scholarly journals Managing risks from virus intrusion into water distribution systems due to pressure transients

2011 ◽  
Vol 9 (2) ◽  
pp. 291-305 ◽  
Author(s):  
Jian Yang ◽  
Mark W. LeChevallier ◽  
Peter F. M. Teunis ◽  
Minhua Xu
Keyword(s):  
Viral Infection ◽  
Negative Pressure ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution Systems ◽  
Quantitative Microbial Risk Assessment ◽  
Pressure Transients ◽  
Negative Pressure Transients ◽  
Negative Pressures

Low or negative pressure transients in water distribution systems, caused by unexpected events (e.g. power outages) or routine operation/maintenance activities, are usually brief and thus are rarely monitored or alarmed. Previous studies have shown connections between negative pressure events in water distribution systems and potential public health consequences. Using a quantitative microbial risk assessment (QMRA) model previously developed, various factors driving the risk of viral infection from intrusion were evaluated, including virus concentrations external to the distribution system, maintenance of a disinfectant residual, leak orifice sizes, the duration and the number of nodes drawing negative pressures. The most sensitive factors were the duration and the number of nodes drawing negative pressures, indicating that mitigation practices should be targeted to alleviate the severity of low/negative pressure transients. Maintaining a free chlorine residual of 0.2 mg/L or above is the last defense against the risk of viral infection due to negative pressure transients. Maintaining a chloramine residual did not appear to significantly reduce the risk. The effectiveness of ensuring separation distances from sewer mains to reduce the risk of infection may be system-specific. Leak detection/repair and cross-connection control should be prioritized in areas vulnerable to negative pressure transients.

scholarly journals Modelling both the continual erosion and regeneration of discolouration material in drinking water distribution systems

2013 ◽  
Vol 14 (1) ◽  
pp. 81-90 ◽  
Author(s):  
W. R. Furnass ◽  
R. P. Collins ◽  
P. S. Husband ◽  
R. L. Sharpe ◽  
S. R. Mounce ◽  
...  
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Transport Model ◽  
Water Distribution Systems ◽  
Sensitivity Analyses ◽  
Drinking Water Distribution Systems ◽  
Proactive Management ◽  
Drinking Water Distribution ◽  
Mass Transport Model

The erosion of the cohesive layers of particulate matter that causes discolouration in water distribution system mains has previously been modelled using the Prediction of Discolouration in Distribution Systems (PODDS) model. When first proposed, PODDS featured an unvalidated means by which material regeneration on pipe walls could be simulated. Field and laboratory studies of material regeneration have yielded data that suggest that the PODDS formulations incorrectly model these processes. A new model is proposed to overcome this shortcoming. It tracks the relative amount of discolouration material that is bound to the pipe wall over time at each of a number of shear strengths. The model formulations and a mass transport model have been encoded as software, which has been used to verify the model's constructs and undertake sensitivity analyses. The new formulations for regeneration are conceptually consistent with field and laboratory observed data and have potential value in the proactive management of water distribution systems, such as evaluating change in discolouration risk and planning timely interventions.

scholarly journals An Approach to Estimating Water Quality Changes in Water Distribution Systems Using Fault Tree Analysis

Resources ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 162 ◽  
Author(s):  
Barbara Tchórzewska-Cieślak ◽  
Katarzyna Pietrucha-Urbanik ◽  
Dorota Papciak
Keyword(s):  
Water Supply ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Fault Tree ◽  
Water Distribution Systems ◽  
Fault Tree Analysis ◽  
Quality Changes ◽  
The Stability ◽  
Water Treatment Station

Given that a consequence of a lack of stability of the water in a distribution system is increased susceptibility to secondary contamination and, hence, a threat to consumer health, in the work detailed here we assessed the risk of such a system experiencing quality changes relating to the biological and chemical stability of water intended for drinking. Utilizing real operational data from a water treatment station, the presented analysis of the stability was performed based on the fault tree method. If they are to protect their critical-status water supply infrastructure, water supply companies should redouble their efforts to distribute stable water free of potentially corrosive properties. To that end, suggestions are made on the safeguarding of water distribution systems, with a view to ensuring the safety of operation and the long-term durability of pipes.

scholarly journals The potential for health risks from intrusion of contaminants into the distribution system from pressure transients

2003 ◽  
Vol 1 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Mark W. LeChevallier ◽  
Richard W. Gullick ◽  
Mohammad R. Karim ◽  
Melinda Friedman ◽  
James E. Funk
Keyword(s):  
Health Risks ◽  
Negative Pressure ◽  
Distribution System ◽  
High Speed ◽  
Distribution Systems ◽  
Transient Pressure ◽  
Pressure Transients ◽  
Data Loggers ◽  
Human Viruses ◽  
Treated Drinking Water

The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.

scholarly journals Development of Multi-Objective Optimal Redundant Design Approach for Multiple Pipe Failure in Water Distribution System

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 553 ◽  
Author(s):  
Young Choi ◽  
Joong Kim
Keyword(s):  
Optimal Design ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Search Algorithm ◽  
Harmony Search ◽  
Water Distribution Systems ◽  
Design Approach ◽  
Pipe Failure ◽  
Multi Objective

This study proposes a multi-objective optimal design approach for water distribution systems, considering mechanical system redundancy under multiple pipe failure. Mechanical redundancy is applied to the system’s hydraulic ability, based on the pressure deficit between the pressure requirements under abnormal conditions. The developed design approach shows the relationships between multiple pipe failure states and system redundancy, for different numbers of pipe-failure conditions (e.g., first, second, third, …, tenth). Furthermore, to consider extreme demand modeling, the threshold of the demand quantity is investigated simultaneously with multiple pipe failure modeling. The design performance is evaluated using the mechanical redundancy deficit under extreme demand conditions. To verify the proposed design approach, an expanded version of the well-known benchmark network is used, configured as an ideal grid-shape, and the multi-objective harmony search algorithm is used as the optimal design approach, considering construction cost and system mechanical redundancy. This optimal design technique could be used to propose a standard for pipe failure, based on factors such as the number of broken pipes, during failure condition analysis for redundancy-based designs of water distribution systems.

Prediction of chlorine and trihalomethanes concentration profile in bulk drinking water distribution systems from laboratory data

2003 ◽  
Vol 3 (1-2) ◽  
pp. 239-246 ◽  
Author(s):  
G. Kastl ◽  
I. Fisher ◽  
V. Jegatheesan ◽  
J. Chandy ◽  
K. Clarkson
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Laboratory Data ◽  
Water Distribution Systems ◽  
Optimum Level ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Chlorine Decay

Nearly all drinking water distribution systems experience a “natural” reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the “optimum level”, considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne’s Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water’s Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.

Risk Assessment Modeling for Water Distribution Systems in Mega Cities

2013 ◽  
Vol 353-356 ◽  
pp. 2957-2960
Author(s):  
Jia Sun ◽  
Guo Ping Yu
Keyword(s):  
Risk Assessment ◽  
Land Subsidence ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Assessment Model ◽  
Strategic Decision ◽  
Mega Cities

In study of a series of damages to water distribution systems caused by urban land subsidence, risk assessment modeling is necessary for risk management especially in Mega-cities. First of all, the Catastrophe Theory was employed to analyze the Catastrophe mechanism, and a function catastrophe simulation model was established accordingly to get the vulnerability index of water distribution system. Secondly, risk entropy model was used to analyze the risk of pipe network suffering the land subsidence with the disorder and uncertainty features according to risk theory. Finally, to get the risk index the water distribution system of Guangzhou city was taken to the risk assessment model utilizing the level of land subsidence identified by the dimensional analytical method. The results showed that the risk of land subsidence under the city water distribution system security upgrade is feasible to provide a risk assessment of the strategic decision-making model.

scholarly journals Using real options for an eco-friendly design of water distribution systems

2014 ◽  
Vol 17 (1) ◽  
pp. 20-35 ◽  
Author(s):  
João Marques ◽  
Maria Cunha ◽  
Dragan A. Savić
Keyword(s):  
Real Options ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
System Development ◽  
Water Distribution Systems ◽  
Distribution Networks ◽  
Embodied Energy ◽  
Real Options Approach ◽  
Materials Used

This paper presents a real options approach to handling uncertainties associated with the long-term planning of water distribution system development. Furthermore, carbon emissions associated with the installation and operation of water distribution networks are considered. These emissions are computed by taking an embodied energy approach to the different materials used in water networks. A simulated annealing heuristic is used to optimise a flexible eco-friendly design of water distribution systems for an extended life horizon. This time horizon is subdivided into different time intervals in which different possible decision paths can be followed. The proposed approach is applied to a case study and the results are presented according to a decision tree. Lastly, some comparisons and results are used to demonstrate the quality of the results of this approach.

scholarly journals Analisis Sistem Distribusi Air Bersih di Perumahan Ciomas Permai Kabupaten Bogor Jawa Barat

2021 ◽  
Vol 6 (2) ◽  
pp. 107-120
Author(s):  
Kiki Rizky Fauziah ◽  
Nora Pandjaitan ◽  
Titiek Ujianti Karunia
Keyword(s):  
Data Analysis ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Distribution System ◽  
Water Distribution Systems ◽  
Secondary Data ◽  
Clean Water ◽  
Customer Requirements

Water distribution systems are often problematic in terms of quantity, pressure, continuity and quality. The research aimed to analyze water distribution system of PDAM Tirta Kahuripan Kabupaten Bogor in Ciomas Permai Residence. The research was conducted by collecting primary and secondary data. Analysis of clean water distribution system was carried out using the EPANET 2.0. Ciomas Permai Residence was located in zone 6 of PDAM Tirta Kahuripan servive areas. The result showed that the quality of the distributed water was in accordance with the applicable standard and continuous for 24 hours even though there were significant discharge differences during peak hours. Based on the measurement on Sunday and Monday, the minimum discharge were 14.4 l/sec and 13.8 l/sec respectively, higher than customer requirements of 7.34 l/sec, The water distribution pressure ranged from 0.7 - 1.35 bar. The result of clean water distribution simulation using EPANET 2.0 showed that the velocity of water and headloss were not accordance with the applicable standards.

scholarly journals Proposed probabilistic models of pipe failure in water distribution system

2018 ◽  
Vol 193 ◽  
pp. 02002
Author(s):  
Thi Minh Lanh Pham ◽  
Hai Ha Pham ◽  
Nguyen Anh Thu Do ◽  
Dinh Hong Le
Keyword(s):  
Water Supply ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Unit Length ◽  
Water Distribution Systems ◽  
Labor Cost ◽  
Experimental Models ◽  
Pipe Failure ◽  
Tree Model

All pipes in water supply network are installed underground, so it is difficult to identify pipe failure location during the operation of a system. Prediction of the risk of pipe failure in the water distribution systems is necessary for preparation of reparations and displacement of a pipe network system. Based on the probability of pipe failure, it will be possible to save money and labor cost for water supply companies. Many studies have been conducted on this topic, some of which used experimental models, others used statistical models in which recently many authors used regression model, but almost all the models come up with calculating the pipe failure rate per unit length of pipe in a year. It is not a direct probability of pipe failure. This article reviews various methods to evaluate pipe failure in water distribution systems. Based on that, the authors proposed two models: Regression Logistic Model and Decision Tree Model that would support an effective decision making for detecting the pipe failure and proposing appropriate solutions.

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