Pollution induced by surface runoff in urban areas constitutes a significant problem. The adoption of control measures aimed at improving the quality of recipient water bodies is a fundamental issue ...in the management of Mediterranean Basin sewer systems. Previous research in Mediterranean areas using small virtual basins has shown that rainfall regimes have a limited impact on the pollutant load and discharge flowing into a receiving body. The aim of our research was to identify a sizing methodology for stormwater tanks located in the Mediterranean Basin. To achieve this, a numerical model of a sewer system, located in the Southern Iberian Peninsula, was developed. Different patterns related to peak periods of rainfall were considered. Furthermore, efficiency indices were used to evaluate and compare the effects of having a stormwater tank in the system. In our study (which considered a real area), significantly varied values were obtained for the pollution load removal rate (η) and the receiver overflow rate (θ). We nevertheless observed that, in our catchment, at a specific volume of V = 60 m3/ha, η and θ reached constant values without experiencing any significant improvement (η = 0.673 and θ = 0.133). Based on our model, this volume was proposed for the stormwater tank. The ATV (German Association for Water Pollution Control) A 128 standard was applied in order to validate the results, and the specific volume obtained (V = 60 m3/ha) matched with the one proposed. Thus, our proposed methodology is simple and different, and it is very easy to apply by obtaining the values of the efficiency indices η and θ through the development of a Storm Water Management Model (SWMM).
The efficiencies of clarifier-type stormwater tanks were determined by analysing settling velocities of settleable solids using the Umwelt- und Fluid- Technik apparatus, and by measuring the ...classical parameters of sewage pollution. The results indicated that the removal of settleable solids was better than anticipated. They were reduced about 79 per cent at a mean surface loading of 2.8 m3 per m2. h. This was a realistic annual mean surface loading of a stormwater tank designed according to the German A128 standard. Taking account of storage and the drain to the sewage works, then at least 90 and 80 per cent of settleable solids and total solids, respectively, were prevented from entering receiving waters. This performance was inadequate only when total pollution was particularly dependent on soluble constituents or the receiving waters were very sensitive.
•Time distribution of rainfall has an influence on dimensioning of stormwater tanks.•Storm water tanks should be dimensioned for the most critical rainfall.•The most critical rainfall distribution is ...quadratic function y=a·x2.•Value of stormwater flow reduction coefficient affects the time of critical rainfall.
The paper presents issues relating to the influence of time distribution of rainfall on the required storage capacity of stormwater reservoirs. The research was based on data derived from simulations of existing drainage systems. The necessary models of catchments and the drainage system were prepared using the hydrodynamic modelling software SWMM 5.0 (Storm Water Management Model). The research results obtained were used to determine the critical rainfall distribution in time which required reserving the highest capacity of stormwater reservoir. In addition, it can be confirmed based on the research that dimensioning of enclosed structures should rely on using the critical precipitation generated as the characteristics of a synthetically developed rainfall vary dynamically in time. In the final part of the paper, the results of the analyses are compared and followed with the ensuing conclusions. The results of the research will have impact on the development of methodologies for dimensioning retention facilities in drainage systems.
Modular geocellular units are applicable for the prevention and minimisation of stormwater runoff and flooding as a sustainable and cost-effective solution of road applications for drainage. The ...integrated units buried are exposed to the dead loads and live loads emerging from the surrounding soil pressure, pore water pressure and surcharge. Thus, a computer program using MATLAB is developed for the assessment of the total vertical and lateral earth pressure exerting on the modules complying with the Australian Standards AS 4678 (2002) and AS 5100.2(2004). Lateral earth pressure concept based on Rankine's theory is adopted in this model as the analytical approach. Closed-form solutions based on the fundamental soil mechanics are applied in the analytical calculation steps made. The model also considers different guidelines such as AASHTO LRFD Bridge Design Specifications (2010) for the stress distribution of vehicular loads according to the selected axle type. In consideration of the interaction of the moving vehicle and the bridge, the dynamic load allowance is also applied in terms of the static equivalent of the dynamic and vibratory effect as prescribed in AS 5100.2 (2004). Based on the results obtained, the numerical and theoretical results generated by the program provide considerable and influential factors in regarding to the parametric study and sensitivity analysis presented in this paper.
The basics of remotely controlled sewers are presented focusing on Leipzig Municipality's sewer control project located in Germany. The consequences of sewer surcharge events are outlined considering ...possible countermeasures. The required data basis, the controllable sewer objects and their relevant control units are pointed out. The presentation is finished exposing the types of control network, possible control algorithms as well as important aspects regarding the decision for/against establishing a remote control system.
The present design of stormwater tanks is based on the creation of storage volume to retain stormwater and the prevention or reduction of stormwater overflows. The treatment of stormwater is often ...improved with mechanical equipment. The general layout rules do usually not include the appropriate choice of design inflow related to the chosen treatment equipment. In the following investigations it was the task to analyze the hydraulic efficiency and the overflow behaviour of a lamella particle separator inside a stormwater tank under different design approaches regarding the chosen design inflow. Therefore six scenarios with different precipitation yield approaches were chosen and applied to a given constant sized catchment to calculate the design inflows. For a given minimum particle size, the necessary number of lamellas were determined for the scenarios and standard stormwater tanks were dimensioned. These stormwater tanks were modelled in the hydrologic model SMUSI to investigate the overflow behaviour of the different tank sizes. The number of overflow events, their duration and maximum flow rates were the results of the modelling. Comparisons to the design inflows were carried out. The treated particles sizes at the overflow events were determined reversible and compared to the original chosen minimum particle sizes.
Assessing the functioning and the performance of urban drainage systems on both rainfall event and yearly time scales is usually based on online measurements of flow rates and on samples of influent ...effluent for some rainfall events per year. In order to draw pertinent scientific and operational conclusions from the measurement results, it is absolutely necessary to use appropriate methods and techniques in order to i) calibrate sensors and analytical methods, ii) validate raw data, iii) evaluate measurement uncertainties, iv) evaluate the number of rainfall events to sample per year in order to determine performance indicator with a given uncertainty. Based an previous work, the paper gives a synthetic review of required and techniques, and illustrates their application to storage and settling tanks. Experiments show that, controlled and careful experimental conditions, relative uncertainties are about 20% for flow rates in sewer pipes, 6-10% for volumes, 25-35% for TSS concentrations and loads, and 18-276% for TSS removal rates. In order to evaluate the annual pollutant interception efficiency of storage and settling tanks with a given uncertainty, efforts should first be devoted to decrease the sampling uncertainty by increasing the number of sampled events.
Optimisation of retention basin decanting Bourgogne, Pierre; Chorda, Jacques
Water science and technology,
01/1995, Volume:
32, Issue:
1
Journal Article, Conference Proceeding
Peer reviewed
Traiter les eaux pluviales représente un enjeu capital pour les prochaines années. De nombreuses expérimentations sont entreprises, notamment dans le domaine de la décantation, technique permettant ...d'obtenir les résultats les plus intéressants dans l'élimination de cette pollution particulière.
En contribution à cone recherche, la Communauté Urbaine de Bordeaux a souhaité développer un nouveau concept de bassin de rétention, permettant de favoriser la décantation et l'évacuation de D pollution recueillie tout en facilitant l'entreden de l'ouvrage, sans mise en jeu d'équipements sophistiqués.
The cleaning of rainwater is a big challenge for the coming years. Numerous experiments are undertaken, especially in the field of elutriation. The option of decanting gives the most interesting results in the elimination of this particular kind of pollution.
By contributing to such research activity, the Bordeaux Urban Community Council wishes to develop a new type of settling basin, enabling an efficient decanting process, a good removal of pollution, as well as easy maintenance, without having to use sophisticated equipment.
Pollution Reduction in Receivers: Storm-Water Tanks Martino, Giuseppe De; De Paola, Francesco; Fontana, Nicola ...
Journal of urban planning and development,
03/2011, Volume:
137, Issue:
1
Journal Article
Peer reviewed
Urban runoff discharges in receiving water are a significant source of pollution. Storm-water tanks are one of the most effective facilities used for reducing the impact of first-flush pollution. ...Nevertheless, because the system performance depends on many parameters, design criteria for storm-water tanks are not completely consolidated in the literature. To assess the influence of the rainfall regime on the system performance, extensive numerical simulations from 45 rain gauges in Campania, Italy, were calculated. A typical Italian urban catchment was considered in simulations. Hydrographs and pollutographs were generated to analyze the operation of different sewer and tank configurations. All simulations showed a negligible influence of the rainfall regime on the phenomenon, thus suggesting a simplified approach to estimate the average pollution reduction by using storm-water tanks. The analysis shows good agreement between the values estimated from the proposed approach and the results provided by continuous simulations.
PDF
