(b) Multi-criteria analysis
         In this method, best possible optimal criteria are selected for evaluation of sites. A total score of 1000 is apportioned among the assessment criteria based on their importance .There is no hard and fast rule for total score. A site sensitivity index (SSI) is developed for different attribute qualities on a scale of 0 to 1. Based on SSI, score for each parameter of various sites is computed. Ranking is done for the individual site alternatives based on summation of the score.   

(c) Hatzichristos and Giaoutzi (2006) demonstrated the use of fuzzy set approach integrated with geographical information system (GIS) for landfill siting. The fuzzy set is considered effective to take decisions on those criteria that are not discrete and which overlap with one another. It is opined that the fuzzy set approach integrated with GIS platform is most relevant for applications where the decision criteria are not discrete and the boundaries between regions are fuzzy or overlapping.

(d) Chang et al. (2008) have presented a fuzzy multi-criteria decision analysis along with a geospatial analysis for the selection of landfill sites. The study developed a spatial decision support system (SDSS) for landfill site selection in a fast-growing urban region. Thematic maps in Geographical information system (GIS) are used in conjunction with environmental, biophysical, ecological, and socioeconomic variables leading to support the fuzzy multi-criteria decision-making (FMCDM). It differs from the conventional methods of integrating GIS with multi-criteria decision making for landfill site selection because the approach follows two sequential steps rather than a full-integrated scheme. The purpose of GIS was to perform an initial screening process to eliminate unsuitable land followed by utilization of FMCDM method to identify the most suitable site using the information provided by the regional experts with reference to different chosen criteria.

3.3 Subsurface investigation for waste management

         Subsurface investigation for waste management is required for deciding the site for landfills and also for delineating the extent of contamination. Several hydrogeological parameters required for landfill site selection are obtained from subsurface investigation conducted for different potential sites. The methodology for subsurface investigation remains similar to any other geotechnical investigation (for example, open pit, bore holes). In addition, several geophysical methods such as electrical resistivity imaging, seismic refraction, ground penetration radar, etc. are used for defining the zone of contamination, establishing the depth of aquifer, and also to reduce the number of bore holes.