Comparison of Trenchless and Excavation Technologies in the Restoration of a Sewage Network and Their Carbon Footprints

Abstract

The restoration of aging sewer networks is a fundamental remediation approach with the aim of renewing or improving existing systems. Remediation methods include repair, renovation, and replacement (renewal). The restoration of a sewer network itself can be performed using either excavation or trenchless technologies. While these technologies offer various advantages, they also present disadvantages. The choice of a restoration technology depends on numerous parameters, including economic factors and local conditions (such as the construction of the existing sewage network, available working space, traffic load, and environmental safety restrictions). In addition to the parameters influencing the choice of restoration technology, recent considerations have been given to constraints related to greenhouse gas emissions and the corresponding carbon footprint. Carbon footprint serves as an indicator of the restoration activity’s dependence on fossil fuels, both during implementation and operation. In the 21st century, concerns regarding carbon footprints have rapidly escalated. The reduction in carbon footprints is a crucial objective from both an economic and an ecological point of view. This article specifically addresses the prospects of monitoring the carbon footprint concerning the partial restoration of a sewer network within the historical core of the city of Brno, located in the Czech Republic. This aspect constitutes the unique and innovative contribution of the paper. The intensity of the energy demand of excavation and trenchless technologies is utilized as a direct measure of the carbon footprint of each technology. The comparative assessment demonstrates that the trenchless technology used achieves a reduction of 59.2% in CO2 emissions compared to the excavation technology. The carbon footprint of Variant 1 (trenchless technology) is 9.91 t CO2 eq., while the carbon footprint of Variant 2 (excavation technology) is 24.29 t CO2 eq. The restoration of open pipelines produces more emissions due to the higher energy consumption, making it more expensive in terms of fuel costs, waste disposal costs, and the corresponding environmental hazards.