This chapter describes research that had been undertaken on selecting sanitary landfill site location and its factors that are suitable for the place. This literatures also included the models that can be used to predict the best location and also about the relation between and models and the GIS application.
2.2 Solid waste
Solid wastes are all the wastes arising from human and animal activities that are normally solid and are discarded as useless or unwanted (Tchobanoglous et al., 1993). Solid waste also is the term to describe non-liquid waste materials from the public (Nair et al., 2007). Solid waste is one of the three major environmental problems in Malaysia and it plays a significant role in the ability of Nature to sustain life within its capacity (http://www.gecnet.info, 2002). Currently, over 23,000 tonnes of waste is produced each day in Malaysia. However, this amount is expected to rise to 30,000 tonnes by the year 2020 (Manaf et al., 2009). From that amount, only less than 5% of the waste is being recycled (http://www.gecnet.info, 2002).
Based on study from Manaf et al., (2009) in Malaysia, there were three major categories of solid waste and each category is under the responsibility of a different government department. For municipal solid waste, it is the responsibility under Ministry of Housing and Local Government (MHLG). Department of Environmennt (DOE) will arranged the schedule or hazardous waste and the clinical waste is under the Ministry of Health (MOH).
2.3 Sanitary Landfill
Landfill selection in an urban area is a critical issue in the urban planning process because of its enormous impact on the economy, ecology and the environmental health of the region (Akbari et al., 2008). As day from day, the growths of urbanization as well as the desire to live in cities, larger amount of wastes are produced and unfortunately the solid waste management problem became bigger (Akbari et al., 2008). Land filling has been used for many years as the most common method for the disposal of solid waste generated by different communities (Komilis et al., 1999). As Zyma (1990) mentioned that numerous factors have to be evaluated in order to place a landfill and then this adequate landfill should have minimum environmental impacts and social acceptance. Besides, an adequate landfill should be in accordance with the respective regulations (Zyma 1990).
Yesilnacar and Cetin (2005) studies that the site selection procedure, however, should make maximum use of the available information and ensure that the outcome of the process is acceptable to most stakeholders. The planning and design of a solid waste landfill management system involves selection of treatment and disposal facilities, allocation of solid wastes and waste residues from the generator to the treatment and disposal sites, and selection of transportation routes (Yesilnacar and Cetin, 2005). Furthermore, many potential criteria, such as distance from residential areas, distance from main roads, investment costs, availability of solid waste, and land slope must be considered in the selection procedure of a landfill location .
Landfill sitting also is a difficult and complex process requiring evaluation of many different criteria (Chang et al. 2007) since it has to combine environmental, economic and social factors. Environmental factors are very important because the landfill may affect the environment and the ecology of the surrounding area (Siddiqui et al. 1996; Kontos et al. 2003; Erkut and Moran 1991). Consideration of economic factors for landfills, it includes the costs development, operation of the site and also transportation of the waste (Delgado et al. 2008; Erkut and Moran 1991; Kontos et al. 2003). Social and political opposition to landfill siting have been indicated as the greatest obstacle for successfully locating waste disposal facilities (Lober 1995). The “Not In My Backyard” (NIMBY) and “Not In Anyone’s Backyard” (NIABY) phenomena (Chang et al. 2008; Kao and Lin 1996; Erkut and Moran 1991; Kontos et al. 2003; Lin and Kao 2005) are becoming popular nowadays because it create big problem to decision maker to choose the suitable place for sanitary landfill while nowadays is encounter insufficient of suitable land.
It is evident that many factors must be consider in making decision for sanitary landfill sitting and geographic information systems (GIS) is an ideal tools for this kind of preliminary studies due to their ability to manage large volumes of spatial data from a variety of sources (Sener et al. 2006).
2.4 Geographical Information System
Geographic information system (GIS) is a computerize database management system that designed to manage large volumes of spatially distributed data from a variety of sources (Charnpratheep et al., 1997). They are ideal for advanced site-selection studies because they efficiently store, retrieve, analyze, and display information according to user-defined specifications (Kao et al., 1997). GIS has been extensively used to facilitate and lower the cost of the landfill site-selection process (Sener et al., 2006).
GIS often been employed for the siting and placement of facilities (Church, 2002). GIS has emerged as a very important tool for land use suitability analysis (Malczewski, 2004). GIS also can recognize, correlate and analyze the spatial relationship between mapped phenomena, thereby enabling policy-makers to link disparate sources of information, perform sophisticated analysis, visualize trends, project outcomes and strategize long-term planning goals (Malczewski, 2004).
GIS as a box of tools for handling geographical data is very useful, however, the list of tools provided by GIS although impressive is not complete. For example in most GIS packages spatial analytical functionality, lies mainly in the ability to perform deterministic overlay and buffer functions (Carver, 1991). Such abilities whilst ideal for performing spatial searches based on nominally mapped criteria, are of limited use when multiple criteria and targets, such as in the case of landfills selection, are applied (Jeff and Baxter, 1996). The integration of GIS with analytical techniques will be a valuable addition in GIS toolbox. Progress in this area is inevitable and future developments will continue to place increasing emphasis upon the analytical capabilities of GIS (Fotheringham and Rogerson, 1994).
GIS have the capability to handle and simulate the necessary economic, environmental, social, technical, and political constraints. Many of the attributes involved in the process of selection of sanitary landfill sites have a spatial representation, which in the last few years has motivated the predominance of geographical approaches that allow for the integration of multiple attributes using geographic information systems (Kontos et al. 2003; Sarptas et al. 2005; Sener et al. 2006; Gomez-Delgado and Tarantola 2006; Delgado et al. 2008; Chang et al. 2008). Site selection procedures can benefit from the appropriate use of GIS.
Common benefits of GIS include its ability to: (a) capture, store, and manage spatially referenced data; (b) provide massive amounts of spatially referenced input data and perform analysis of the data; (c) perform sensitivity and optimization analysis easily; and (d) communicate model results (Vatalis and Manoliadis 2002).
GIS also provides a spatial framework to land use analysis and it has been recognized as a useful decision support technology. The role of GIS is to generate a set of feasible solutions representing the relative land suitability with respect to any given map layers and to display it. Nevertheless, it does not provide means to deal with multiple decision factors. There has been a recent trend to integrate GIS with other software for better decision making in planning.
2.5 Previous Study on GIS in Sanitary Landfill Site Selection
2.5.1 Case Study in Iran (Akbari et al., 2008)
According to Akbari et al., (2008) a good waste disposal area has few characteristics such as it should be away from the place which has the history of flooding. From previous study done by Allen et al., (2001), landuse, road and other environmental factor must be considered in selecting the suitable waste disposal area. In this study, raster-based and vector-based is used to identify potential waste sites based on suitability of topography and proximity to geographic features (Kier et al.,1993).
In locating the suitable waste disposal area, this study was concern about public health. According to first stage, Akbari et al. (2008) in considering the high rate of urbanization, one should take the long term land use planning of suburbs into consideration to locate the disposal area. In this study also, Akbari et al. (2008) use the combining method. In the first stage, GIS used as the method to predict some of the unacceptable area based on criteria. Then, the study continues the analyzing by using fuzzy multicriteria decision making (Zadeh, 1965).
For the parameter in this study, most of the criteria that has been used follow the previous study such as proper heigt and slope, faults, surface water sources, water wells, urban and rural area, agriculture area, road networks and coastal zone (Kamariah, 1998; Halvadakis, 1993; Vassiloglou, 2001)
Result for this study as almost based on the second stage which is using Fuzzy Multicriteria Decision Making (Zadeh, 1965). FMCDM method is therefore chosen for ranking different landfill sites based on decisions given by a group of experts (Chang et al., 2007).
2.5.2 Case Study in China (Wang et al., 2008)
GIS used as the main system in designing the suitable places for the sanitary landfill site. GIS has been extensively used to facilitate and lower the cost of the sanitary landfill site-selection process (Charnpratheep et al., 1997). Some of the siting technique combine GIS with the multiple criteria analysis (Kao and Lin, 1996; Lin and Kao, 1998) and for this case study, Wang et al., (2008) choose to use Analytical Hierarchy Process (AHP) as a decision making technique. Actually, AHP is often used to compare the relative suitability of a small number of alternatives concerning the overall goal (Wang et al., 2008).
In this study, the criteria that been used is based on the relevant International literature (Kontos et al., 2005; Al-Jarrah and Abu-Qdais, 2006; Sener et al., 2006) and also regulation in China. For the criteria, Wang et al., (2008) split into two groups which is environmental criteria that limit to geographical areas. The second group is about economic factors. As mention in journal, the criteria that has been used for selecting suitable site are residential area, surface water bodies, ground waters, airport areas, land uses, slopes of land surface and roads. Wang et al., (2008) use the price of the land as the economic factor in selecting suitable site. Other criterion for the economic factor is the cost for the transportation. They lower the transportation cost by deciding the waste production center should be 500m from the main road. According to Wang et al., (2008) economic factor is important for developing countries and should be considered for solid waste landfill.
From the overall study, integration of GIS with the multi criteria evaluation technique, AHP can be the best method for completing in selecting suitable site for the sanitary landfill. AHP gives some advantage for the user because it can provide large and many data in selecting suitable site (Charnpratheep et al., 1997; Chang et al., 2008). AHP also provided great flexibility in the aggregation procedure (Wang et al., 2008).
2.5.3 Case Study in India (Sumathi, 2005)
In this case study, Sumathi et al, (2005) use the combination of GIS method and also MCDA or Multi Criteria Decision Method. A GIS-based MCDA integrates and transforms spatial and aspatial data into a decision. It involves the utilization of geographical data, the decision maker’s preferences and the manipulation of data and preferences to arrive at uni-dimensional values of alternatives (Sumathi et al., 2005).
Consequently, it may be considered as a rather complex multi-criteria decision making process involving numerous stakeholders and public interest groups. Hipel (1982) proposed an earlier version of multi-criteria modeling incorporating fuzzy set theory to solve solid waste disposal problems in Canada. MCDA have primarily been employed to solve site selection problems in solid waste management (Vuk et al., 1991; Pereira and Duckstein, 1993; Hokkanen and Salminen, 1994, 1997). Kontos et al. (2005) described a methodology which comprises several methods from different scientific fields such as multiple criteria analysis, geographic information systems, spatial analysis and spatial statistics to evaluate the suitability of the study region in order to optimally site a landfill. Padmaja et al. (2006) identified a solid waste disposal site in Hyderabad city using an analytical hierarchy process and GIS.
The criteria that has been used in this case study are, lake and ponds, rivers, water supply sources, groundwater table, groundwater quality, infiltration, air quality index, geology, fault line, elevation, land use, habitation, highways and sensitive sites.
2.5.4 Case Study in Sabah, Malaysia (Lunkapis, 2004)
Study in Sabah by Lunkapis (2004) is using Geographical Information System (GIS) as decision support tool for landfills siting. Using only GIS as a tool for selecting landfill site still can give the ideal sites. From this study, the criteria used for this study is determine by following the guidelines produced by the Ministry of Environment Malaysia in 1995 and also the collaboration with the Sandakan Spatial Planning Working Group.
In this study also, Lunkapis (2004) used the two major criteria which are constraints and factor that has been used for an ideal siting of landfills. The constraints were related to roads, open water, protected areas, urban, rural residential areas, soil permeability and soil type, land use and distance to transportation routes (Lunkapis, 2004).
In this project, there were some problems regarding management issue and budget allocation. On one hand the advocate proposed that the existing landfill should be maintained due to the lack of funding to open a new one (Lunkapis, 2004). Lunkapis (2004) also said that the existing dumping site were large enough to cater for many years to come and the only requirement was the budget must be allocated for better management and maintainance.
2.6 Combining GIS with other method
2.6.1 GIS with Analytical Hierarchy Process (AHP)
Siddiqui et al. (1996) were the first to combine geographic information system (GIS) and AHP procedure to aid in site selection. Similarly, Charnpratheep et al. (1997) utilized fuzzy set theory with GIS for the screening of landfill sites in Thailand. Chang et al. (2008) combined GIS and fuzzy multi-criteria decision-making for landfill siting in the suburban area of the City of Harlingen. Nema and Gupta (1999) proposed an improved formulation based on a multi-objective integer programming approach to reach the optimal configuration of a regional hazardous waste management system. Ishizaka and Tanaka (2003) discussed the risk for the waste disposal system in Japan, is considering public conflict in the site selection process. Recently, several publications have tackled landfill siting problems using GIS and multi-criteria analysis or intelligent system approaches in Greece, Turkey, and Jordan (Vatalis and Manoliadis, 2002; Kontos et al., 2005; Al-Jarrah and Abu-Qdais, 2005; Sener et al., 2006; Wang et al., 2008).
2.6.2 GIS with Multi Criteria Evaluation (MCE)
Multi-criteria evaluation (MCE) is used to deal with the difficulties that decision makers encounter in handling large amounts of complex information. The principle of the method is to divide the decision problems into more smaller understandable parts, analyze each part separately, and then integrate the parts in a logical manner (Malczewski 1997). The integration of GIS and MCE is a powerful tool to solve the landfill site selection problem because GIS provide efficient manipulation and presentation of the data and MCE supplies consistent ranking of the potential landfill areas based on a variety of criteria (Sener et al. 2006). Higgs (2006) reported the potential of integrating multi-criteria techniques with GIS in waste facility location and documented through a review of the existing literature to highlight the opportunities and challenges facing decision makers at different stages of the waste facility management process.
Vatalis and Manoliadis (2002) used GIS digital map overlay techniques in order to find the suitable landfill sites in Western Macedonia, Greece. Differing siting constraints were considered, and numerical and qualitative criteria were applied in their investigation. The resulting alternative sites were also evaluated using multi-criteria evaluation models. Lin and Kao (1998) developed a model which was applicable for vector-based data. Integrated with a GIS, the model was capable of processing digital spatial data to facilitate landfill siting analysis. Leao et al. (2001) described a method to quantify the relationship between the demand and supply of suitable land for waste disposal over time, using GIS and modeling techniques. Allen et al. (2003) have studied the development of a GIS model for locating landfill sites, an Interreg IIC funded by EU research project and conducted by a team of Irish and Portuguese engineering geologists, civil engineers, and GIS experts from universities and local government. The primary objective of the project has been reported so as to establish a transferable, trans-national GIS site selection framework that could be applicable throughout the European Union, thus creating a GIS landfill model for the location of new landfill sites over the next few years.
2.6.3 GIS with System Simulation Model (SSM)
A performance-based design approach can provide more efficient and cost-effective solutions. Selection of landfill design components satisfying some predefined performance criteria is possible using geographic information systems (GIS) and system simulation models (SSM). Recently, with the help of new developments in the area of software technologies, integration of GIS and SSM technologies into expert systems or decision support systems has become important for landfill design applications (Lukasheh et al. 2001). GIS can efficiently handle databases and perform queries to analyze geographic data to be classified geologically and hydrogeologically, which can help landfill site selection (Lukasheh et al. 2001; Dorhofer and Siebert 1998). SSM like hydrogeologic evaluation of landfill performance (HELP) were developed to assist in the design of landfill elements. The integration of GIS and SSM in one unified system is stated to provide an interface for data storage, database access, and data display using the GIS and allow a single designer to accomplish a complete design and evaluation and provide with a predictive tool using SSMs (Lukasheh et al. 2001).
2.7 Chapter summary
Based on this chapter, the most method that has been used by previous research is combining Geographical Information System (GIS) and Analytical Hierarchy Process (AHP). Basically, using only GIS software is enough to predict suitable places for sanitary landfill site. But to get more exact value for prediction, combining with the AHP is better. This is because AHP can combine many criteria in one time. More than that, using AHP can make the criteria that been use for prediction more flexibility depends on the scaling weighting. Combing GIS with AHP also is a better method because if use GIS only, the raw data may only came from map, but AHP can join map and also other data such as economic factor as the scaling weighting.