Storm Sewer System Research Articles

Field data analysis of active chlorine-containing stormwater samples

Many municipalities in Canada and all over the world use chloramination for drinking water secondary disinfection to avoid DBPs formation from conventional chlorination. However, the long-lasting monochloramine (NH2Cl) disinfectant can pose a significant risk to aquatic life through its introduction into municipal storm sewer systems and thus fresh water sources by residential, commercial, and industrial water uses. To establish general total active chlorine (TAC) concentrations in discharges from storm sewers, the TAC concentration was measured in stormwater samples in Edmonton, Alberta, Canada, during the summers of 2015 and 2016 under both dry and wet weather conditions. The field-sampling results showed TAC concentration variations from 0.02 to 0.77 mg/L in summer 2015, which exceeds the discharge effluent limit of 0.02 mg/L. As compared to 2015, the TAC concentrations were significantly lower during the summer 2016 (0–0.24 mg/L), for which it is believed that the higher precipitation during summer 2016 reduced outdoor tap water uses. Since many other cities also use chloramines as disinfectants for drinking water disinfection, the TAC analysis from Edmonton may prove useful for other regions as well. Other physicochemical and biological characteristics of stormwater and storm sewer biofilm samples were also analyzed, and no significant difference was found during these two years. Higher density of AOB and NOB detected in the storm sewer biofilm of residential areas – as compared with other areas – generally correlated to high concentrations of ammonium and nitrite in this region in both of the two years, and they may have contributed to the TAC decay in the storm sewers. The NH2Cl decay laboratory experiments illustrate that dissolved organic carbon (DOC) concentration is the dominant factor in determining the NH2Cl decay rate in stormwater samples. The high DOC concentrations detected from a downstream industrial sampling location may contribute to a high stormwater NH2Cl decay rate in this area.

Urban stormwater inundation simulation based on SWMM and diffusive overland-flow model.

With rapid urbanization, inundation-induced property losses have become more and more severe. Urban inundation modeling is an effective way to reduce these losses. This paper introduces a simplified urban stormwater inundation simulation model based on the United States Environmental Protection Agency Storm Water Management Model (SWMM) and a geographic information system (GIS)-based diffusive overland-flow model. SWMM is applied for computation of flows in storm sewer systems and flooding flows at junctions, while the GIS-based diffusive overland-flow model simulates surface runoff and inundation. One observed rainfall scenario on Haidian Island, Hainan Province, China was chosen to calibrate the model and the other two were used for validation. Comparisons of the model results with field-surveyed data and InfoWorks ICM (Integrated Catchment Modeling) modeled results indicated the inundation model in this paper can provide inundation extents and reasonable inundation depths even in a large study area.

Effects of submerged zone, media aging, and antecedent dry period on the performance of biochar-amended biofilters in removing fecal indicators and nutrients from natural stormwater

Biochar has demonstrated promising performance as an amendment to biofilter soil media in removing fecal indicator bacteria (FIB) from simulated stormwater. However, there is no study that investigates its efficacy in treating natural stormwater runoff. Additional information, including the effects of antecedent dry period, microbial biofilm, and presence of a saturation zone on the performance of biochar-augmented biofilters are needed to inform their field implementation. This study uses laboratory column experiments to monitor FIB (enterococci and Escherichia coli) and nutrient removal capacity of biochar-amended biofilters for 140days using natural stormwater. Our study also investigates the effects of antecedent dry days (ADD) and the presence of a saturation zone (SZ) on the performance of lab-scale biochar-amended biofilters. The results suggest insignificant influence of the ADD and SZ on FIB removal performance, however biofilters with a SZ perform significantly better in removing nitrate-nitrogen compared to those without a SZ. In addition, it appears that the presence of biofilm augments nutrient removal capacity but reduces FIB removal capacity. Our observations indicate that biochar-amended biofilters are able to treat (to comply with recreational water quality standard for FIB) urban stormwater runoff for the duration of the experiment. Nitrate- and ammonium-nitrogen removal in the biologically aged biofilters is found to be 50–60% while the total dissolved phosphorus and the organic nitrogen removal is 20–30%. Our results inform full-scale design of biochar-amended biofilters in order to meet the total maximum daily load (TMDL) and municipal separate storm sewer system (MS4) permitting requirement for FIB and nutrients.

우수관거 조도계수 개선에 따른 강우-유출 특성 분석

우수관거 조도계수 개선에 따른 강우-유출 특성 분석

Development of Effective Procedures for Illicit-Discharge Risk Mapping

AbstractAuthorities of municipal separate storm-sewer systems (MS4s) are required to address illicit discharges as part of the United States’ National Pollutant Discharge Elimination System’s (NPDE...

Improved understanding of combined sewer systems using the Illinois Conveyance Analysis Program (ICAP)

Understanding the conveyance of sewer networks is vital, especially in cases of great variability in flow rates, such as in combined sanitary and storm sewer systems. Conventional conveyance studies in sewer systems often have extended computation times due to complexity of the solution, or alternatively make assumptions that ignore the water-surface profile within a pipe. In previous research, the hydraulic performance graph (HPG) was successfully used for open-channel capacity determination. The HPG summarizes the results of many backwater calculations for a reach so that these calculations do not need to be repeated. This article describes algorithms utilized by the Illinois Conveyance Analysis Program that uses the HPGs to describe the conveyance of a system, identify bottlenecks for varying conditions, conserve mass by tracking outflow and overflows under stepwise steady flow conditions. The software is freely available at https://github.com/obergshavefun/icap/wiki.

Evaluation of Modeled Bacteria Loads Along an Impaired Stream Reach Receiving Discharge from a Municipal Separate Storm Sewer System in Independence, Mo.

Evaluation of Modeled Bacteria Loads Along an Impaired Stream Reach Receiving Discharge from a Municipal Separate Storm Sewer System in Independence, Mo.

Analysis of pollution characteristics and first flush effect in rainfall runoff in separate storm sewer system in upstream of Tangxi River,Chaohu Catchment

Analysis of pollution characteristics and first flush effect in rainfall runoff in separate storm sewer system in upstream of Tangxi River,Chaohu Catchment

New Approach to Estimate Velocity at Limit of Deposition in Storm Sewers Using Vector Machine Coupled with Firefly Algorithm

AbstractOne of the crucial issues regarding a storm sewer system is the ability to avoid sediment depositions on the pipe invert. In this study, the mean flow velocity under the limit of sediment d...

Experimental study of hydraulics and sediment capture efficiency in catchbasins.

Catchbasins (also known as gully pot in the UK and Australia) are used to receive surface runoff and drain the stormwater into storm sewers. The recent interest in catchbasins is to improve their effectiveness in removing sediments in stormwater. An experimental study was conducted to examine the hydraulic features and sediment capture efficiency in catchbasins, with and without a bottom sump. A sump basin is found to increase the sediment capture efficiency significantly. The effect of inlet control devices, which are commonly used to control the amount of flow into the downstream storm sewer system, is also studied. These devices will increase the water depth in the catchbasin and increase the sediment capture efficiency. Equations are developed for predicting the sediment capture efficiency in catchbasins.

Risk analysis of combined rainwater detention and pumping systems

Storm sewer systems (SSSs) are complex, with many hydraulic, mechanical and electrical components which may fail during natural extreme events, changing environmental conditions (including urban development), or simply due to poor maintenance. System complexity and management are important and still debated concepts within the framework of SSS risk analysis. A new probabilistic model for a conceptualized urban SSS, including a storage unit (SU) and a pumping station (PS), shows how single-component risk analysis can be extended to complex SSSs and demonstrates the combined effect of key design parameters (SU volume, detention time, prescribed outflow discharge) and management strategy on the overall SSS risk of failure. The risk of failure evaluated in a typical case study, demonstrates that economic restrictions leading to the loss of reliability of PS elements and the lack of redundant mechanical elements represent a major threat to SSSs and suggests a new risk-based definition of ’extended’ SU.

Water Level Loggers as a Low-Cost Tool for Monitoring of Stormwater Control Measures

Stormwater control measures (SCMs) are a key component of watershed health in urbanized areas. SCMs are used to increase infiltration and reduce discharge to streams or storm sewer systems during rain events. Monitoring is important for the evaluation of design and causes of failure in SCMs. However, the expense of monitoring means it is not always included in stormwater control planning. This study shows how low-cost water level loggers can be used to answer certain questions about SCM performance. Five case studies are presented that use water level loggers to evaluate the overflow of basins, compare a traditional stormpipe trench with an infiltration trench, monitor timing of blue roof storage, show the effects of retrofitting a basin, and provide long term performance data. Water level loggers can be used to answer questions about the timing and location of stormwater overflows, which helps to evaluate the effectiveness of SCMs. More expensive monitoring and modeling can be used as a follow up if needed to more thoroughly assess a site. Nonetheless, low-cost monitoring can be a first step in identifying sites that need improvement or additional monitoring.

Funkcjonowanie osadników i zbiorników przepływowych w warunkach zlewni miejskiej i podmiejskiej (Sokołówka i Dzierżązna)

<p>The presence of small artificial water reservoirs is typical of the landscape of small agricultural catchments. The old mill dammings are used today mostly for recreation and fish farming. Moreover, they are a very important part of the hydrological system of small rivers, stabilizing and shaping the discharge and physico-chemical characteristics of water. Coupled with the landscape function of the ponds goes their functioning in conditions of strong human pressure in the urban space. A canalized rivers in the urban parts of its courses picks up rubbishes washed down from the surface and coming from a storm sewer system and sometimes from leachate from a sanitary sewage system.</p><p>An example of hydrological systems operating in such environments are Dzierżązna and Sokołówka catchments (Fig. 1). The first one is located north of Zgierz in the impact zone of the city of Łódź. Despite agro-forestry character, a significant impact on water quality is the chalets area and the A2 motorway crossing the catchment. The Sokołówka catchment is flowing through the urban area of the Łódź city. Both of the river flows are highly variable, and the water is heavily contaminated and has a high load of suspension (Tab. 1)</p><p>In both of the catchments the role of artificial reservoirs created to improve the quality of water is the important issue. In the Dzierżązna catchment the several retention and infiltration ponds are working for regulating the outflow from the A2 motorway. In the Sokołówka valley the biofilter has been recently built (Fig. 2). It was constructed in order to purify urban storm- and waste water (sequential biofiltration system of Sokołówka – SSBS). The main purpose of the constructed SSBS was to remove sediments, suspended solids, particulate pollutants, petroleum hydrocarbons, heavy metals, nutrients and bacterial contamination from storm-water runoff through sedimentation and filtration mechanisms.</p><p>The paper discusses the construction of both systems and technical solutions. To evaluate the effectiveness of their operation analyzed changes in the basic characteristics of physicochemical water parameters (water temperature, conductivity (SEC), pH, the concentration of dissolved oxygen, turbidity (NTU)) measured before and after both of cleansing systems in the year and multiyear (Fig. 3, Fig. 4).</p><p>Attention has been also paid to the distribution of the mineral sediment deposited on the bottom of the biofilter SSBS system (Fig. 5). It was found that lowering the temperature in the winter and the appearance of a compact ice cap adversely affect the ability of biofilm to absorb pollutants causing (relative to the hot half year) an increase of conductivity, a higher pH and reducing of oxygenation of water.</p><p>Identified mean changes of the selected physicochemical parameters of water discharged from the area of the A2 motorway to the Dzierżązna river system and as a result of the SSBS system operation to Sokołówka river (Fig. 6).</p><p>All the measured parameters are reduced after passing through both of systems. As a result of mechanical sedimentation the greatest reduction is suspended material transported by water – in the SSBS on average about 16% less than in untreated waters (in the Dzierżązna catchment this element was not measured). The pH of the water in both systems changes to the same extent – decreases by 10% in the Dzierżązna, and 7% in SSBS.</p>

Application of a Neuro-Fuzzy GMDH Model for Predicting the Velocity at Limit of Deposition in Storm Sewers

AbstractThe velocity at limit of deposition, namely, the velocity below which the sediments start to form stationary deposits on the pipe invert, plays a key role in designing an effective storm sewer system. In fact, an accurate evaluation of the aforesaid velocity permits to prevent the formation of sediment deposits in the pipe, and, consequently, a decreasing of the hydraulic capacity of the same pipe. Nowadays, different methods based on artificial intelligence are applied to analyze and solve problems of scientific and practical interest, among which the analysis of sediment transport mechanism in clean storm sewer networks. In this study, neuro-fuzzy based group method of data handling (NF-GMDH), an adaptive learning network, has been utilized to predict the velocity at limit of deposition in partially-filled circular storm sewer networks under noncohesive bed load sediment transport and clean pipe conditions. The NF-GMDH network has been developed using the particle swarm optimization (PSO). Four ...

Effective impervious area for runoff in urban watersheds

AbstractEffective impervious area (EIA), or the portion of total impervious area (TIA) that is hydraulically connected to the storm sewer system, is an important parameter in determining actual urban runoff. EIA has implications in watershed hydrology, water quality, environment, and ecosystem services. The overall goal of this study is to evaluate the application of successive weighted least square (WLS) method to urban catchments with different sizes and various hydrologic conditions to determine EIA fraction. Other objectives are to develop insights on the data selection issues, EIA fraction, EIA/TIA ratio, and runoff source area patterns in urban catchments. The successive WLS method is applied to 50 urban catchments with different sizes from less than 1 ha to more than 2000 ha in Minnesota, Wisconsin, Texas, USA as well as Europe, Canada, and Australia. The average, median, and standard deviation of EIA fractions for the 42 catchments with residential land uses are found to be 0.222, 0.200, and 0.113, respectively. These values for the EIA/TIA ratio in the same 42 catchments are 0.50, 0.48, and 0.21, respectively. While the EIA/TIA results indicate the importance of EIA, 95% prediction interval of the mean EIA/TIA is found to be 0.07 to 0.93, which shows that using an average value for this ratio in each land use to determine EIA from TIA in ungauged urban watersheds can be misleading. The successive WLS method was robust and is recommended for determining EIA in gauged urban catchments. Copyright © 2016 John Wiley & Sons, Ltd.

Inter-Event and Intra-Event Variations of Indicator Bacteria Concentrations in the Storm Sewer System of the City of Östersund, Sweden

AbstractAn episode of microbiological contamination of the drinking water supply of the City of Ostersund, Sweden (63°10′45″N; 14°38′09″E) prompted a study of fecal pollution in four storm drainage catchments discharging in the vicinity of the water treatment plant intake, with the overall aim of determining the presence and variation of standard fecal indicator bacteria strains and total suspended solids (TSS) in stormwater from urban catchments with specific land uses and sizes varying from 5 to 40 ha. Four bacteria strains used as indicators of fecal pollution in Sweden were studied: total coliforms, enterococci, Escherichia coli (E. coli) and Clostridium perfringens (C. perfringens). In dry weather, indicator bacteria concentrations in storm sewers conveying baseflow did not exceed 100 colony forming units (CFU)/100 mL, but during wet weather, total coliform and enterococci concentrations increased 102 to 103 times, compared to those in baseflow, and considerably less in the case of E. coli and C. p...

Benchmarking laboratory observation uncertainty for in-pipe storm sewer discharge measurements

Summary The uncertainty associated with discharge measurement in storm sewer systems is of fundamental importance for hydrologic/hydraulic model calibration and pollutant load estimation, although it is difficult to determine as field benchmarks are generally impractical. This study benchmarks discharge uncertainty in several commonly used sensors by laboratory flume testing with and without a woody debris model. The sensors are then installed in a field location where laboratory benchmarked uncertainty is applied to field measurements. Combined depth and velocity uncertainty from the laboratory ranged from ±0.207–0.710 in., and ±0.176–0.631 fps respectively, and when propagated and applied to discharge estimation in the field, resulted in field discharge uncertainties of between 13% and 256% of the observation. Average daily volume calculation based on these observations had uncertainties of between 58% and 99% of the estimated value, and the uncertainty bounds of storm flow volume and peak flow for nine storm events constituted between 31–84%, and 13–48% of the estimated value respectively. Subsequently, the implications of these observational uncertainties for stormwater best-management practice evaluation, hydrologic modeling, and Total Maximum Daily Load development are considered.

Evaluation of Variability in Response to the NPDES Phase II Stormwater Program in Virginia

AbstractAuthorities of municipal separate storm sewer systems (MS4s) in small urbanized areas (population less than 100,000) are required to implement stormwater control measures (SCMs) to mitigate and reduce the impacts of urbanization on stormwater runoff under Phase II of the National Pollutant Discharge Elimination System’s (NPDES) stormwater program. This 16–year-old policy has been challenged in its effectiveness in maintaining or improving water quality, but reviews are scarce because of the policy’s subjective requirements, and because it governs MS4s across a wide variety of characteristics, objectives, and institutional capacity. This research models SCM selection as a function of these differences, thereby systematically evaluating the policy’s outcome in its constituents. The results show that certain characteristics of an MS4 community significantly affect the selection of SCMs, suggesting that regulations may need to be refined to address distinct groups of MS4s. The results also reveal inef...

A novel approach to model dynamic flow interactions between storm sewer system and overland surface for different land covers in urban areas

In this study, we developed a novel approach to simulate dynamic flow interactions between storm sewers and overland surface for different land covers in urban areas. The proposed approach couples the one-dimensional (1D) sewer flow model (SFM) and the two-dimensional (2D) overland flow model (OFM) with different techniques depending on the land cover type of the study areas. For roads, pavements, plazas, and so forth where rainfall becomes surface runoff before entering the sewer system, the rainfall–runoff process is simulated directly in the 2D OFM, and the runoff is drained to the sewer network via inlets, which is regarded as the input to 1D SFM. For green areas on which rainfall falls into the permeable ground surface and the generated direct runoff traverses terrain, the deduction rate is applied to the rainfall for reflecting the soil infiltration in the 2D OFM. For flat building roofs with drainage facilities allowing rainfall to drain directly from the roof to sewer networks, the rainfall–runoff process is simulated using the hydrological module in the 1D SFM where no rainfall is applied to these areas in the 2D OFM. The 1D SFM is used for hydraulic simulations in the sewer network. Where the flow in the drainage network exceeds its capacity, a surcharge occurs and water may spill onto the ground surface if the pressure head in a manhole exceeds the ground elevation. The overflow discharge from the sewer system is calculated by the 1D SFM and considered a point source in the 2D OFM. The overland flow will return into the sewer network when it reaches an inlet that connects to an un-surcharged manhole. In this case, the inlet is considered as a point sink in the 2D OFM and an inflow to a manhole in the 1D SFM. The proposed approach was compared to other five urban flood modelling techniques with four rainfall events that had previously recorded inundation areas. The merits and drawbacks of each modelling technique were compared and discussed. Based on the simulated results, the proposed approach was found to simulate floodings closer to the survey records than other approaches because the physical rainfall–runoff phenomena in urban environment were better reflected.

Economic and environmental assessment of office building rainwater harvesting systems in various U.S. cities.

Rainwater harvesting (RWH) systems implemented in office buildings under heterogeneous urban settings in the United States, including combined and separated storm sewer systems, will result in varying environmental and economic costs and benefits across multiple water sectors. The potable water saving and stormwater abatement potentials were found to strongly correlate with the local annual precipitation totals and patterns, specifically the long-period antecedent dry weather period. Given the current water rates and stormwater fees in large U.S. cities, RWH systems implemented in office buildings may not be cost-effective compared to the municipal supplies over their lifetime, except in Seattle, which has the highest stormwater fees in the country ($77.50/1000 sf impervious surface/month). The minimum net life cycle costs range from -$1.60 (Seattle) to $11.9 (Phoenix) per m(3) of rainwater yield, resulting in a potential economic gain of over $520 (Seattle) to a net loss of $800 (Phoenix) per building annually. By preventing the rooftop runoff from entering the wastewater treatment plant, between 3 and 9 kg N eq per year could be reduced in combined sewer systems depending on local conditions. This N reduction comes at the expense 0.7-4.6 kg CO2 eq per m(3) rainwater yield. In separate sewer systems, eutrophication reduction benefits result from reducing N loading associated with stormwater runoff. The overall sustainability of implementing RWH depends on the site-specific functional, economic, and environmental benefits, impacts, and trade-offs.