As society progresses and becomes more complicated, improvements and demanded in the quality of life according to various interest groups. In relation to environment concerns, waste landfill sites in particular have been of concern. Conflicts involving treatment of such sites and decision making policies have been a point of contention between local governments, residents, and concerned organizations. To resolve these conflicts, this study developed the Multi-Criteria Spatial Decision Support System (MC-SDSS). The results of the case study revealed several conclusions; first, the approach used in this study can help to yield a better consensus for deciding upon waste landfill sites; next, by conducing sensitivity analysis, technical errors which can occur during the decision making process can be minimized; and finally, resistance from specific opposition groups can be effectively dealt with by using MC-SDSS.