Susceptibility of Distribution Systems to Negative Pressure Transients
Susceptibility of Distribution Systems to Negative Pressure Transients

Author: Kala K. Fleming

Publisher: American Water Works Association

Published: 2006

Total Pages: 140

ISBN-13: 1583215115

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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.

Pathogen Intrusion Into the Distribution System
Pathogen Intrusion Into the Distribution System

Author: Gregory J. Kirmeyer

Publisher: American Water Works Association

Published: 2001

Total Pages: 286

ISBN-13: 1583211020

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Reports on a project that identifies pathogen routes of entry into water distribution systems and develops monitoring and control strategies for protecting the system. Contains chapters on pathogens and pathways, existing control strategies, transient surge modeling, pressure monitoring, field monitoring, recommended control strategies, and recommendations to utilities. The project was completed by a multi-disciplinary team of engineers and practitioners with funding from the American Water Works Association Research Foundation and the Environmental Protection Agency. The book is not indexed. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Impacts of Cross-Connections in North American Water Supplies
Impacts of Cross-Connections in North American Water Supplies

Author: J. Lee

Publisher: IWA Publishing

Published: 2004-01-01

Total Pages: 228

ISBN-13: 1843398435

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For many years, cross-connections and backflow have been well understood. Programs to prevent unhealthy situations from happening have been in place for many years. However, a general and extensive study on their impacts, types of programs, incidents, and financial repercussions has not been conducted. Many computer models for steady state or quasi-steady state simulation exist, but applications for transient state simulation, especially demonstrating backflow incidents, have rarely been done.The first objective of this project was to assess the impacts, financial and otherwise, of cross-connections and cross-connection control in North American water supplies and to North American water purveyors. The project team also planned to create and use a computer model to simulate and demonstrate hydraulic changes in the transient state.Of the over 700 utilities surveyed, 91% were found to have a cross-connection control program. Survey data indicated 65% of cross-connections were indirect and 35% were direct. Sudden changes of water demands in piping networks can cause sub-atmospheric pressures within the systems resulting in backflow incidents. Systems with larger variances in ground elevations have the greater possibility of creating sub-atmospheric pressures as water demands in the systems change.Originally published by AwwaRF for its subscribers in 2003 This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below

Public Water Supply Distribution Systems
Public Water Supply Distribution Systems

Author: National Research Council

Publisher: National Academies Press

Published: 2005-04-12

Total Pages: 57

ISBN-13: 0309181844

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The Water Science and Technology Board has released the first report of the Committee on Public Water Supply Distribution Systems: Assessing and Reducing Risks, which is studying water quality issues associated with public water supply distribution systems and their potential risks to consumers. The distribution system, which is a critical component of every drinking water utility, constitutes a significant management challenge from both an operational and public health standpoint. This first report was requested by the EPA, as the agency considers revisions to the Total Coliform Rule with potential new requirements for ensuring the integrity of the distribution system. This first report identifies trends relevant to the deterioration of drinking water quality in distribution systems and prioritizes issues of greatest concern according to high, medium, and low priority categories. Of the issues presented in nine EPA white papers that were reviewed by the committee, cross connections and backflow, new or repaired water mains, and finished water storage facilities were judged by the committee to be of the highest importance based on their associated potential health risks. In addition, the report noted that two other issues should also be accorded high priority: premise plumbing and distribution system operator training. This first report will be followed in about 18 months by a more comprehensive final report that evaluates approaches for risk characterization and identifies strategies that could be considered to reduce the risks posed by water-quality deteriorating events.

Drinking Water Distribution Systems
Drinking Water Distribution Systems

Author: National Research Council

Publisher: National Academies Press

Published: 2007-01-22

Total Pages: 405

ISBN-13: 0309103061

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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.

Water Distribution System Handbook
Water Distribution System Handbook

Author: Larry W. Mays

Publisher: McGraw Hill Professional

Published: 1999-10-21

Total Pages: 615

ISBN-13: 007177677X

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All-in-one, state-of-the-art guide to safe drinking water Civil engineers and anyone else involved in any way with the design, analysis, operation, maintenance or rehabilitation of water distribution systems will find practical guidance in Water Distribution Systems Handbook. Experts selected by Handbook editor Larry W. Mays provide historical, present day, and future perspectives, as well as state-of-the-art details previously available only in specialized journals. You get a comprehensively detailed exploration of every facet of the hydraulics of pressurized flow; piping design and pipeline systems; storage issues; reliability analysis and distribution, and more. Detailed information on the latest technology contributions and on enhancements to the EPANET model are included. You'll also find case studies that range from the small municipal systems found in every U.S. town, to large systems common to great urban centers like New York, London and Paris.

Impact of Distribution System Water Quality on Disinfection Efficacy
Impact of Distribution System Water Quality on Disinfection Efficacy

Author: Hé́lène Baribeau

Publisher: American Water Works Association

Published: 2005

Total Pages: 324

ISBN-13: 1583214100

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Assesses the impact of dynamic water quality conditions in the distribution system on the inactivation of microorganisms in bulk water. Addresses questions about the usefulness of maintaining a secondary residual and the target level to be maintained. Bridges research related to distribution system water quality with that of microbial inactivation.