. This help in avoiding the contamination of the water bodies by the waste materials deposited in the landfills. The other important factor of consideration under this criterion is the depth of the underground water table. This factor is important since it helps in determining whether or not the location of the landfill in a certain place will contaminate the underground water. Places, where the underground water table is deeply seated, are preferred for the location of landfills while those with relatively deep and shallow water table are deemed as fairly suitable and unsuitable respectively. Land use criteria This criterion for the selection of the landfilling sites focuses on the activities taking place within the given area to be selected. One component of the land use criteria is the general environmental criterion which focuses on the natural features that may be affected due to the establishment of the landfill. Landfills should not be constructed in areas near water bodies, the built environment, areas of great agricultural potential and pastures to avoid health effects on the populations. Additionally, the selection of landfill sites should be far from the roads. This ensures that there is easy transportation and additional costs of maintenance of the landfills are reduced. The other criteria for the selection of the landfills is the humanistic criterion and encompasses the distance from the residential areas and the distance from the generation areas. The Process of site selection The selection process for the suitable landfill sites involves the use of the Geographical Information Systems (GIS) technology. This process of landfill site selection involves various steps such as identifying the objective, identification of the factors and constraints, weighting the factors, mapping the criteria and the final selection of the landfill site and its construction. When using the GIS model in landfill site selection, there are two main steps that are involved. The first step is the elimination of the areas that are considered unsuitable for the construction of landfills. Such areas may be considered unsuitable due to such factors as the environmental and health risks as well as the additional costs that may be incurred in the construction of landfills within those areas. This step of landfill site selection requires the collection and manipulation of data. The exclusion criteria is important in the selection of landfill sites because it helps in the elimination of sites that are not suitable for landfill construction, hence the reduction of environmental, economic and health risks. Fig 1: Landfill site selection process The other important process during landfill site selection is the weighting of residual areas. Residual areas in this context refers to the remaining areas after the elimination of unsuitable sites. Central to this step is the recognition that not all the remaining areas are suitable for the construction of landfills. This is because other areas may be deemed better than the others. Consequently, the residual areas undergo thorough assessment based on several criteria such as the geological characteristics of the land, the availability of buildings and reserved areas. Based on these factors and many more, the appropriate site for landfill construction is chosen. The other important step in the selection of landfills is the geotechnical assessment. After the initial stages of landfill site selection, it is important to carry out an evaluation of the geological and hydrological characteristics of the identified sites for landfill construction. Additionally, the area must be subjected to environmental impact assessment. Among the geotechnical factors used to determine the suitability of landfill sites are; surface runoff patterns, hydrogeology, bedrock lithology and hydrogeological factors. Environmental impact assessment is important in ensuring that the construction of a landfill in a given area does not have adverse effects on the environment and health of the surrounding population. 3. Landfill Design The designing of a landfill takes place immediately after the site selection process has been accomplished. However, it is important for best practices to be considered in designing landfills to ensure that the landfilling process is environmentally sound. The best landfill designs commonly incorporate a proper understanding of the surrounding environment such that it has minimal environmental impacts. Additionally, the design of a landfill also determines its costs of operation (Townsend et al., 2015, p. 22-35). One of the factors that influence the design of a landfill is the surrounding environment. A good landfill design requires a deep understanding of the surrounding environment. Moreover, environmental assessment should be performed to ensure the development of a sound landfill design. Among the considerations that should be made when designing environmentally sound landfills are the impacts of the landfill on both the surface and ground water, the ambient air quality as well as the noise levels. If an area is considered unsuitable for the construction of landfill owing to reports from environmental assessment, the designing of the landfill should not proceed (Koerner, 2012, p. 512-715). Another important factor that should be considered in designing landfills is the site-layout. The proposed design of the landfills should be developed in such a way that encourage the recycling and reuse of materials, reduce the adverse impacts on the environment, reduce the health and safety risks both to the landfill operators and the public as well as making maximum use of resources within the landfill site. The commonly used design involves the filling of the landfill s independent sites after which immediate rehabilitation is done. Other factors that are considered within the site layout are the accessibility of the landfill as well as the existence of infrastructure for the operation of the landfill. Furthermore, the surface hydrology and drainage are important considerations in the development of efficient landfill designs (Chakrabarti, 2013, p. 404). Surface hydrology helps in determining the ways of controlling the run-off to minimize the chances of pollution. In places that are prone to high rainfall for instance, the control of run-off is important. This is because of the need to minimize water pollution from the production of leachates. The surface hydrology landfill designs encompasses the diversion of surface drainages and storm water so that the flow of water is far from the landfill. In addition, the design should include downslope drainage that involves the separation of polluted water from unpolluted surface water and the final control of polluted water within the landfill site. The other consideration that should be made in designing a landfill is leachate management. Landfills are subject to the production of leachates and efficient ways should be devised of managing the leachates (Aziz, 2016, p. 49). The production of leachate in the landfills is as a result of precipitation, infiltration surface runoff and landfill storage capacity. This means that the design of the landfill must incorporate leachate management systems to function effectively. The landfill design must provide for the containment of the hazardous wastes as well as other types of wastes. This involves the use of leachate collection is used in the complete separation of wastes and the leachates from the underlying rock masses. Fig 2; Landfill design. The landfill design should take into consideration the landfill cover systems. The landfill cover systems are used in the promotion of surface water runoff and minimize erosion, preventing the exposure of the surrounding population from direct exposure to the wastes, controlling gas emissions and occurrence of disease causing vectors. Furthermore, the landfill cover systems are used in the landfill remediation processes. An example is the use of the landfill cover systems in the remediation of abandoned sites and near-surface contaminated areas (Nordisk, 2014, p. 57). The design of a landfill should ensure efficient landfill gas management. Landfill gas refers to the different types of gases that are released in landfill sites due to the action of microorganisms. The landfill gas comprises mainly methane and carbon dioxide. The production of landfill gas is due to chemical reactions taking place between the waste materials in the landfill, biological actions on the waste materials by the microorganisms and the evaporation of unstable compounds. The design of a landfill should be in such a way that it can utilize the landfill gas produced (Pariatamby &Tanaka, 2013, p. 51). The efficient design of the landfills should ensure that infrastructure is installed to recover the landfill gas for treatment to minimize its impacts on the environment. 4. Landfill Operations The operation of landfills is a controversial topic in the management of the environment today. This is mainly because poor landfill operation results in both long-term and short-term adverse consequences on the environment (ICWM et al., 2012, p. 61). One of the components of the operations of the landfill is waste checking and acceptance. This is important in the management of wastes since it determines where the different types of wastes are deposited. Additionally, the checking of wastes involves the separation of the different types of wastes before disposal. This involves the removal of wastes that can be recycled or reused before the final disposal of the other wastes. The engineered landfill contain facilities such as the elevators and viewing platforms to help in the assessment of the waste loads before disposal. Another important process in the operation of landfills is the placement and compaction of wastes. Landfill operation involves the putting tight controls on the placement of litter to reduce the chances of existence of pests and vectors that can cause health risks to the surrounding population (Schmoll, 2006, p. 645). The efficient operation of the landfill requires that the waste materials be placed and compressed into thin layers using the compactors. The desired thickness for the landfill wastes after compaction should be 0.5 meters with the compactor making three to five passes over the wastes to ensure that maximum compaction is achieved. In cases where the quarantine wastes are deposited, they should be buried immediately to avoid environmental contamination. The other important process in the operation of the landfills is the covering of the wastes. Although depositing the wastes in the landfill is essential, the process is incomplete without the covering of the wastes to reduce their negative impacts on the environment. Landfill waste cover is important because of several reasons such as maintaining the aesthetic beauty of the land, maintaining the quality of ambient air by reducing odors, controlling litter and disease vectors. Although most landfills employ the use of soil as the cover material, the choice of cover materials for the landfills depends on factors such as the types of wastes to be disposed, the location of the landfill as well as the past performance of the site. In the cases where the cover material used in a landfill is soil, it should contain a certain degree of organic matter to help reduce the landfill odors. Other materials that can be used in covering the landfills include; mulches, foams, ravel and cover mats. Environmental monitoring and reporting is another important process in the operation of landfills. Environmental monitoring and reporting involves the measures taken to protect the environment from the negative environmental consequences that may occur. Additionally, it encompasses the early detection of the potential environmental issues and devising methods minimize their impacts. The process of environmental monitoring and reporting entails the preparation of the environmental monitoring plan for the landfills, engaging the landfill staff in ensuring adherence to the set guidelines on waste disposal, submission of the annual environmental reports of the site and the introduction of a culture in which the landfill workers are able to identify the potential environmental problems posed by the landfills and taking the necessary corrective actions before the occurrence of such impacts. 5. Landfill Monitoring Compliance with the set environmental and other regulatory standards is important in the operation of the landfills (Williams, 2013, p. 83). However, not all landfills comply with environmental regulations, hence, the need for landfill monitoring. Landfill monitoring takes into account different aspects such as the leachate management, landfill gas monitoring and surface water monitoring. Surface water monitoring in landfills is important since it prevents the contamination of the surface waters by the chemical materials from the wastes thus ensuring a secure environment. Leachate management ensures that the infiltration of leachates into the ground water is minimized thus reducing ground water pollution effects while landfill gas management improves the quality of air in the surrounding areas. References Aziz, H. A. (2016). Control and treatment of landfill leachate for sanitary waste disposal. Hershey: Information Science Reference, p. 49. Chakrabarti, A. (2013). CIRP design 2012: sustainable product development. London, Springer, p. 404. Chang, N.-B., & Pires, A. (2015). Sustainable solid waste management: a systems engineering approach. Chichester: Wiley and Sons. p. 714. Das, B. M. (2011). Principles of foundation engineering. Stamford, CT, Cengage Learning, p. 23. International Conference on Waste Management and the Environment, Popov, V., Itoh, H., & Brebbia, C. A. (2012). Waste management and the environment VI. Southampton, WIT, p. 61. Koerner, R. M. (2012). Designing with Geosynthetics. [Upper Saddle River, N.J.], Xlibris, p. 512-715. Nemerow, N. L. (2009). Environmental engineering. Hoboken, N.J., Wiley, p. 246. Nordisk Ministerråd. (2014). Nordic initiatives to abate methane emissions: a catalogue of best practices. Nordic Council of Ministers, p. 57. Pariatamby, A., & Tanaka, M. (2013). Municipal solid waste management in Asia and the Pacific Islands: challenges and strategic solutions. Singapore: Springer, p. 51. Schmoll, O. (2006). Protecting groundwater for health: managing the quality of drinking-water sources. Cornwall, U.K., World Health Organization, p. 645. Steiner, F. R., & Butler, K. S. (2007). Planning and urban design standards. Hoboken, NJ, John Wiley, p. 306. Townsend, T. G., Powell, J., Jain, P., Xu, Q, Tolaymat, T., & Reinhart, D. R. (2015). Sustainable practices for landfill design and operation. New York, Springer, p. 22-35. Vaughn, J. (2009). Waste management: a reference handbook. Santa Barbara, Calif, ABC-CLIO, p. 54. Velinni, A. A. (2007). Landfill research trends. New York, Nova Science Publishers, p. 39. Williams, P. T. (2013). Waste treatment and disposal. Hoboken, N.J., Wiley, p. 83. Read More