Estimating greenhouse gas emissions arising from the maintenance of sewer networks

As the push to reduce global carbon emissions intensifies, infrastructure managers are rethinking how maintenance is planned and executed to minimise greenhouse gases without sacrificing the performance of their infrastructure networks. This paper addresses this need. The work includes a detailed description of the estimation of greenhouse gas emissions that arise from common sewer maintenance interventions. These detailed estimates were subsequently used to project emissions from three maintenance scenarios for a large sewer network. The study found that emissions from maintenance mainly originate from materials, and that emissions from transport, traffic congestion, and machinery were of secondary importance. The current practice promises the lowest emissions up to 2035 but does not address the ageing pipe network. As a consequence, the network condition and performance deteriorate further as failures rapidly accumulate. Embracing preventive maintenance coupled with circular economy thinking is shown to be an effective solution to improve the network condition and performance, while at the same time offering savings of 6222 t carbon dioxide a year. These findings provide infrastructure managers with a detailed example of the potential of circular economy thinking in reducing long-term emissions along with insights into the expected trade- offs that arise with network performance and resource utilisation.