Risk Assessment of Public Wastewater Treatment Facilities for Climate Crisis Adaptation: The Case of Sejong City

This study assessed the climate crisis risks of public wastewater treatment facilities in Sejong City, where structural and operational vulnerabilities are increasing owing to the accelerating impact of climate change. Nine public wastewater treatment facilities with a treatment capacity of more than 500 m<sup>3</sup> per day were analyzed to evaluate the risks associated with 6 major climatic factors, namely heat wave, cold wave, heavy rainfall, snowfall, high wind, and drought across 3 key domains: facility, operator, and public services. The evaluation method involved calculating the “likelihood of occurrence” using extreme climate indices based on Representative Concentration Pathway scenarios, deriving the “magnitude of impact” for each sector through survey-based checklists, and then applying a process to calculate quantitative risk by integrating these two factors. Heat waves posed the greatest risk across all facilities, followed by droughts and heavy rainfall, whereas snowfall and high winds had relatively low impact. These findings indicate that the climatic vulnerability of Sejong City’s wastewater treatment facilities is primarily influenced by high temperatures and precipitation fluctuations. The primary reason for the highest risk associated with heat waves is that biological treatment processes, the core of wastewater treatment facilities, react sensitively to temperature changes, directly affecting treatment efficiency. Furthermore, it was found to have a significant impact on work environment safety, such as the risk of heat-related illnesses for facility managers with a high proportion of outdoor work. Consequently, establishing an operation and management system focused on heat-wave response is essential, along with addressing compound climatic factors, such as droughts and heavy rainfall, through proactive strategies. Furthermore, this study presented a quantitative risk assessment methodology for climate adaptation in public wastewater treatment facilities, which is expected to contribute to the development and implementation of climate-adaptive urban water management policies at the municipal level.