Modelling of groundwater infiltration into sewer systems

Abstract

Groundwater infiltration into urban sewers represents a problem that influences costs and management of technical systems. The hydrodynamic groundwater software MODFLOW is used to analyse the influencing variables of the infiltration processes. Besides the hydraulic conductivity of the soil and the piezometric head in the vicinity of the sewer pipe, properties of the sewer trench, the shape and the size of leaks are important influencing factors. A nonlinear-regression method is applied to develop a one-dimensional approach in accordance with the MODFLOW results and Darcy's law. Monte Carlo simulations and the developed one-dimensional model are used to assess the leak area and the range of pressure loss in the vicinity of the pipe leaks. By additional sensitivity analysis it was found that the infiltration factor and the conductivity of the backfill are very important for the calculation of the leak area.

A coupled discrete element model for the simulation of soil and water flow through an orifice

“…The maximum fluid velocity is 0.006 m/s at 0.01 m away from the orifice into the model, and the Reynolds number can be calculated: R e = ρ f | u f | L pore / μ = 1000 × 0.006 × (0.7 × 0.0015)/0.001 = 6.3. In practical cases, the Darcy's law in Equation is valid as long as the Reynolds number is less than 10 and has been widely used to simulate water flow around the defective pipe .…”

“…The maximum fluid velocity is 0.006 m/s at 0.01 m away from the orifice into the model, and the Reynolds number can be calculated: R e = ρ f |u f |L pore /μ = 1000 × 0.006 × (0.7 × 0.0015)/0.001 = 6.3. In practical cases, the Darcy's law in Equation (1) is valid as long as the Reynolds number is less than 10 [47] and has been widely used to simulate water flow around the defective pipe [48,49]. Guo et al [12] conducted experimental studies of soil erosion around defective sewer pipes, and six tests were performed using the setup with a lateral orifice by changing the water level and sand size.…”

Analysis and integrated modelling of groundwater infiltration to sewer networks

“…Another approach, which we make use of in the present paper, is to simulate groundwater flow and hydraulic head by an advanced numerical groundwater model in order to estimate the potential for infiltration of groundwater to the sewer system. In similar studies, Karpf and Krebs (2013) use the commercial groundwater model MODFLOW (USGS Office of Groundwater, Reston, VA) to simulate the groundwater head while Guo et al (2013) develop an approximate solution for two-dimensional groundwater infiltration to sewer systems. Browne et al (2008) develop a model for simulating intended infiltration to storm water infiltration systems in both saturated and unsaturated zones.…”

Assessment of Causes and Effects of Groundwater Level Change in an Urban Area (Warsaw, Poland)

“…Natural infiltration is modified as a result of land use, and the total balance should include the amount of water from leaks in water supply and sewage networks, which are difficult to estimate. Water loss in numerous underground water systems in Poland and the world is large, and the actual loss varies widely [18]. As much as 60% of distributed water may be lost through leakage from the distribution system [14], and losses in the water system reach, e.g., 18% in Great Britain, 30% in France, 20-34% in Spain and the Czech Republic, 30-60% in Croatia, and as much as 75% in Albania.…”