Sérgio T. Coelho

Urban water infrastructure asset management – a structured approach in four water utilities

Water services are a strategic sector of large social and economic relevance. It is therefore essential that they are managed rationally and efficiently. Advanced water supply and wastewater infrastructure asset management (IAM) is key in achieving adequate levels of service in the future, particularly with regard to reliable and high quality drinking water supply, prevention of urban flooding, efficient use of natural resources and prevention of pollution. This paper presents a methodology for supporting the development of urban water IAM, developed during the AWARE-P project as well as an appraisal of its implementation in four water utilities. Both water supply and wastewater systems were considered. Due to the different contexts and features of the utilities, the main concerns vary from case to case; some problems essentially are related to performance, others to risk. Cost is a common deciding factor. The paper describes the procedure applied, focusing on the diversity of drivers, constraints, benefits and outcomes. It also points out the main challenges and the results obtained through the implementation of a structured procedure for supporting urban water IAM.

Water distribution systems flow monitoring and anomalous event detection: A practical approach

Methods to detect outliers in network flow measurements that may be due to pipe bursts or unusual consumptions are fundamental to improve water distribution system on-line operation and management, and to ensure reliable historical data for sustainable planning and design of these systems. To detect and classify anomalous events in flow data from district metering areas a four-step methodology was adopted, implemented and tested: i) data acquisition, ii) data validation and normalization, iii) anomalous observation detection, iv) anomalous event detection and characterization. This approach is based on the renewed concept of outlier regions and depends on a reduced number of configuration parameters: the number of past observations, the true positive rate and the false positive rate. Results indicate that this approach is flexible and applicable to the detection of different types of events (e.g., pipe burst, unusual consumption) and to different flow time series (e.g., instantaneous, minimum night flow).

Infrastructure Asset Management of Urban Water Systems

IAM methods partially differ from those applicable to managing other types of assets. One of the reasons is the fact that such infrastructures have indefinite lives, in order to satisfy the permanent needs of a specific public service. Infrastructures are not replaceable as a whole, only piecemeal. Consequently, in a mature infrastructure, all phases of assets lifetime coex‐ ist. Additionally, in network-based infrastructures, it is frequently not feasible to allocate levels of service to individual components because there is a dominant system behavior (e.g. symptoms and their causes often occur at different locations).

Performance assessment of water supply and wastewater systems

This paper addresses the issue of performance assessment in water and wastewater systems by reviewing two of the tools that are available to the companies operating in this field: systems of performance indicators and technical performance assessment through simulation. The paper focuses on a technical performance evaluation framework and its application to wastewater systems. The assessment is carried out through the application of utility functions to the networks elements, and the production of performance-oriented graphs that yield concise and informative views about the systems behaviour. Two case studies involving a combined sewer system and a separate domestic system are presented in order to illustrate the method.

Stochastic data mining tools for pipe blockage failure prediction

Abstract Failure prediction plays an important role in the management of urban water systems infrastructures. An accurate description of the deterioration of urban drainage systems is essential for optimal investment and rehabilitation planning. In the study presented in this paper, a new method to predict sewer pipe failure based on robust decision trees is proposed. Five other different stochastic failure prediction models – the non-homogeneous Poisson process, the zero-inflated non-homogeneous Poisson process, classical decision tress (CART and Random Forest algorithms), the Weibull accelerated lifetime model and the linear extended Yule process – are also implemented and explored in order to identify models that combine good failure prediction results with robustness. The six models were tested on the asset register and pipe failure register of a large US wastewater utility; only pipe blockage failures were considered in this study. The linear extended Yule process and the zero-inflated non-homogeneous Poisson process presented the overall best results throughout the models’ comparison, showing a good ability to detect pipes with high likelihood of blockage failure. Decision trees based on robust random forests only detected pipes with high likelihood of failure when considering a short-term prediction window; the accuracy of the predictions was one of the best when using the robust decision tree model. The Weibull accelerated lifetime model provided some of the best medium-term predictions but performed less well for shorter prediction windows.

Moving urban water infrastructure asset management from science into practice

iGPI, the National Initiative for Infrastructure Asset Management is a Portuguese collaborative project led by LNEC (National Civil Engineering Laboratory, Portugal) through which 19 water utilities develop their own infrastructure asset management (IAM) systems and plans in a joint training and capacitation programme. Technical assistance to the participating utilities is ensured by LNEC, IST (Technical University of Lisbon) and Addition, a software development company. The water utilities get collective as well as one-on-one support and specific training. They benefit from networking with the other utilities in a common and simultaneous process, with similar difficulties and challenges, leading to an effective sharing of solutions. The developed products, including training materials, templates and guidelines for developing strategic and tactical IAM plans, are available to the general public. This project has greatly contributed to the establishment of reference methodologies and standards for IAM planning, in a range of utilities of widely diverse size and context, effectively defining an accepted best practice. This paper discusses the projects format and its advantages, and goes on to describe the main outcomes, including selected cases and final products.

Diagnosis of Hydraulic Performance of Water Supply Systems

Hydraulic simulation and demand analysis have been, for some years now, key research areas for the water supply team at the National Laboratory of Civil Engineering of Portugal. It is felt that the planning, design, operation and control of water supply and distribution system are greatly improved by the use of adequate analysis and processing tools.

Profiling Residential Water Consumption

Understanding the factors that influence daily and weekly water consumption patterns in distribution systems is fundamental for both long term tasks, such as planning, design, expansion or rehabilitation of the systems, and short term tasks, such as routine system operation or emergency management. This paper describes the development of a Portuguese nationwide program for characterizing residential water consumption, through the use of a specific consumption data analysis protocol and the build-up of a database of demand patterns; and for associating it with a range of easily obtained, potential relatable factors that include the technical features of the network (e.g., service pressure, network state and maintenance level, use of household tanks), billing and customer statistics and a range of social-demographic variables, such as age, social-economic level and mobility of consumers, age and type of buildings, and economic activities. The program is currently being test-run on a set of 20 metering districts from 9 water utilities, comprising a variety of network types and demand characteristics across representative urban areas of Portugal. The metering districts range in size from 2,000 to 12,000 connected properties, and have mostly been monitored since 2005 (in some cases, 2004). Total consumption is continuously monitored during the main seasonal scenarios (typically winter and summer) in the areas selected. Standardized daily demand patterns and consumption statistics are produced for each day of the week, as well as for each season, in case there is seasonality in the area. Social-demographic information is based on statistics obtained from the 2001 National Census for the basic statistical units, which are around 300 dwellings in size. After the initial run, the program is to be disseminated and made accessible to all water utilities willing to participate, on a voluntary basis and with data anonymity. This will be done mostly through a dedicated website containing the consumption database, together with query and analysis tools, as well as a supervised mechanism to submit new cases in standard format. It is believed that the publication of the result database and its continued growth will provide the water industry designers, consultants and managers with much more reliable and updated data on water consumption than previously available. It will also represent a means to estimate demand through correlation and profiling, in cases when there are no records to work from. The paper discusses the demand analysis performed, as well as the development of the set of potential explanatory factors (technical features of the network and social-demographic variables), and illustrates with the results obtained so far. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).

Boosting innovation in the water sector – the role and lessons learned from collaborative projects

A key worldwide challenge in most sectors is to boost the effective adoption of innovation, as underpinned by the new European Union research programme Horizon 2020, which focuses on increasing innovation in Europe from 2014 to 2020. This is particularly relevant in the water sector, often perceived as conservative and averse to change. This paper discusses the role that collaborative knowledge-transfer projects can play in effectively rolling out R&D in the water industry. LNEC (Laboratório Nacional de Engenharia Civil) has designed a structured model based on a phased programme and a network of utilities and researchers. The paper presents the core principles, the rationale, the model and methods used, and the theoretical background, as well as the projects impact, outcomes and products. The discussion highlights the lessons learnt and provides a formal analysis of the advantages of focusing on middle management as an effective entry point, even if innovation is needed across the organization. Making training materials, guidelines, use cases, data and software publicly available after the projects end has proven to have a decisive multiplying effect. The paper also argues in favour of the collaborative model as a basis for R&D sustainability, and details on-going and planned developments.

Hydraulic Performance and Rehabilitation Strategies

Over the past twenty years a major financial effort has been made to improve the water supply in Portugal. A significant evolution can be observed, with 77% of the population currently connected to public systems and a target of 95% by the year 2000. Supplying a high percentage of the population is however not sufficient by itself. The quality of the service provided to the users is a fundamental issue, particularly where continuity of supply, water quality and reliability are concerned. Recent surveys based on simplified criteria indicate that 40% of the population supplied are thought to enjoy a good service, 54% an adequate service, and 6% a poor service.