IMPACT DES MATÉRIAUX DE TOITURES SUR LA CONTAMINATION MÉTALLIQUE DES EAUX DE RUISSELLEMENT URBAINES

13 p. (version initiale du 24 mai 2006, mise en forme)National audienceDepuis les années 1990, plusieurs travaux de recherche ont montré que les eaux de ruissellement de toitures ont des teneurs élevées en éléments traces métalliques. Les résultats d'échantillonnages d'eaux de ruissellement menés à Paris révèlent que les niveaux de métaux dans les eaux de ruissellement de toitures sont très supérieurs à ceux des eaux de ruissellement de chaussées ou de cours. Dans ce contexte urbain précis, cet apport métallique a pu être imputé à la corrosion des matériaux métalliques utilisés pour la couverture des toits et l'évacuation des eaux pluviales. Cependant, les connaissances sur les différents éléments de toiture et matériaux incriminés dans cette corrosion, leur taux de relargage, leur fréquence d'utilisation restent à ce jour très limitées. Ces connaissances sont pourtant des éléments clés pour le développement de stratégies de réduction à la source des flux polluants, telles que préconisées par la directive européenne cadre sur l'eau (Directive 2000/60 CE). Cet article résume les résultats des études menées à Paris sur les eaux de ruissellement de toiture et présente la stratégie générale et expérimentale du projet de recherche « TOITEAU », qui a débuté en octobre 2005

A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France)

International audienceToday, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of theEuropean Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on thecity scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil

Evaluation of roofing materials emissions at the city scale: Statistical approach for computing roofing area distribution

International audienceRoofing materials are considered as a major source of urban runoff contamination. Today, in the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required at the city scale, and therefore the development of assessment tools is needed. However, at the city scale, the important diversity of roofing materials represents a difficult task. In fact, the most restrictive step when estimating contaminant flows for large-scale territories is the estimation of the roofing materials surfaces area, for which no direct data exists. This paper aims to describe the proposal statistical approach for computing roofing materials area distribution. This method is based on two steps. The first one is the sampling theory which aims to define the required size of the selected sample which represents the proportion R (%) from any total urban area surface. The second step is based on applying the estimation theory. In fact, after determining the proportion R (%), we estimate the unknown distribution of roofing materials in an urban area by performing a sample representing R (%) from the total urban area surface. The reliability of the methodology has been proved for tow different urban areas with known roofing materials distribution. Results obtained showed that a sample representing R=4% of the zone area should be randomly generated

Efficiency of source control systems for reducing runoff pollutant loads: Feedback on experimental catchments within Paris conurbation.

International audience: Three catchments, equipped with sustainable urban drainage systems (SUDS: vegetated roof, underground pipeline or tank, swale, grassed detention pond) for peak flow mitigation, have been compared to a reference catchment drained by a conventional separate sewer system in terms of hydraulic behaviour and discharged contaminant fluxes (organic matter, organic micropollutants, metals). A runoff and contaminant emission model has been developed in order to overcome land use differences. It has been demonstrated that the presence of peak flow control systems induces flow attenuation even for frequent rain events and reduces water discharges at a rate of about 50% depending on the site characteristics. This research has also demonstrated that this type of SUDS contributes to a significant reduction of runoff pollutant discharges, by 20%-80%. This level of reduction varies depending on the considered contaminant and on the design of the drainage system but is mostly correlated with the decrease in runoff volume. It could be improved if the design of these SUDS focused not only on the control of exceptional events but also targeted more explicitly the interception of frequent rain events

Quality of roof harvested rainwater from houses in Île-de-France area, France

International audienceBacteriological and physico-chemical water quality parameters were measured in rainwater from 10 harvesting tanks, belonging to two types of rainwater harvesting systems (outside tanks for garden watering and underground tanks for both outdoor and indoor uses) in Île-de-France area (France). The presence of fecal coliforms, enterococci, Pseudomonas spp., coliforms, total flora at 22°C and 36°C and total DAPI direct counts showed a microbiological contamination in water and sediment samples for both tank types. However, the harvested rainwater quality suited some existing water quality guidelines for different non-potable purposes (bathing water or reused wastewater). To our knowledge, the presence of microorganisms in sediment compartment in rainwater harvesting tank has been studied for the first time here. Results showed that the sediment could be a reservoir of re-contamination for some microbial species, which would survive in the sediment and may be resuspended in the water column. In parallel, physical-chemical parameters (temperature, turbidity, conductivity, pH and dissolved organic carbon) of collected rainwater were found in the ranges reported in the literature. Algal blooms, principally green algae, occurred in the outside tanks during spring and summer as shown by the high chlorophyll levels (the highest chlorophyll content reached 209.8 µg/L with a water pH of 9.37). Nitrate and phosphate concentrations in water samples were low (respectively less than 5 mg/L and 0.5 mg/L) but high enough to support the development of microorganisms and especially photosynthetic microorganisms in the outside tanks. The difficulty to evaluate the microbial quality of roof-harvested rainwater due to the lack of suitable quality standards is underlined. Depending on the usage of the harvested rainwater, some treatments may be needed to get a better microbial quality and direct measurements for pathogens may be also needed to establish whether or not such harvested rainwater is safe for different types of uses

Modelling the Zn emissions from roofing materials at Créteil city scale - Defining a methodology

11 p.International audienceToday, urban runoff is considered as an important source of environment pollution. Roofing materials, in particular the metallic ones are considered as a major source of urban runoff contamination. An accurate evaluation of contaminant flows from roofs is thus required at the city scale. This paper aims to describe the definition of an appropriate methodology for evaluating the zinc emission at the city scale. This methodology is based on combining two different methods. The first one is an automatic classification and the second one is a theoretical urban study site. In order to obtain representative data, the choice of the study site was based on the diversity of land use and the urban and social context. Finally some results and future works will be presented

A decade of monitoring micropollutants in urban wet-weather flows: What did we learn?

Urban wet-weather discharges from combined sewer overflows (CSO) and stormwater outlets (SWO) are a potential pathway for micropollutants (trace contaminants) to surface waters, posing a threat to the environment and possible water reuse applications. Despite large efforts to monitor micropollutants in the last decade, the gained information is still limited and scattered. In a metastudy we performed a data-driven analysis of measurements collected at 77 sites (683 events, 297 detected micropollutants) over the last decade to investigate which micropollutants are most relevant in terms of 1) occurrence and 2) potential risk for the aquatic environment, 3) estimate the minimum number of data to be collected in monitoring studies to reliably obtain concentration estimates, and 4) provide recommendations for future monitoring campaigns. We highlight micropollutants to be prioritized due to their high occurrence and critical concentration levels compared to environmental quality standards. These top-listed micropollutants include contaminants from all chemical classes (pesticides, heavy metals, polycyclic aromatic hydrocarbons, personal care products, pharmaceuticals, and industrial and household chemicals). Analysis of over 30,000 event mean concentrations shows a large fraction of measurements (> 50%) were below the limit of quantification, stressing the need for reliable, standard monitoring procedures. High variability was observed among events and sites, with differences between micropollutant classes. The number of events required for a reliable estimate of site mean concentrations (error bandwidth of 1 around the “true" value) depends on the individual micropollutant. The median minimum number of events is 7 for CSO (2 to 31, 80%-interquantile) and 6 for SWO (1 to 25 events, 80%-interquantile). Our analysis indicates the minimum number of sites needed to assess global pollution levels and our data collection and analysis can be used to estimate the required number of sites for an urban catchment. Our data-driven analysis demonstrates how future wet-weather monitoring programs will be more effective if the consequences of high variability inherent in urban wet-weather discharges are considered

La gestion alternative des eaux pluviales permet-elle une maîtrise efficace des flux de micropolluants? Retour d'expérience des projets Matriochkas, MicroMégas et Roulépur

Novatech 2019, LYON, FRANCE, 01-/07/2019 - 05/07/2019The pooling of results from three French projects (Matriochkas, MicroMégas and Roulépur), within the framework of a working group on methodological harmonisation, makes it possible to analyse the performance of a wide range of stormwater control measures (SCMs) in terms of micropollutant load reduction. Data covers 12 management systems, in 9 different urban contexts. The results highlight the diversity of runoff contamination levels and of their distribution between dissolved and particulate phases. They show significant reductions in particulate pollutants for all filtration-based systems, and less for those that only allow sedimentation. Performance is more limited for the dissolved phase, for which concentration reduction is limited and significant load reductions are only achieved due to a reduction in runoff volumes in structures promoting evapotranspiration.La mise en commun de résultats issus des projets français Matriochkas, MicroMégas et Roulépur, dans le cadre d'un groupe de travail d'échanges et d'harmonisation méthodologiques, permet d'analyser l'efficacité de la gestion alternative des eaux pluviales en termes de réduction des flux de micropolluants, pour 12 dispositifs de gestion et 9 contextes urbains différents. Les résultats soulignent la diversité des niveaux de contamination des eaux de ruissellement, et de leur distribution entre phases dissoutes et particulaires. Ils démontrent des abattements importants des polluants particulaires pour l'ensemble des systèmes basés sur la filtration, et moindre pour ceux ne permettant que la sédimentation. Les performances sont plus limitées pour les concentrations dissoutes, de sorte que seul un abattement des volumes de ruissellement, dans les ouvrages favorisant l'évapotranspiration, permet une réduction significative des flux de micropolluants dissou

Le développent d'un guide méthodologique pour l'évaluation des performances des ouvrages de maîtrise à la source des eaux pluviales

Novatech 2019, LYON, FRANCE, 01-/07/2019 - 05/07/2019Evaluating the performance of sustainable drainage systems (SuDS) in a field context presents a number of methodological problems. For this reason, as a part of three French research projects focused on this type of evaluation, Matriochkas, Micromegas and Roulepur, a working group on methodological harmonisation was established in order to facilitate the inter-comparison of results between the projects and propose a methodological guideline for practitioners carrying out such evaluations. The guideline proposes an approach where performance is evaluated with respect to a service function that the SuDS aims to achieve, itself identified from local issues. Its first section presents the various service functions which may be assigned to these devices. Next, performance indicators are defined for a selection of the identified service functions, common within the French context and studied as a part of the three projects. Three categories of indicators are identified: hydrologic indicators (relative to water flows), pollutant indicators and socio-technical indicators. Examples of instrumentation and of the application of the proposed indicators drawn from the experience of the three projects are also presented.L'évaluation in situ des performances des ouvrages de maîtrise à la source des eaux pluviales pose un grand nombre de questions d'ordre méthodologique. Ainsi, dans le cadre de trois projets de recherche français dédiés à ce type d'évaluation, Matriochkas, Micromegas et Roulépur, un groupe de travail sur l'harmonisation des méthodes a été constitué afin de faciliter l'inter-comparaison des résultats issus des projets, mais aussi de rédiger un guide méthodologique à destination des acteurs opérationnels pouvant être amenés à faire ce type d'étude. Ce guide propose une démarche où la performance est évaluée pour chaque fonction de service visée pour l'ouvrage, en réponse à des enjeux locaux. La première partie du guide détaille les fonctions de service pouvant être attendues de ce type d'ouvrage. Ensuite, des indicateurs de performance sont déclinés pour une sélection de fonctions de service couramment rencontrées dans le contexte français et qui ont pu être abordées au cours des projets. Ces indicateurs se regroupent en trois catégories: les indicateurs hydrologiques (relatifs aux flux d'eau), les indicateurs pollutifs (relatifs aux polluants) et les indicateurs sociotechniques. Le guide s'appuie sur des exemples issus des trois projets pour présenter des cas pratiques de dispositifs métrologiques et d'application des indicateurs proposés

Le bâti - une source de contamination en micropolluants des eaux de ruissellement ? Cas des émissions de métaux, biocides, alkylphénols et bisphénol A

Le LEESU, dans le cadre de l'Observatoire des Polluants Urbains OPUR, s'intéresse depuis une vingtaine d'années aux sources et flux de contaminants dans les eaux pluviales urbaines. Les travaux menés dès la fin des années 1990 à Paris, ont souligné la contribution majeure des matériaux du bâti, et en particulier des matériaux de couverture, à la contamination métallique des eaux de ruissellement. Ces émissions métalliques ont par la suite été quantifiées et modélisées plus précisément à partir d'expérimentations sur bancs d'essais. Plus récemment, l'attention s'est portée sur le cas des micropolluants organiques, qui pour certains pourraient également être émis par les matériaux organiques utilisés dans le bâti ou leurs revêtements/traitements. On citera en particulier le cas du lessivage de biocides inclus dans les revêtements de façade ou épandus lors du traitement anti-mousses des toitures. Les travaux actuellement en cours au LEESU illustrent par ailleurs la prévalence de deux familles de micropolluants organiques préoccupants pour les milieux aquatiques (BisphénolA et alkylphénols) dans de nombreux matériaux de construction entrant en contact avec la pluie et leur extractabilité à l'eau