Transportation analysis for sludge landfill site selection

Abstract

A solution framework for the Sludge Landfill Site Selection Problem (SLSSP) which arises in the context of environmental planning is presented. The problem may be defined as follows: given a set of environmentally acceptable candidate landfill sites, identify the site which minimizes a weighted combination of two objectives (system descriptors): the present worth value of the transportation operation costs and the resulting population disturbance of the chosen set of transportation routes. The solution framework relies on an analysis algorithm which identifies K shortest travel time routes between one candidate landfill site and each of the water treatment plants. Based on a prespecified tradeoff between present worth and population disturbance, the transportation routes associated with each landfill site are selected and the site's two resulting system descriptors are computed. The solution methodology is demonstrated on data developed for the City of Phoenix, Arizona. In addition, computational experiments are performed to test the quality of solution and its sensitivity to different tradeoffs between the two system descriptors. As a result of this study, city officials were dissuaded away from a prefavored landfill site. Final selection from the set of pareto-optimal solutions was postponed pending results of ongoing efforts to enlarge the collection operation by including sludge disposed in other neighboring cities.