Caty Werey

Condition grading for dysfunction indicators in sewer asset management

Asset management is an increasing concern for the water and wastewater industry. Condition assessment of sewer segments is an important component of sewer asset management and relies mostly on visual inspection. Observed defects are translated into a score for each segment. Although most protocols give a segment a condition grade by comparing its score with a subjective scale of numerical values, we propose a protocol to calibrate thresholds for each asset stock. Thresholds are calculated according to two sets of parameters: overall condition of the asset stock in question (estimated by a representative sample or provided by the utility manager) and assignment-error weighting (determined by the utility manager) linked to either over-estimation or under-estimation of condition grade. This method is applied to 150 km of sewers from the Greater Lyon asset stock. Sensitivity analyses of these parameters are then implemented. Three hypotheses about overall condition of the asset stock are combined with three matrices of assignment-error weights. Both parameters influence thresholds and change the assessment of the studied segments. The synthesis of such sensitivity analyses can be used to prioritise complementary investigations.

Transitioning to sustainable urban water management systems: how to define expected service functions?

Sustainable water management is a worldwide challenge for the twenty-first century. It involves replacing traditional management approaches with a new concept, often referred to as sustainable urban water management (SUWM). This paradigm shift means that SUWM systems must include new services, some of which have already emerged. However, no publications have presented the expected SUWM system in terms of the full range of services it would need to include, and no publications have proposed a method for identifying the services the system must provide. This paper proposes a method for identifying these services and presents a generic petal diagram to represent the service functions of the SUWM system. Moreover, this paper presents a new method for defining these services in a specific territory. This method is based on the confrontation between a general representation and the objectives of the stakeholders in a given system in a given territory. The method is illustrated with a full-scale case study on the Doua eco-campus (Lyon University). This method is intended to aid practitioners to manage its system and to transition to SUWM. It is designed to improve the transparency of decision formulation and to involve stakeholders in the process.

Gestion patrimoniale des réseaux d'assainissement : de l'état des réseaux à la planification de leur réhabilitation − Outils, méthodes et perspectives

En France, la gestion patrimoniale des reseaux d’assainissement est une preoccupation croissante. Certains reseaux commencent en effet a dater et vont necessiter des renouvellements importants et couteux pour les decennies a venir. A travers leur mise en œuvre sur les reseaux de Caen et de Bordeaux, cet article presente deux modeles complementaires, Indigau et GompitZ, permettant de decrire l’etat du reseau et de prioriser les troncons a rehabiliter.