The reliability of sediment transport predictions in sewers: influence of hydraulic and morphological uncertainties

Banasiak, Robert; Tait, Simon

doi:10.2166/wst.2008.297

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…Solids transport and deposited bed erosion/deposition processes in gravity sewers are extremely complex due to the interactions between numerous solids classes, variable inflow volumes, and the large scales of urban sewer systems [1]. However, sewer designers and operators still attempt to model these complicated processes to prevent excess solids deposition, which can result in a reduced sewer hydraulic capacity, increased pollution from combined sewer overflows (CSOs), and an increased number of sewer blockages [2].…”

Section: Introductionmentioning

confidence: 99%

SewerSedFoam: A Model for Free Surface Flow, Sediment Transport, and Deposited Bed Morphology in Sewers

Murali

Hipsey

Ghadouani

et al. 2020

Water

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This paper aims to bridge the gap in the detailed modelling of flow and sediment process interactions in sewers through the development of a computational fluid dynamics (CFD) model. It draws on previous models developed for surface water sediment transport in the OpenFOAM CFD framework and builds on them to improve their suitability for sewer sediment processes. Three distinct sediment processes, suspended sediment transport, bedload transport, and deposited bed morphology, are incorporated into a free surface flow solver, interFoam. This sewer sediment model, called SewerSedFoam, models the impacts of sediment deposition and erosion on flow velocity by using dynamic mesh deformation to capture the movement of the deposited bed and its morphology. Further, three sediment classes, two suspended and one bedload sediment, can be modelled along with some bed stabilization and consolidation effects during deposition and erosion, respectively. The functionality of the overall model in modelling sewer sediment deposition and erosion is promising, although the validation of a large magnitude sediment erosion event has been limited by the availability of granular data in existing case studies.

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Section: Introductionmentioning

confidence: 99%

SewerSedFoam: A Model for Free Surface Flow, Sediment Transport, and Deposited Bed Morphology in Sewers

Murali

Hipsey

Ghadouani

et al. 2020

Water

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“…In the case of nuclear engineering, for example, it is not known whether such flows are likely to affect the radiative environment in terms of heat formation and radiochemical interactions with the conduit materials. In the case of civil engineering, it is equally unclear whether bedforms may hinder the ability of waste and run-off water systems to function efficiently (Banasiak and Tait, 2008;Banasiak and Verhoeven, 2008;Lange and Wichern, 2013;Matoušek ;Skipworth et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

The influence of relative fluid depth on initial bedform dynamics in closed, horizontal pipe flow

Rice

Fairweather

Hunter

et al. 2017

International Journal of Multiphase Flow

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Particle bed depth in horizontal pipe flow measured with acoustic backscatter.  Evolution of bedforms over time observed and categorized into five types.  Bedform type influenced by initial flow rate, relative fluid depth.  Observed bedform evolution supports distinct ripple and dune modes.  Universal scalings for pipe, channel and environmental flows proposed.

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“…In studies on the erosion of in-sewer sediment, and concluded that microbiological activity had an effect on the strength of sewer sediment bed. and Banasiak and Tait (2008), also concluded that biochemical properties and changes in deposit composition are of importance in sediment transport behaviour.…”

Section: Biological Transformation Process Effectsmentioning

confidence: 94%

“…Reactions regarding biological transformation processes with sewer sediments have been previously studied Banasiak et al, , 2008. These previous researchers conclude that biochemical properties and changes in the deposit composition are of importance and affect the sediment transport behaviour.…”

Section: Initial Studies On the Effects Of The Biodegradability Of Th...mentioning

confidence: 99%

“…The low accuracy achieved is basically related with the differences in nature and behaviour of the sediments, and dynamics of the flow in a sewer network. The transformation processes because the cohesive nature that the sewer sediment generally exhibits in highly dense and impervious urban areas, together with interactions between particles and microbiological activity (see Chapter 4, Section 4.3.3) can have also a significant influence on the in-pipe deposits behaviour regarding resistance to erosion Banasiak and Tait, 2008;.…”

Section: Overview On the Sediment Release And Transport Of Sewer Sedi...mentioning

confidence: 99%

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In-sewer organic sediment transport : study of the release of sediments during wet-weather from combined sewer systems in the Mediterranean region in Spain

Seco

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The accumulation of sediments in combined sewer systems may give rise to significant quality problems, which sometimes are overlooked. Solids deposited in the network may lead to more frequent overflows into natural waters, where are often discharged without treatment during the beginning of storms events. When organic solids, released from in-sewer deposits, reach natural receiving waters, may produce serious impacts. Waters environments are degraded due mainly to the high oxygen biochemical demand, the ammonia contribution and other pollutants. This study focuses on the release of highly-organic sediments having being accumulated inside a combined sewer network. After prolonged dry-periods, typical in Mediterranean region, sediments are re-suspended and conveyed when storm runoff appears. The aim of the research is to develop a methodology able to predict their potential erosion and subsequent mobilization through the network. To achieve that goal, it is needed to improve the knowledge on the processes occurring during long dry-periods, and analyse the variables involved that might affect the erodibility of the deposits. To achieve reliable results in water quality modelling, it is essential the availability of consistent and detailed field data. Highly-organic non-homogeneous sediment samples collected from a combined sewer system were used for the laboratory assessment of the characteristics and the behaviour regarding erosion. Varying strength of the bed with depth allow for a more appropriate representation of the movement of solids in sewerage by introducing in the model a more realistic behaviour. The results obtained have shown that the prediction of organic sediment mobilization and transport is complex but possible to accomplish. However, more effort is needed to ensure the transferability of the results for a more general application of the predictive model obtained. This research has mainly contributed in a more detailed knowledge of the organic sediment bed structure regarding strength to erosion. The acquired knowledge can be applied for improvements in the prediction of pollutant loads that can reach watercourses, pursuing the receiving waters protection as a final goal. Los depósitos de sedimentos en sistemas unitarios de alcantarillado pueden dar lugar a importantes problemas de calidad de aguas, muchas veces ignorados. La acumulación de sedimentos en estos sistemas puede generar el aumento en la frecuencia de vertidos a medios naturales receptores durante una tormenta. La presencia de sólidos de origen orgánico en los vertidos de aguas sin tratar puede producir impactos perjudiciales en las aguas receptoras. Los medioambientes acuáticos son afectados principalmente por las altas demandas de oxígeno y las contribuciones de nitrógeno originados en los sedimentos orgánicos. Este estudio se centra en los procesos de re-suspensión de sedimentos altamente orgánicos que se han acumulado en las redes de alcantarillado unitario. Luego de largos períodos secos típicos en la región Mediterránea, los depósitos de sedimentos son re-movilizados y transportados a través del sistema por la escorrentía producida por una tormenta. El objetivo de la investigación es desarrollar una metodología que sea capaz de predecir el potencial de erosión y posterior movilización de los sedimentos orgánicos a través del sistema. Para ello, es necesario mejorar el conocimiento que se tiene sobre los procesos que ocurren durante largos períodos sin lluvias y analizar las variables involucradas que puedan influir en la erosión de los depósitos. Contar con la disponibilidad de datos de campo confiables es esencial en el logro de resultados válido en un modelo de calidad de aguas. Muestras de sedimento no homogéneo y altamente orgánico se recogieron en un sistema de alcantarillado unitario. A través de ensayos en laboratorio, estos sedimentos se utilizaron para la evaluación de sus características y comportamiento vinculado a la erosión. La introducción en el modelo de una ley de tensión crítica de arrastre más realista permite una mejor representación de la movilización de los sedimentos. Los resultados obtenidos muestran que la predicción del transporte de sedimentos orgánicos de alcantarillado es posible de realizar aunque es un tema muy complejo. Mayores esfuerzos son aún necesarios para lograr la transferencia directa de los resultados para una aplicación más generalizada del modelo predictivo obtenido. Una de las principales contribuciones de esta investigación está vinculada al logro de un conocimiento más detallado de la estructura de los depósitos de sedimento orgánico en relación a su resistencia a la erosión. El conocimiento adquirido podría ser aplicado en la mejora en las predicciones de cargas contaminantes que llegan a cursos de agua naturales durante vertidos. Todo ello, siguiendo como objetivo final, la protección de las aguas naturales receptoras.

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The reliability of sediment transport predictions in sewers: influence of hydraulic and morphological uncertainties

Cited by 9 publications

References 19 publications

SewerSedFoam: A Model for Free Surface Flow, Sediment Transport, and Deposited Bed Morphology in Sewers

SewerSedFoam: A Model for Free Surface Flow, Sediment Transport, and Deposited Bed Morphology in Sewers

The influence of relative fluid depth on initial bedform dynamics in closed, horizontal pipe flow

In-sewer organic sediment transport : study of the release of sediments during wet-weather from combined sewer systems in the Mediterranean region in Spain

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