Assessing Potential Impacts Associated With Contamination Events In Water Distribution Systems
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Assessing Potential Impacts Associated With Contamination Events In Water Distribution Systems
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Author :
language : en
Publisher:
Release Date : 2010
Assessing Potential Impacts Associated With Contamination Events In Water Distribution Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
An understanding of the nature of the adverse effects that could be associated with contamination events in water distribution systems is necessary for carrying out vulnerability analyses and designing contamination warning systems. This study examines the adverse effects of contamination events using models for 12 actual water systems that serve populations ranging from about 104 to over 106 persons. The measure of adverse effects that we use is the number of people who are exposed to a contaminant above some dose level due to ingestion of contaminated tap water. For this study the number of such people defines the impact associated with an event. We consider a wide range of dose levels in order to accommodate a wide range of potential contaminants. For a particular contaminant, dose level can be related to a health effects level. For example, a dose level could correspond to the median lethal dose, i.e., the dose that would be fatal to 50% of the exposed population. Highly toxic contaminants may be associated with a particular response at a very low dose level, whereas contaminants with low toxicity may only be associated with the same response at a much higher dose level. This report focuses on the sensitivity of impacts to five factors that either define the nature of a contamination event or involve assumptions that are used in assessing exposure to the contaminant: (1) duration of contaminant injection, (2) time of contaminant injection, (3) quantity or mass of contaminant injected, (4) population distribution in the water distribution system, and (5) the ingestion pattern of the potentially exposed population. For each of these factors, the sensitivities of impacts to injection location and contaminant toxicity are also examined. For all the factors considered, sensitivity tends to increase with dose level (i.e., decreasing toxicity) of the contaminant, with considerable inter-network variability. With the exception of the population distribution (factor 4 above), sensitivity to the various factors tends to be highest at lower impact levels (e.g., impacts below the 80th percentile). Conversely, for the population distribution factor, sensitivity is lowest at the lower impact levels. For injection duration, impacts generally are higher for longer duration injections. Definite patterns are present in the sensitivity of impacts to injection time, but these vary substantially across the networks. As would be expected, impacts are larger for larger mass injections, but the sensitivity can vary dramatically depending on dose level and the network. Estimated impacts can be sensitive to assumptions about how population is distributed in a network, particularly at high impact levels and high dose levels, again with considerable variability across networks. Finally, impacts can be sensitive to assumptions about ingestion patterns in the potentially exposed population, with sensitivities varying across networks and tending to be highest for high dose levels. When considered in combination with the other factors (but not including the ingestion model used), impacts at low dose levels (levels at which the effects of highly toxic contaminants can be significant) are most sensitive to injection duration. Similarly, when considered in combination, impacts at higher dose levels (levels required for significant effects from contaminants with low toxicity) are most sensitive to injection mass. At low dose levels, for a likely range in injection masses, impacts are not particularly sensitive to injection mass. The influence of the various factors on the location of high percentile injection locations can be as important or more important than their influence on the magnitudes of impacts. In addition, the choice of contaminant has a major influence on which nodes are high impact injection locations. The sharing (overlap) of the same high-percentile injection nodes for different values of a factor can vary substantially by contaminant and impact level (percentile of impact). Overlap tends to decrease with decreasing toxicity of the contaminant and increasing impact level for all the factors considered, with considerable variability among the networks. Our results demonstrate the great variability in the impacts and the sensitivity of impacts to various factors that can occur in different water systems during a contamination event. Although definite patterns exist in the nature and magnitude of impacts and sensitivities for the diverse set of water systems examined, these results also show that substantial inter-network variability limits the ability to predict or extrapolate these results to other systems. Therefore, although water systems do exhibit some similarities in the magnitude and pattern of impacts during contamination events, each individual water system should be treated as unique.
Assessing Inhalation Exposures Associated With Contamination Events In Water Distribution Systems
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Author :
language : en
Publisher:
Release Date : 2016
Assessing Inhalation Exposures Associated With Contamination Events In Water Distribution Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
When a water distribution system (WDS) is contaminated, short-term inhalation exposures to airborne contaminants could occur as the result of domestic water use. The most important domestic sources of such exposures are likely to be showering and the use of aerosol-producing humidifiers, i.e., ultrasonic and impeller (cool-mist) units. A framework is presented for assessing the potential effects of short-term, system-wide inhalation exposures that could result from such activities during a contamination event. This framework utilizes available statistical models for showering frequency and duration, available exposure models for showering and humidifier use, and experimental results on both aerosol generation and the volatilization of chemicals during showering. New models for the times when showering occurs are developed using time-use data for the United States. Given a lack of similar models for how humidifiers are used, or the information needed to develop them, an analysis of the sensitivity of results to assumptions concerning humidifier use is presented. The framework is applied using network models for three actual WDSs. Simple models are developed for estimating upper bounds on the potential effects of system-wide inhalation exposures associated with showering and humidifier use. From a system-wide, population perspective, showering could result in significant inhalation doses of volatile chemical contaminants, and humidifier use could result in significant inhalation doses of microbial contaminants during a contamination event. From a system-wide perspective, showering is unlikely to be associated with significant doses of microbial contaminants. In conclusion, given the potential importance of humidifiers as a source of airborne contaminants during a contamination event, an improved understanding of the nature of humidifier use is warranted.
Drinking Water Distribution Systems
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2007-01-22
Drinking Water Distribution Systems written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-01-22 with Science categories.
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.
Distribution System Water Quality Challenges In The 21st Century
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Author : Michael J. MacPhee
language : en
Publisher:
Release Date : 2005
Distribution System Water Quality Challenges In The 21st Century written by Michael J. MacPhee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Political Science categories.
Offering a high-level view of key distribution system water quality issues that utilities will confront in the coming decades, and a new view of an integrated treatment process, this book covers such topics as microbial regrowth and recontamination, risks associated with release of trace metals from system scale, and impacts of secondary disinfection practices. This resource targets water utility managers, water quality professionals, policy makers, regulators, consultants, and educators.
Contaminated Water Supplies At Camp Lejeune
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2009-09-06
Contaminated Water Supplies At Camp Lejeune written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-09-06 with Medical categories.
In the early 1980s, two water-supply systems on the Marine Corps Base Camp Lejeune in North Carolina were found to be contaminated with the industrial solvents trichloroethylene (TCE) and perchloroethylene (PCE). The water systems were supplied by the Tarawa Terrace and Hadnot Point watertreatment plants, which served enlisted-family housing, barracks for unmarried service personnel, base administrative offices, schools, and recreational areas. The Hadnot Point water system also served the base hospital and an industrial area and supplied water to housing on the Holcomb Boulevard water system (full-time until 1972 and periodically thereafter). This book examines what is known about the contamination of the water supplies at Camp Lejeune and whether the contamination can be linked to any adverse health outcomes in former residents and workers at the base.
Water Contamination Emergencies
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Author : K Clive Thompson
language : en
Publisher: Royal Society of Chemistry
Release Date : 2007-10-31
Water Contamination Emergencies written by K Clive Thompson and has been published by Royal Society of Chemistry this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-10-31 with Science categories.
Contamination of water supplies and the immediate availability of appropriate emergency responses to chemical, biological, radiological or nuclear (CBRN) events which result in contaminated water are becoming increasingly relevant and significant issues in the water industry and in the wider world. Consequently, new strategies and technologies are being constantly evolved and refined by leading experts in the field in order to achieve rapid and effective responses to water contamination events. Water Contamination Emergencies: Enhancing our Response brings together contributions from leading scientists and experts from both academia and industry in the field of water contamination and emergency planning. The book covers a wide range of topics including responses to water contamination emergencies, impacts on public health and commerce, risk assessment, analysis and monitoring, emergency planning, control and planning and threats to the water industry. This book is ideal for specialists in the field of water contamination and emergency response planning, especially researchers and professionals in industry and government who require an authoritative and highly specialised resource on water contamination management. The reader will gain an appreciation of the activities supporting the development of responses to contamination events; emergency actions required in response to the contamination of drinking water; and incident management. Also discussed are the importance of communication between organisations and the public; consumer perceptions and the need for robust and rapid screening of samples taken in response to potential contamination events in order to help answer the key question "Is this water safe to drink?"
Securing Water And Wastewater Systems
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Author : Robert M. Clark
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-10-04
Securing Water And Wastewater Systems written by Robert M. Clark and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-04 with Technology & Engineering categories.
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.
Water Quality In Drinking Water Distribution Systems
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Author : Mirjam Blokker
language : en
Publisher: MDPI
Release Date : 2020-12-02
Water Quality In Drinking Water Distribution Systems written by Mirjam Blokker and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-12-02 with Science categories.
Safe drinking water is paramount for the health and wellbeing of all human populations. Water is extracted from surface and groundwater sources and treated to comply with drinking water standards. The water is then circulated through the drinking water distribution system (DWDS). Within the DWDS, water quality can deteriorate due to microbiological growth, chemical reactions, interactions with ageing and deteriorating infrastructure, and through maintenance and repair activities. Some DWDS actions may serve to improve water quality; however, these can adversely impact the drinking water system and cause instances of poor water quality or disease outbreaks. We invited papers covering examinations of DWDS design and operational practices and their impact on water quality. We received papers based on practical research in real DWDS and laboratory test facilities. We also received papers on novel modelling approaches. A wide range of water quality aspects was gathered, including temperature, disinfection, bacterial communities and biofilm, (fecal) contamination and QMRA, and the effects of flushing and intermittent supply.
A Review Of The Epa Water Security Research And Technical Support Action Plan
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Author : National Research Council
language : en
Publisher: National Academies Press
Release Date : 2004-02-09
A Review Of The Epa Water Security Research And Technical Support Action Plan written by National Research Council and has been published by National Academies Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004-02-09 with Nature categories.
The report examines a draft plan, prepared by the Environmental Protection Agency, that identifies critical security issues for drinking water and wastewater and outlines related research and technical support needs. This report recommends increased attention to interagency coordination and encourages additional consideration of current restrictions on secure information dissemination. It further suggests that EPA incorporate the results of their research activities into an integrated water security guidance document to improve support for water and wastewater utilities.
Risk Analysis And Adaptive Response Planning For Water Distribution Systems Contamination Emergency Management
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Author : Amin Rasekh
language : en
Publisher:
Release Date : 2012
Risk Analysis And Adaptive Response Planning For Water Distribution Systems Contamination Emergency Management written by Amin Rasekh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
Drinking water distribution systems (WDSs) hold a particularly critical and strategic position in preserving public health and industrial growth. Despite the ubiquity of this infrastructure, its importance for public health, and increased risk of terrorism, several aspects of emergency management for WDSs remain at an undeveloped stage. A set of methods is developed to analyze the risk and consequences of WDS contamination events and develop emergency response support tools. Monte Carlo and optimization schemes are developed to evaluate contamination risk of WDSs for generation of critical contamination scenarios. A multicriteria optimization approach is proposed that treats likelihood and consequences as independent risk measures to find an ensemble of uniformly-distributed critical scenarios. This approach provides insight into system risk and potential mitigation options not available under maximum risk or maximum consequences analyses. Static multiobjective simulation-optimization schemes are developed for generation of optimal response mechanisms for contamination incidents with twoconflicting objectives of minimization of health consequences and impacts on non-consumptive water uses. Performance of contaminant flushing and containment are investigated. Pressure-driven hydraulic analysis is performed to simulate the complicated system hydraulics under pressure-deficit conditions. Performance of a novel preventive response action? injection of food-grade dye directly into drinking water? for mitigation of health impacts as a contamination threat unfolds is explored. The emergency response is formulated as a multiobjective optimization problem for the minimization of risks to life with minimum false warning and cost. A multiobjective optimization scheme is used for the management of contamination events for diverse contaminant agents without interruption of firefighting. A dynamic modeling scheme is developed that accounts for the time-varying behavior of the system during an emergency. Effects of actions taken by the managers and consumers as well as the changing perceived contaminant source attributes are included in the simulation model to provide a realistic picture of the dynamic environment. A dynamic optimization scheme is coupled with the simulation model to identify and update the optimal response recommendations during the emergency. Machine learning approaches are employed for real-time characterization of contaminant sources and identification of effective response strategies for a timely and effective response to contamination incidents and threats. In contrast to traditional approaches that perform whole analysis after a contamination event occurs, proposed machine learning methods gain system knowledge in advance and use this extracted information to identify contamination attributes after an incident occurs.