<  Back to the Polytechnique Montréal portal

Using nodal infection risks to guide interventions following accidental intrusion due to sustained low pressure events in a drinking water distribution system

Fatemeh Hatam, Mirjam Blokker, Marie-Claude Besner, Gabrielle Ebacher and Michèle Prévost

Article (2019)

[img]
Preview
Published Version
Terms of Use: Creative Commons Attribution .
Download (6MB)
Cite this document: Hatam, F., Blokker, M., Besner, M.-C., Ebacher, G. & Prévost, M. (2019). Using nodal infection risks to guide interventions following accidental intrusion due to sustained low pressure events in a drinking water distribution system. Water, 11(7). doi:10.3390/w11071372
Show abstract Hide abstract

Abstract

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 di�erent 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.

Uncontrolled Keywords

QMRA; sustained pressure drops; accidental intrusion; infection risk fromCryptosporidium; pressure-driven hydraulic analysis

Open Access document in PolyPublie
Subjects: 1000 Génie civil > 1000 Génie civil
1500 Génie de l'environnement > 1500 Génie de l'environnement
1500 Génie de l'environnement > 1501 Qualité de l'eau, pollution
Department: Département des génies civil, géologique et des mines
Research Center: CIEP - Chaire industrielle en eau potable
Funders: NSERC Industrial Chair on Drinking Water / Chaire industrielle CRSNG en eau potable
Date Deposited: 05 Jul 2022 11:57
Last Modified: 06 Jul 2022 01:20
PolyPublie URL: https://publications.polymtl.ca/4936/
Document issued by the official publisher
Journal Title: Water (vol. 11, no. 7)
Publisher: MDPI
Official URL: https://doi.org/10.3390/w11071372

Statistics

Total downloads

Downloads per month in the last year

Origin of downloads

Dimensions

Repository Staff Only