Selection method for rehabilitation of water distribution networks

Selecting most suitable methods for rehabilitation of water main networks has become a challenging task; considering the wide range of emerging trenchless methods. Developing decision support methods is expected to assist municipalities in North America and elsewhere in carrying out the selection process effectively. This paper introduces a new concept for choosing cost effective rehabilitation methods accounting for cost and duration of each rehabilitation method being considered along with its impact on environment using Multi-Objective evaluation methodology (MOM). The first objective, cost of rehabilitation, is calculated considering a number of cost elements including social cost. Social cost, in the developed methodology accounts for cleaning costs, loss of sales tax, number of impacted vehicles and pedestrians, etc. The second objective is the duration of the rehabilitation method under consideration. The environmental impact is considered as the third objective. It is modeled considering several factors using the Analytical Hierarchy Process (AHP). In order to demonstrate the essential features, a hypothetical example has been developed to test the model robustness. Results show that a cost effective method can be selected by combining cost, duration, and impact on environment.