Location analysis helps manage solid waste in Central Portugal

By the beginning of the 1990s, the Portuguese Centro Region was suffering from extremely serious solid-waste-sector problems. The Portuguese Centro Region Coordination Agency asked me to prepare a document identifying the main issues involved in finding a solution to the existing problems and to propose a master plan for intervention. My proposal defined a network of sanitary landfills and transfer stations covering the whole region (23,700 square km; 1,714,000 inhabitants). The proposal was the basis for the discussions held at the regional council and for the solution that is currently being implemented. To define the network, I developed a mixed-integer optimization model combining elements of a p-median model and a capacitated-facility-location model with transshipments.