Rehabilitation Of Sewers Using Trenchless Technologies for Ahvaz City

Wastewater collection networks are a part of urban infrastructure and their repair and maintenance impose lots of costs on society. In evaluating the methods of reconstruction and renovation of sewage collection networks, only direct costs are generally considered and social and environmental costs are not considered. In this research, to evaluate the sewer reconstruction methods and to choose the appropriate method, four main criteria were chosen for decision-making according to the environmental conditions of the project. Social and environmental criteria, in addition to conventional technical and economic criteria, have been used in decision-making. Based on the decision criteria and proposed reconstruction methods, questionnaires were applied to use the AHP method for decision-making. The results showed that the technical criterion is preferable to other criteria, and the OmegaLiner and CIPP methods have a higher priority in the application. In the case of Ahvaz city, the main problem is the lack of resilience of the urban sewage collection network against rainwater infiltration. Furthermore, the high level of underground water with the trench instability has caused the application of open-trench methods to encounter many other social problems in addition to technical problems. Unfortunately, most of the sewage network in Ahvaz is worn out and the main sewage collection lines are under construction. In general, it is recommended to use trenchless methods to build the sewage collection network in Ahvaz city. OmegaLiner and CIPP methods are preferred among reconstruction methods.