Multi-Criteria Decision Making in the sustainability assessment of sewerage pipe systems.

This paper focuses on the sustainability analysis of different constituent materials for sewerage pipes by using a specific multi - criteria decision making (MCDM) method based on the value analysis and the multi-attribute utility theory. The scientific added value of this research consists of developing a method that minimizes the subjectivity involved in the process of quantification and comparison of different alternatives of materials to construct sewerage pipelines. In this context, a requirements tree is defined to derive a non-dimensional sustainability index for each alternative. The method is also supported by use of value functions and weights assigned to each criteria and indicator part of this requirements tree. These value functions were established during seminars and questionnaires solved by specialists and senior managers from the Spanish public sector. Besides, the weights were derived from the use of an Analytical Hierarchical Process. The model is used to assess the sustainability of 8 alternatives including rigid reinforced and non-reinforced concrete pipes as well as flexible polypropylene, polyethylene, polyvinyl chloride and glass-fibre reinforced polyester pipes. Nominal diameters of 400, 800, 1200 and 2000 were chosen as those representatives for urban and rural sewerage networks. The conclusions obtained from the research confirm that the sustainability indexes are similar for diameters of 400 mm and below, independently of the material. In addition, it has been also concluded that concrete solutions are clearly better in terms of sustainability for wider diameters with respect to the other alternative materials. [ABSTRACT FROM AUTHOR]