Integrated structural analysis and life cycle assessment of equivalent trench-pipe systems for sewerage

The demand for sanitation infrastructures is increasing due to a rise in the urban population. To meet the need for wastewater collection, the construction of sewer networks must comply with a series of technical parameters that indicate whether a solution is feasible or not. Considering that this construction implies a series of environmental impacts, this study coupled a structural analysis of one linear metre of sewer constructive solutions with their life cycle impacts. Different pipe materials (concrete, polyvinylchloride (PVC) and high-density polyethylene (HDPE)) were combined with different trench designs and their environmental performance was assessed using Life Cycle Assessment (LCA). These solutions complied with technical parameters consisting of traffic loads and pavement conditions, among others. Concrete pipes embedded in granular matter result in fewer environmental impacts, such as Global Warming Potential or Cumulative Energy Demand. Further, re-using the excavated soil results in up to 80 % of environmental savings with respect to extracting new materials. Concerning traffic loads and pavement conditions, failures in plastic pipes could be avoided if these are embedded in concrete. Moreover, the environmental impacts of this solution are similar to those resulting from the substitution of pipes that do not comply with the mechanical requirements of the construction site. Therefore, proper planning is needed to provide cities with sewers that are resilient to time and external loads and reduce the urban environmental impacts.