Stormwaters, flowing into storm sewers, are known to significantly increase the annual pollutant loads entering urban receiving waters and this results in significant degradation of the receiving water quality. Knowledge of the characteristics of stormwater pollution enables urban planners to incorporate the most appropriate stormwater management strategies to mitigate the effects of stormwater pollution on downstream receiving waters. This requires detailed information on stormwater quality, such as pollutant types, sediment particle size distributions, and how soluble pollutants and heavy metals attach themselves to sediment particles. This study monitored stormwater pollution levels at over 150 locations throughout the Netherlands. The monitoring has been ongoing for nearly 15 years and a total of 7,652 individual events have been monitored to date. This makes the database the largest stormwater quality database in Europe. The study compared the results to those presented in contemporary international stormwater quality research literature. The study found that the pollution levels at many of the Dutch test sites did not meet the requirements of the European Water Framework Directive (WFD) and Dutch Water Quality Standards. Results of the study are presented and recommendations are made on how to improve water quality with the implementation of Sustainable Urban Drainage Systems (SUDS) devices.
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This study focuses on characterising stormwater in order to be able to determine the impact of stormwater on receiving waters and to be able to select the most appropriate stormwater handling strategy
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Floating wetland treatment systems (FWTS) are an innovative stormwater treatment technology currently being trialled on a larger scale in Australia. FWTS provide support for selected plant species to remove pollutants from stormwater discharged into a water body. The plant roots provide large surface areas for biofilm growth, which serves to trap suspended particles and enable the biological uptake of nutrients by the plants. As FWTS can be installed at the start of the construction phase, they can start treating construction runoff almost immediately. FWTS therefore have the potential to provide the full range of stormwater treatment (e.g. sediment and nutrient removal) from the construction phase onwards. A 2,100m 2 FWTS has been installed within a greenfield development site on the Sunshine Coast, Queensland. A four-year research study is currently underway which will target the following three objectives; (1) characterise the water quality of runoff from a greenfield development in the construction and operational phases; (2) verify the stormwater pollution removal performance of a FWTS during the construction and operational phases of a greenfield development; and (3) characterise the ability of FWTS to manage urban lake health. This extended abstract presents the proposed research methodology and anticipated outcomes of the study
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A baseline study was performed to characterize the stormwater quality from the upstream roofs and road areas. Results showed variations in stormwater quality. This may inhibit single-step treatment performance. Therefore, a ‘treatment train’ of several SUDS measures was developed in order to achieve high pollutionremoval rates and to help prevent loss of valuable archaeological deposits and thereby reduce subsidence.
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Although permeable pavements have been used all over the world in recent years to infiltrate and treat stormwater, only limited research has been undertaken to investigate and compare the long-term performance of these sustainable urban drainage system devices. This paper presents the results of an extensive international review of research on the reduction of infiltration capacity of permeable pavements over time. The results of these studies, coupled with specific knowledge of the key environmental factors on the individual research locations and infiltration testing methods used, enables the maintenance of these SUDS to be strategically planned in order to meet specific European and international infiltration capacity guidelines.
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SummaryConstructed wetlands have been used for decades on industrial areas to treat stormwater. European regulations and local ambitions for water quality dictate lower emissions before the water is discharged to the drainage system, surface water or infiltrated to ground water. The increase in the required removal efficiency requires a better understanding of the characteristics of pollutants and cost-effective performance of constructed wetlands. In this chapter detailed characteristics of stormwater from (industrial) areas is given together with monitored removal efficiencies and the cost of constructed wetlands. Some case studies with constructed wetlands are selected and reviewed in this chapter which can be regarded as Best Management Practices (BMPs). In most cases the constructed wetlands are not monitored in detail but perceived to be effective. Long-term performance, however, remains an issue. New monitoring techniques such as underwater drones and full scale testing can be applied to get new insights on optimizing the hydraulic capacity and removal efficiency of wetlands. Last but not least: international knowledge exchange on constructed wetlands and new monitoring techniques can be promoted by interactive online tools.
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Storm sewers are known to significantly contribute to annual pollutant loads to receiving water bodies. The storm sewers of the city of Almere discharge the stormwater of 1384 ha of impervious area via 700 storm sewer outfalls (SSOs) to the local receiving water system. This water system suffers from eutrophication and long term build-up of pollutant levels in the sediment bed. In order to be able to select the most effective stormwater management strategy, the municipality of Almere and Water Authority Zuiderzeeland have launched a 2 year extensive monitoring project to measure the stormwater quality and the potential impact of source control and end of pipe measures to decrease the emission via SSOs. Source control measures, such as removal of illicit connections and increasing the cleaning frequency of gully pots showed to be most effective. The potential impact of end of pipesolutions based on settling showed to be very limited due to the low settleability of solids in the storm water of Almere at the SSOs.
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Sedimentation devices have been widely implemented to remove suspended solids and attached pollutants from stormwater before entering surface waters. The treatment performance of these best management practices (BMPs) on fine particles is rarely investigated in a standardized way. To overcome this information gap a reliable and standardized testing procedure is formulated.Four devices have been tested on their suspended sediments removal efficiency at different discharges and particle sizes, using the newly developed standardized full scale test method. The observed removal rates of the facilities with a storage volume in the order of 1.5 m3 and settling surface around 1 m2 drop to low removal efficiencies at flow rates of 10 l/s or more. For small sized sediments (up to 63 μm) the removal efficiency is below 50%. The results of the experiments can be used to improve both the design and the dimensions of stormwater treatment devices.
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In recent years, there has been a steady increase in the number of bioretention systems installed worldwide. However, there has only been limited research on the long-term effectiveness of these sustainable urban drainage system devices. This paper presents the results of a series of controlled field experiments investigating the pollutant removal efficiency of three bio-filtration system that have been in service for over five years in the Sunshine Coast in Australia. The results of this study suggest that the long-term pollution removal performance of these systems may not be as effective as previously thought and further research is needed.
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Sustainable urban drainage systems (SuDS) or nature-based solutions (NBSs) are widely implemented to collect, store and infiltrate stormwater. The buildup of pollutants is expected in NBSs, and Dutch guidelines advise monitoring the topsoil of bio-swales every 5 years. In the Netherlands, almost every municipality has implemented bio-swales. Some municipalities have over 300 bio-swales, and monitoring all their NBSs is challenging due to cost and capacity. In this study, 20 locations where bio-swales with ages ranging between 10 and 20 years old were selected for a field investigation to answer the following question: is the soil quality of bio-swales after 10 years still acceptable? Portable XRF instruments were used to detect potential toxic elements (PTEs) for in situ measurements. The results showed that for copper (Cu), zinc (Zn) and lead (Pb), 30%, 40% and 25% of the locations show values above the threshold and 5%, 20% and 0% above the intervention threshold, meaning immediate action should be taken. The results are of importance for stakeholders in (inter)national cities that implement, maintain, and monitor NBS. Knowledge of stormwater and soil quality related to long-term health risks from NBS enables urban planners to implement the mostappropriate stormwater management strategies. With these research results, the Dutch guidelines for design, construction, and maintenance can be updated, and stakeholders are reminded that the monitoring of green infrastructure should be planned and executed every 5 years.
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