Life cycle sustainability assessment (LCSA) for selection of sewer pipe materials

Sewer systems, over their life cycle, suffer deterioration due to aging, aggressive environmental factors, increased demand, inadequate design, third party intervention, and improper operation and maintenance activities. As a result, their state and overall long-term performance can be affected, which often requires costly and extensive maintenance, repair, and rehabilitation. Furthermore, these pressures can enhance the risk of failures (e.g., sewer leakage) which in turn can have serious impacts on the environment, public safety and health, economics, and the remaining service life of these assets. Effective asset management plans must be implemented to address long-term sustainability principles, i.e., economic growth, human health and safety, and environmental protection, simultaneously. The aim of this paper is to evaluate and compare four typical sewer pipe materials [i.e., concrete, polyvinyl chloride (PVC), vitrified clay, and ductile iron] and identify sustainable solutions. Two comprehensive life cycle sustainability assessment (LCSA) frameworks were applied. The first LCSA framework was based on the integration of emergy synthesis, life cycle assessment (LCA), and life cycle costing (LCC). In this framework, emergy synthesis has been applied to integrate the results from environmental analysis (i.e., LCA) and economic analysis (i.e., LCC) to an equivalent form of solar energy: a solar emergy joule. The second LCSA framework was based on a conventional, multi-criteria decision-making technique, i.e., the analytical hierarchy process, to integrate the results from environmental analysis (i.e., LCA) and economic analysis (i.e., LCC) and find the most sustainable solution over the sewer pipe life cycle. The results demonstrate that PVC pipe is the most sustainable option from both environmental and economic view points and can ensure a more sustainable sewer system.