Search

Traditional improvement actions for monitoring sewerage networks (liquid and solid) in urban areas require a significant human and technical investment from the urban sanitation administration, due to the increase in costs of monitoring tools and means of transport on-site in the long run. The approach we developed aims to propose integration of the citizen in the process of monitoring the operation of sanitation infrastructures. We consider that a strong citizen contribution to the improvement of sanitation, both liquid and solid, also contributes to a better protection of the environment. The name given to the approach described in the article is Geo-CollaboraTIC. It combines Geographic Information Systems (GIS) and Information & Communication Technologies (ICT). To implement it, we developed an interactive and collaborative online spatially referenced interface. We explained the operating principle of this technology, which uses real-time geo-localization of topological and multimedia data (photos and videos). Such facilities of the modern world make possible, on the one hand, to reduce surveillance and monitoring costs, and on the other hand, to take over the Council of Europe's citizen consultations (decisional communication/citizen/initiation). The participation of citizens in the life of their city strengthens the dialogue about its future and the protection of their environment. As tradicionais ações de melhoria para o monitoramento das redes de esgoto, líquido e sólido, em áreas urbanas exigem um investimento significativo da administração de saneamento urbano para recursos humanos e técnicos devido ao alto custo das ferramentas de monitoramento e dos meios de deslocamento in situ em longo prazo. A abordagem que desenvolvemos visa propor a integração do cidadão no processo de monitoramento das infraestruturas de saneamento. Consideramos que ao contribuir para a melhoria do saneamento, tanto líquido como sólido, o cidadão também contribui para uma melhor proteção do meio ambiente. O nome dado à abordagem descrita no artigo é Geo-CollaboraTIC. Ela combina Sistemas de Informação Geográfica (SIG) e Tecnologias de Informação e Comunicação (TIC). Para a sua implementação, desenvolvemos uma interface online interativa e colaborativa, de referência espacial. Este trabalho explica o princípio de operação desta tecnologia, que utiliza a geo-localização em tempo real de dados topológicos e multimídia, como fotos e vídeos. Estas facilidades do mundo moderno permitem reduzir os custos de vigilância e monitorização, bem como envolver as consultas dos cidadãos conforme o Conselho da Europa (comunicação/cidadão/iniciativa decisória). A participação dos cidadãos na vida da sua cidade reforça o diálogo sobre o seu futuro e a proteção do seu ambiente

Insufficient public and municipal investment represent a major challenge for the long term management of urban drainage systems. Utilities are challenged to develop efficient rehabilitation strategies in order to maintain the level of service. Closed-circuit television (CCTV) inspection is used since the 1980’s as industry standard for sewer investigation system and structural performance evaluation. Due to budget restrictions, inspection rates are generally low and municipalities tend to inspect only a small part of their network (e.g. in France, less than 5% according to Ahmadi et al., 2014). Since the definition of rehabilitation strategies is limited by the lack of information about sewer condition and remaining life, deterioration models have been developed to forecast the evolution of the system according to its current and past condition. One of the main factors hampering the uptake of deterioration modelling by utilities is the lack of real scale evidence of the tangible benefits provided. In particular, most utilities are concerned by the minimum amount of CCTV data required and the relevance of using such models on their networks with limited data availability. Finally, most utilities acknowledge the uncertainties in the procedure of sewer condition assessment, mainly due to the subjectivity of the coding operator. There is a strong need to quantify precisely the uncertainty of the sewer condition assessment procedure and its influence on the outcomes of deterioration modelling. The thesis aims at addressing these gaps by assessing the performance of sewer deterioration modelling using a case study with high CCTV data availability and by identifying the influence of CCTV data quality and availability on modelling performance. The study has been performed with a statistical (GompitZ) and a machine learning (Random Forest) deterioration models using the extensive CCTV database of the cities of Braunschweig and Berlin in Germany. Our results show, that at network level, both machine learning and statistical models can simulate with sufficient accuracy the condition distribution of the network, even in case of low data availability. At the pipe level, the machine learning model outperforms the statistical model. Regarding CCTV data uncertainty, our results highlight that the probability to inspect correctly a pipe in poor condition is close to 80-85% and thus the probability to overestimate the (good) condition of the pipe is close to 15-20% (False Negative). The impact of the uncertainties on the prediction of a deterioration model is not negligible. The analysis shows that the required replacement rate to maintain a constant proportion of segments in poor condition is underestimated if the uncertainties are not included in the analysis., Les infrastructures de collecte et de traitement des eaux usées représentent un investissement considérable pour les municipalités. La plupart des collectivités sont aujourd’hui confrontées au problème de la gestion durable de leur patrimoine vieillissant avec des besoins urgents de réhabilitation des infrastructures. Elles se doivent donc d’élaborer des stratégies de gestion patrimoniale efficace pour maintenir le niveau de service rendu et limiter l’augmentation des redevances. L’inspection télévisée (ITV) est la méthode standard utilisée depuis des décennies pour l'évaluation de la condition structurelle des réseaux d’assainissement. Dû à l’absence de réglementation et aux coûts élevés d’inspection, la plupart des collectivités n’ont qu’une connaissance partielle de la condition de leur réseau et manquent d’information pour planifier efficacement les actions de maintenance et renouvellement. Pour pallier à cette situation, des modèles numériques de détérioration ont été développés pour simuler la condition des conduites non-inspectées et prévoir l´évolution future de la condition des réseaux. Un des obstacles majeurs à l’appropriation de ces outils par les collectivités est le manque de preuves à grande échelle de leur bonne performance. D’autre part, l'influence de la quantité de données disponibles pour étalonner les modèles sur la fiabilité des prédictions est mal connue. Les taux d’inspection étant relativement faibles, les collectivités sont rarement assurées d’avoir les données nécessaires pour développer des modèles fiables. Enfin, de nombreuses collectivités reconnaissent les incertitudes liées aux données d’inspection mais aucune étude n’a pu mettre en évidence l’influence de ces incertitudes sur les résultats de modélisation. Ce travail de thèse vise à évaluer la performance des modèles de détérioration ainsi qu’à évaluer l’influence de la quantité de données disponibles sur la qualité de prédiction. Enfin, cette thèse a pour objectif de quantifier la fiabilité des données d’inspection et d’analyser l’influence de leur incertitude sur la performance des modèles de détérioration.

International audience; Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas.

International audience; Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced by historical decisions and implementations. The current decisions taken in sewer asset management will, therefore, have a long-lasting impact on the functionality and quality of future services provided by these networks. These decisions can be supported by different approaches ranging from various inspection techniques, deterioration models to assess the probability of failure or the technical service life, to sophisticated decision support systems crossing boundaries to other urban infrastructure. This paper presents the state of the art in sewer asset management in its manifold facets spanning a wide field of research and highlights existing research gaps while giving an outlook on future developments and research areas.

Real time control (RTC) is considered as a cost-efficient solution for combined sewer overflow (CSO) reduction as it optimises the available capacity of sewer networks. RTC helps to prevent the need for construction of additional retention volumes, increases the network adaptability to changes in water management policies, and above all alleviates the environmental impact of CSOs. Following increasing interest in water quality-based RTC (QBR), this thesis demonstrates a simple and nothing-to-lose QBR strategy to reduce the amount of CSO loads during storm events. The performance of the QBR strategy, based on Mass-Volume (MV) curves prediction, is evaluated by comparison to a typical hydraulics-based RTC (HBR) strategy. A proof-of-concept study is first performed on a small catchment of 205 ha to test the new QBR concept using 31 storm events during a two-year period. Compared to HBR, QBR delivers CSO load reduction for more than one third of the events, with reduction values from 3 to 43 %. The QBR strategy is then implemented on the Louis Fargue catchment (7700 ha) in Bordeaux, France and similarly compared with the HBR strategy. By implementing QBR on 19 storm events over 15 months, its performance is consistent, bringing valuable benefits over HBR, with 17 out of 19 events having load reduction varying between 6 and 28.8 %. The thesis further evaluates the impact of MV curve prediction uncertainty (due to model prediction uncertainty) on the performance of the QBR strategy, using a representative storm event. The resulting range of uncertainty is limited. Besides, results of the sensitivity study show that the choice of the QBR or HBR strategy should take into account the current tank volumes and their locations within the catchment., La gestion en temps réel (GTR) est considérée comme une solution économiquement efficace pour réduire les déversements par temps de pluie car elle optimise la capacité disponible des réseaux d'assainissement. La GTR permet d'éviter la construction de volumes de rétention supplémentaires, d'augmenter l'adaptabilité du réseau aux changements de politiques de gestion de l'eau et surtout d'atténuer l'impact environnemental des déversoirs d'orage. À la suite de l'intérêt croissant pour la GTR fondée sur la qualité de l'eau (QBR), cette thèse démontre une stratégie simple et efficace pour les charges polluantes déversées par temps de pluie. La performance de la stratégie QBR, basée sur la prédiction des courbes masse-volume (MV), est évaluée par comparaison avec une stratégie typique de GTR à base hydraulique (HBR). Une étude de validation de principe est d'abord réalisée sur un petit bassin versant de 205 ha pour tester le nouveau concept de QBR en utilisant 31 événements pluvieux sur une période de deux ans. Par rapport à HBR, QBR offre une réduction des charges déversées pour plus d'un tiers des événements, avec des réductions de 3 à 43 %. La stratégie QBR est ensuite mise en oeuvre sur le bassin versant de Louis Fargue (7700 ha) à Bordeaux, France et comparée à nouveau à la stratégie HBR. En implémentant QBR sur 19 événements pluvieux sur 15 mois, ses performances sont constantes et apportent des avantages précieux par rapport à HBR, 17 des 19 événements ayant une réduction de charge variant entre 6 et 28.8 %. La thèse évalue en outre l'impact de l'incertitude de prédiction de la courbe MV (due à l'incertitude de prédiction du modèle) sur la performance de la stratégie QBR, en utilisant un événement pluvieux représentatif. La marge d'incertitude qui en résulte est faible. En outre, l'étude de sensibilité montre que le choix de la stratégie QBR ou HBR doit tenir compte des dimensions réelles des bassins et de leur emplacement sur le bassin versant.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]RIVAGE [ADD1_IRSTEA]Hydrosystèmes et risques naturels [ADD2_IRSTEA]Hydrosystèmes et risques naturelsThe Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE), Ghent, BEL, 28-/10/2018 - 31/10/2018; International audience; Water and sewer networks and levees must be managed in a way that guarantees their performance over time. Maintaining their service in the long-term involves huge public health and safety, social, economic and environmental stakes. This calls for integrated asset management rules and strategies to mitigate the consequences of ageing and possible obsolescence integrating life cycle approaches. The aim of this article is to present the various approaches developed by Irstea with its partners over several years relating to these three types of infrastructure. It also proposes elements of comparison and synthesis between these approaches with respect to their objectives and implementation.

River Flow 2018, Villeurbanne, FRA, 05-/09/2018 - 08/09/2018; International audience; Sewer overflow is one of the main causes of urban floods. Using an urban model called MURI recently built by Irstea, a series of experiments are carried out in order to simulate overflowing cases. The first configuration that was studied is a single street of 5.4 m in length, 0.15 m in width with a slope of 0.1% and two street inlets (of which the orifice diameter is 14 mm) that ensure the connection with the sewer network. Inflows of 2 and 3 L/s are used for the street and an inflow of 0.5 L/s for the sewer network that is partially closed in order to obtain overflow at the street inlets. The rising of the weir downstream the street permitted to have enough water depth to measure the vertical profiles of velocities. This study allowed us to investigate how the overflow process influence the water depth and the velocity field around the street inlet. The differences of results between the two street inflows reveals the complexity and explains the difficulty to calculate exchange flow.; Ppour comprendre les inondations par débordement de réseau, des expériences ont été effectuéees dans le modèle urbain MURi au laboratoire d'hydraulique d'Irstea à Villeurbanne. la complexité des écoulements rend difficile le calcul des débits d'échange.

The present study deals with the exposure of four different mortar formulations in the headspace of two distinct sewer networks prone to biodeterioration phenomenon due to the presence of hydrogen sulphide. Cylindrical specimens composed of two cements, ordinary Portland cement (OPC) and calcium aluminate cement (CAC), with or without a substitution of 75% of cement by blast furnace slag (BFS) were prepared and exposed. During the exposure, the evolution of cement materials was monitored. After 4 years exposure, OPC materials without BFS are deeply deteriorated at high speed. Best performances have been observed with CAC mortars correlated to their higher content in aluminium ion (Al3+). The rank of durability observed on site is OPC\OPC+BF\CAC+BFS\CAC. Molecular biology analysis revealed that microbial diversity is varying according to binder type as well as during the exposure duration.; L'étude porte sur une exposition de 4 ans de mortiers dans deux réseaux d'assainissement présentant des concentrations éleÎes en H2S. les formulations des mortiers sont à base de ciment portland, de ciment aux laitiers de hauts fourneaux, de ciment d'aluminate de calcium avec ou sans laitier de hauts fourneaux. Après 4 ans, les mortiers à base de ciment portland sont très détériorés contrairement à ceux formulés avec les ciments d'aluminate de calcium et cela peut être corrélé avec la teneur éleÎe en ions aluminium dans ces derniers.

Bio-deterioration of concrete, which is very common in sewer system and waste water treatment plant, results in significant structure degradation. Normally, the process can be described by the two following parts: 1) Biochemistry reactions producing biogenic aggressive species in biofilms which are spread on the surface of concrete. As one of the most significant biogenic acid in sewer pipes, sulfuric acid (H2SO4) is produced by sulfur oxidizing bacteria (SOB). 2) Chemical reactions between biogenic aggressive species and cement hydration products which is responsible for concrete deterioration. A reactive transport model is proposed to simulate the bio-chemical and chemical deterioration processes of cementitious materials in contact with SOB and H2S or sulfuric acid solution. This model aims at solving simultaneously transport and biochemistry/chemistry in biofilms and cementitious materials by a global coupled approach. To provide an appropriate environment for SOB to grow, the surface neutralization of concrete (i.e., the absorption of H2S and aqueous H2S corrosion) is considered. To obtain the amount of biogenic H2SO4, the bio-oxidation of H2S by the activation of bacteria is simulated via a simplified model. To provide a suitable environment for SOB to grow, the abiotic pH reduction of concrete process is introduced. The production rate of H2SO4 is governed by the pH in the biofilms and the content of H2S in gas.It is assumed that all chemical processes are in thermodynamical equilibrium. The dissolution of portlandite (CH) and calcium silicate hydrates (C-S-H) and the precipitation of gypsum (C¯S H2) and calcium sulfide are described by mass action law and threshold of ion activity products. To take into account the continuous decrease of the Ca/Si ratio during the dissolution of C-S-H a generalization of the mass action law is applied. By simplifying the precipitation process of gypsum, a damage model is introduced to characterize the deterioration of concrete due to the swelling of gypsum. Thus, the porosity evolution and deterioration depth during deterioration process are taken into account. Only diffusion of aqueous species are considered. Different diffusion coefficients are employed for various ions and Nernst-Planck equation was implemented. The effect of the microstructure change during deterioration on transport properties is considered as well. For both biofilms and cementitious materials, the balance equations of total mass of each atom (Ca, Si, S, K, Cl) are used to couple transport equations and (bio-)chemical reactions. The model is implemented within a finite-volume code, Bil. Following the introduction of principle of the finite volume method, the coupling of the bio-chemistry process in biofilms and chemistry process in cementitious materials is illustrated. By this model, some experiments reported in literature, including chemical immersion tests (statical solution condition and flow solution condition) and microbiological simulation tests, are simulated. The numerical results and the experimental observations are compared and discussed. The influence of properties of cementitious materials (initial porosity, carbonated layer, etc.) and environmental factors (concentration of H2SO4, content of H2S, etc.) are investigated by this model as well. Furthermore, a long term predictionis conducted

ISUD - 9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, STRASBOURG, FRANCE, 27-/08/2014 - 29/08/2014; Sewer deposit is a complex mix of mineral and organic materials whose dynamics remain poorly understood to such a point that the transport formulas, mainly developed for rivers sediment, are still missing accuracy. IFSTTAR researches aims at helping networks managers by investigating hydraulics and solid transport occurring in urban sewer networks. The current paper presents an experimental study of the influence of the hydraulic parameters on the deposit bathymetry. Various ultrasonic devices are used in the study to measure the transversal variation of the deposit and the velocity profiles sewer. The results show the relation between the deposit height and the bottom shear stress and will be presented and discussed in paper. In similar cases studies (hydraulics conditions), results of bottom shear stress profiles are different.

Cementitious materials biodeterioration in sewer networks is an important problem for sewer networks managers. This deterioration process is due to the implication of two biofilm involved in the sulfur cycle. Microorganisms of the first biofilm will reduce sulfate and organic sulfur compounds into H2S in the effluent and then, the second biofilm oxidizes it into sulfuric acid in the structure headspace. This biogenic acid usually leads to the cementitious matrix dissolution. However, cementitious materials do not equivalently face biogenic acid attack. In very aggressive conditions, those made of ordinary Portland cement are highly deteriorated while those based on calcium aluminate cement show good on-site performances. So far, only chemical testing standard procedures are available to predict service life of materials intended for sewer networks but they are not representative of the phenomenon because they do not consider microbial development. Nowadays, it is necessary to develop a new test that could be standardiable involving microorganisms. Such a test has been developed at Ifsttar and provides interesting results.

Sewer networks should withstand several aggressions, including biodeterioration processes. This study is focusing on cementitious materials since, depending on their composition, these materials do not display the same behaviour when biogenic sulfuric acid attack occurs. In severe conditions, ordinary Portland cement materials can be deteriorated, while calcium aluminate cement (CAC) materials show good resistance to biogenic corrosion. Results show that this durability difference is due to the difference of cement mineralogy. Firstly, the H2S abiotic oxidation into elemental sulfur is less favourable on CAC. Hence it provides much less nutrients for sulfur-oxidizing microorganisms. Then, the presence of high aluminium content in CAC provides a combination of interesting properties to face biogenic acid attack. The hydrated alumina reacts with acid to create an alumina gel layer, stable up to pH 3-4. The acid attack leads to the release of aluminium ions displaying a bacteriostatic effect on neutrophilic sulfur-oxidizing microorganisms. Finally, an alumina gel precipitates on the surface. This gel has an impact on cement surface porosity which therefore reduces the acid impact and probably limiting biofilm adhesion.

Asset management ensures that the best decisions are made for elements of the asset in order to reduce risks, optimize performance and minimize costs. A proactive asset management includes development of prioritization schemes for selection of inspection and rehabilitation needs. In this regard, we have identified the following bottlenecks which are addressed in this manuscript. First, there is a need of elaborating inspection programs based on deterioration models in order to be more cost-effective. The influence of availability and quality of data (imprecision, uncertainty, incompleteness) on models’ predictive power has not been studied in depth. We propose two methods to establish the list of the most informative factors from a representative sample of an asset stock. Among other results, this study would suggest that having imprecision in the database is preferable to having a database with no information on one specific factor. Second, once segments are inspected, they should be evaluated by a condition grading protocol. Though various condition grading protocols have been developed, they all fail to undertake the sensitivity of managers and stakeholders to the over or under-estimation of assets’ condition grade as many sources of uncertainty could be found within the condition assessment process. We propose a procedure in order to deal with this uncertainty. We also carry out some sensitivity analyses of parameters employed in this procedure. The results of these sensitivity tests are then applied to a part of the Greater Lyon asset stock. The results show that the assessment of segments into a condition grade depends heavily on the hypotheses that a manager could make about the under or over-estimation of its assets’ condition. Third, at the moment small number of utilities has completely inspected and evaluated their asset stocks. Therefore, the use of a representative sample from an asset stock in order to calibrate decision-support models as deterioration models seems mandatory. Nevertheless, in this regard we should tackle with following problematic issues: 1) How to draw a representative sample of an asset stock which reflects the characteristics of this asset stock? and 2) What is the impact of used sample on the calibration outcomes of these multivariate models? Hence, by drawing several samples with different sizes according to different sampling methods and applying Monte Carlo method, we have proposed a procedure in order to study the influence of available sample on the outcomes of a multivariate model. By proposing some statistical analyses, we showed that the calibration process depends extremely on available sample which could results, if this latter is not drawn properly, into erroneous conclusions., La gestion patrimoniale vise à choisir les meilleures décisions d’actions à mener sur les éléments du patrimoine, pour limiter les risques, optimiser les performances et réduire les couts. Dans ce manuscrit, nous avons adapté la définition spécifique de la gestion proactive des réseaux d’assainissement aux pratiques des gestionnaires pour passer de la maintenance post-défaillance à une politique de gestion patrimoniale proactive sur le long-terme. Pour cela, nous avons identifié les verrous suivants qui sont abordés dans le manuscrit. Premièrement, il est nécessaire de pouvoir élaborer les programmes d’inspections à partir de modèles de détérioration pour optimiser les budgets alloués. Malgré le développement de nombreux modèles de détérioration, l’influence de la qualité et de la disponibilité des données (incomplétude, imprécision, incertitude) sur la puissance prédictive des modèles n’a pas été étudiée en détail. Nous avons abordé cette question en proposant deux méthodes pour déterminer la liste des facteurs les plus informatifs à partir d’un échantillon représentatif. Entre autres, nos résultats suggèrent que l’imprécision sur une donnée est préférable à ne pas disposer de cette donnée. Nous avons également montré que la notion de « quartier » pourrait être utilisée, sous certaines conditions, pour compenser la non-connaissance de l’âge des conduites. Deuxièmement, une fois les conduites inspectées, leur état de santé doit être évalué à l’aide d’un protocole identique pour l’ensemble du patrimoine. Il est nécessaire que le protocole utilisé puisse minimiser les erreurs de sur- ou sous-estimation en fonction des choix des gestionnaires. Nous avons proposé une procédure prenant en compte ces choix, ainsi que l’état global du patrimoine considéré. Les études de sensibilité réalisées à partir des données d’inspection d’une partie du patrimoine du Grand Lyon montrent que l’état de santé évalué dépend fortement des choix faits par le gestionnaire concernant la sur- ou sous-estimation. Troisièmement, peu de patrimoines ont actuellement été complètement inspectés et évalués. Ainsi, l’utilisation d’un échantillon représentatif d’un patrimoine semble obligatoire pour pouvoir calibrer des modèles justifiant les décisions comme par exemple un modèle de détérioration. Après avoir généré différents échantillons de différentes tailles et selon différentes méthodes d’échantillonnage, à l’aide de la méthode de Monte Carlo, nous avons pu proposer une procédure pour étudier l’influence des caractéristiques de l’échantillon sur les résultats du modèle de détérioration. A partir d’analyses statistiques, nous avons montré que le processus de calage (des modèles) dépend fortement de l’échantillon disponible, et cela peut donc conduire à des résultats erronés.

The primary function of sewage networks, with a view to protecting public health, is to collect wastewater and convey it to wastewater treatment plant. Under specific operating conditions leading to the production of hydrogen sulfide (H2S), major deterioration of concrete infrastructures is observed in the gas phase of these same networks. Studies have shown that an H2S environment leads to the selection, in contact with cement walls, of bacteria enable oxidizing reduced sulfur compounds (sulfo-oxidizing bacteria), biological oxidation leading to the production of acid and sulfate. In the context of the "NF EN 598" standard for ductile cast iron pipes and the "NF EN 14647" standard requiring the validation of coatings that can be used in such conditions using purely chemical tests that are not very representative of reality, LISBP, in partnership with Saint-Gobain PAM, carried out this Phd work with the industrial objective of developing a biodeterioration test for cementitious materials.To meet this objective, this research project was based on a literature review of the phenomena involved in the biodeterioration of cementitious materials in wastewater networks, with a view to proposing a model experimental set-up for the coupled study, on the scale of an industrial pipe section, of the biological and chemical transformations determining the fate of the cementitious materials used. This study was based on experimental laboratory work and the development of numerical models, aimed at selecting and understanding biogenic acid-producing sulfo-oxidizing bacteria. Finally, 2 types of cementitious materials were exposed and studied afer exposure by analysis of the chemical, mineralogical and microstructural evolutions of the tested materials. In this way, a model system was proposed, defining an experimental set-up (associated analytical techniques) and methods for exploiting the measurements. With this approach, a new test protocol is proposed, helping to assess the resistance of cementitious coatings used in sewer networks to biogenic acid attack. This three-month test protocol will ultimately provide a decision-making aid for the management of existing wastewater networks and the design of future networks.; La fonction première des réseaux d’assainissement, en vue de la protection sanitaire des populations, est la collecte des eaux usées et leur acheminement vers les installations de traitement. Dans des conditions d’exploitations particulières conduisant à la production de sulfure d’hydrogène (H2S), des détériorations majeures des infrastructures en béton sont observées dans les phases aériennes de ces mêmes réseaux. En effet, des études ont montré qu’un environement H2S entrainait la sélection au contact des parois cimentaires de bactéries capables d’oxyder les composés soufrés réduits (bactéries sulfo-oxydantes), oxydation biologique conduisant à la production d’acide et de sulfate. Dans un contexte normatif « NF EN 598 » concernant les canalisations en fonte ductile et « NF EN 14647 » imposant la validation des revêtements utilisables dans de telles conditions par des tests uniquement chimiques peu représentatifs de la réalité, le LISBP en partenariat avec l’entreprise Saint-Gobain PAM, ont mené ce travail de thèse avec pour objectif industriel le dévelopment d’un test de biodétérioration des revêtements cimentaires. Pour répondre à cet objectif ce projet de recherche s’est articulé autour d’une analyse bibliographique des phénomènes participant à la biodétérioration des matériaux cimentaires en réseau d’assainissement et ce afin de proposer un dispositif expérimental modèle permettant, à l’échelle d’une section de canalisation industrielle, l’étude couplée des transformations biologiques et chimiques déterminant le devenir des revêtements cimentaires utilisés. Cette étude s’est alors appuyée sur un travail expérimental en laboratoire et le développement de models numériques, visant la sélection et la compréhension de bactéries sulfo-oxydantes productrices de l’acide biogéniques. Finalement 2 types de matériaux cimentaires ont été exposés et étudiés par une analyse près exposition des évolutions chimiques, minéralogiques et microstructurelles des revêtements testés. Ainsi un système modèle, définissant un dispositif expérimental (techniques analytiques associées) et les méthodes d’exploitation des mesures, a été proposé. Par cette approche, un nouveau protocole d’essai est proposé, participant à l’évaluation de la résistance des revêtements cimentaires utilisés en réseau d’assainissement face à des attaques d’acide biogénique. Ce protocole d’essais d’une durée de trois mois assurera à terme une aide à la décision dans la gestion des réseaux d’assainissement existants et la conception des réseaux futurs.

Asset management ensures that the best decisions are made for elements of the asset in order to reduce risks, optimize performance and minimize costs. A proactive asset management includes development of prioritization schemes for selection of inspection and rehabilitation needs. In this regard, we have identified the following bottlenecks which are addressed in this manuscript. First, there is a need of elaborating inspection programs based on deterioration models in order to be more cost-effective. The influence of availability and quality of data (imprecision, uncertainty, incompleteness) on models’ predictive power has not been studied in depth. We propose two methods to establish the list of the most informative factors from a representative sample of an asset stock. Among other results, this study would suggest that having imprecision in the database is preferable to having a database with no information on one specific factor. Second, once segments are inspected, they should be evaluated by a condition grading protocol. Though various condition grading protocols have been developed, they all fail to undertake the sensitivity of managers and stakeholders to the over or under-estimation of assets’ condition grade as many sources of uncertainty could be found within the condition assessment process. We propose a procedure in order to deal with this uncertainty. We also carry out some sensitivity analyses of parameters employed in this procedure. The results of these sensitivity tests are then applied to a part of the Greater Lyon asset stock. The results show that the assessment of segments into a condition grade depends heavily on the hypotheses that a manager could make about the under or over-estimation of its assets’ condition. Third, at the moment small number of utilities has completely inspected and evaluated their asset stocks. Therefore, the use of a representative sample from an asset stock in order to calibrate decision-support models as deterioration models seems mandatory. Nevertheless, in this regard we should tackle with following problematic issues: 1) How to draw a representative sample of an asset stock which reflects the characteristics of this asset stock? and 2) What is the impact of used sample on the calibration outcomes of these multivariate models? Hence, by drawing several samples with different sizes according to different sampling methods and applying Monte Carlo method, we have proposed a procedure in order to study the influence of available sample on the outcomes of a multivariate model. By proposing some statistical analyses, we showed that the calibration process depends extremely on available sample which could results, if this latter is not drawn properly, into erroneous conclusions., La gestion patrimoniale vise à choisir les meilleures décisions d’actions à mener sur les éléments du patrimoine, pour limiter les risques, optimiser les performances et réduire les couts. Dans ce manuscrit, nous avons adapté la définition spécifique de la gestion proactive des réseaux d’assainissement aux pratiques des gestionnaires pour passer de la maintenance post-défaillance à une politique de gestion patrimoniale proactive sur le long-terme. Pour cela, nous avons identifié les verrous suivants qui sont abordés dans le manuscrit. Premièrement, il est nécessaire de pouvoir élaborer les programmes d’inspections à partir de modèles de détérioration pour optimiser les budgets alloués. Malgré le développement de nombreux modèles de détérioration, l’influence de la qualité et de la disponibilité des données (incomplétude, imprécision, incertitude) sur la puissance prédictive des modèles n’a pas été étudiée en détail. Nous avons abordé cette question en proposant deux méthodes pour déterminer la liste des facteurs les plus informatifs à partir d’un échantillon représentatif. Entre autres, nos résultats suggèrent que l’imprécision sur une donnée est préférable à ne pas disposer de cette donnée. Nous avons également montré que la notion de « quartier » pourrait être utilisée, sous certaines conditions, pour compenser la non-connaissance de l’âge des conduites. Deuxièmement, une fois les conduites inspectées, leur état de santé doit être évalué à l’aide d’un protocole identique pour l’ensemble du patrimoine. Il est nécessaire que le protocole utilisé puisse minimiser les erreurs de sur- ou sous-estimation en fonction des choix des gestionnaires. Nous avons proposé une procédure prenant en compte ces choix, ainsi que l’état global du patrimoine considéré. Les études de sensibilité réalisées à partir des données d’inspection d’une partie du patrimoine du Grand Lyon montrent que l’état de santé évalué dépend fortement des choix faits par le gestionnaire concernant la sur- ou sous-estimation. Troisièmement, peu de patrimoines ont actuellement été complètement inspectés et évalués. Ainsi, l’utilisation d’un échantillon représentatif d’un patrimoine semble obligatoire pour pouvoir calibrer des modèles justifiant les décisions comme par exemple un modèle de détérioration. Après avoir généré différents échantillons de différentes tailles et selon différentes méthodes d’échantillonnage, à l’aide de la méthode de Monte Carlo, nous avons pu proposer une procédure pour étudier l’influence des caractéristiques de l’échantillon sur les résultats du modèle de détérioration. A partir d’analyses statistiques, nous avons montré que le processus de calage (des modèles) dépend fortement de l’échantillon disponible, et cela peut donc conduire à des résultats erronés.

Sewer networks are subjected to many corrosion agents leading to deterioration of variant magnitude. One type of damage can be ascribed to concrete corrosion by biogenic sulfuric acid. According to field data, cementitious materials have different behaviours depending more especially on cement type. Those made with calcium aluminate cement (CAC) offer better performance than those made of ordinary Portland cement (OPC). This difference of durability may have three origins that can be combined. The first one is due to the oxidation of hydrogen sulfide at the surface of each materials leading to a lower amount of elemental sulfur deposited on CAC materials due to the difference of matrix composition (chemical composition and mineralogy). Elemental sulfur is then oxidized into sulfuric acid by microorganisms and leads to cementitious materials corrosion. The second one, the alumina content of CAC materials stabilizes the surface pH at around 3-4 and therefore limits the development of the most deleterious sulfur oxidizing bacteria. The last one, the aluminium content of CAC has a bacteriostatic effect on some microorganisms, limiting biofilm development. All that results are participating at the good performances of CAC materials.

International audience; Le projet MENTOR a pour objectifs de proposer une méthodologie permettant d'analyser, de qualifier et de mettre en place des points de mesures pertinents pour une gestion efficace des eaux urbaines dans le but de mieux quantifier et mieux qualifier les rejets aux milieux aquatiques récepteurs. Ce projet permettra la mise au point d'outils opérationnels destinés aux gestionnaires et aux responsables de métrologie des réseaux d'assainissement urbains. Il fournira également des recommandations au niveau. Cet article présente la démarche du projet et quelques exemples de résultats.

Suburban areas are subject to strong anthropogenic modifications, which can influence hydrological processes. Sewer systems, ditches, sewer overflow devices and retention basins are introduced and large surface areas are sealed off. The knowledge of accurate flow paths and watershed boundaries in these suburban areas is important for storm water management, hydrological modelling and hydrological data analysis. This study proposes a new method for the determination of the drainage network based on time efficient field investigations and integration of sewer system maps into the drainage network for small catchments of up to 10 km2. A new method is also proposed for the delineation of subcatchments and thus the catchment area. The subcatchments are delineated using a combination of an object-oriented approach in the urban zone and GIS based terrain analysis with flow direction forcing in the rural zone. The method is applied to the Chaudanne catchment, which belongs to the Yzeron river network, and is located in the suburban area of Lyon, France. The resulting subcatchment map gives information about subcatchment response and contribution. The method is compared to six other automatic catchment delineation methods based on stream burning, flow direction forcing and calculation of subcatchments for inlet points. None of the automatic methods could correctly represent the catchment area and flow paths observed in the field. The watershed area calculated with these methods differs by as much as 25% from the area computed with the new method.

Bacterial aggregation and/or adhesion are key factors for colonization of the digestive ecosystem and the ability of probiotic strains to exclude pathogens. In the present study, two probiotic strains, Lactobacillus rhamnosus CNCM-I-3698 and Lactobacillus farciminis CNCM-I-3699, were evaluated as viable or heat-killed forms and compared with probiotic reference Lactobacillus strains (Lb. rhamnosus GG and Lb. farciminis CIP 103136). The autoaggregation potential of both forms was higher than that of reference strains and twice that of pathogenic strains. The coaggregation potential of these two beneficial micro-organisms was evaluated against several pathogenic agents that threaten the global safety of the feed/food chain: Escherichia coli, Salmonella spp., Campylobacter spp. and Listeria monocytogenes. The strongest coaggregative interactions were demonstrated with Campylobacter spp. by a coaggregation test, confirmed by electron microscopic examination for the two forms. Viable forms were investigated for the nature of the bacterial cell-surface molecules involved, by sugar reversal tests and chemical and enzymic pretreatments. The results suggest that the coaggregation between both probiotic strains and C. jejuni CIP 70.2(T) is mediated by a carbohydrate-lectin interaction. The autoaggregation potential of the two probiotics decreased upon exposure to proteinase, SDS or LiCl, showing that proteinaceous components on the surface of the two lactobacilli play an important role in this interaction. Adhesion abilities of both Lactobacillus strains were also demonstrated at significant levels on Caco-2 cells, mucin and extracellular matrix material. Both viable and heat-killed forms of the two probiotic lactobacilli inhibited the attachment of C. jejuni CIP 70.2(T) to mucin. In conclusion, in vitro assays showed that Lb. rhamnosus CNCM-I-3698 and Lb. farciminis CNCM-I-3699, as viable or heat-killed forms, are adherent to different intestinal matrix models and are highly aggregative in vitro with pathogens, especially Campylobacter spp., the most commonly reported zoonotic agent in the European Union. This study supports the need for further in vivo investigations to demonstrate the potential food safety benefits of Lb. rhamnosus CNCM-I-3698 and Lb. farciminis CNCM-I-3699, live or heat-killed, in the global feed/food chain.

Sewer networks are subjected to biodeterioration, a damaging process based on the production of sulfuric acid by microorganisms in specific conditions. Aerial part of this phenomenon can be divided in four elementary stages. The study of the mechanisms both on-site and in the lab could generate consistent information for the design of an accelerated test. The present study highlights the absolute need of H2S addition for an effective and standardizable accelerated biodeterioration test. This test, developed by Ifsttar, brings interesting results. In near future, it will be a way to rank materials according to their ability to resist to biodeterioration, and to select only the more durable ones.

The present study aims at understanding the morphological characteristics of sediment deposits inside the combined sewer networks of the city of Nantes, also in connection with the flow characteristics measured during the morphological survey. The present study has been supported by the project VITRES 2009, under a collaboration between the French institute IFSTTAR , department GER-HA, and the LEESU.This report aims at:1)Presenting the results of preliminary tests carried out with a SONAR profiler Pipeprof 1512, manufactured by MARINE ELECTRONICS ltd.2)Describing a procedure to use the SONAR, analyse the data and display the results.3)Describing the results obtained from laboratory and sewer applications.; RAPPORT DE CONTRAT

Une connaissance précise des débits et des charges polluantes transitant dans les collecteurs est nécessaire pour obtenir une meilleure gestion des réseaux d'assainissement urbain et une minimisation des flux déversés au milieu récepteur. Les méthodes traditionnelles sont basées sur des techniques éprouvées telles que les méthodes acoustiques et les prélèvements suivis d'analyse. Bien que ces méthodes donnent satisfaction pour la majorité des cas, la mise en oeuvre de capteur peut s'avérer délicate. Cet article présente l'étude expérimentale entreprise en vue de préciser les potentialités des profileurs ultrasonores. Après quelques rappels de théorie, les matériels mis en oeuvre et les expérimentations effectuées sont détaillés. Ensuite les premiers résultats sont présentés et discutés. Enfin les pistes de travaux complémentaires sont exposées.

Afin de répondre à des objectifs aussi bien techniques que réglementaires ou financiers, les besoins en instrumentation des réseaux d'assainissement sont en constante progression. Mais le choix des sites adaptés à l'implantation du matériel de mesures peut s'avérer délicat car les performances de ces matériels sont très tributaires des conditions d'écoulement. Les recherches en cours au GEMCEA combinent des études numériques et expérimentales afin de mieux décrire et prévoir les conditions hydrauliques dans les collecteurs. L'objectif à terme est de disposer d'une méthodologie d'aide à l'instrumentation, incluant la qualification des sites, l'implantation des capteurs et le post-traitement des mesures. Cet article présente d'abord les différentes étapes de la méthodologie. Celle-ci est ensuite illustrée par son application à l'influence d'un coude à 90° sur la répartition des vitesses, et ses implications sur une mesure de débit.

Summary Stormwater models are valuable tools in urban planning as well as stormwater system design and management. Although the hydraulic simulation of pipes and channels in these models is often quite sophisticated, the hydrologic simulation of the flow contributing to the hydraulic elements is frequently greatly simplified. Hydrologic simulation of urban catchments is made particularly complex due to the presence of features such as streets, small pipes, and channels. In this study, we develop a new model called the U-McIUH (Urban Morpho-climatic Instantaneous Unit Hydrograph), which defines the IUH as the probability density function of the travel time from a random location in the urban terrain to the outlet. Flow paths are extracted from a specially processed digital elevation model that incorporates hillslopes, streets, pipes, and channels, and travel times are computed in each cell using the average wave celerity from kinematic wave theory. These expressions depend on the upstream contribution of flow and the excess rainfall intensity, so they incorporate the so-called climatic dependence of the IUH, which is the dependence of the unit hydrograph on the rainfall intensity. Rainfall pulses of different intensities are convoluted with their respective IUH and superimposed to generate the response to a given storm event. The application of the model to a real catchment provides good reproduction of observed hydrographs, suggesting that the U-McIUH is able to capture some significant hydrologic properties of the catchment. The model is studied by analyzing the effects of (1) the upstream contribution of flow on the travel time formulation, (2) the variation of flow velocities within the urban catchment, (3) the non-linear dependence of the IUH on the rainfall intensity (i.e. the climatic dependence), and (4) the spatial distribution of imperviousness. Overall, these results suggest that the presence of artificial elements in urban watersheds has a significant role in determining the travel times and thus the hydrologic response of the watershed.

Despite the fact that microorganisms are important for both the function of sewers and potential ecological or public health risk due to sewer failures, little is currently known about the diversity of microbial communities present within the sewers. Sewer biofilms are in this context of particular interest as the microbial load in biofilms is significantly higher than in the flowing wastewater. In this study the microbial community of biofilms sampled from three different sites, in two different sewer systems, in dry weather, was characterized. This was performed using denaturant gradient gel electrophoresis (DGGE) for community profiling and fluorescence in situ hybridization and catalyzed reporter deposition (CARD-FISH) for visualisation. DGGE profiling showed good reproducibility within the triplicate samples from two of the three sampling sites. A total of 26 bands were detected on the electrophoresis gel. Of these, 4 were found in all three sites and 10 were unique to one site only. This illustrates considerable microbial diversity within sewer biofilms even at sites which are predominantly combined sewer catchments.

International audience; Rehabilitation of sewer networks has to serve various objectives, both in terms of present general performance, and in terms of long term sustainability. Part of these stakes are external to the sewerage utility operation, such as social impacts of sewer failures, or social impacts of works. These external impacts are to some extend considered in real life decisions, and should therefore also be taken into account in decision support systems. CARE-S project (2003-05 EU 5th Framework Program), Computer Aided Rehabilitation of Sewer systems, has developed a decision support environment and software prototype, including data management procedures, a set of performance indicators, models describing the condition and evolution of sewers, models describing the risks and consequences of failures, a database describing rehabilitation technologies with their characteristics, an assessment of socio-economic criteria, a long term planning tool, multi-criteria decision tools. The objective is to help utility managers to rehabilitate the right pipe, at the right time, with the right technology. Criteria concern on one hand impacts during rehabilitation works, criteria used for the selection of the best technique for rehabilitating the concerned pipe in a multi-criteria decision making procedure, on the other hand impacts during a failure, criteria used for the selection of pipes candidates for rehabilitation. We worked out criteria such as time loss due to traffic deviation, economic loss for trades due to accessibility problems during works but also criteria concerning ground water or surface water pollution damages risk during overflow or due to exfiltrations from the pipes. Concerning floods damages in celars during overflow, valuation has taking into account methods used for river flooding damages concerning material goods ( Werey & alii, 2005). A second project INDIGAU Performance Indicators for urban sewer networks asset management (financed by the ANR, French Research Agency, 2007-10) goes further on with the valuation of the impact criteria using methods coming from the environmental economics such as Willigness to pay (Rozan, 2004) or contigent ranking (Hurlimann & Mckay, 2007) recently used for giving a value to intangible damages or impacts such as odors problems or loss of sentimental affect goods such as photographs during floods due to overflows of the networks (Larabi, 2009). In our paper we will present the valuation of such criteria taking into account, social and environmental impacts in a generally technical decision process for sewer networks rehabilitation.

Turbidity sensors can be used to continuously monitor the evolution of pollutant mass discharge. For two sites within the Paris combined sewer system, continuous turbidity, conductivity and flow data were recorded at one-minute time intervals over a one-year period. This paper is intended to highlight the variability in turbidity dynamics during wet weather. For each storm event, turbidity response aspects were analysed through different classifications. The correlation between classification and common parameters, such as the antecedent dry weather period, total event volume per impervious hectare and both the mean and maximum hydraulic flow for each event, was also studied. Moreover, the dynamics of flow and turbidity signals were compared at the event scale. No simple relation between turbidity responses, hydraulic flow dynamics and the chosen parameters was derived from this effort. Knowledge of turbidity dynamics could therefore potentially improve wet weather management, especially when using pollution-based real-time control (P-RTC) since turbidity contains information not included in hydraulic flow dynamics and not readily predictable from such dynamics.

Many buried systems modify the urban soil characteristics, and especially the subsoil water flow. Since the urban groundwater flow can be influenced by these modifications, there is a relation between the base flow observed in sewer systems due to drainage infiltration, and the piezometric levels fluctuations. The hydrological behaviour of urban catchments is affected by these phenomenon and one has to take it into account in urban hydrological models. This study presents the finding using a numerical groundwater model to represent groundwater drainage by trenches and buried pipes. This modelling is first implemented at a local scale first, and then at a catchment scale, which corresponds to a small urban area located at Nantes (Pin Sec, 31 ha). The sensitivity analysis, which is done at a local scale for a unit element of 100m x 100m reveals that the best representation consists in a consideration of a sewer pipe similar to a field drainage system. Furthermore, the model is highly sensitive to soil properties such as hydraulic conductivity. Both the local and catchment scales reveal the piezonetric head drawdown near the trench.

A precise determination of the pollutant loads processed through the sewer networks is required for legal, environmental and management reasons. Such a determination requires a good evaluation of concentrations, which is not an easy task because samplers or sensors can perform measurements in a cross-sectional area of only a few locations, and this local information must then be extrapolated across the whole cross-sectional area of the sewer network. This latter step is problematical. A great deal of attention must be given to suspended solids because they are prone to settle and display heterogeneous concentration patterns. A two-dimensional sampler has been designed to measure the variation of suspended solids concentration throughout a cross-sectional area. This paper presents the principles upon which the conception of this experimental device was based and the building process. Experimental results are presented and discussed.

Sound management of sewer networks and minimization of the pollution discharged into receiving waters through combined sewer overflows need in-depth knowledge of the flow rates and pollutant loads conveyed in sewers. This knowledge relies on a good assessment of the spatial distribution of the velocities in a cross section, as they are involved both in flowrate, and distribution of concentration. The possibility of assessing this distribution by using computational fluid dynamics is explored and compared with experimental results collected from real sewers.