An assessment of gully pot sediment scour behaviour under current and potential future rainfall conditions

Gully pots actively trap sediments transported by urban runoff to prevent in-pipe blockages and surface flooding. However, due to poor maintenance (resulting in sediment build-up) and increasingly extreme wet weather events, the scour of previously-deposited sediments from gully pots is identified as a potential contributor to EU Water Framework Directive failure. While basal sediment scour deterministic models have been developed and validated using laboratory and field gully pot data sets, the ability of these models to predict behaviour at sites other than those for which they were established has not been addressed. Nor has the impact of future rainfall predictions on the role of gully pots as sediment sources been systematically examined. As a contribution to addressing these knowledge gaps, the performance of two gully pot basal sediment scour models of distinct complexity levels are evaluated under current and future rainfall conditions. The output from Model One suggests that the scour-induced total suspended solids in gully pot discharge can be kept well below 25 mg/L if the gully pot fullness level is maintained at under 60%. Results identify the opportunity to incorporate the actual/targeted ecological status of recipients in scheduling gully pot maintenance operations and that proactive gully pots maintenance will reduce the impacts of increased rainfall intensity/duration on the magnitude of sediment scour. Results from Model Two suggest that fine sediments are particularly susceptible to in-pot scour. For example, sediment with a specific gravity of 1.1 and diameter of >63 μm accounts for 50% of scour-induced total suspended solids in gully pot discharge. The effluent suspended solids concentrations predicted by the two models differ by up to two orders of magnitude. However, without further empirical field data pertaining to their respective competences/applications, neither model could be discounted at this stage. For example, the use of Model One is more appropriate in the establishment of gully pot maintenance schedules, with Model Two more suited to the dimensioning of gully pots based on performance requirements. This application, however, relies on the development and adoption of a more stringent regulation on gully pots discharge

SUDS, LID, BMPs, WSUD and more - The evolution and application of terminology surrounding urban drainage

Open Access articleThe management of urban stormwater has become increasingly complex over recent decades. Consequently, terminology describing the principles and practices of urban drainage has become increasingly diverse, increasing the potential for confusion and miscommunication. This paper documents the history, scope, application and underlying principles of terms used in urban drainage and provides recommendations for clear communication of these principles. Terminology evolves locally and thus has an important role in establishing awareness and credibility of new approaches and contains nuanced understandings of the principles that are applied locally to address specific problems. Despite the understandable desire to have a ‘uniform set of terminology’, such a concept is flawed, ignoring the fact that terms reflect locally shared understanding. The local development of terminology thus has an important role in advancing the profession, but authors should facilitate communication between disciplines and between regions of the world, by being explicit and accurate in their application

Metal size distribution in rainfall and snowmelt-induced runoff from three urban catchments

The size distribution of metals transported by urban runoff has implications for treatment type and design, predicting their mobility and evaluating their potential impact on receiving waters. There is an urgent need to better understand the distribution of metals between fractions, particularly those in the sub-dissolved fractions. As a contribution to addressing this need, this study characterises the size distribution of Cd, Cr, Cu, Ni, V and Zn using conventional and novel techniques. Data is presented as event mean concentrations (EMC) of a total of 18 rainfall and snowmelt events at three urban sites. For all studied metals in all events and at all sites, the contribution of the truly dissolved fraction made a greater contribution to the total concentrations than the colloidal fraction. Truly dissolved Cd and Zn concentrations contributed (on average) 26% and 28% respectively, of the total EMCs with truly dissolved Cu and Ni contributing (on average) 18%. In contrast, only 1% (V) and 3% (Cr) were identified in the truly dissolved fraction. The greatest contribution of truly dissolved Cd, Cu and Zn concentrations (relative to total oncentrations) were reported during rainfall events. However, no seasonal differences were identified and differences between the sites regarding the EMCs distribution by fractions were not at a statistically significant level (p N 0.05) for any metal or event. The loads of truly dissolved and colloidal metals did not follow the patterns of particulate metal loads indicating particulates are not the main source of subdissolved metals. The data suggests that ultrafiltration as a treatment technique would not efficiently mitigate the risks posed by metals to receiving water cologie

Making Waves : Collaboration in the time of SARS-CoV-2-rapid development of an international co-operation and wastewater surveillance database to support public health decision-making

The presence of SARS-CoV-2 RNA in wastewater was first reported in March 2020. Over the subsequent months, the potential for wastewater surveillance to contribute to COVID-19 mitigation programmes has been the focus of intense national and international research activities, gaining the attention of policy makers and the public. As a new application of an established methodology, focused collaboration between public health practitioners and wastewater researchers is essential to developing a common understanding on how, when and where the outputs of this non-invasive community-level approach can deliver actionable outcomes for public health authorities. Within this context, the NORMAN SCORE "SARS-CoV-2 in sewage" database provides a platform for rapid, open access data sharing, validated by the uploading of 276 data sets from nine countries to-date. Through offering direct access to underpinning meta-data sets (and describing its use in data interpretation), the NORMAN SCORE database is a resource for the development of recommendations on minimum data requirements for wastewater pathogen surveillance. It is also a tool to engage public health practitioners in discussions on use of the approach, providing an opportunity to build mutual understanding of the demand and supply for data and facilitate the translation of this promising research application into public health practice. (C) 2021 Elsevier Ltd. All rights reserved.Peer reviewe

Snow quality in urban areas

The studies reported on this thesis aim to provide information and increase knowledge about the quality of urban snow and the path of pollutants. The results develop a basis for decisions regarding the prevention of environmental damage. A number of projects have been carried out to provide more detailed knowledge about: snow quality in cities, sediments that had accumulated during the winter, and that were left at the surface when the snow had melted, and the paths of pollutants at urban snow deposit. For these purposes studies have been performed in laboratory, pilot and full scale. The snow quality was studied in the city of Luleå with regard to variation with time and area. The aim was to investigate urban snow in its actual environment, throughout an entire winter season. Snow samples were taken in a housing area and in the city centre, at sites with different traffic load. It was found that traffic or activities related to traffic was a major source of heavy metals and phosphorus in urban snow, both in the city centre and the housing area. Also the type of area and the design of the street were important for the snow quality. A clear relation between the pH and the quantity of suspended solids in the snow was found. Higher pH values were found in snow from sites with higher traffic loads, compared to sites with small quantities of particles which were the no-traffic sites. The dissolved fractions showed more complicated results. The concentration of the studied substances in the snow was affected by the precipitation at the site with no traffic. At the street where the snow was left beside the street, the concentration of substances increased with time, while the precipitation was of less importance. The mass loads of substances increased with time for both the streets, where the snow stayed in the vicinity of the street, and for the non-traffic site. For the site with traffic the snow handling operations evidently affected the mass loads. This was especially the case for particle-connected substances. As a result of the increased interest in reuse of friction material the sediment which remained along the streets after snow melt was studied with regard to physical and chemical characteristics. The side walk affected the amount of substances on the street more than the traffic load. For the streets without sidewalk an increased traffic load increased the amounts of sediment. The particle size distribution of the sediments swept from the street with a sidewalk differed from the distribution at the streets without a sidewalk. With two exceptions the smallest size fraction (>75 µm) had the largest concentration of heavy metals. For composite samples the concentration increased with traffic load. The pathways of pollutants in urban snow deposits have been studied in three different scales; laboratory, pilot, and full-scale. The initial snow, melt water and sediment were analysed with regard to chemical content. It was found that the dissolved substances to a great extent folowed with the melt water while for the particle bounded substances as much as 90-99% stayed in the sediment below the deposit. The dissolved substances left the snow in the beginning of the melt period, while the substances connected to particles showed a uniform release. The laboratory study showed that melt- freeze cycles delayed the release of substances. Almost all substances were attached to particles in the snow, while in the melt water a large part was in solution. It should be noted that a so-called acid shock was not found during these studies.Godkänd; 1997; 20061128 (haneit

Snow quality in urban areas

The studies reported on this thesis aim to provide information and increase knowledge about the quality of urban snow and the path of pollutants. The results develop a basis for decisions regarding the prevention of environmental damage. A number of projects have been carried out to provide more detailed knowledge about: snow quality in cities, sediments that had accumulated during the winter, and that were left at the surface when the snow had melted, and the paths of pollutants at urban snow deposit. For these purposes studies have been performed in laboratory, pilot and full scale. The snow quality was studied in the city of Luleå with regard to variation with time and area. The aim was to investigate urban snow in its actual environment, throughout an entire winter season. Snow samples were taken in a housing area and in the city centre, at sites with different traffic load. It was found that traffic or activities related to traffic was a major source of heavy metals and phosphorus in urban snow, both in the city centre and the housing area. Also the type of area and the design of the street were important for the snow quality. A clear relation between the pH and the quantity of suspended solids in the snow was found. Higher pH values were found in snow from sites with higher traffic loads, compared to sites with small quantities of particles which were the no-traffic sites. The dissolved fractions showed more complicated results. The concentration of the studied substances in the snow was affected by the precipitation at the site with no traffic. At the street where the snow was left beside the street, the concentration of substances increased with time, while the precipitation was of less importance. The mass loads of substances increased with time for both the streets, where the snow stayed in the vicinity of the street, and for the non-traffic site. For the site with traffic the snow handling operations evidently affected the mass loads. This was especially the case for particle-connected substances. As a result of the increased interest in reuse of friction material the sediment which remained along the streets after snow melt was studied with regard to physical and chemical characteristics. The side walk affected the amount of substances on the street more than the traffic load. For the streets without sidewalk an increased traffic load increased the amounts of sediment. The particle size distribution of the sediments swept from the street with a sidewalk differed from the distribution at the streets without a sidewalk. With two exceptions the smallest size fraction (>75 µm) had the largest concentration of heavy metals. For composite samples the concentration increased with traffic load. The pathways of pollutants in urban snow deposits have been studied in three different scales; laboratory, pilot, and full-scale. The initial snow, melt water and sediment were analysed with regard to chemical content. It was found that the dissolved substances to a great extent folowed with the melt water while for the particle bounded substances as much as 90-99% stayed in the sediment below the deposit. The dissolved substances left the snow in the beginning of the melt period, while the substances connected to particles showed a uniform release. The laboratory study showed that melt- freeze cycles delayed the release of substances. Almost all substances were attached to particles in the snow, while in the melt water a large part was in solution. It should be noted that a so-called acid shock was not found during these studies.Godkänd; 1997; 20061128 (haneit