Petit guide pratique pour la gestion des projets d'assainissement : fascicule 1 : les réseaux

L'étude et la mise en œuvre de canalisations d'assainissement doivent répondre à un nombre croissant d'exigences techniques, économiques et environnementales . Le guide apporte des recommandations essentielles pour une gestion rigoureuse des projets à même de répondre à de telles exigences. Il aborde successivement les points suivants : la prise de commande, les différentes contraintes (la loi sur l'eau, les aides au financement, les contraintes d'urbanisme, la coordination générale des réseaux, les études techniques préalables, l'hygiène et la sécurité de chantier, l'exploitation future du réseau), l'ordonnancement du projet, les dossiers techniques, la dévolution des travaux, la préparation de chantier, la qualité de mise en œuvre des remblais, la réception des travaux

Biofabrication: an overview of the approaches used for printing of living cells

The development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable and reproducible printing of cells. This review outlines the general principles and current progress and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing. It is expected that significant advances in cell printing will result from synergistic combinations of these techniques and lead to optimised resolution, throughput and the overall complexity of printed constructs

Experimental evaluation of apparent tissue surface tension based on the exact solution of the Laplace equation

The notion of apparent tissue surface tension offered a systematic way to interpret certain morphogenetic processes in early development. It also allowed deducing quantitative information on cellular and molecular parameters that is otherwise difficult to obtain. To accurately determine such tensions we combined novel experiments with the exact solution of the Laplace equation for the profile of a liquid drop under the employed experimental conditions and used the exact solution to evaluate data collected on tissues. Our results confirm that tissues composed of adhesive and motile cells indeed can be characterized in terms of well-defined apparent surface tension. Our experimental technique presents a way to measure liquid interfacial tensions under conditions when known methods fail

Influence d'une préhydratation sans confinement sur les performances hydrauliques des GSB

National audienceIt is recommended to confine geosynthetic clay liners (GCLs) used in sealing works in progress during their implementation. In the case of a use in sealing of underground works (shaft walling, superior slab for example) GCLs can be hydrated after their installation and before confining because of risk of construction site or of unfavourable weather conditions. The objective of the study presented is to estimate the impact of such a prehydration towards the later hydraulic performances of the GCL, in particular when its containment is realized at this water content state, for several GCL which discriminate themselves mainly by their bonding type allowing to contain the bentonite. The results indicate a maintaining of their hydraulic performance for some GCLs prehydrated without containment cover. But this observation is not valid for all the GCLs.Il est recommandé de confiner les géosynthétiques bentonitiques (GSB) utilisés en étanchéité d'ouvrages à l'avancement lors de leur mise en oeuvre. Dans le cas d'une utilisation en étanchéité d'ouvrages souterrains, les GSB peuvent se trouver hydratés après leur pose et avant confinement du fait d'aléas de chantier ou de conditions météo défavorables. L'objectif de l'étude présentée est d'évaluer l'incidence d'une telle préhydratation vis-à-vis des performances hydrauliques ultérieures du géosynthétique bentonitique, et notamment lorsque son confinement est réalisé dans cet état hydrique, pour plusieurs GSB qui se distinguent principalement par leur mode de liaisonnement permettant de contenir la bentonite. Les premiers résultats indiquent un maintien des performances hydrauliques pour certains GSB préhydratés sans confinement. Ce constat n'est pas généralisable à tous les GSB

Performance-based Criteria for the Control of GCBs in Landfill Applications

International audienceWhile geosynthetic clay barriers (GCBs) are commonly used in landfill applications, it is well known that their hydraulic properties may deteriorate over time as a result of ion exchange following contact with various types of fluids (rainwater that has percolated through a landfill cover, landfill leachate, etc.). The potential for evolution of GCB hydraulic properties is typically assessed using oedopermeameter (oedometer permeability tests), but such tests are very timeconsuming and there is therefore a need for criteria that can be tested in a rapid and cost-effective fashion in order to provide information regarding the adequacy of a given product for a given application. The ongoing LIXAR2 project described herein aims at identifying such criteria and assessing to what extent they correlate with the results of oedopermeameter tests. This paper describes the project and presents some of the findings available to date. A preliminary selection of criteria includes: cation exchange capacity (CEC), proportion of smectite (which was found to be strongly correlated to CEC), proportion of exchange-site occupation by sodium, calcium carbonate content, free swelling capacity and carbon and oxygen isotope fractionation in the carbonate phase of the bentonite

Approche française pour l'équivalence en barrière passive d'installations de stockage de déchets

Landfill barriers are essential for the protection of groundwater resources. With respect to landfill geological barriers, European legislation (Directive 1999/31/EC) specifies minimal requirements in terms of thickness and reduced permeability. For situations where requirements cannot be met under natural conditions, the Directive introduces the notion of equivalence. While this notion has been transposed into member state regulations, its interpretation may vary however. This paper summarizes the French approach to the notion of equivalence in landfill geological barriers. Essential aspects of this approach are the importance of demonstrating limited aquifer vulnerability through a detailed geological and hydrogeological investigation, a protective limit to the reduction of compacted clay barrier thickness and the importance of including qualitative reasoning in the assessment of equivalence, in addition to the results of model calculations. The paper pinpoints some shortcomings of model calculations that neglect in particular the influence of reduced barrier thickness on the risks related to possible barrier material defects

French approach to equivalence in landfill geological barriers

International audienceLandfill barriers are essential for the protection of groundwater resources. With respect to landfill geological barriers, European legislation (Directive 1999/31/EC) specifies requirements in terms of minimal thickness and maximum permeability. For situations where requirements cannot be met under natural conditions, the Directive introduces the notion of "equivalence". While this notion has been transposed into member state regulations, its interpretation may vary however. This paper summarizes the French interpretation of the Directive with respect to equivalence in landfill geological barriers. Essential aspects of the French approach are the importance of demonstrating limited aquifer vulnerability through a detailed geological and hydrogeological investigation, a safety limit on the reduction of compacted clay barrier thickness and the importance of including qualitative reasoning in the assessment of equivalence in addition to the results of model calculations. The paper pinpoints some shortcomings of model calculations that neglect in particular the fact that reducing barrier thickness increases the risks associated with potential barrier material defect

Swell index, oedopermeametric, filter press and rheometric tests for identifying the qualification of bentonites used in GCLs

International audienceGeosynthetic clay liners (GCLs) are used in landfill liner applications and there is a need for a better control of the features of the bentonite in the GCL received on site, particularly in the European context where a wide variety of bentonites can be encountered. This paper presents the results of a project aiming at a rapid identification of the nature of the bentonite in a given GCL. The interaction between the bentonite and the fluid is increased by producing dispersions then testing its structuration in less than a few hours with filter press tests and flow curves. The results of those tests are intersected with swell index tests, electrical conductivity values and oedopermeametric tests

Réactualisation du guide sur l'équivalence en étanchéité passive d'installation de stockage de déchets

National audienceThe objective of the Equivalence Guide is to define rules of good practice with respect to equivalent solutions for landfill mineral barriers. The guide refers primarily to non-hazardous waste landfills. The guide, which was first drafted in 2002, was updated in 2008, by a working group composed of the main organisations working on landfill mineral barriers in France. The update also benefited from feedback from professional partners (consultants, landfill operators, geosynthetic suppliers, ...). This paper summarizes the main changes with respect to the previous version.Le « Guide Équivalence » a pour objectif de définir des règles de bonne pratique en matière de recherche de solutions « équivalentes » en étanchéité passive d'installation de stockage de déchets. Les principaux sites concernés par ce guide sont les installations de stockage de déchets nondangereux (ISDND). Ce guide, dont la première version date de 2002, a été réactualisé par un Groupe de Travail constitué des principaux organismes intervenant sur la thématique des barrières minérales d'ISD en France. Cette réactualisation a également bénéficié d'un retour d'expérience recueilli auprès de la profession (bureaux d'étude, exploitants, fournisseurs de géosynthétiques). Cet article fait une synthèse des principales modifications par rapport à la version antérieure

Indicateurs de performance pour le contrôle des GSB en étanchéité d'installation de stockage de déchets

National audienceUsers of geosynthetic clay liners (GCLs) in landfill applications, need indicators that are relatively simple and cheap to measure, to help them assess whether a given product is suitable for a given application, in particular with respect to medium to long term hydraulic performance. The objective of the LIXAR2 project was to identify such indicators, based on detailed characterizations of the main GCLs used in French landfills. Results highlight in particular the diversity of composition that the term bentonite may cover and the importance of basing choices on performance indicators rather than simply on denominations such as Na-natural, Ca-activated, etc.Les utilisateurs de géosynthétiques bentonitiques (GSB) en installations de stockage de déchets (ISD) ont besoin d'indicateurs dont la mesure est relativement simple et peu coûteuse, leur permettant de contrôler l'adéquation d'un produit par rapport à une application donnée, notamment pour ce qui concerne les performances hydrauliques à moyen et à long terme. Le projet LIXAR2 a eu pour objectif d'identifier de tels indicateurs, sur la base de caractérisations détaillées des principaux GSB utilisés en ISD en France. Les résultats illustrent notamment la variabilité de composition que peut recouvrir le terme « bentonite » et la nécessité de baser les choix sur des indicateurs de performance plutôt que sur les simples dénominations « Na-naturelle », « Ca-activée », etc