Sewer Sediment and its Relation with the Quality Characteristics of Combined Sewer Flows

1990 ◽  
Vol 22 (10-11) ◽  
pp. 247-257 ◽  
Author(s):  
M. Verbanck
Keyword(s):  
Suspended Solids ◽  
Particulate Material ◽  
Main Trunk ◽  
Rainfall Events ◽  
Combined Sewer ◽  
First Results ◽  
Sandy Material ◽  
Complex Phenomena ◽  
Pollution Emissions ◽  
Dry Weather Flow

Combined sewer lines in the centre of Brussels are laid at very slack gradients, resulting during dry-weather in a systematic deficit of the load of particulate material at the outlet. The first results of a data collection programme are documented, with regard to the influence of in-sewer deposits upon pollution emissions. The monitoring of suspended solids load in the Main Trunk showed the extent of sediment deposition/resuspension processes in the system. Over a long period of time, the accumulation of deposits on sewer inverts is clearly noticeable. The total volume of deposition in the network also appears to be much more influenced by rainfall events than by human sewer-cleaning practices. Particle size analyses of sewer sediment samples have shown that most deposits in running sewers are composed of sandy material, which reduces the hydraulic capacity, but is suspected to have only slight adverse pollutional impact. Samples with finer material and higher organic contents were however found in some protected locations, not submitted to continuous dry-weather flow. From the experience gained in this study, it is strongly believed that the acquisition of detailed field data is essential in order to assess correctly the complex phenomena involved.

Technical solutions envisaged in managing solids in combined sewer networks

1996 ◽  
Vol 33 (9) ◽  
pp. 237-244 ◽  
Author(s):  
Ghassan Chebbo ◽  
Dominique Laplace ◽  
André Bachoc ◽  
Yves Sanchez ◽  
Benoit Le Guennec
Keyword(s):  
Large Scale ◽  
Suspended Solids ◽  
Drainage Area ◽  
Bed Load ◽  
Urban Drainage ◽  
Combined Sewer ◽  
Wet Weather ◽  
Technical Solutions ◽  
Dry Weather Flow ◽  
Sewer Networks

Solids in combined sewer networks represent two important technical questions: - the clogging of man-entry sewers, and - pollution in urban wet weather discharges, whose main vectors are generally suspended solids. In this paper, we shall present first, curative technical solutions which avoid or remove deposits in man-entry sewers. We shall discuss the partial extraction of the largest solids; selective trapping of bed load solids, which form deposits; and the displacement of deposits using dry weather flow flushing waves. We shall then examine technical solutions to control pollution in urban wet weather discharges. This will show that decantation is an efficient means of fighting pollution. However, it is not always feasible because it involves large scale investments. Complementary methods should, therefore, be developed and used at different points in the water's passage through an urban drainage area.

The transfer of solids in combined sewer networks

1995 ◽  
Vol 31 (7) ◽  
pp. 95-105 ◽  
Author(s):  
G. Chebbo ◽  
A. Bachoc ◽  
D. Laplace ◽  
B. Le Guennec
Keyword(s):  
Organic Matter ◽  
Suspended Solids ◽  
Rainfall Event ◽  
Bed Load ◽  
Surface Slope ◽  
Rainfall Events ◽  
Sediment Deposits ◽  
Combined Sewer ◽  
Stress Variations ◽  
Sewer Networks

Suspended solids are the main vectors of pollution in combined sewer wet weather flows. In spite of being very fine, they decant rather quickly except in the case of light rainfall events rich in organic matter. The part originating from sewer sediment deposits provides a large proportion of organic matter mass. By analysing the content and the volume of sewer deposits at different points from upstream to downstream, it emerges that the main source of this contribution is probably located in man-entry sewers. In one of these, sewer trunk no. 13 in Marseilles, five hundred metres of which were monitored continuously for sediment build-up over three years, the deposit volume grows mainly during certain rainfall events and its surface slope tends to an equilibrium with the (millimetric) particle size. Theoretical bed-load and suspension thresholds have been validated, then analysed for various situations and sections. A typology of the vulnerable areas, in several networks, has been drawn up, as well as a study of shear stress variations during a rainfall event. The sediment deposits seem to occur in particular hydraulic discontinuity zones where transport capacities can drop sharply.

Spatial variability of characteristics and origins of urban wet weather pollution in combined sewers

2005 ◽  
Vol 52 (3) ◽  
pp. 53-62 ◽  
Author(s):  
M. Kafi-Benyahia ◽  
M.G. Gromaire ◽  
G. Chebbo
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Suspended Solids ◽  
Spatial Scales ◽  
Urban Runoff ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Wet Weather ◽  
Wet Weather Flow ◽  
Dry Weather Flow

An experimental on-site observatory of urban pollutant loads in combined sewers was created in the centre of Paris to quantify and characterise the dry and wet weather flow in relation to spatial scale. Eight rainfall events were studied from April 2003 to May 2004. Samples were analysed for suspended solids, organic matter, nitrogen and heavy metals. Results confirm the extent of wet weather pollution. They have shown the relative homogeneity of SS and organic matter characteristics from one urban catchment area to another. Two groups of heavy metals were identified. The first one concerns Cu, which has a higher concentration in wet weather flow (WWF) than in dry weather flow (DWF), and runoff. The second includes Cd, Pb and Zn, where higher concentrations were measured in urban runoff than in WWF and DWF. A first evaluation of contribution of wastewater, urban runoff and sewer deposit erosion sources to wet weather pollution was established and has highlighted the contribution of wastewater and sewer deposits to this pollution. However, it has shown that sewer deposit erosion remains an important source of wet weather pollution at different spatial scales.

Origins and characteristics of urban wet weather pollution in combined sewer systems: the experimental urban catchment “Le Marais” in Paris

1998 ◽  
Vol 37 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Marie-Christine Gromaire-Mertz ◽  
Ghassan Chebbo ◽  
Mohamed Saad
Keyword(s):  
Waste Water ◽  
Sewer System ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Sources Of Pollution ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Wet Weather ◽  
Wet Weather Flow ◽  
Different Sources

An experimental urban catchment has been created in the centre of Paris, in order to obtain a description of the pollution of urban wet weather flows at different levels of the combined sewer system, and to estimate the contribution of runoff, waste water and sewer sediments to this pollution. Twenty-two rainfall events were studied from May to October 1996. Dry weather flow was monitored for one week. Roof, street and yard runoff, total flow at the catchment outlet and waste water were analysed for SS, VSS, COD and BOD5, on both total and dissolved fraction. Results show an evolution in the characteristics of wet weather flow from up to downstream: concentrations increase from the catchment entry to the outlet, as well as the proportion of particle-bound pollutants and the part of organic matter. A first evaluation of the different sources of pollution establishes that a major part of wet weather flow pollution originates from inside the combined sewer, probably through erosion of sewer sediments.

A statistical approach to pollutant emissions from combined sewer systems

1997 ◽  
Vol 36 (8-9) ◽  
pp. 95-100 ◽  
Author(s):  
Robin G. Veldkamp ◽  
Jan B. M. Wiggers
Keyword(s):  
Suspended Solids ◽  
Statistical Approach ◽  
Low Frequency ◽  
Pollutant Emissions ◽  
Frequency Of Occurrence ◽  
Single Event ◽  
Sewer Systems ◽  
Impervious Area ◽  
Combined Sewer ◽  
Kjeldahl Nitrogen

This research is based on CSO emissions from Dutch sewer systems. During the years 1982 to 1989 research was done on several sewer systems, all of them equiped with a single overflow weir. Pollutant emissions were calculated from the measurements, whereby each storm was considered as a single event. Extreme emissions have a detrimental, sometimes even desastrous effect on water quality. Such extreme emissions are the result of heavy storms, giving it a low frequency of occurrence. From the measurements a statistical model was developed enabling the user to forecast extreme waste emissions with a certain return period in a range of 2 to 10 years. Five pollutants are put in the model: BOD, COD, Kjeldahl nitrogen, total phosphate and suspended solids. The model operates with standardized emission values in kg per ha of impervious area. When the model is used in practice the runoff area to the specific overflow under consideration has to be known.

Treatment of tunnel wash water and implications for its disposal

2014 ◽  
Vol 69 (10) ◽  
pp. 2029-2035 ◽  
Author(s):  
M. Hallberg ◽  
G. Renman ◽  
L. Byman ◽  
G. Svenstam ◽  
M. Norling
Keyword(s):  
Traffic Safety ◽  
Urban Areas ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Particulate Material ◽  
Wash Water ◽  
Polluted Water ◽  
Solids Concentration ◽  
Low Concentrations ◽  
Road Tunnels

The use of road tunnels in urban areas creates water pollution problems, since the tunnels must be frequently cleaned for traffic safety reasons. The washing generates extensive volumes of highly polluted water, for example, more than fivefold higher concentrations of suspended solids compared to highway runoff. The pollutants in the wash water have an affinity for particulate material, so sedimentation should be a viable treatment option. In this study, 12 in situ sedimentation trials were carried out on tunnel wash water, with and without addition of chemical flocculent. Initial suspended solids concentration ranged from 804 to 9,690 mg/L. With sedimentation times of less than 24 hours and use of a chemical flocculent, it was possible to reach low concentrations of suspended solids (<15 mg/L), PAH (<0.1 μg/L), As (<1.0 μg/L), Cd (<0.05 μg/L), Hg (<0.02 μg/L), Fe (<200 μg/L), Ni (<8 μg/L), Pb (<0.5 μg/L), Zn (<60 μg/L) and Cr (<8 μg/L). Acute Microtox® toxicity, mainly attributed to detergents used for the tunnel wash, decreased significantly at low suspended solids concentrations after sedimentation using a flocculent. The tunnel wash water did not inhibit nitrification. The treated water should be suitable for discharge into recipient waters or a wastewater treatment plant.

Comparison of Parameters Characterizing Organic Matter in a Combined Sewer During Rainfall Events and Dry Weather

1999 ◽  
Vol 71 (4) ◽  
pp. 408-417 ◽  
Author(s):  
Pierre Servais ◽  
Martin Seidl ◽  
Jean-Marie Mouchel
Keyword(s):  
Organic Matter ◽  
Rainfall Events ◽  
Combined Sewer

scholarly journals Performance and uncertainties of TSS stormwater sampling strategies from online time series

2018 ◽  
Vol 78 (6) ◽  
pp. 1407-1416
Author(s):  
Santiago Sandoval ◽  
Jean-Luc Bertrand-Krajewski ◽  
Nicolas Caradot ◽  
Thomas Hofer ◽  
Günter Gruber
Keyword(s):  
Time Series ◽  
Suspended Solids ◽  
Sampling Strategy ◽  
Sampling Strategies ◽  
Sampling Errors ◽  
Time Step ◽  
Sewer System ◽  
Time Intervals ◽  
Combined Sewer ◽  
One Year

Abstract The event mean concentrations (EMCs) that would have been obtained by four different stormwater sampling strategies are simulated by using total suspended solids (TSS) and flowrate time series (about one minute time-step and one year of data). These EMCs are compared to the reference EMCs calculated by considering the complete time series. The sampling strategies are assessed with datasets from four catchments: (i) Berlin, Germany, combined sewer overflow (CSO); (ii) Graz, Austria, CSO; (iii) Chassieu, France, separate sewer system; and (iv) Ecully, France, CSO. A sampling strategy in which samples are collected at constant time intervals over the rainfall event and sampling volumes are pre-set as proportional to the runoff volume discharged between two consecutive sample leads to the most representative results. Recommended sampling time intervals are of 5 min for Berlin and Chassieu (resp. 100 and 185 ha area) and 10 min for Graz and Ecully (resp. 335 and 245 ha area), with relative sampling errors between 7% and 20% and uncertainties in sampling errors of about 5%. Uncertainties related to sampling volumes, TSS laboratory analyses and beginning/ending of rainstorm events are reported as the most influent sources in the uncertainties of sampling errors and EMCs.

Appraisal of Changes in Watercourse Quality as a Result of Sewer Reconstruction

1990 ◽  
Vol 22 (10-11) ◽  
pp. 213-221
Author(s):  
A. D. Parkinson ◽  
P. S. Davis ◽  
A. J. Saul
Keyword(s):  
Computer Modelling ◽  
River Basin Management ◽  
Research Centre ◽  
Combined Sewer Overflows ◽  
Basin Management ◽  
North West ◽  
Combined Sewer ◽  
First Results ◽  
The University ◽  
University Of Manchester

Major sewerage work in Littleborough near Rochdale in North West England resulted in the closure of eight Combined Sewer Overflows and the construction of a new overflow incorporating downstream storage. The paper describes the method, named the CARP procedure, used in setting the frequency and volume of discharge from the new overflow and, therefore, the size of the tank. The effect of the resewerage work on the River Roch is being studied as a collaborative exercise involving the University of Manchester, Water Research Centre and North West Water. This is part of the River Basin Management Programme of the Water Industry of England and Wales (Clifforde et al, 1986). First results indicate that the tank will not operate as frequently as predicted by computer modelling. The discharge from the new Combined Sewer Overflow would not appear to significantly effect the river. This is to be confirmed by further fieldwork.

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