Evaluation of Carbon Footprint of Pipeline Materials during Installation, Operation, and Disposal Phases

Most of the pipelines in the US are rapidly reaching the end of their useful service life. Now they need replacing or rehabilitating. In general, selection of a pipeline installation method is solved by selecting the lowest cost method; however, with an increase in public concerns about reducing emissions to the environment generated by human activities, other factors should be considered while choosing the pipe material and the installation method for a new pipeline: direct cost, social cost, and environmental impact. This study focuses on the environmental impact during installation, operation, and disposal phases of the pipeline life cycle. The life cycle of a pipeline can be categorized into four phases: fabrication, installation, operation, and disposal. The fabrication stage, which is the first phase of the pipeline life cycle, was examined in a previous study, and the results showed that prestressed concrete cylinder pipes (PCCPs) are the most environmentally friendly compared with polyvinylchloride (PVC), high-density polyethylene (HDPE) pipes, and cured-in-place pipes (CIPPs). This study includes the pipeline installation phase, operation phase, and disposal phase. The major construction activities in the installation stage are transporting pipes and equipment to the job site, excavation, loading, backfilling, compaction, and repaving. The energy consumed in the operation phase includes pumping energy and pipe cleaning. For the disposal phase, the study will consist of the energy consumed for disposal of the material of the pipes, which cannot be recycled. The objective of this study is to quantify the carbon footprint and to analyze the environmental sustainability of 30 m (100 ft) of pipeline during the installation, operation, and disposal phases. For the study, a pipeline installation analysis and consideration of ${\mathrm{CO}}_2$ emissions was conducted for three different installation methods: open cut, pipe bursting, and CIPP. The study focuses on a large-diameter 90 cm (36-in.) sewer pressure pipe operating at 690 kPa (100 psi) internal pressure for 100 years of operation. The pipeline materials included in this study are PCCP, PVC, HDPE, and CIPP. The results show that PVC pipe has a lower environmental impact than PCCP, HDPE, or CIPP.