Groundwater infiltration, surface water inflow and sewerage exfiltration considering hydrodynamic conditions in sewer systems

Abstract

Sewer systems are closely interlinked with groundwater and surface water. Due to leaks and regular openings in the sewer system (e.g. combined sewer overflow structures with sometimes reverse pressure conditions), groundwater infiltration and surface water inflow as well as exfiltration of sewage take place and cannot be avoided. In the paper a new hydrodynamic sewer network modelling approach will be presented, which includes--besides precipitation--hydrographs of groundwater and surface water as essential boundary conditions. The concept of the modelling approach and the models to describe the infiltration, inflow and exfiltration fluxes are described. The model application to the sewerage system of the City of Dresden during a flood event with complex conditions shows that the processes of infiltration, exfiltration and surface water inflows can be described with a higher reliability and accuracy, showing that surface water inflow causes a pronounced system reaction. Further, according to the simulation results, a high sensitivity of exfiltration rates on the in-sewer water levels and a relatively low influence of the dynamic conditions on the infiltration rates were found.

A Flow-Calibrated Method to Project Groundwater Infiltration into Coastal Sewers Affected by Sea Level Rise

“…Karpf et al [16,19,21] have used a multiregression method to analyze inflow and infiltration (I/I) in Dresden, Germany. A series of 400 WWTP influent hydrographs were used to separate three forms of I/I: groundwater, surface water, and rainwater.…”

“…Planning and management tools are needed to predict increases in GWI and prioritize sanitary sewer rehabilitation. To quantify GWI, researchers have developed various methods, including GWI potential maps [18], fluid mechanics models with infiltration or permeability coefficients [16], and commercial software models [19][20][21][22]. However, these models use a general infiltration or permeability coefficient and do not account for changes in GW head.…”

Groundwater flooding in a river‐connected alluvial aquifer

“…Here we distinguish groundwater flooding via connections to wastewater collection infrastructure from sewer backup, and define the former as shallow groundwater that enters a home via holes or cracks in the wastewater collection system under elevated groundwater pressure, and not by blockage in the wastewater collection system. Complex relationships between groundwater infiltration, surface water inflow, and sewage exfiltration during a flood have been modeled, indicating river stage fluctuations can lead to groundwater flooding, and ultimately overload sewage systems (Cloutier et al, ; Karpf et al, ; Sommer et al, ).…”

Evaluation of defective sewer pipe–induced internal erosion and associated ground deformation using laboratory model test

“…Sewer pipes deteriorate with time, resulting in cracks, fractures and openings that allow soil in the vicinity to migrate into the pipe during ground water infiltration and instantaneous sewer exfiltration processes (Bertrand-Krajewski et al 2006;Cardoso et al 2006;Meguid and Dang 2009;Karpf et al 2011). The continuation of this process over a prolonged period forms a cavity around the defect with an associated low-strength zone, which propagates towards the ground surface with groundwater fluctuation, finally causing a sinkhole (Zheng 2007;Balkaya et al 2012;Guo et al 2013).…”