Sensitivity analysis of some critical factors affecting simulated intrusion volumes during a low pressure transient event in a full-scale water distribution system

Ebacher, Gabrielle; Besner, Marie‐Claude; Clement, B.G.; Prévost, Michèle

doi:10.1016/j.watres.2012.05.006

Cited by 30 publications

(19 citation statements)

References 10 publications

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“…For the events with 1, 10 and 24 h of sustained depressurization, the estimated intrusion volumes through all leak openings were 0.8, 8 and 19 m 3 , respectively. Using the orifice equation, some studies have produced estimates of the intrusion volumes through leakage points for transient PDCs [1,13,22]. The total intrusion volumes resulting from a momentary pump shutdown for different intrusion conditions through leakage orifices and submerged air vacuum valves (AVVs) ranged from 10 to 360 L in the same network [22].…”

Section: Discussionmentioning

confidence: 99%

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Using Nodal Infection Risks to Guide Interventions Following Accidental Intrusion due to Sustained Low Pressure Events in a Drinking Water Distribution System

Hatam

Blokker

Besner³

et al. 2019

Water

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Improving the risk models to include the possible infection risk linked to pathogen intrusion into distribution systems during pressure-deficient conditions (PDCs) is essential. The objective of the present study was to assess the public health impact of accidental intrusion through leakage points in a full-scale water distribution system by coupling a quantitative microbial risk assessment (QMRA) model with water quality calculations based on pressure-driven hydraulic analysis. The impacts on the infection risk of different concentrations of Cryptosporidium in raw sewage (minimum, geometric mean, mean, and maximum) and various durations of intrusion/PDCs (24 h, 10 h, and 1 h) were investigated. For each scenario, 200 runs of Monte Carlo simulations were carried out to assess the uncertainty associated with the consumers’ behavioral variability. By increasing the concentrations of Cryptosporidium in raw sewage from 1 to 560 oocysts/L for a 24-h intrusion, or by increasing the duration of intrusion from 1 to 24 h, with a constant concentration (560 oocysts/L), the simulated number of infected people was increased by 235-fold and 17-fold, respectively. On the first day of the 1-h PDCs/intrusion scenario, a 65% decrease in the number of infected people was observed when supposing no drinking water withdrawals during low-pressure conditions at nodes with low demand available (<5%) compared to no demand. Besides assessing the event risk for an intrusion scenario, defined as four days of observation, the daily number of infected people and nodal risk were also modeled on different days, including during and after intrusion days. The results indicate that, for the case of a 1-h intrusion, delaying the start of the necessary preventive/corrective actions for 5 h after the beginning of the intrusion may result in the infection of up to 71 people.

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Section: Discussionmentioning

confidence: 99%

“…Besides low pressure, the presence of external contamination and pathways are essential for intrusion to occur [21]. Adjusting the presence of potential pathway for intrusion based on the state of decay of the piping has been proposed [22,23].…”

Section: Introductionmentioning

confidence: 99%

Using Nodal Infection Risks to Guide Interventions Following Accidental Intrusion due to Sustained Low Pressure Events in a Drinking Water Distribution System

Hatam

Blokker

Besner³

et al. 2019

Water

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“…In Russia, centralized water supply systems which are used to supply drinking water to consumers require urgent improvement [1]. Even if water purification is qualitative, there is still a possibility that infectious agents can penetrate water supply networks, for example, when water distribution systems are worn out, or in case of a damage done to water pipelines [2,3]. Cases of acute enteric infections caused by infectious agents caught from water haven't been examined sufficiently due to epidemiologic analysis insensitivity and absence of research that allows to establish a direct correlation between drinking water contamination and a growth in sporadic incidence [4,5].…”

mentioning

confidence: 99%

“…Exposure was assessed on the basis of openly published research results 4 [9,10]. To assess probability of catching rotavirus and enterovirus infections, we applied "dose -response" exponential relationship model calculated as per the following formula (2): Р infection probability = 1 -exp (-dose * k), (2) where k quotient amounted to 0.00374 for enterovirus [22]; 0.173 [9], for rotavirus.…”

mentioning

confidence: 99%

On quantitative assessment of microbe risk caused by exposure to enteric viruses in drinking water

Baydakova¹,

Unguryanu²,

Mikhailova³

2019

Health Risk Analysis

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The authors assessed microbiological risks of acute intestinal infections (AII) with viral etiology caused by drinking water taken from centralized water supply systems among overall urban population in Arkhangelsk region over [2006][2007][2008][2009][2010][2011][2012][2013][2014][2015][2016][2017]. The research was performed with Quantitative Microbial Risk Assessment (QMRA) procedure. It was revealed that acute intestinal viral infections prevailed among intestinal infections; the most widely spread ones were rotavirus infection (86.9%), norovirus infection (7.7%), and enterovirus infection (3.7%). The authors also performed comparative analysis of spatial distribution and long-term dynamics of incidence with AII which were possibly caused by infectious agents entering a body with water. The analysis revealed that rotavirus and norovirus infections frequently occurred in Arkhangelsk, Novodvinsk, Koryazhma, and Kotlas. Incidence with rotavirus infection among population in Koryazhma and Arkhangelsk grew 1.5-1.6 times faster than epidemiological processes on the reference territory. Coliphages contents were equal to Р 95 in drinking water taken from centralized water supply systems in Arkhangelsk and Koryazhma, and it was 1.4 and 2.2 times higher respectively than the hygienic standard. Rotavirus, norovirus, and enterovirus infections were highly likely to occur in and rotavirus infection, in Koryazhma (R=0.95). Average probability of norovirus infection (R=0.58) and enterovirus infection (R=0.43) was detected in Koryazhma. The research results indicate that Quantitative Microbial Risk Assessment (QMRA) procedure is feasible and significant within the system of sanitary-epidemiologic surveillance over water treatment; it substantiates the necessity to create and implement virology monitoring over centralized drinking water supply.

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“…Recent estimates of intrusion volumes based on transient modeling work (Ebacher et al, 2012) have shown that flooded air vacuum valve (AVV) chambers expose the distribution system to a significant contamination risk under negative‐pressure conditions because untreated water above the AVV outlet orifice can be drawn into the distribution system during negative‐pressure episodes. AVVs are large‐orifice air valves, designed to exhaust large quantities of air when pipes are filling and to allow air to enter the distribution system if negative pressures take place.…”

mentioning

confidence: 99%

Submerged appurtenances and pipelines: An assessment of water levels and contaminant occurrence

2013

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Submerged air vacuum valves and pipe leaks are potential entry points of contaminated water into drinking water distribution systems under low‐pressure conditions. Water levels in 20 valve vaults and 17 groundwater wells were monitored weekly for 8 months. The assembled data set indicated that water mains and air vacuum valves were commonly submerged in the investigated system. Urban runoff was found to be the dominant source of flooding in 11 of the 16 vaults containing water. A subset of 14 vaults and 10 piezometers were sampled for microbial and chemical parameters. Concentrations of chemical contaminants generally did not exceed drinking water standards. However, high counts of microbial fecal indicators were detected in numerous vaults. Runoff volumes of up to 255 L/mm of rainfall were found to enter a tested vault, and runoff water was identified as the main source of pesticides, personal care products, microbial fecal indicators, and hydrocarbons in vaults.

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Sensitivity analysis of some critical factors affecting simulated intrusion volumes during a low pressure transient event in a full-scale water distribution system

Cited by 30 publications

References 10 publications

Using Nodal Infection Risks to Guide Interventions Following Accidental Intrusion due to Sustained Low Pressure Events in a Drinking Water Distribution System

Using Nodal Infection Risks to Guide Interventions Following Accidental Intrusion due to Sustained Low Pressure Events in a Drinking Water Distribution System

On quantitative assessment of microbe risk caused by exposure to enteric viruses in drinking water

Submerged appurtenances and pipelines: An assessment of water levels and contaminant occurrence

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