EVALUATING THE EFFICIENCY OF HOUSEHOLD STORMWATER DETENTION SYSTEM

This paper describes the evaluation of water storing capacity of a household stormwater detention system based on field data. Collection of field data is often sidelined due to the cost and human capital incurred. However, the true value of field data is demonstrated here by comparing the observed and design data. A field test is completed in a real-life terrace house, utilizing the house’s 95m2 side canopy as roof catchment and 4.40m x 4.70m car porch area to station a detention tank. Precast concrete modular units with 3.9m3 effective storage volume are assembled within the tank. Downpipe with 0.1m diameter is installed to connect the roof gutter to the detention tank; while pipeline with 0.05m diameter is installed as the outlet from tank to the house perimeter drain. The mentioned setup is subjected to actual rainfalls from December 2019 till February 2020 that corresponded with the peak of Northeast Monsoon season. Ten observed storm events with peak hourly total rainfall readings ranging from 22 to 48mm are selected for analysis. Rainfall and water level readings from the field test allow the derivation of roof runoff volume and detained water volume in the tank. It is found that the household stormwater detention system is able to capture about 50% of the roof runoff. However, the current setup is found to cause flooding for rainfall over 40mm. The flooding issue, however, is undetected by the design data that underestimated the water storing capacity. This is due to the use of uncommon precast concrete modular units that may not have its flow characteristics represented by existing formula and model. No matter how uncommon the modular units be, various types and forms of stormwater detention system are becoming the new normal in the industry and field test is the best tool to validate their performances.

Elimination of flow rate restriction for system of storm water sewage with the help of drag-reducing polymers

The flow-rate restriction for storm sewage network is substantiated. Possible causes of flooding of territories by storm water in the case of emergency and methods of storm waters management are considered. The article is devoted to an increase in throughput of storm sewage networks with the help of in-line storm water detention tank installed at the beginning of storm sewage network and dragreducing polymers (DRP). It is proposed to introduce DRPs in the form of solution directly into the sewage network through a storm-water inlet or through a sewer manhole. The introduction is conducted from a tank (cistern) in which there is a device for preparing an aqueous solution from the raw materials of DRP. For a square (in horizontal plane) catchment, in the case of point-type water drainage, the numerical simulation of the work of a system of storm water sewage with the help of DRP has been carried out.

Turbidity in Combined Sewer Sewage: An Identification of Stormwater Detention Tanks

Combined sewer overflow remains a major threat to surface water quality. A stormwater detention tank is an effective facility to control combined sewer overflow. In this study, a new method for the selective collection of combined sewer sewage during wet weather based on real-time turbidity control is established to reduce the load of pollutants entering a river using a stormwater detention tank with a limited volume. There was a good correlation found between turbidity and the concentrations of total suspended solids (TSS) (R2 = 0.864, p < 0.05), total phosphorus (TP) (R2 = 0.661, p < 0.01), and chemical oxygen demand (COD) (R2 = 0.619, p < 0.01). This study shows that turbidity can be used to indicate the concentration of TSS, TP, and COD in the sewage of the combined sewer systems in wet weather. Based on the adopted first flush detection approach, total nitrogen (TN) and TP showed the first flush effect, whereas the first flush effect of TSS and COD was not obvious. The results show that it is impossible to effectively control combined sewer overflow by only treating the initial rainwater.

Green Technology: Transformation of Domestic Bio-Waste into Electricity Energy to Mitigate the Global Energy and Environmental Vulnerability

Background Green Technology, a sustainable mechanism is being proposed to fulfill the complete need of energy for a building that can be created by the building itself by the transformation process of domestic biowaste into electricity energy in site.Results The results suggested that the transformation of domestic biowaste including human feces to execute into converting process into an anaerobic tank bioreactor (BR) in the cellar which can form biogas (CH4) by methanogenesis that can be converted into electricity energy to power the entire building. Besides, the discharged waste water in another detention tank can be conducted a complete treatment process of primary, secondary, tertiary and UV application to utilize it for gardening.Conclusions Implementation of this technology indeed shall be an inventive field of science where a building can form electricity by itself to complete its total energy need without any connection with the utility authorities which is benevolent to environment.

Dimensioning of Required Volumes of Interconnected Detention Tanks Taking into Account the Direction and Speed of Rain Movement

This article is aimed at defining the impact of the direction and velocity of waves of rainfall as they pass over interconnected stormwater detention tank systems. The simulations were conducted for a real urban catchment area as part of the Storm Water Management Model (SWMM) 5.1 programme. The results permit us to conclude that the direction and velocity of a moving wave of rainfall have a significant influence on the required volumes of interconnected stormwater detention tank systems. By comparing the modelling test results for stationary rainfall and rainfall moving over the urban catchment area, it has been demonstrated that differences in the required volume of the detention tank located at the terminal section of a stormwater drainage system are inversely proportional to the adopted value of the diameter of the outfall channel for upstream storage reservoirs. In extreme cases, the differences may be up to several dozen percentage points. Furthermore, it has been proven that the arrangement of the stormwater detention tanks in relation to one another and the adopted diameter of the outfall channel are key factors in identifying the degree to which the detention tanks are hydraulically dependent on one another.

A critical evaluation of the methods for the determination of required volumes for detention tank

Simplified methods allow a straightforward and quick determination of parameters of interest. A simplified method of calculation to be used must provide sufficiently accurate simulation results. This paper presents the results of tests completed to evaluate the effects of the parameters which describe a sewer catchment area and network on the value of Tp, a parameter applied in the Dziopak method [18]. The results of 2997 hydrodynamic simulations allowed to formulate an artificial neural network the application of which enabled the determination of the value of Tp dependent on the design parameters of a sewer catchment area and network. The artificial neural network had a very low error R2 = 0.9972 between the expected and determined values of Tp. The completed tests indicated a relationship by which an increase of the rainfall duration, a parameter used in the dimensioning of detention tank, is concomitant to an increase in the value of Tp. The calculations made so far included an assumption that the Tp value is constant irrespective of the design rainfall duration for the dimensioning of detention tank; this assumption has led to gross calculation errors. The paper also provides proof that the inclusion of these relationships allows a more precise determination of the service volume required for a multi-chamber detention tank.