Selection of criteria and methods for a comparative evaluation of environmental sustainability of open-cut and no-dig technologies for new installations and in situ rehabilitation of water pipes

Metropolitana Milanese (MM Spa), the water authority of the city of Milan, has carried out, on both water and sewage networks, installation of new pipelines and rehabilitation of the already existing ones using no-dig technologies, i.e. techniques alternative to open cut excavations. To spread such techniques, having evident advantages with respect to the traditional ones, a procedure to assess its sustainability in different cases was developed based on SAT analysis (Technology Sustainable Assessment), a procedure adopted to support the decision-making process, including a set of indicators that take into account the technological, environmental, economic and social aspects. To take into account the most relevant aspects in the specific case the SAT procedure was modified: the environmental impacts were calculated by LCA, the economic costs as direct costs and the social ones as indirect costs (including logistic aspects) and risks for the exposed population (workers and general population). To setup the methodology, two significant case studies of the city of Milan in order to disclose and assess the environmental, social and economic impacts which should be used for decision making.