Modeling Wipe-Induced Blockages of Sewer Pipes

Katayoun Kargar and Darko Joksimovic, Toronto Metropolitan University, ON, Canada


Sewer pipe networks play a crucial role in preserving public health and safety, necessitating their uninterrupted functionality. Various factors contribute to blockages in these networks, ranging from the accumulation of substances like sediments, fats, oils, and grease to intrusion by tree roots, and the buildup of non-biodegradable items such as wet wipes and sanitary products. The advent of the COVID-19 pandemic has further exacerbated the issue, as the improper disposal of wipes into sewers has led to severe blockage problems, resulting in sewer backups, flooding, and overflows. Despite the global prevalence of this problem, there has been a notable lack of research on the hydraulic consequences of blockages caused by the accumulation of wipes and guidelines for modelling such occurrences in sewer systems. To bridge this knowledge gap, an extensive study was conducted, incorporating laboratory experiments that replicated real-world issues related to wipes snagging and accumulating in the presence of sewer defects. The experiments involved creating various degrees of blockages under different flow rates to assess the hydraulic effects, by measuring the resulting increase in water level upstream. Four different numerical modelling approaches to represent such conditions using the Storm Water Management Model (SWMM) were investigated, including adjusting the local head loss coefficient, modifying the Manning's roughness coefficient, filling the pipe section, and employing an orifice. This research not only sheds light on the hydraulic impacts of wipe-induced blockages but also provides valuable guidance for the modelling and representation of such conditions in sewer system asset management.

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