scholarly journals Estimation of combined sewer overflow discharge: a software sensor approach based on local water level measurements

2016 ◽  
Vol 74 (11) ◽  
pp. 2683-2696 ◽  
Author(s):  
Malte Ahm ◽  
Søren Thorndahl ◽  
Jesper E. Nielsen ◽  
Michael R. Rasmussen
Keyword(s):  
Mass Balance ◽  
Water Level ◽  
Drainage System ◽  
Urban Drainage ◽  
Combined Sewer Overflow ◽  
Software Sensor ◽  
Flow Measurements ◽  
Combined Sewer ◽  
Sewer Overflow ◽  
Local Water

Combined sewer overflow (CSO) structures are constructed to effectively discharge excess water during heavy rainfall, to protect the urban drainage system from hydraulic overload. Consequently, most CSO structures are not constructed according to basic hydraulic principles for ideal measurement weirs. It can, therefore, be a challenge to quantify the discharges from CSOs. Quantification of CSO discharges are important in relation to the increased environmental awareness of the receiving water bodies. Furthermore, CSO discharge quantification is essential for closing the rainfall-runoff mass-balance in combined sewer catchments. A closed mass-balance is an advantage for calibration of all urban drainage models based on mass-balance principles. This study presents three different software sensor concepts based on local water level sensors, which can be used to estimate CSO discharge volumes from hydraulic complex CSO structures. The three concepts were tested and verified under real practical conditions. All three concepts were accurate when compared to electromagnetic flow measurements.

Correlation of combined sewer overflow reduction due to real-time control and resulting effect on the oxygen concentration in the river

1998 ◽  
Vol 37 (12) ◽  
pp. 69-76 ◽  
Author(s):  
W. Rauch ◽  
P. Harremoës
Keyword(s):  
Real Time ◽  
Oxygen Concentration ◽  
Drainage System ◽  
Performance Criteria ◽  
Combined Sewer Overflow ◽  
Real Time Control ◽  
Time Control ◽  
Resulting Effect ◽  
Combined Sewer ◽  
Sewer Overflow

Real-time control of the sewer system is a frequently applied measure for the abatement of pollution caused by urban runoff in the receiving water. Although the goal is an improvement of the water quality the actual aim of real-time control is usually formulated as the reduction/avoidance of combined sewer overflow. However, testing a virtual drainage system by means of a three-month rain series, hardly any correlation between the combined sewer overflow reduction and the resulting effect on the oxygen concentration in the river has been found. The efficiency of real-time control for pollution abatement by means of artificial performance criteria has to be doubted.

scholarly journals Probabilistic modelling of combined sewer overflow using the First Order Reliability Method

2008 ◽  
Vol 57 (9) ◽  
pp. 1337-1344 ◽  
Author(s):  
S. Thorndahl ◽  
K. Schaarup-Jensen ◽  
J. B. Jensen
Keyword(s):  
Statistical Characteristics ◽  
Urban Drainage ◽  
Combined Sewer Overflow ◽  
Parameter Uncertainties ◽  
First Order Reliability Method ◽  
First Order ◽  
Reliability Method ◽  
Combined Sewer ◽  
Model Mouse ◽  
Sewer Overflow

This paper presents a new and alternative method (in the context of urban drainage) for probabilistic hydrodynamical analysis of drainage systems in general and especially prediction of combined sewer overflow. Using a probabilistic shell it is possible to implement both input and parameter uncertainties on an application of the commercial urban drainage model MOUSE combined with the probabilistic First Order Reliability Method (FORM). Applying statistical characteristics on several years of rainfall, it is possible to derive a parameterization of the rainfall input and the failure probability and return period of combined sewer overflow to receiving waters can be found.

Combined sewer overflow over an oblique weir at Rat Creek in Edmonton, Alberta

2010 ◽  
Vol 37 (3) ◽  
pp. 477-488
Author(s):  
Elizabeth Valentine ◽  
Kurt Kronebusch ◽  
David Z. Zhu ◽  
N. Rajaratnam ◽  
Sid Lodewyk ◽  
...  
Keyword(s):  
Urban Drainage ◽  
Combined Sewer Overflow ◽  
Rating Curve ◽  
Flow Conditions ◽  
Sewer System ◽  
Sewer Systems ◽  
Model Study ◽  
Combined Sewer ◽  
Sewer Overflow

Oblique weirs are commonly used in urban drainage systems to remove excess flow from a sewer, in particular, a combined sewer system that has limited conveyance capacity. It is important to understand the hydraulics of these weirs to properly monitor the amount of the overflows as well as to design and improve sewer systems. The Rat Creek structure in Edmonton, Alberta, is a combined sewer overflow structure with a weir at an oblique alignment to the centerline of the sewer. A physical model study of the structure was conducted. The results show that both the approach flow conditions and the chamber geometry can significantly affect the hydraulic performance of the weir and invalidate the application of standard weir equations. A unique flow regime with a linear head–discharge rating curve was observed. The effects of modifying the weir and the hanging baffle wall downstream of the weir were also studied and reported. The results of this case study help to improve the understanding of the hydraulics of oblique weirs in sewer systems.

Monitoring of Combined Sewer Overflow Tanks: Results of 500 Years of Measurement Records

2006 ◽  
Vol 1 (1) ◽  
Author(s):  
G. Weiss ◽  
H. Brombach ◽  
Ch. Wöhrle
Keyword(s):  
State Of The Art ◽  
Combined Sewer Overflow ◽  
Hydrological Data ◽  
Level Measurement ◽  
Combined Sewer ◽  
Simulation Results ◽  
Sewer Overflow ◽  
Local Water ◽  
And Performance ◽  
Basic Features

In Germany, today about 24,000 combined sewer overflow tanks (CSO tanks) are in operation. For their dimensioning and design, German standards are available and respected. However, efficiency and performance of these costly structures are usually not known by the operator nor by the local water authority. Thus, a trend towards monitoring the overflow activity is observed. This paper points out the state-of-the-art in CSO overflow monitoring. Basic features of water level measurement as well as some plausibility checks for the data are shown. Evaluation of overflow data is rather difficult. Assessment of the overflow activity versus hydrological data, e.g. by comparison with simulation results, is costly. A much simpler way of evaluation is the ranking and rating of measured overflow activity. On the 8th ICUD 1999, already a paper on this subject was presented. Now, 6 years later, the database of the ranking has grown to more than 500 years of measurement.

Estimating inflow to a combined sewer overflow structure with storage tank in real time: evaluation of different approaches

2014 ◽  
Vol 70 (7) ◽  
pp. 1143-1151 ◽  
Author(s):  
G. Leonhardt ◽  
M. D'Oria ◽  
M. Kleidorfer ◽  
W. Rauch
Keyword(s):  
Water Level ◽  
Bayesian Approach ◽  
Measurement Errors ◽  
Combined Sewer Overflow ◽  
Online Application ◽  
Storage Model ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Sewer Overflow ◽  
The Bayesian Approach

The performance assessment of storage tanks and combined sewer overflow (CSO) structures in sewer systems requires knowledge of the total inflow from the catchment during rainfall events. Many structures are, however, only equipped with sensors to measure water level and/or outflows. Based on the geometry of the tank, expressed as a level-storage relationship, inflow can be calculated from these data using a simple conceptual storage model. This paper compares a deterministic and a Bayesian approach for estimating the inflow to a CSO structure from measurements of outflows and water level. The Bayesian approach clearly outperforms the deterministic estimation which is very sensitive to measurement errors. Although computationally more demanding, the use of a simple linear storage model allows the online application of the Bayesian approach to repeatedly estimate inflow in short time intervals of a few minutes. The method could thus be used as an online software sensor for inflow to storage structures in sewer systems.

scholarly journals Alternatives how to mitigate urban flooding and CSO in urbanized areas used in European cities and towns

2021 ◽  
Vol 1209 (1) ◽  
pp. 012017
Author(s):  
M Csóka ◽  
G Rózsa ◽  
I Marko ◽  
Š Stanko
Keyword(s):  
Green Infrastructure ◽  
Urban Areas ◽  
Slovak Republic ◽  
Drainage System ◽  
Urban Flooding ◽  
Combined Sewer Overflow ◽  
Real Time Control ◽  
Urban City ◽  
Combined Sewer ◽  
Sewer Overflow

Abstract Urban flooding and combined sewer overflow in city, or town areas represents potential risk in environmental, economic, or social aspects. The goal of this study is to process and evaluate efficiency of individual solutions to reduce occurrence of flooding in urban areas caused by intense rainfall events. The known conventional solutions are stormwater chambers, or storage drains. The new trend in reduction of stormwater drainage into combined sewer system are parts of blue-green infrastructure. Blue-green infrastructure represents environmental urban infrastructure which consists of sensitively selected urban vegetation combined with ingenious hydrological elements of urban city drainage. The study also deals with experimental usage of decentralized real time control, based on a gossip-based algorithm of moveable gates in sewage network. Experiment was proposed for drainage system of the city of Cosenza in Italy. Evaluation will assess application value of individual proposed solutions for the reduction of combined sewer overflow for Slovak republic and its urban cities, or towns.

Experience with Vortex Separators for Combined Sewer Overflow Control

1993 ◽  
Vol 27 (5-6) ◽  
pp. 93-104 ◽  
Author(s):  
H. Brombach ◽  
C. Xanthopoulos ◽  
H. H. Hahn ◽  
W. C. Pisano
Keyword(s):  
Separation Efficiency ◽  
Operational Reliability ◽  
Second Phase ◽  
Combined Sewer Overflow ◽  
Specific Storage ◽  
Impervious Area ◽  
Evaluation Phase ◽  
Combined Sewer ◽  
Sewer Overflow ◽  
Overflow Control

In 1987 the first vortex solids separator facility in Germany was installed for combined sewer overflow (CSO) control. The separation efficiency was optimized in the hydraulic laboratory using scaled down models with artificial tracers to simulate typical sewage particulates. The station has two parallel operating vortex separators and serves a connected and impervious area of about 11 hectares (ha) and 1,500 people. The specific storage volume of the station is 7.2 m3 per ha. Two evaluation programs were conducted. The first evaluation phase noted the operational reliability, hydraulic loads, overflow frequencies and water mass balances. The second phase monitored separation efficiencies. The evaluation showed that vortex solids separators are now ready for use in CSO control.

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