Verification And Control Of Pressure Transients And Intrusion In Distribution Systems

The objectives of this project were to verify that

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 book describes the causes and effects of transient (water hammer) events in liquid-filled pipes, and describes how the powerful and stable Wave Plan Method (WPM) can be used to address transients during surge modeling. The authors compare and contrast WPM with the Method of Characteristics (MOC), which is the other widely-used surge analysis tool. While MOC can be useful for many situations, the larger and more complex a model becomes, the more the computational efficiency of WPM is necessary to avoid longer and longer analysis times. The authors also describe how WPM is more generalizable than MOC, which is a term that describes a suite of tools consisting of several variants that were developed to address different modeling situations. This book provides details on surge modeling in general and the use of WPM in particular. This includes pressure attenuation, determination of wave speeds in different pipe types and various liquid media, pump and turbine characteristics curves, and the effects of boundary conditions. The discussion of boundary conditions includes an extensive look at the effects of the air-water interface as it applies to bulk air intrusion into pipelines, and as it relates to the use of air/vacuum valves as surge protection. The authors discuss surge protection design for different real-world scenarios, and how to model of a full list of surge control devices, including a detailed discussion of check valves. Last, the book describes the assumptions and uncertainties encountered during data collection and model building, and examines the potential effect of these uncertainties. Where uncertainties cannot be mitigated, the authors discuss ways to increase the safety factor of surge protection designs.

A collection of articles by leading international experts on modeling and control of potable water distribution and sewerage collection systems, focusing on advances in sensors, instrumentation and communications technologies; assessment of sensor reliability, accuracy and fitness; data management including SCADA and GIS; system

CD-ROM contains chapter 4 and appendices A & B.

This volume presents a unique and comprehensive glimpse of current and emerging issues of concern related to potable water. The themes discussed include: (1) historical perspective of the evolution of drinking water science and technology and drinking water standards and regulations; (2) emerging contaminants, water distribution problems and energy demand for water treatment and transportation; and (3) using alternative water sources and methods of water treatment and distribution that could resolve current and emerging global potable problems. This volume will serve as a valuable resource for researchers and environmental engineering students interested in global potable water sustainability and a guide to experts affiliated with international agencies working toward providing safe water to global communities.

Encyclopedia of Environmental Health, Second Edition, Six Volume Set presents the newest release in this fundamental reference that updates and broadens the umbrella of environmental health, especially social and environmental health for its readers. There is ongoing revolution in governance, policies and intervention strategies aimed at evolving changes in health disparities, disease burden, trans-boundary transport and health hazards. This new edition reflects these realities, mapping new directions in the field that include how to minimize threats and develop new scientific paradigms that address emerging local, national and global environmental concerns. Represents a one-stop resource for scientifically reliable information on environmental health Fills a critical gap, with information on one of the most rapidly growing scientific fields of our time Provides comparative approaches to environmental health practice and research in different countries and regions of the world Covers issues behind specific questions and describes the best available scientific methods for environmental risk assessment

Urban water and wastewater systems have an inherent vulnerability to both manmade and natural threats and disasters including droughts, earthquakes and terrorist attacks. It is well established that natural disasters including major storms, such as hurricanes and flooding, can effect water supply security and integrity. Earthquakes and terrorist attacks have many characteristics in common because they are almost impossible to predict and can cause major devastation and confusion. Terrorism is also a major threat to water security and recent attention has turned to the potential that these attacks have for disrupting urban water supplies. There is a need to introduce the related concept of Integrated Water Resources Management which emphasizes linkages between land-use change and hydrological systems, between ecosystems and human health, and between political and scientific aspects of water management. An expanded water security agenda should include a conceptual focus on vulnerability, risk, and resilience; an emphasis on threats, shocks, and tipping points; and a related emphasis on adaptive management given limited predictability. Internationally, concerns about water have often taken a different focus and there is also a growing awareness, including in the US, that water security should include issues related to quantity, climate change, and biodiversity impacts, in addition to terrorism. This presents contributions from a group of internationally recognized experts that attempt to address the four areas listed above and includes suggestions as to how to deal with related problems. It also addresses the new and potentially growing issue of cyber attacks against water and waste water infrastructure including descriptions of actual attacks, making it of interest to scholars and policy-makers concerned with protecting the water supply.