Planning maintenance strategies for Italian urban drainage systems applying CARE-S

For wastewater management utilities, asset management can be defined as managing infrastructure capital assets to minimize the total cost of owning and operating them, while delivering the service levels customers desire. CARE-S was carried out as a joint European initiative supported by the European Commission, with a budget of 5 million Euro. CARE-S is a decision support system including models and tools for the design and the exploration of rehabilitation strategies and programs for wastewater network. It provides twenty fundamental instruments for estimating the current and future condition of networks, i.e. performance indicators (PI), selecting and ranking of rehabilitation projects and long-term investment needs. The procedure for selection and ranking of projects is supported by tools for analysis of structural failures and hydraulic performance. Socio-economic issues are also included in the priority ranking process. The CARE-S user can choose between three possible approaches for developing a framework of strategic, proactive rehabilitation of the system, one for evaluating the current system performances, another for defining rehabilitation plans to solve system deficiencies and, the third, for developing the calculation of long-term strategies of rehabilitation. The performance analysis approach consists of the definition and the evaluation of a set of performance indicators (concerning pipe failures, operational failures, environmental impacts, customer complaints, etc.) that are calculated on network level, zone level, or even on pipe level. The second approach offered by CARE-S to the users is the definition of a multicriteria procedure for the evaluation and selection of pipelines that should be candidates for rehabilitation. The total costs of all viable rehabilitation projects usually exceed the available budget. So the projects must be ranked by efficiency criteria in order to spend the money on those projects promising the most positive effects. The third approach that can be applied using CARE-S provides the development and the calculation of long-term strategies of rehabilitation. It is an approach that refers to the condition class of pipes and to the efficiency of rehabilitation programs. The long-term strategy module of CARE-S is designed for the forecast of future rehabilitation needs, and the benefits that can be expected from selected strategies by calculating the pros and cons in terms of indicators with or without rehabilitation. The paper describes the application of CARE-S to the urban drainage system of the historical center of Reggio Emilia town, managed by ENIA municipality. Reggio Emilia (150000 inhabitants and a catchment of 231 km2) is located at 50 km North – West from Bologna in Emilia Romagna (Northern Italy(. ENIA can be graded as a well organized municipality compared to the average Italian standard: a sufficient number of data is available in digitalized format and GIS interface of the system is ready-made. Nevertheless, the data availability is not homogeneous for all the sewer systems managed and frequently, even if data are collected, the quality is not that requested by CARE-S tools. The municipality of ENIA does not have a scheme prioritizing important areas for rehabilitation, therefore the first scope of the application has been to plan CCTV inspections, on the bases of the results of CARE-S selected tools and on network characteristics and criticality. Planning rehabilitation actions to be applied in the next years and developing the calculation of long-term strategies of rehabilitation has been the second goal of the application. The decision making has been based on information gained through the CCTV inspection we planned and the municipality performed and on results of CARE-S structural tools. In summary, the paper presents, for the first time a comprehensive application of CARE-S to an Italian case study as a project on rehabilitation optimization.