Estimating life cycle emissions in managing practical sewer pipeline projects

The objectives of this paper are 1) to estimate emissions in managing a sewer pipeline project from a life cycle perspective; and 2) to develop methods that can be used to assist engineers and stakeholders in the estimation especially when data are limited. The motivation is to provide an approach that can be used readily in practice to evaluate emissions in managing a sewer pipeline or a general infrastructure system by using available data. The life cycle assessment tool is applied over the pipe material manufacturing, installation, and maintenance phases. In the material manufacturing and installation phase, this research routinely tends to collect and evaluate detailed inventories data. The results show that the manufacturing phase contributes the most emissions. Material transportation in the installation also generates great amounts which are highly impacted by the transportation distance of vehicles. Emissions from activities such as equipment use and architecture and engineering services are not negligible which need to be considered in practice. In the maintenance phase, the study develops methods to estimate emissions based on the Markov chains model. The developed methods make it possible to estimate emissions within a given duration conventionally and at a 'steady state' phase once a strategy is applied. The study also presents a method to conduct the model sensitivity analysis using simulating results from Matlab tools. The analysis shows that the model has decent robustness. In addition, the methodology proposed may be applied to estimate emissions in other infrastructure management as well.