INVESTIGATION OF OPTIMUM LANDFILL SITE IN OSOGBO (STATE OF OSUN)

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INVESTIGATION OF OPTIMUM LANDFILL SITE IN OSOGBO (STATE OF OSUN)

 

 

BY

ALABI IBRAHIM AKINTAYO

(SVG/12/0335)

 

A PROJECT REPORT SUBMITTED TO THE DEPARTMENT OF

SURVEYING AND GEOINFORMATICS, SCHOOL OF

 

ENVIRONMENTAL TECHNOLOGY, FEDERAL UNIVERSITY OF TECHNOLGY, AKURE, ONDO STATE, NIGERIA.

 

IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF BACHELOR OF TECHNOLOGY (B. TECH) DEGREE IN SURVEYING

 

AND GEOINFORMATICS.

 

 

 

 

                                                                                                                                                                                                                              OCTOBER, 2017.


 



PROJECT TOPICS

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CERTIFICATION

 

This is to certify that this report is a detailed account of the final-year project undertaken by ALABI IBRAHIM AKINTAYO at Federal University of Technology, Akure, and has been prepared in accordance with regulations guiding the preparation of reports in the Department of Surveying and Geo-informatics, Federal University of Technology, Akure

 

……………………………….. ………..…………………….

 

ALABI I.A. (Student)    DATE

 

……………………………….. ………..…………………….

 

DR. AJAYI G. E. (Supervisor)         DATE

 

 

……………………………….. ………..…………………….

 

PROF. IDOWU T. O. (H.O.D)          DATE



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DEDICATION

 

I dedicate this project report to my parents, Alh. Chief and Late Mrs. Alabi.



PROJECT TOPICS

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ACKNOWLEDGEMENT

 

My sincere appreciation goes to God Almighty for sparing my life throughout my five-year educational program at Federal University of Technology, Akure.

I would also like to express my sincere gratitude to my supervisor, Dr. G.E. AJAYI for his continuous support and guidance. I learnt a lot from him. He has always been a source of inspiration for tackling various problems from different perspective. The experience I had with him is priceless.

I am also indebted to my beloved parents, Alh. Chief and Late Mrs. Alabi who are standing like rock by me through thick and thin, may Almighty God in his infinite mercy grant them the best of this life and the life after death.

Also, I appreciate the immense support and encouragement received from Alh. And Alhaja Nurain Fajinmolu, Surv. Amoo N.B., and my colleagues whom I am fortunate and proud of having such as Busari Toheeb, Akinade Basith, Olusesi Sheriffdeen, Alamu Yusuff, Oloko Bilqees and the likes.

My appreciation also goes to the head of the department in person of PROF. T.O. Idowu, and all the lecturers in the department for their valuable counsel guidance.



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ABSTRACT

 

The amount of waste disposed of worldwide has increased substantially reflecting changes in consumption patterns. Consequently, worldwide commercial, industrial and household waste is now a bigger problem than ever. Despite an increase in alternative techniques for disposing of waste, landfilling remains the primary means of waste disposal.

Increased environmental awareness and deepening environmental concerns in recent years have forced attention on the need to move towards a more sustainable society. These changes in attitudes in many parts of the world have been supported by changes in laws and policies regarding the environment and waste disposal. In this context, the pressures and requirements placed on decision makers dealing with landfilling by government and society have increased, as they now have to make decisions taking into considerations public satisfaction, environmental safety and economic practicality. This situation has created a need for more consistent and objective methods for making decisions; improved access to, and better management of environmental information. At the international level, criteria of differing degrees of detail exist as guidelines for the optimum siting of landfills.

Selecting the most suitable site for landfill can avoid any ecological and socio-economic effects. The increase in industrial and economic development, along with the increase of population growth in Osogbo town generates tremendous amount of solid waste within the region. Factors such as the scarcity of land, life span of landfill, and environmental considerations warrant that the scientific and fundamental studies are carried out in determining the suitability of a landfill site. The analysis of spatial data and consideration of regulations, and accepted criteria are part of the important elements in the site selection. The project presents a multi criteria decision making method using Geographic Information System (GIS) with the integration of Fuzzy Logic Multi-

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Criteria Decision Making (FMCDM) technique for landfill suitability site evaluation. By using the fuzzy logic method (classification of suitable areas in the range of 0 to 1 scale), the superposing of the information layers related to drainage, soil, land use/land cover, slope, land use and geology maps was performed in the study. Only after omission of inappropriate areas was the suitability examination of the residue areas accomplished. Based on the analysis, five (5) potential sites are suitable for the construction of a landfill are proposed, two of which belong to the most suitable zone, and the existing waste disposal site was belonged to the unsuitable zone.



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                                             CHAPTER ONE 

                                             INTRODUCTION

 BACKGROUND TO THE STUDY

 

Waste is a material discharged and discarded from each stage of daily human life activities, which leads to adverse impacts on human health and the environment (Bringi, 2007). Solid waste refers to the leaves/ twinges, food remnants, paper/cartons, textile materials, bones, ash/dust/stones, dead animals, human and animal excreta, construction and demolishing debris, biomedical debris, household hardware (electrical appliances, furniture, etc) (Sha’Ato et al., 2007; Babatunde et al., 2013). Solid waste is a global environmental problem in today’s world both in less developing and developed countries. Increasing population, rapid economic growth and the rise in community living standards accelerate solid waste generation in the world (Elmira et al., 2010). Solid waste can be classified into different types, depending on their source; household waste is generally classified as municipal waste; industrial waste as hazardous waste, and biomedical waste or hospital waste as infectious waste (US Law-Solid Waste Act 2, 1999). Integrated solid waste management includes the selection and application of suitable techniques, technologies and management programs to achieve specific waste management objectives and goals (Tchobanoglous and Kreith, 2002). The current waste management techniques include:

  • Source reduction

 

  • Recycling

 

  • Waste transformation

 

  • Landfilling

 

Landfill is currently the most widely used method of waste disposal in Nigeria especially in the state of Osun and is likely to continue to be the main disposal option for the short to medium



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term despite considerable efforts in recycling and waste minimization. Although there is a public opposition to landfills, it is necessary and there is no combination of waste management technique that does not require landfilling to make them work because of the residual problem associated with other waste management scheme. Landfill siting is an extremely difficult task to accomplish because the site selection process depends on different factors and regulations. Environmental factors are very important because the landfill may affect the surrounding biophysical environment and the ecology of the area (Dikshit et al., 2000; Mummolo, 1996; Siddiqui et al., 1996; Erkut and Moran, 1991; Lober, 995). Landfilling, because of its cost effectiveness, has become the most favoured management in Osun state, after previous attempt at incineration had failed. The untreated rubbish being placed in the landfill voids comprises of biodegradable solids such as vegetable, paper and metal, inert solids such as glass and plastics and other unclassified materials. These constitute a great threat to underground water quality and hence pose danger to the health of the populace. Solid waste; when left unattended to for a long time, constitutes health hazards, causes offensive odour, and pollutes the underground water sources and decreases aesthetics and quality (Federal Ministry of Environment). The inability to manage these wastes effectively in Nigeria becomes an issue of great concern. This is because apart from the destruction of aesthetics of landscape by the waste dumpsites, some of the municipal solid wastes contain both organic and inorganic toxic pollutants (such as heavy metals) that threaten the health of humans and the entire ecosystem. Proper management of solid waste is critical to the health and well-being of urban residents (World Bank, 2003). Nigerians had been concerned with solid waste disposal; but their concern had not gone beyond physical removal of waste from the streets. It has been a common practice to dispose solid wastes using open dump or the use of an open burning. It is evident that, many factors must be incorporated into landfill




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siting decisions and GIS is ideal for this kind of preliminary studies due to its ability to manage large volumes of spatial data from a variety of sources. It efficiently stores, retrieves, analyzes and displays information according to user defined specifications (Siddiqui, 1996). The integration of Geographical information system(GIS) and Multi-criteria decision analysis (MCDA) is a powerful tool to solve the landfill site selection problem, because GIS provides efficient manipulation and presentation of the data and MCDA supplies consistent ranking of the potential landfill areas based on a variety of criteria. In this project, six (6) criteria; distance to drainage, soil, road network, geological features, distance to residential area and land use land cover will be analyses using geographical information system and multi-criteria decision making approach with “fuzzy logic” set theory to produced suitable landfill sites and access if the existing landfill site meet the stipulated standard.

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STATEMENT OF PROBLEM

 

State of Osun is known to be one of the rapid developing states in Nigeria because of the high level of security and peace in the state. Osogbo, which is the state capital, is the fastest developing


 




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town in the state both residentially and industrially. These rapid developments in industries was influenced by the micro-credit scheme made available by the state government to intending entrepreneurs. This rapid urbanization of the Osun state capital, has led to a serious need for a defined and coordinated means of waste disposal and management. While most of the liquid waste are channeled through gutters and drainages down to rivers and other water bodies, there are no generally known means of managing either the proper disposal or recycling of solid waste. The solid waste, as it was known, cannot merge into the water bodies without polluting or even blocking the flow of water. This leaves land as the only avenue for disposal of solid waste. The method of waste disposal which most people have now resorted to in Osogbo, the Osun State capital, is the use of dump sites. The dump sites, more often than not, happen to be a little piece of land which has been left fallow. Some of them are beside uncompleted buildings, and some on an unused or virgin piece of land. Some are even brazen enough to create such dump sites in front of buildings inhabited by people. Poor waste disposal and management poses public health and safety threats to development occurring on or around the disposing sites. Some of these threats include explosive or oxygen-deficient conditions caused by landfill gas migrating through soils into building structures and utilities; differential settlement of the disposal area causing instability in foundations and structures built over the fill; and human or wildlife exposure to potential chemical, biological, radiological and physical hazards of uncovered waste at the site. As a result of health, economic and social issues consequent on the indiscriminate dumping and inadequate management of municipal solid waste (MSW), the state government of Osun established Osun State Environmental Sanitation Authority(O-ESA) to monitor the environmental quality and to ensure a refuse free environment. However, despite the government efforts on making the




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environment clean in Osogbo metropolis, people seem to be careless about their environment, many people prefer dumping refuse at places they considered convenient to them.

 PROJECT AIM AND OBJECTIVES

 AIM

The aim of the study is to identify suitable solid waste dumpsites for proper waste management in Osogbo, the State of Osun Capital.

OBJECTIVES

The objectives of the study are to:

 

  1. Determine the convenient landfill disposal site by using multi-criteria decision making process based on fuzzy logics to overcome the problems arising from improper land filling for the study area.
  2. Generate solid waste suitability and constraint maps for the study area.

 

  1. Assess the compliance of the existing dump site with the suitability zone map.

 JUSTIFICATION FOR THE PROJECT

One of the major environmental problems in urban areas is the shortage of land for waste disposal. In as much as it is desirable to establish waste disposal (landfill) sites, it is essential that the site selection should be based on sound geological, geophysical, hydro geological, hydrological and ecological considerations. The growing issues of environmental pollutions associated with improper management of municipal solid waste in Osun state, especially the state capital, and its consequence on the health of the populace call for adoption and management of proper waste management schemes. In September 2015, several hundreds of people of Ido-Osun, Offatedo, Aduramigba, Egbedi, Onibueja and some other villages around Ido-Osun protested against the operation of landfill site located around trade fair Ido-osun due to perpetual release




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of fume from the site during the summer (Osun defender). It is a matter of common knowledge that these strong, unpleasant and dangerous gases or smoke have adverse effect on human heath, as a matter of fact this was what bred protest. Due to rapid increase in the production and consumption processes, societies generate as well as reject solid materials regularly from various sectors; agricultural, commercial, domestic, industrial and educational sectors. The integration of GIS and MCDA is a powerful tool to solve the landfill site selection problem, because GIS provides efficient manipulation and presentation of the data and MCDA supplies consistent ranking of the potential landfill areas based on a variety of criteria. Hence, this project work undertaken a detailed study involving geophysical, and hydrological investigation aimed at delineating suitable sites for solid waste dumpsite in aid of proper waste management scheme and determine if the existing dumpsites meet stipulated criteria using multi-criteria decision analysis; fuzzy logic and GIS.

 STUDY AREA

 

The study area is located in Osun state and covers two local government areas, which are Olorunda, and Oshogbo local Government area. It can be closely mapped between latitudes7°45’02.59’’N, and 7°59’02.59’’N and between longitudes 4°31’ 16.13’’E and 4°42’15.49’’E with an average elevation of about 320m above mean sea level, covering an area of 148km².


 



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Figure 1.2: Study Area Map

SCOPE OF THE PROJECT

 The scope of this project covers the following exercises;

 

  • Data acquisition

 

  • Data preprocessing and processing

 

  • Determination of membership function

 

  • Combination of fuzzy membership value for selection of suitable landfill site



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CHAPTER TWO

 

  • LITERATURE REVIEW

 

This chapter reviews some of the existing literatures on selection of optimum landfill site, the Concept of solid waste and solid waste management, the criteria that have been used, the integration of GIS and the applicability of Fuzzy Logic method for the site selection in the present study area are critically examined.

  • CONCEPT OF SOLID WASTE AND SOLID WASTE MANAGEMENT

 

Solid waste is the term used to describe non-liquid waste materials arising from domestic, trade, commercial, agricultural, industrial activities and from public services. Once waste generation is an inevitable aspect of life, it becomes a matter of urgent need to observe the process from generation to disposal in order to determine the areas of critical concern and tackle them in order to avoid pollution and to preserve good health. Solid Waste Management (SWM) is defined as the control, generation, storage, collection, transfer and transport, processing and disposal of solid waste consistent with best practices of public health, economic and financial, administrative, legal and environmental considerations (Othman, 2002). Waste management is a global environmental issue which constitutes a very significant problem in today’s world (ESRI, 2001). The disposal of municipal solid waste has been a great problem faced by all nations over the world. As population grows and prospers, the amount of waste generated also increases. Initially waste generated was dumped above or below ground in rural areas, which was the most economical method of waste disposal. However, due to the growing concern for ground water resources contamination, public health and safety and scarcity of suitable land, land filling has become expensive now-a-day. Also, due to the increased public awareness of the health and safety problems associated with landfills, finding appropriate land has been a challenge for the government and the other bodies involved in




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waste management. Thus, the problem of waste disposal is persistent and demands careful attention all over the globe. According to UNEP (2004), solid waste generation has become an increasing environmental and public health problem everywhere in the world, particularly in developing countries; Nigeria is no exception.

  • TYPE OF SOLID WASTE

Solid waste can be classified into different types depending on their source. Household waste is generally classified as municipal waste, industrial waste as hazardous and biological waste or hospital waste as infectious waste.

  • MUNICIPAL SOLID WASTE

 

Municipal solid waste consists of household waste, construction and demolition debris, sanitation residue, and waste from streets. This garbage is generated mainly from residential and commercial complexes. With rising urbanization and change in lifestyle and food habits, the amount of municipal solid waste has been increasing rapidly and its composition changing. (Wikipedia, 2017)

 

  • INDUSTRIAL WASTE

 

Industrial wastes are considered hazardous as they may contain toxic substances. Certain types of household waste are also hazardous. Industrial wastes could be highly toxic to humans, animals, and plants; are corrosive, highly inflammable, or explosive; and react when exposed to certain things e.g. gases. Household waste that can be categorized as hazardous waste include old batteries, shoe polish, paint tins, old medicines, and medicine bottles. (Wikipedia, 2017)


 




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image

 

Figure 2.1: Incineration method of waste disposal

 

 RECYCLING

 

It involves: (1) the collection and seperation of waste materials; (2) the preparation of these materials for reuse, reprocessing, and remanufacture; and (3) the reuse, reprocessing, and remanufacture of these materials. Recycling is an important factor in helping to reduce the demand on resources and the amount of waste require disposal by landfilling (Tchobanoglous, 1993). Reusing waste products can be simply made by the public by returning drink containers to bottling manufacturers and the donation of used clothes, shoes, furniture, and electrical products to charities and retailers. Product recycling primarily involves melting glass and metals, pulping of


 



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paper waste so that the end product is useful as a raw material to manufacturers. Benefits of waste recovery include conserving finite resources, lowering the need for mining or harvesting virgin material, reducing inert residues from incinerators, and fewer demands on landfills (Kreith, 1994).

LANDFILLING

 

Landfills are often the most cost-efficient way to dispose waste, especially in countries like Nigeria with large open spaces. While resource recovery and incineration both require extensive investments in infrastructure, and material recovery also requires extensive manpower. A landfill site (also known as a tip, dump, rubbish dump, garbage dump or dumping ground) is a site for the disposal of waste materials by burial and the oldest form of waste treatment (although the burial part is modern; historically, refuse was just left in piles or thrown into pits). Historically, landfills have been the most common method of organized waste disposal and remain so in many places around the world. Landfills can be regarded as a viable and abundant source of materials and energy. In the developing world, waste pickers often scavenge for still-usable materials.



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  • LANDFILL SITE SELECTION CRITERIA

 

The major goal of the landfill site selection process is to ensure that the disposal facility is located at the best location possible with little negative impact to the environment or to the population. For landfill siting, a substantial evaluation process is needed to identify the best available disposal location which meets the requirements of government regulations and best minimizes economic, environmental, health, and social costs. In selecting a new landfill site, there are many criteria which need to be considered before the selection process will be conducted, such as distance to road or access, distance to residential areas, distance to airport, the slope, aspect, geology, soil type etc. In fact, different researchers have used varying criteria for site selection purposes due mainly to the fact that different criteria apply to different region and all facilities.

Sumathi et al., (2007) carried out a study on the siting of a new landfill in the Pondichery region using a Multi-Criteria Decision Analysis (MCDA) and overlay analysis using Weighted Linear Combination (WLC) method and Geographic Information System (GIS). Water supply resources, sensitive sites, land use, air quality, groundwater quality and geology are the several factors considered in the siting process.

Dragoljub et al., (2001) evaluated and standardized eight (criteria) in the mountainous region of High-Herzegovina in the republic of Ireland, the criteria include; vegetation, slope, elevation, aspect, geology distance to road, settlement and river body to established suitable areas for landfill site selection based by incorporating Analytical Hierarchy Process (AHP). In their study, they identified five suitable zones out of which 67.0% of the territory belongs to the restricted areas, 11.0% has low suitability, 6.1% has moderate suitability, 5.9% has high suitability and 10.0% has very high suitability.



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  • Akbari, et al., (2008) combined GIS fuzzy multi criteria decision analysis to locate a proper waste disposal area in Bandar Abbas, Iran. The criteria considered are those of Coastline zone, Transportation Network, Surface Water Sources, Faults, Urban and Rural Areas, Industrial Centers, Agricultural Centers, Geology and Slope. The criteria selected were based on the quest to protect the area from strong wind, persevered the aesthetics value of the environment, ensure public health and nuisance safety among others.

    Ojo et al., (2014) used six criteria of soil, geology, lineament density, geomorphology, distance from drainage and road to produce a constraint map for landfill site selection in Akure Metropolis, southwestern Nigeria. The criteria selected were based on some stipulated standard of environmental protection Agency(EPA) landfill manual 2001 and previous research works of Olorunfemi and Ojo (2001); Robalo and Vendes, (2003) and Choududhury and Das, (2012). In this, it was clearly stated that landfill site must be located away from any residential area, it must be located outside protective water supply reservoir or area prone to flooding, must not be tectonically active (i.e. must be located outside area of known seismicity), drainage system in the area must be such that minimizes seepage water entering the landfill site.

    Er. Subhrajyoti Choudhury and Er.Sujit Das (2012) have used the principal sub criteria of Lithology, Geomorphology, Slope, Drainage, Population, Distance from major Roads, Distance from major Streams and Distance from Drainage for landfill site selection for Dharmanagar Nagar Panchayet, those criteria were selected according to study areas local characteristics.

    The morphometric parameters of slope, aspect and contour were overlaid alongside with the buffer analysis of drainage, river, settlement, and land use land cover by Shweta Karsauliya (2013), to get seventeen suitable sites for solid waste using the surroundings of River Yamuna,


     



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  • India as a case study. In his work, one of the sites was found 13.5km away from Taj Mahal in east direction.

    The most commonly used selection criteria in most of the countries is the road access which is either from the main road as well as rural road to the location of the landfill site. The second commonly used selection criteria is the residential areas. These criteria are important to prevent the occurrence of health problems to the residents around the landfill site.

     

    • SPATIAL MULTI-CRITERIA DECISION ANALYSIS (MCDA)

    Decision analysis is a set of systematic procedures for analyzing complex decision problems. These procedures include dividing the decision problems into smaller more understandable parts, analyzing each part, and integrating the parts in a logical manner to produce a meaningful solution (Malczewski, 1997). In general, MCDA problems involve six components (Keeney and Raiffa, 1976; Pitz and McKillip, 1984), these are highlighted below;

    1. A goal or a set of goals the decision maker wants to achieve,

     

    1. The decision maker or a group of decision makers involved in the decision making process with their preferences with respect to the evaluation criteria,
    2. A set of evaluation criteria (objectives and/or physical attributes)
  •  

    1. The set of decision alternatives,

     

    1. The set of uncontrollable (independent) variables or states of nature (decision environment
    2. The set of outcomes or consequences associated with each alternative attribute pair.
  • MCDA techniques can be used to identify a single most preferred option, to rank options, to list a limited number of options for subsequent detailed evaluation, or to distinguish acceptable from


     



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  • unacceptable possibilities (Dodgson, 2000). There are many MCDA approaches which differ in how they combine and utilize the data. MCDA approaches can be classified on the basis of the major components of multi-criteria decision analysis. Any spatial decision problem can be structured into three major phases: intelligence which examines the existence of a problem or the opportunity for change, design which determines the alternatives and choice which decides the best alternative (Simon, 1960).

     

    • GENERAL CONTROLS ON WASTE DISPOSAL SITE SELECTION

    In Ireland, previous uncontrolled waste disposal site selection has resulted in localized groundwater pollution, although in most cases the small quantities of waste involved have limited the extent and impact of the problem (Daly,1983,1987). However, as the character of the waste changes and the quantity multiplies, groundwater pollution effects will proliferate if tip site selection practices do not also change. It is clear that a more rigorous scientific approach to waste disposal site selection must be adopted, rather than an approach dominated exclusively by economic criteria, as has tended to be the case in the past. We believe that there is an urgent need to begin immediately a nationwide geological survey to locate suitable tip sites for both domestic and industrial waste, in order to produce directories of such sites for future consideration. Although we stress the importance of geological controls, there are clearly many others considerations which must be met when choosing a tip site. The main factors which control the suitability of waste disposal sites (Daly & Wright 1982), are: –

    1. Geological – both bedrock and drift lithology, and geological structure.

     

    1. Hydrological/Hydrogeological – pathways and rate of flow of rainwater passing into and through the subsurface, subsurface hydrogeological features, i.e. aquifers, surface runoff characteristics.



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unacceptable possibilities (Dodgson, 2000). There are many MCDA approaches which differ in how they combine and utilize the data. MCDA approaches can be classified on the basis of the major components of multi-criteria decision analysis. Any spatial decision problem can be structured into three major phases: intelligence which examines the existence of a problem or the opportunity for change, design which determines the alternatives and choice which decides the best alternative (Simon, 1960).

 

  • GENERAL CONTROLS ON WASTE DISPOSAL SITE SELECTION

In Ireland, previous uncontrolled waste disposal site selection has resulted in localized groundwater pollution, although in most cases the small quantities of waste involved have limited the extent and impact of the problem (Daly,1983,1987). However, as the character of the waste changes and the quantity multiplies, groundwater pollution effects will proliferate if tip site selection practices do not also change. It is clear that a more rigorous scientific approach to waste disposal site selection must be adopted, rather than an approach dominated exclusively by economic criteria, as has tended to be the case in the past. We believe that there is an urgent need to begin immediately a nationwide geological survey to locate suitable tip sites for both domestic and industrial waste, in order to produce directories of such sites for future consideration. Although we stress the importance of geological controls, there are clearly many others considerations which must be met when choosing a tip site. The main factors which control the suitability of waste disposal sites (Daly & Wright 1982), are: –

  1. Geological – both bedrock and drift lithology, and geological structure.

 

  1. Hydrological/Hydrogeological – pathways and rate of flow of rainwater passing into and through the subsurface, subsurface hydrogeological features, i.e. aquifers, surface runoff characteristics.



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  1. Topographical – slope of ground, and exposure to the elements, especially wind.

 

  1. Ecological – effect on plant and animal habitats.

 

  1. Climate – local microclimate, rainfall, wind velocity etc.

 

  1. Engineering – physical management.

 

  1. Social Environment – noise, smell, litter, visual impact, proximity to housing, domestic water wells, etc.
  2. Economic – distance from source of waste, roads, access to the site, management costs arising from the physical characteristics of the site, etc.

The first three groups of factors primarily control the suitability of tip sites, although other factors may override these in certain circumstances. Thus a multidisciplinary approach to waste disposal site selection is desirable, to ensure that all factors affecting the suitability of sites for waste disposal are taken into consideration (Daly,1983,1987).

  • GEOLOGICAL CONTROLS ON WASTE DISPOSAL SITES

 

From a geological standpoint, sites suitable for landfill projects are subject to stringent criteria in order to ensure that pollution effects, particularly groundwater contamination, are minimized. Factors which determine suitability of tip sites from a geological/hydrogeological standpoint are:

  1. Bedrock Lithology – rock type, grainsize characteristics, texture, homogeneity bedding characteristics, etc.
  2. Quaternary Geology – character, thickness and homogeneity of unconsolidated drift.

 

  1. Hydrological Properties – of both bedrock and drift, i.e. porosity, permeability, hydraulic conductivity, attenuation potential etc.
  2. Geological Structure – attitude of bedding, folding, faulting, jointing, including discontinuities on all scales.



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    1. Hydrogeology – groundwater levels, distribution of aquifers and aquicludes, groundwater flow patterns etc.
    2. Surface Runoff Patterns  –  size  and  discharge of streams running   through the                                         site – controlled by the topography of the site.
    3. Topography – inclination of sloping sites, shelter from wind, visual impact.
  1.  

    Optimal natural waste disposal sites should have a thick cover of low permeability drift such as boulder clay overlying low permeability bedrock, and a thick unsaturated zone (Daly,1983,1987). Secondary permeability in the bedrock should be low, i.e. the bedrock should be relatively free of discontinuities, particularly fractures and cleavage. In addition, the attenuating potential of the drift, and to a lesser extent the bedrock must be high. Sites with such optimal characteristics are probably fairly common, but their ability to protect groundwater will be diminished in areas of high rainfall, where leachate may be washed more rapidly down through the overburden. Nevertheless, such sites should be sought as they offer the best natural protection to groundwater, and together with appropriate waste management techniques, they can considerably curtail the pollution potential of leachate infiltrating the ground. Furthermore, in the long term, identification of such sites may be extremely cost effective (Daly,1987), as they can substantially reduce the waste management overheads compared to sites which offer no natural groundwater protection. In short, it is argued, that a combination of careful selection of a hydrogeologically suitable site and prudent site management practices can offer the best protection to groundwater from contamination by tip sites.

    • FUZZY LOGIC THEORY

    The basis of this theory was formed by Lofti Zadeh (1965). He is considered the founder of fuzzy logic. According to Zadeh, fuzzy logic has two different meanings. In the narrow sense, fuzzy logic is a logic system that is an extension of classical logic. In a broader sense, fuzzy logic is




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    1. mostly a synonym with the fuzzy set theory: the theory that refers to the class of objects with unclear borders, whose membership is measured in specific degrees. It is of great importance to recognize that fuzzy logic is different from traditional logic systems. Fuzzy logic is very close to human perception. In its essence, fuzzy logic has many-valued logic that admits some medium values between traditional statements: yes/no, true/false, white/black. Fuzzy logic draws on the experience of experts in the form of linguistic if-then rules. In the last decade, fuzzy set theory has been success-fully applied in many different areas of engineering including automatic control, system identification, pattern recognition, design of structures, structural modeling and many more (Adam E. Gaweda, 2003). The property that makes fuzzy set theory particularly interesting is its ability to handle the imprecision inherently present in a system. Fuzzy reasoning becomes a powerful tool for solving problems when human expert knowledge is available. Even more attractive is the idea of utilizing fuzzy set theory in data driven extraction of easy to understand rule-based models (Adam E. Gaweda, 2003). In a more general context, this concept is based on the fact that certain fuzzy systems possess the universal approximation property (Wang, 1992). For the most complex systems where a few numerical data exist and where only ambiguous and imprecise information may be available, fuzzy reasoning provides a way to understand system behavior by allowing us to interpolate approximately between observed input and output situations.

      Fuzzy logic is an alternative logical foundation coming from artificial intelligence (AI) technology with several useful implications for spatial data handling. Contrary to traditional logic, fuzzy logic accommodates the imprecision in information, human cognition, perception and thought. This is more suitable for dealing with real world problems, because most human reasoning is imprecise. Major advantage of this fuzzy logic theory is that it allows the natural description, in linguistic




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