Stormwater Collection Systems Research Articles

Hydraulic characteristics and flow trajectories under two-sided asymmetric inflow conditions for a deep storage tunnel system

Deep storage tunnels (DSTs) are used in densely urbanized areas to relieve stormwater collection systems, thereby reducing urban floods and runoff pollution, due to their substantial storage capacity. The computation of the hydraulic characteristics and flow trajectories of DSTs under rapid filling scenarios can help to predict sediment deposition and pollutant accumulation associated with the stored runoff, as well as the likelihood of operational problems, such as excessive surging. However, such assessments are complicated by various inflow scenarios encountered in tunnel systems during their operation. In this study, the Suzhou River DST in China is selected as a study case. Particles were tracked, and hydraulic analysis was conducted with scaled model experiments and numerical models. The flow field, particle movement, air‒water phase, and pressure patterns in the DST were simulated under various one- and two-sided inflow scenarios. The results showed that with regards to the design conditions involving two-sided inflows, flow reversals occurred with stepwise increases in the water surface and pressure. In contrast, this phenomenon was not observed under the one-sided inflow scenario. Under the asymmetric two-sided inflow scenarios, water inflows led to particle accumulation near the shaft, reducing the received inflows. However, under the symmetric inflow conditions, particles were concentrated near the middle of the tunnel. Compared to those under the symmetric inflow scenario, asymmetric inflow caused surface wave and entrapped air reductions. This study could provide support for regulation of the inflow of the Suzhou River DST and for prediction of sediment and pollutant accumulation.

Assessing mercury pollution at a primary ore site with both ancient and industrial mining and smelting activities

The Minamata Convention on Mercury has mandated a renewed global effort to tackle Hg pollution. The present study evaluates Hg pollution at a primary Hg production site exploited since the Qin Dynasty (200s BC), with intensive industrial scale production over the past four decades. This single location accounts for over 95% total Hg production in China in recent years. To assess the environmental risk and effectiveness of recently implemented control measures, we collected 90 soil samples, 60 plant tissue samples, 47 sediment samples, and 47 river water samples from the site and its vicinity. A site-specific conceptual site model was established based on the sources, migration transformation pathways of Hg pollutant and its exposure scenarios. The maximum soil Hg concentration reached 10,451 mg kg−1, posing a high health and ecological risk. Vegetable and crop Hg concentrations outside the site reached 0.23 mg kg−1 in rice grains and 4.24 mg kg−1 in green onion. The highest health risk, with a hazard quotient of 130.66, was observed in the Ore Storage Site, which reduced to 17.14 when Hg bioavailability was considered. Risk control measures implemented in recent years included a stormwater collection system and capping of the tailing pond area with clean imported soil. These measures were generally successful; however, Hg in the tailings were found to be contaminating the imported surficial soil due to rainfall saturation and upward migration, suggesting a need for long-term post remedial site monitoring and maintenance. We also found that mining and smelting activities have contaminated a 6 km stretch of a nearby river, with sediment Hg concentrations reaching 2819 mg kg−1, and water column concentrations reaching 193.21 ng L−1. The sediment and water concentrations are highly correlated (R2 = 0.78), suggesting that, with risk control measures in place, a reservoir of Hg in polluted river sediment is now driving pollution in the water column. This work demonstrates that primary Hg mining has caused widespread and serious soil and water pollution. Risk control measures can reduce human health and ecological risks, but robust monitoring and maintenance are required for remediation to be effective in the long-term.

Spatial Analysis of the Water Harvesting Potential of Permeable Pavements in Australia

An increase in impermeable surface areas with urban development contributes to the rapid and large amount of surface runoff during rainfall. This often requires higher capacity stormwater collection systems, which can cause stress on the existing drainage system and this subsequently contributes to urban flooding. However, urban runoff can be reduced and managed for flood control and converted into a useful resource by harvesting and reusing the water. This can be achieved by switching from impermeable to permeable pavements. However, the amount of stormwater that can be harvested in a permeable pavement system depends on many factors, including rainfall, the water reuse demand and the materials used. This research aims to assess the requirements for permeable pavement design across Australia to balance demand, runoff reduction and construction requirements. A design approach employing the hydrological effects of the infiltration system was adopted for the analysis, along with a spatial analysis for a probabilistic prediction. A relationship was also established to predict a probable design thickness of pavement for various parameters. The research showed that in most Australian cities, for a 120 mm permeable pavement thickness, 40–80% of rainfall-runoff could be harvested, meeting about 10–15% of domestic water demand. The approach developed in this study can be useful for screening the potential of permeable pavements for water harvesting and for predicting spatially where a circular economic approach can be more efficient.

Integrated approach for low impact development locating in dense residential areas based on sustainable development criteria

The study proposed a practical approach for low impact development (LID) placement in dense residential urban catchments considering social, economic, and technical criteria. The objective is to shift the current technical orientation in LIDs' locating to a practical one with a specific level of residents' cooperation. Four stages were conducted, including (i) acquiring the residents' socio-economic information; (ii) hydraulic simulation of the stormwater collection system in the status quo, (iii) regionalization of the urban catchment using data mining, and (iv) proposing specific LIDs locating scenarios. The field study lasted around four months in a dense residential area with a combination of old/new buildings in the eastern Tehran metropolis. Regionalization was conducted by combining pre-processing/clustering techniques, resulting in six regions (preliminary results) and four regions after the clustering integration in the post-processing study. The regions have different priorities for the LIDs locating, including (i) cooperative cluster, 57 sub-catchments (SCs) and appropriate for rain barrel (RB) and green roof (GR) locating; (ii) semi-cooperative cluster, 12 SCs, appropriate for RB or GR locating; (iii) 15 SCs with infrastructural constraints in the third cluster and appropriate for RB; and (iv) non-cooperative cluster, 34 SCs, inappropriate for LIDs locating. Accordingly, seven locating scenarios were specified, and the developed EPA-SWMM model was modified to evaluate the scenarios for mitigating the study area's node flooding problems. The finding shows that the overflow volume reduced in a range of 36.7-93.1%, 28.3-78.7%, and 16.3-66.4% under the rainfall with 2, 5, and 10 years return periods, respectively.

Prioritization of Bottlenecks in the Main Stormwater Collection System for Rehabilitation Measures, Case Study: Tehran Catchment, Iran

Prioritization of Bottlenecks in the Main Stormwater Collection System for Rehabilitation Measures, Case Study: Tehran Catchment, Iran

Mitigation of Suspendable Road Dust in a Subpolar, Oceanic Climate

Tire and road wear particles (TRWP) are a significant source of atmospheric particulate matter and microplastic loading to waterways. Road wear is exacerbated in cold climate by the widespread use of studded tires. The goal of this research was to assess the anthropogenic levers for suspendable road dust generation and climatic conditions governing the environmental fate of non-exhaust particles in a wet maritime winter climate. Sensitivity analyses were performed using the NORTRIP model for the Capital region of Reykjavík, Iceland (64.1° N). Precipitation frequency (secondarily atmospheric relative humidity) governed the partitioning between atmospheric and waterborne PM10 particles (55% and 45%, respectively). Precipitation intensity, however, increased proportionally most the drainage to waterways via stormwater collection systems, albeit it only represented 5% of the total mass of dust generated in winter. A drastic reduction in the use of studded tires, from 46% to 15% during peak season, would be required to alleviate the number of ambient air quality exceedances. In order to achieve multifaceted goals of a climate resilient, resource efficient city, the most important mitigation action is to reduce overall traffic volume. Reducing traffic speed may help speed environmental outcomes.

Integrating Structural Resilience in the Design of Urban Drainage Networks in Flat Areas Using a Simplified Multi-Objective Optimization Framework

Structural resilience describes urban drainage systems’ (UDSs) ability to minimize the frequency and magnitude of failure due to common structural issues such as pipe clogging and cracking or pump failure. Structural resilience is often neglected in the design of UDSs. The current literature supports structural decentralization as a way to introduce structural resilience into UDSs. Although there are promising methods in the literature for generating and optimizing decentralized separate stormwater collection systems, incorporating hydraulic simulations in unsteady flow, these approaches sometimes require high computational effort, especially for flat areas. This may hamper their integration into ordinary commercially designed UDS software due to their predominantly scientific purposes. As a response, this paper introduces simplified cost and structural resilience indices that can be used as heuristic parameters for optimizing the UDS layout. These indices only use graph connectivity information, which is computationally much less expensive than hydraulic simulation. The use of simplified objective functions significantly simplifies the feasible search space and reduces blind searches by optimization. To demonstrate the application and advantages of the proposed model, a real case study in the southwest city of Ahvaz, Iran was explored. The proposed framework was proven to be promising for reducing the computational effort and for delivering realistic cost-wise and resilient UDSs.

Comparing the Effects of Different Daily and Sub-Daily Downscaling Approaches on the Response of Urban Stormwater Collection Systems

Change in the spatiotemporal pattern of precipitation is one the most important effects of climate change. This may result in considerable changes in urban flooding and yield a variation in the rate and volume of stormwater, resulting in the failure of stormwater collection systems. In the current paper, the effects of different downscaling methods on a built urban network have been assessed and compared. The case study is a 320-ha urban watershed with a built stormwater collection system located in the City of Tehran, Iran. Two single (SDSM and DMDM) and two multisite downscaling techniques with a daily temporal resolution have been employed and two sub daily (based of GEV distribution and MOF) methods have been used to further disaggregate the downscaled data. To evaluate the climate change impacts, three climate change scenarios, i.e. RCP 2.6, RCP 4.5 and RCP 8.5, have been used. Based on our findings, DMDM appears to outperform the other techniques in terms of our statistical similarity and dissimilarity metrics for daily downscaling. In addition, the sub-daily disaggregation method via GEV distribution delivers better results in comparison to the MOF. After simulating the stormwater collection system based on the downscaling results, we found that the number of flooded channels and junctions using RCP 8.5 results is significantly higher than RCP 4.5 and RCP 2.6 scenarios, indicating the relatively high risk of urban flooding under RCP 8.5 scenario.

Assessing Redundancy in Stormwater Structures Under Hydraulic Design

As environmental change is happening at an unprecedented pace, a reliable and proper urban drainage design is required to alleviate the negative effects of unexpected extreme rainfall events occurring due to the natural and anthropogenic variations such as climate change and urbanization. Since structure/configuration of a stormwater network plays an imperative role in the design and hydraulic behavior of the system, the goal of this paper is to elaborate upon the significance of possessing redundancy (e.g., alternative flow paths as in loops) under simultaneous hydraulic design in stormwater pipe networks. In this work, an innovative approach based on complex network properties is introduced to systematically and successively reduce the number of loops and, therefore, the level of redundancy, from a given grid-like (street) network. A methodology based on hydrodynamic modelling is utilized to find the optimal design costs for all created structures while satisfying a number of hydraulic design constraints. As a general implication, when structures are subject to extreme precipitation events, the overall capability of looped configurations for discharging runoff more efficiently is higher compared to more branched ones. The reason is due to prevailing (additional) storage volume in the system and existing more alternative water flow paths in looped structures, as opposed to the branched ones in which only unique pathways for discharging peak runoff exist. However, the question arises where to best introduce extra paths in the network? By systematically addressing this question with complex network analysis, the influence of downstream loops was identified to be more significant than that of upstream loops. Findings, additionally, indicated that possessing loop and introducing extra capacity without determining appropriate additional pipes positions in the system (flow direction) can even exacerbate the efficiency of water discharge. Considering a reasonable and cost-effective budget, it would, therefore, be worthwhile to install loop-tree-integrated stormwater collection systems with additional pipes at specific locations, especially downstream, to boost the hydraulic reliability and minimize the damage imposed by the surface flooding upon the metropolitan area.

Adverse impact of municipal solid waste transportation on collected stormwater biosolids quality

The objective of this paper was to identify possible specific contamination of stormwater biosolids, with a special emphasis on pollution associated with transportation of municipal solid wastes to the waste utilization plant. The study area for sampling includes two selected points of separate stormwater collection system in Cracow. Samples of stormwater and biosolids were collected during spring-summer-autumn season addressed towards rainy days to check the scope of the problem The results led to conclusion, whether the waste utilization plant impacts the stormwater quality, compared to the high-traffic road. The largest pollutants found in stormwater near the plant were nutrients (nitrogen, phosphorus) however general content of organic matter in biosolids collected in separated stormwater system also confirmed adverse impact of solid waste transportation on stormwater sludge (biosolids) quality.

Mechanisms that lead to violent geysers in vertical shafts

ABSTRACTSupported with laboratory observations, this paper describes the mechanisms that lead to violent eruptions in stormwater and combined sewer systems. This paper also derives the upper limit for the geyser eruption velocity in these systems. The mathematical analysis shows that the maximum velocity of a gas–liquid mixture eruption in a vertical shaft is that of its mixture sound speed. The analysis also shows that the pressure gradient needs to increase substantially for the eruption velocity to approach the air–water mixture sound speed. The derived upper limit for the geyser eruption velocity is assessed using two test cases: a geyser event in a stormwater collection system in Minneapolis and our laboratory experiments.

Mechanical behaviour and load bearing mechanism of high porosity permeable pavements utilizing recycled tire aggregates

The benefits of Permeable Paving Systems (PPS) in minimizing surface water run-off which in turn reduces the imposed pressure on stormwater collection systems at the time of flash flooding have been recently remarked profoundly. In addition, the PPS have additional advantages such as filtering the pollutants for downstream water collection systems and accommodating transformation of nutrients and water to the surrounding vegetation. Inclusion of end-of-life tire products in the mixture of PPS can adjust the flexibility of the final product. Tire aggregates will potentially enhance the final product performance in areas where the ground movement or intrusion of roots can cause damage to conventional rigid pavement systems. The effect of addition of waste tire and rubber aggregates to solid granular material have been investigated in the past; however, their focus have been mainly on creating highly compacted mixtures. In contrast; in this study; mixtures of soft (end-of-life tire aggregates) and rigid aggregates (crushed rock) with a relatively high porosity was tested to evaluate their suitability for construction of permeable pavements which require high porosity. The flexibility of mixtures and their stress dependant behaviour was investigated based on the volumetric fraction of soft aggregates in the blend. The transitional soft-rigid behaviour of the mixture can be utilized to mitigate the unexpected deformation induced on the pavement. The compressive behaviour of highly permeable mixtures under ko loading and deviatoric shear provides an insight on the formation of force chains in the mixtures between the rigid particles. In addition, monitoring the compressive behaviour of rigid-soft aggregates under ko loading explains soft aggregates cushioning impact on improving the compressibility and shear behaviour of the mixture.

An assessment of the quality and use of rainwater as the basis for sustainable water management in suburban areas

A common economic use of rainwater is the basis for strategies that will allow the water sector to adapt to progressive climate change. Rainwater is a basic part of water resources that ensures the renewal of the surface and groundwater, therefore they should be protected against pollution and be managed and used in places of rainfall. This is particularly true for heavily urbanized, agricultural and industrial areas. Stormwater collection and storage systems have been introduced in many countries [1]. The water obtained in this way is a valuable source of fresh water, thanks to which it is possible to reduce the demand for tap water by almost 60% or use it during periods of drought [1, 2]. The idea of the sustainable management of water resources and the increasing ecological consciousness of society have allowed installations for the collection and use of rainwater in residential houses and public buildings to become an increasingly popular phenomenon [3, 4]. The research and assessment of rainwater quality is a guarantee of safety for its users. The article presents the results of research on the physical and chemical quality of rainwater collected directly from precipitation. Samples for research were collected in a suburban area during March-November 2015. The pH, turbidity, permanganate index, OWO, nitrogen compounds, phosphates, oxygen content, acidity, basicity, conductivity, hardness, and heavy metals content were determined. The obtained results were the basis for indicating the possibility of using rainwater for various economic purposes.

The Comparison of Velocity Formulas Used in Stormwater and Sewage Design

The Comparison of Velocity Formulas Used in Stormwater and Sewage Design The diameter and the slope of the pipe for the desired discharge value are calculated in stormwater / sewage systems design by using different velocity formulas. In Turkey, governmental offices that prepare contracts for stormwater and sewage collection systems prefer and use different velocity formulas. In this study, the effects of using such formulas on system characteristics are investigated in an attempt to provide guidance for system designers.

Hybrid green infrastructure for reducing demands on urban water and energy systems: a New York City hypothetical case study

Green infrastructure shows promise as a “best management practice” for controlling stormwater runoff, particularly in older cities with combined sewer systems. Green infrastructure systems have been used to both mitigate pollutant loading to adjacent waterways as well as to reduce burdens on municipal wastewater and stormwater collection and treatment systems during storm events. Although the electric and water/wastewater networks are closely linked, wastewater, water supply, and energy systems have been typically studied in isolation. Here, we present a hypothetical case study for applying a modular hybrid green infrastructure approach to manage stormwater in the Newtown Creek sewershed in New York City. We provide background information on current and projected stormwater flows to the Newtown Creek Wastewater Treatment Plant (WWTP) and evaluate how interception and storage rainwater in the Newtown Creek sewershed could offset inflows to the WWTP and how this offset of stormwater inflows might result in reduced electric grid burdens and cost savings for the city. Our assessment indicates that a 0.66 % conversion of impervious sewershed surface area to modular hybrid green infrastructure could reduce stormwater inflow volumes (i.e., for an annual median storm) to the Newtown Creek WWTP by 10 %. We estimate that this would result in a 14-MWh reduction in energy required for wastewater treatment per storm event. Collectively, our results suggest that implementation of modular hybrid green infrastructure can significantly reduce burdens on urban water and energy systems, thereby helping to mitigate water-energy nexus challenges associated with climate change and population growth.

Smart Network Modeling for Effective Planning of Sustainable Urban Areas

In response to unprecedented urban and population growth and related strain on stormwater collection systems, smart‐water‐network modeling technology helps manage and reduce the risks of urban runoff.

Urban stormwater construction method selection using a hybrid multi-criteria approach

Construction of urban stormwater collection systems has inherent complexities in terms of the number of conflicting criteria and stakeholders involved in the process. These conditions make it a must to choose a suitable construction method which considers all the aspects of the problem. In this study, selection of the most suitable construction method in urban stormwater collection systems is performed using a systematic and structured hybrid Multi-criteria Decision Making approach. The approach combines Fuzzy Analytical Hierarchy Process (FAHP) and Compromise Programming (CP). This combination reduces the tedious and time consuming process of pair-wise comparisons needed for conventional AHP, which makes it a more desirable approach for decision makers. A real case-study in the city of Tehran, Iran is used to show the complexities of the problem and the suitability of the approach. Discussing the results, new insights are presented on the parameter p in CP technique. The results reveal that the utilized approach has potential to be applied for method selection in other fields of urban construction.

Life cycle assessment of the City of Atlanta, Georgia’s centralized water system

The main goal of this study was to conduct a life cycle assessment (LCA) for the City of Atlanta’s (CoA) centralized water system in order to understand the sources of the largest environmental impacts in the system. The boundaries of the water system we studied included the water supply system, the wastewater collection and treatment system, and the stormwater collection system. The CoA has separate wastewater and stormwater collection systems; therefore, they are considered separately. We defined the functional unit (FU) of our study to be 1 m3 of water distributed to the point-of-use, and our scope includes infrastructure construction and decommissioning in addition to system operation. We used the US Life Cycle Inventory (USLCI) and ecoinvent databases to inventory all emissions and resource use. We determined the major impacts of the water system and the sources that create these impacts using TRACI v2.1, which is the life cycle impact assessment (LCIA) methodology developed for North America by the Environmental Protection Agency (EPA). In addition, a method to evaluate the impact of freshwater consumption on ecosystem was used in this study because it is excluded in TRACI v2.1. The four major impacts of the CoA’s centralized water system were carcinogenic effects, ecotoxicity, non-carcinogenic effects, and eutrophication; respectively, they contribute 62, 8, 6, and 5 % of the average impacts of a US resident per year (2008) for the annual water use of a single-family home resident. Notably, the input which causes 68 % of the carcinogenic effects, which has the largest normalized impact, was from infrastructure construction which is often ignored in the literature. Freshwater consumption had a relatively low impact, with an evaporative water loss of 0.23 m3 per FU and a moderate level of water stress on the middle Chattahoochee River Basin; however, the impact of freshwater consumption would rapidly increase with population growth due to increased water consumption and expansion of the impervious area in the CoA. This study is distinctly different from other LCA studies because it includes infrastructure construction, which was a major contributor to the water system’s environmental impacts. Our results suggest that infrastructure construction should be considered in LCA studies for centralized water systems. It is worth noting, however, that European datasets were used to determine emissions and resource use related to infrastructure. Results would be more accurate if inventory datasets for US infrastructure were available.

Design of Improved Stormwater Management System for the Federal University of Technology Akure

Stormwater management is becoming a problem in many cities due to rapid urbanization and poor infrastructure. Proper drainage system conveys stormwater from the road to a suitable disposal area. FUTA is well planned with good networks of roads. However, many of them are without functioning drains. The paper presents a pragmatic approach to the design of an improved stormwater management in FUTA. The entire catchment area was divided into subcatchments that form the designated units for data collection. The result of the field work showed that over half (57.31%) of the drainage area are grass land and the paved road covered 10.96%. the unpaved road and built up area covered 10.29% and 9.76% respectively. Others areas are thick forest (7.66%) and rock area (4.02%). The design of stormwater collection systems were based on the principles of hydraulics as explained by Manning. The drain size was based on the maximum discharge from each subcatchment and the time of concentration computed with Kirpichbs formula. If this design is implemented, common flash flood and siltation along roads in FUTA will be completely eliminated. http://dx.doi.org/10.4314/njt.v33i4.7

Air‐stream temperature correlation in forested and urban headwater streams in the Southern Appalachians

AbstractAir temperature can be an effective predictor of stream temperature. However, little work has been done in studying urban impacts on air‐stream relationships in groundwater‐fed headwater streams in mountainous watersheds. We applied wavelet coherence analysis to two 13‐month continuous (1 hr interval) stream and air temperature datasets collected at Boone Creek, an urban stream, and Winkler Creek, a forest stream, in northwestern North Carolina. The main advantage of a wavelet coherence analysis approach is the ability to analyse non‐stationary dynamics for the temporal covariance between air and stream temperature over time and at multiple temporal scales (e.g. hours, days, weeks and months). The coherence is both time and scale‐dependent. Our research indicated that air temperature generally co‐varied with stream temperature at time scales greater than 0.5 day. The correlation was poor during the winter at the scales of 1 to 64 days and summer at the scales of 1.5 to 4 days, respectively. The empirical models that relate air temperature to stream temperature failed at these scales and during these periods. Finally, urbanization altered the air‐stream temperature correlation at intermediate time scales ranging from 2 to 12 days. The correlation at the urban creek increased at the 12‐day scale, whereas it decreased at scales of 2 to 7 days as compared with the forested stream, which is probably due to heated surface runoff during summer thunderstorms or leaking stormwater or wastewater collection systems. Our results provide insights into air‐stream temperature relationships over both time and scale domains. Identifying controls over time and scales are needed to predict water temperature to understand the future impacts that interacting climate and land use changes will have on aquatic ecosystem in river networks. Copyright © 2014 John Wiley & Sons, Ltd.