Susceptibility Of Potable Water Distribution Systems To Negative Pressure Transients

Low or negative pressure transients (also called surge or water hammer) create temporary opportunities for external chemical and microbial contaminants at higher pressure to enter the water distribution system, creating potential health hazard and potential weakening of distribution pipes, leading to failure. This study investigates how such events as power outages, pump shutdowns, valve operations, main flushing, firefighting, and main breaks can create significant rapid, temporary drops in system pressure. The report offers useful recommendations for using surge models to optimally locate pressure monitors and to minimize the occurrence and impact from low- and negative-pressure transients.

Protecting and maintaining water distributions systems is crucial to ensuring high quality drinking water. Distribution systems-consisting of pipes, pumps, valves, storage tanks, reservoirs, meters, fittings, and other hydraulic appurtenances-carry drinking water from a centralized treatment plant or well supplies to consumers' taps. Spanning almost 1 million miles in the United States, distribution systems represent the vast majority of physical infrastructure for water supplies, and thus constitute the primary management challenge from both an operational and public health standpoint. Recent data on waterborne disease outbreaks suggest that distribution systems remain a source of contamination that has yet to be fully addressed. This report evaluates approaches for risk characterization and recent data, and it identifies a variety of strategies that could be considered to reduce the risks posed by water-quality deteriorating events in distribution systems. Particular attention is given to backflow events via cross connections, the potential for contamination of the distribution system during construction and repair activities, maintenance of storage facilities, and the role of premise plumbing in public health risk. The report also identifies advances in detection, monitoring and modeling, analytical methods, and research and development opportunities that will enable the water supply industry to further reduce risks associated with drinking water distribution systems.

The objectives of this project were to verify that

Protecting and maintaining water distributions systems is crucial to ensuring high quality drinking water. Distribution systems-consisting of pipes, pumps, valves, storage tanks, reservoirs, meters, fittings, and other hydraulic appurtenances-carry drinking water from a centralized treatment plant or well supplies to consumers' taps. Spanning almost 1 million miles in the United States, distribution systems represent the vast majority of physical infrastructure for water supplies, and thus constitute the primary management challenge from both an operational and public health standpoint. Recent data on waterborne disease outbreaks suggest that distribution systems remain a source of contamination that has yet to be fully addressed. This report evaluates approaches for risk characterization and recent data, and it identifies a variety of strategies that could be considered to reduce the risks posed by water-quality deteriorating events in distribution systems. Particular attention is given to backflow events via cross connections, the potential for contamination of the distribution system during construction and repair activities, maintenance of storage facilities, and the role of premise plumbing in public health risk. The report also identifies advances in detection, monitoring and modeling, analytical methods, and research and development opportunities that will enable the water supply industry to further reduce risks associated with drinking water distribution systems.

Access to potable drinking water is a necessity and basic human right. Most North Americans obtain treated water through water distribution networks, an essential part of municipal infrastructure that is subject to decay and degradation. Amongst the factors influencing pipe failure are events that trigger abrupt pressure changes, or transients, which can cause pipe breakages in the short term, and general fatigue in the long term. The ability to quantify these transients as they occur is important for effective asset management, and for preventing and mitigating the occurrence of failure. Current practices take a largely reactive approach to event detection, and few systems capable of real-time transient detection have ever been implemented. This research addresses the need for an online monitoring framework aimed towards understanding pressure transient effects and behaviour. The proposed system uses an Internet of Things approach, combining pressure sensors with Raspberry Pi computers, as well as open-source tools that transmit and display the data. The data analysis combines computationally inexpensive methods in order to achieve an accurate decision-making tool for both transient detection and abnormal transient risk identification. The techniques used include different filtering and detrending methods, feature extraction for dimensionality reduction, three-sigma statistical process control, and classification using voting methods. The process also includes a second process, based on statistical process control and trained using transient data identified in the original process, in order to assign a risk for a transient to cause damage, as well as identify transients that are particularly severe. Data was collected from a unique laboratory water distribution network as well as a field installation in Guelph, Ontario. The results showed that the framework achieves real-time transient identification with reasonable detection and error rates. Further analysis illustrated the effect of factors such as transient source location, active flow in the pipes, and transient type, on transient propagation and detection. The performance of the framework proves the concept of IoT-based systems for pressure monitoring and event detection in municipal water infrastructure.

Water distribution systems are made up of pipe, valves and pumps through which treated water is moved from the treament plant to homes, offices, industries, and other consumers. The types of materials and equipment used by each water system are usually governed by local conditions, past practices, and economics. Consequently, drinking water professionals must be knowledgeable about common types of equipment and operating methods that are available. Completely revised and updated, Water transmission and distribution includes information on the following: distribution system design and operation and maintenance ; piping materials ; valves, pumps, and water meters ; water main installation ; backfilling, main testing, and installation safety ; fire hyfrants ; water storage ; water services ; cross-connection control ; motors and engines ; instrumentation and control ; information management and public relations.--Cover page [4].

There are two groups of specialists involved in the development and application of water quality models, each of which have a different perspective on the use of models: Academics and scientists - chemistry specialists and microbiologists who develop the models. Practitioners - modelers and distribution engineers who use them to solve problems. There are limitations and constraints in the characterization of the underlying processes and the practical application of models to distribution networks, which require further research. The objectives of the research were to characterize the current state of predictive distribution system water quality models and to identify critical research needs for their improvement. The project reviewed both the development and application of models. The report is intended to both steer future research and to act as a general reference on water quality modeling. The report combines a literature review with the practical experience of the project team. The content of a draft report was discussed at an international workshop attended by academics, engineers, scientists, and hydraulic modelers with the objective of agreeing on specific research needs necessary to improve predictive modeling for water quality in distribution systems. The conclusions of the report are derived from the workshop and form the basis of 11 specific research briefs that have been submitted to AwwaRF for consideration of funding. Researchers often focus on modeling the individual processes that control water quality rather than fully modeling water quality throughout distribution systems. For these "process models" to be applied to real distribution networks, they need to be extended to take in account the physical characteristics of the system?the special and temporal variations in flow, velocity and water age, and the effects of mixing water that has traveled along different flow paths.